Birth and adaptive evolution of a hominoid gene that supports high neurotransmitter flux.

The enzyme glutamate dehydrogenase (GDH) is important for recycling the chief excitatory neurotransmitter, glutamate, during neurotransmission. Human GDH exists in housekeeping and brain-specific isotypes encoded by the genes GLUD1 and GLUD2, respectively. Here we show that GLUD2 originated by retroposition from GLUD1 in the hominoid ancestor less than 23 million years ago. The amino acid changes responsible for the unique brain-specific properties of the enzyme derived from GLUD2 occurred during a period of positive selection after the duplication event.

Lean Management (LM): Bases, eines i avantatges de la seva utilització al Sector Sanitari. Aplicació del LM a l’hospital St. Rafael de Barcelona per optimitzar el flux de pacients a la consulta externa de Traumatología.

Aquest projecte presenta, per una banda, una revisió del Lean Management i de l'estat actual de la seva aplicació al sector sanitari. Es descriuen els principis i la filosofia en què es basa aquest sistema, les eines i tècniques que li són pròpies, així com les avantatges que aporta cadascuna d’elles a l'empresa en general i, més concretament, al sector sanitari. D'altra banda, també descriu una petita aplicació pràctica de la metodologia Lean per al control de fluxos de pacients al servei d’atenció ambulatòria de l’Hospital Sant Rafael de Barcelona, amb l’objectiu de disminuir el temps total que els pacients tarden en ser atesos pel metge, a través d’eines que alhora aporten valor afegit a tant a pacients com a professionals.

Metabolic Flux and Compartmentation Analysis in the Brain In vivo.

Through significant developments and progresses in the last two decades, in vivo localized nuclear magnetic resonance spectroscopy (MRS) became a method of choice to probe brain metabolic pathways in a non-invasive way. Beside the measurement of the total concentration of more than 20 metabolites, (1)H MRS can be used to quantify the dynamics of substrate transport across the blood-brain barrier by varying the plasma substrate level. On the other hand, (13)C MRS with the infusion of (13)C-enriched substrates enables the characterization of brain oxidative metabolism and neurotransmission by incorporation of (13)C in the different carbon positions of amino acid neurotransmitters. The quantitative determination of the biochemical reactions involved in these processes requires the use of appropriate metabolic models, whose level of details is strongly related to the amount of data accessible with in vivo MRS. In the present work, we present the different steps involved in the elaboration of a mathematical model of a given brain metabolic process and its application to the experimental data in order to extract quantitative brain metabolic rates. We review the recent advances in the localized measurement of brain glucose transport and compartmentalized brain energy metabolism, and how these reveal mechanistic details on glial support to glutamatergic and GABAergic neurons.

Tretze maneres de mirar les biblioteques, la descoberta i el catàleg: escala, flux de treball i atenció

En aquest article s'analitza el paper del catàleg dins l’actual època de transició, i l'utilitza per il·lustrar descobriments i línies de treball més genèriques de les biblioteques. L’autor constata que hi ha un renaixement de l'interès per les dades del catàleg i el catàleg en si mateix, però no obstant, s’explica com això es produeix en un moment en què el catàleg s'està reconfigurant d’una manera que podria suposar la seva desaparició com a component identificable per separat dels serveis de les biblioteques. El catàleg està sent assumit pels entorns de descoberta més grans de la biblioteca, mentre que les dades del catàleg estan fluint cap a altres escales, sistemes i serveis. De manera més general analitza com les tendències d’Internet estan afectant els serveis bibliotecaris.

Repercussion of a deficiency in mitochondrial ß-oxidation on the carbon flux of short-chain fatty acids to the peroxisomal ß-oxidation cycle in Aspergillus nidulans.

The fungus Aspergillus nidulans contains both a mitochondrial and peroxisomal ß-oxidation pathway. This work was aimed at studying the influence of mutations in the foxA gene, encoding a peroxisomal multifunctional protein, or in the scdA/echA genes, encoding a mitochondrial short-chain dehydrogenase and an enoyl-CoA hydratase, respectively, on the carbon flux to the peroxisomal ß-oxidation pathway. A. nidulans transformed with a peroxisomal polyhydroxyalkanoate (PHA) synthase produced PHA from the polymerization of 3-hydroxyacyl-CoA intermediates derived from the peroxisomal ß-oxidation of external fatty acids. PHA produced from erucic acid or heptadecanoic acid contained a broad spectrum of monomers, ranging from 5 to 14 carbons, revealing that the peroxisomal ß-oxidation cycle can handle both long and short-chain intermediates. While the ∆foxA mutant grown on erucic acid or oleic acid synthesized 10-fold less PHA compared to wild type, the same mutant grown on octanoic acid or heptanoic acid produced 3- to 6-fold more PHA. Thus, while FoxA has an important contribution to the degradation of long-chain fatty acids, the flux of short-chain fatty acids to peroxisomal ß-oxidation is actually enhanced in its absence. While no change in PHA was observed in the ∆scdA∆echA mutant grown on erucic acid or oleic acid compared to wild type, there was a 2- to 4-fold increased synthesis of PHA in ∆scdA∆echA cells grown in octanoic acid or heptanoic acid. These results reveal that a compensatory mechanism exists in A. nidulans that increases the flux of short-chain fatty acids towards the peroxisomal ß-oxidation cycle when the mitochondrial ß-oxidation pathway is defective.

Increasing the carbon flux toward synthesis of short-chain-length--medium-chain-length polyhydroxyalkanoate in the peroxisome of Saccharomyces cerevisiae through modification of the beta-oxidation cycle.

Short-chain-length-medium-chain-length polyhydroxyalkanoates were synthesized in Saccharomyces cerevisiae from intermediates of the beta-oxidation cycle by expressing the polyhydroxyalkanoate synthases from Aeromonas caviae and Ralstonia eutropha in the peroxisomes. The quantity of polymer produced was increased by using a mutant of the beta-oxidation-associated multifunctional enzyme with low dehydrogenase activity toward R-3-hydroxybutyryl coenzyme A.

Concepts of metastasis in flux: the stromal progression model.

The ability of tumor cells to leave a primary tumor, to disseminate through the body, and to ultimately seed new secondary tumors is universally agreed to be the basis for metastasis formation. An accurate description of the cellular and molecular mechanisms that underlie this multistep process would greatly facilitate the rational development of therapies that effectively allow metastatic disease to be controlled and treated. A number of disparate and sometimes conflicting hypotheses and models have been suggested to explain various aspects of the process, and no single concept explains the mechanism of metastasis in its entirety or encompasses all observations and experimental findings. The exciting progress made in metastasis research in recent years has refined existing ideas, as well as giving rise to new ones. In this review we survey some of the main theories that currently exist in the field, and show that significant convergence is emerging, allowing a synthesis of several models to give a more comprehensive overview of the process of metastasis. As a result we postulate a stromal progression model of metastasis. In this model, progressive modification of the tumor microenvironment is equally as important as genetic and epigenetic changes in tumor cells during primary tumor progression. Mutual regulatory interactions between stroma and tumor cells modify the stemness of the cells that drive tumor growth, in a manner that involves epithelial-mesenchymal and mesenchymal-epithelial-like transitions. Similar interactions need to be recapitulated at secondary sites for metastases to grow. Early disseminating tumor cells can progress at the secondary site in parallel to the primary tumor, both in terms of genetic changes, as well as progressive development of a metastatic stroma. Although this model brings together many ideas in the field, there remain nevertheless a number of major open questions, underscoring the need for further research to fully understand metastasis, and thereby identify new and effective ways of treating metastatic disease.

Measurement of absolute cell volume, osmotic membrane water permeability, and refractive index of transmembrane water and solute flux by digital holographic microscopy.

ABSTRACT. A dual-wavelength digital holographic microscope to measure absolute volume of living cells is proposed. The optical setup allows us to reconstruct two quantitative phase contrast images at two different wavelengths from a single hologram acquisition. When adding the absorbing dye fast green FCF as a dispersive agent to the extracellular medium, cellular thickness can be univocally determined in the full field of view. In addition to the absolute cell volume, the method can be applied to derive important biophysical parameters of living cells including osmotic membrane water permeability coefficient and the integral intracellular refractive index (RI). Further, the RI of transmembrane flux can be determined giving an indication about the nature of transported solutes. The proposed method is applied to cultured human embryonic kidney cells, Chinese hamster ovary cells, human red blood cells, mouse cortical astrocytes, and neurons.

Flux and composition of settling particles across the continental margin of the Gulf of Lion: the role of dense shelf water cascading

Settling particles were collected using sediment traps deployed along three transects in the Lacaze-Duthiers and Cap de Creus canyons and the adjacent southern open slope from October 2005 to October 2006. The settling material was analyzed to obtain total mass fluxes and main constituent contents (organic matter, opal, calcium carbonate, and siliciclastics). Cascades of dense shelf water from the continental shelf edge to the lower continental slope occurred from January to March 2006. They were traced through strong negative near-bottom temperature anomalies and increased current speeds, and generated two intense pulses of mass fluxes in January and March 2006. This oceanographic phenomenon appeared as the major physical forcing of settling particles at almost all stations, and caused both high seasonal variability in mass fluxes and important qualitative changes in settling material. Fluxes during the dense shelf water cascading (DSWC) event ranged from 90.1 g m(-2) d(-1) at the middle Cap de Creus canyon (1000 m) to 3.2 g m(-2) d(-1) at the canyon mouth (1900 m). Fractions of organic matter, opal and calcium carbonate components increased seaward, thus diminishing the siliciclastic fraction. Temporal variability of the major components was larger in the canyon mouth and open slope sites, due to the mixed impact of dense shelf water cascading processes and the pelagic biological production. Results indicate that the cascading event remobilized and homogenized large amounts of material down canyon and southwardly along the continental slope contributing to a better understanding of the off-shelf particle transport and the internal dynamics of DSWC events.

Nitrogen dynamics in soil management systems. I - flux of inorganic nitrogen (NH4+ and NO3-)

In agricultural systems the N-NH4+ and N-NO3- contents is significantly affected by soil management. This study investigated the dynamics of inorganic nitrogen (N; NH4+ and NO3-) in an experimental evaluation of soil management systems (SMSs) adopted in 1988 at the experimental station of the ABC Foundation in Ponta Grossa, in the Central South region of the State of Paraná. The objective of this study was to evaluate the changes in N-NH4+ and N-NO3- flux in the surface layer of a Red Latosol arising from SMSs over a 12-month period. The experiment was arranged in a completely randomized block design in split plots, in three replications. The plots consisted of the following SMSs: 1) conventional tillage (CT); 2) minimum tillage (MT); 3) no-tillage with chisel plow every three years (NT CH); and 4) continuous no-tillage (CNT). To evaluate the dynamics of inorganic N, the subplots represented samplings (11 sampling times, T1 - T11). The ammonium N (N-NH4+) and nitric N (N-NO3-) contents were higher in systems with reduced tillage (MT and NT CH) and without tillage (CNT) than in the CT system. In the period from October 2003 to February 2004, the N-NH4+ was higher than the N-NO3- soil content. Conversely, in the period from May 2004 to July 2004, the N-NO3- was higher than the N-NH4+ content. The greatest fluctuation in the N-NH4+ and N-NO3- contents occurred in the 0-2.5 cm layer, and the highest peak in the N-NH4+ and N-NO3- concentrations occurred after the surface application of N. Both N-NH4+ and N-NO3- were strongly correlated with the soil organic C content, which indicated that these properties vary together in the system.

Seasonal dependence in the solar neutrino flux

Mikheyev-Smirnov-Wolfenstein (MSW) solutions of the solar neutrino problem predict a seasonal dependence of the zenith angle distribution of the event rates, due to the nonzero latitude at the Super-Kamiokande site. We calculate this seasonal dependence and compare it with the expectations in the no-oscillation case as well as just-so scenario, in the light of the latest Super-Kamiokande 708-day data. The seasonal dependence can be sizable in the large mixing angle MSW solution and would be correlated with the day-night effect. This may be used to discriminate between MSW and just-so scenarios and should be taken into account in refined fits of the data.

Soil CO2 flux: a method comparison of closed static chambers in a sugarcane field

A large variety of techniques have been used to measure soil CO2 released from the soil surface, and much of the variability observed between locations must be attributed to the different methods used by the investigators. Therefore, a minimum protocol of measurement procedures should be established. The objectives of this study were (a) to compare different absorption areas, concentrations and volumes of the alkali trapping solution used in closed static chambers (CSC), and (b) to compare both, the optimized alkali trapping solution and the soda-lime trapping using CSC to measure soil respiration in sugarcane areas. Three CO2 absorption areas were evaluated (7; 15 and 20 % of the soil emission area or chamber); two volumes of NaOH (40 and 80 mL) at three concentrations (0.1, 0.25 and 0.5 mol L-1). Three different types of alkaline traps were tested: (a), 80 mL of 0.5 mol L-1 NaOH in glass containers, absorption area 15 % (V0.5); (b) 40 mL of 2 mol L-1 NaOH retained in a sponge, absorption area 80 % (S2) and (c) 40 g soda lime, absorption area 15 % (SL). NaOH concentrations of 0.5 mol L-1 or lower underestimated the soil CO2-C flux or CO2 flux. The lower limit of the alkali trap absorption area should be a minimum of 20 % of the area covered by the chamber. The 2 mol L-1 NaOH solution trap (S2) was the most efficient (highest accuracy and highest CO2 fluxes) in measuring soil respiration.

Contribution of macroporosity to water flux of a soil under different tillage systems

In view of the importance of the macroporosity for the water transport properties of soils, its quantitative assessment is a challenging task. Measurements of hydraulic conductivity (K) at different soil water tensions and the quantification of water-conducting macropores (θM) of a soil under different tillage systems could help understand the effects on the soil porous system and related hydraulic properties. The purpose of this study was to assess the effects of Conventional Tillage (CT), Chisel Plow (CP) and No Tillage (NT) on θM and on K; and to quantify the contribution of macroporosity to total water flux in a loam soil. A tension disc infiltrometer was used at two soil water pressure heads (-5 cm, and 0) to infer θM and K, during fallow. Macroporosity was determined based on the flow contribution between 0 and -5 cm water potentials (K0, K5, respectively), according to the Hagen-Poiseuille equation. The K0 values were statistically higher for CT than for NT and CP. The K5 values did not differ statistically among treatments. The mean K values varied between 0.20 and 3.70 cm/h. For CT, θM was significantly greater than for CP and NT, following the same trend as K0. No differences in θM were detected between CP and NT. With CT, the formation of water-conducting macropores with persistence until post-harvest was possible, while under CP preparation, the water-conducting macropores were not persistent. These results support the idea that tillage affects the soil water movement mainly by the resulting water-conducting macropores. Future studies on tillage effects on water movement should focus on macroporosity.