378 research outputs found
A two-stage planning model for power scheduling in a hydro-thermal system under uncertainty
Accepted versio
Quantification of antithrombin isoform proportions in plasma samples of healthy subjects, sepsis patients, and in antithrombin concentrates
Antithrombin (AT) circulates in plasma in two isoforms, AT-alpha (90-95%) and AT-beta (5-10%). AT isoform proportions were measured in plasma samples of 17 healthy subjects and 26 posttraumatic or postoperative septic patients, as well as in 4 commercially available AT concentrates. Total AT was immune-purified from plasma and concentrates. Micellar electrokinetic chromatography was used to analytically separate and quantify the isoforms. Compared with plasma samples of healthy donors, septic plasmas revealed significantly reduced AT activity (p < 0.001) and beta-isoform content (p < 0.05). AT-beta correlated inversely with urea and creatinine serum concentrations (p < 0.01), indicating a relationship between better renal function and higher beta-isoform content. beta-Isoform neither correlated with age, gender, and 28-day mortality, nor with plasma concentrations of various inflammatory and organ function parameters. The commercial AT concentrate, which is equivalent to the current WHO standard, had an AT-beta content close to that found in plasma of healthy subjects. The availability of this novel quantitative AT isoform assay allows, for the first time, a closer look at the role of AT isoforms in hemostasis and sepsis pathophysiology. Copyright (C) 2002 S. Karger AG, Basel
Legislaciones entre Brasil y Paraguay para el manejo de la cuenca hidrográfica del rio Apa, Paraguay
En vista de la necesidad de desarrollar e implementar medidas conjuntas en relación a los aspectos normativos y técnicos para la gestión y conservación del agua de la cuenca hidrográfica del rio Apa, que une a dos paÃses, Paraguay y Brasil, debe haber acuerdos mutuos para una mejor administración hÃdrica entre ambos paÃses. Este trabajo tuvo por objetivo principal comparar las legislaciones vigentes de Paraguay y Brasil relacionadas a los Recursos hÃdricos en la Cuenca hidrográfica Transfronteriza del Rio Apa, de esa manera realizar un análisis comparativo de las normas y procedimientos legales, las autoridades ambientales, sus funciones y sanciones vigentes en cada paÃs. La metodologÃa utilizada fue de análisis documental, a partir de la cual se pudo identificar una serie de puntos referidos al tema de estudios. Se ha encontrado vacios y superposiciones entre las legislaciones en ambos paÃses. Relacionado a los recursos hÃdricos, se refieren principalmente a la protección de las cuencas hidrográficas, la protección de las nacientes y los bosques que actúan como protectores de estos sitios. Con relación a las diferencias, se ha encontrado principalmente lo referente a la legislación forestal en la dimensión con la que tienen que contar los bosques protectores. En la ley paraguaya se debe dejar una franja de bosque protector de por lo menos 100 metros en ambas márgenes, en el lado brasileño 30 metros de bosques ribereños de hasta 10 metros de ancho del cauce hÃdrico. Análogamente, las legislaciones de ambos paÃses tienen por objetivo proteger los cauces hÃdricos.CONACYT - Consejo Nacional de Ciencia y TecnologÃaPROCIENCI
Joining by forming technologies: current solutions and future trends
The progressively more demanding needs of emissions and costs reduction in the transportation industry are pushing engineers towards the use of increasingly lightweight structures. This goal can be achieved only if dissimilar and/or new materials, including polymers and composites, are joined together to create complex structures. Conventional fusion welding processes have often been proven inadequate to this task because of the high heat input reducing the joint mechanical properties or even making the joining process impossible. Joining by forming technologies take advantage on the plastic deformation to create sound joints out of even very dissimilar materials. Over the last 25 years, several new processes, with increasing potential in effectively joining virtually every structural material, have been invented and developed. In the paper, a comprehensive overview of the most utilized joining by forming processes is given. For each process, an analysis of the current research trends and hot topics is provided, highlighting strengths and weaknesses for industrial applications
Chloroplast-localized 6-phosphogluconate dehydrogenase is critical for maize endosperm starch accumulation
Plants have duplicate versions of the oxidative pentose phosphate pathway (oxPPP) enzymes with a subset localized to the chloroplast. The chloroplast oxPPP provides NADPH and pentose sugars for multiple metabolic pathways. This study identified two loss-of-function alleles of the Zea mays (maize) chloroplast-localized oxPPP enzyme 6-phosphogluconate dehydrogenase (6PGDH). These mutations caused a rough endosperm seed phenotype with reduced embryo oil and endosperm starch. Genetic translocation experiments showed that pgd3 has separate, essential roles in both endosperm and embryo development. Endosperm metabolite profiling experiments indicated that pgd3 shifts redox-related metabolites and increases reducing sugars similar to starch-biosynthetis mutants. Heavy isotope-labelling experiments indicates that carbon flux into starch is altered in pgd3 mutants. Labelling experiments with a loss of cytosolic 6PGDH did not affect flux into starch. These results support the known role for plastid-localized oxPPP in oil synthesis and argue that amyloplast-localized oxPPP reactions are integral to endosperm starch accumulation in maize kernels
Ricin B chain targeted to the endoplasmic reticulum of tobacco protoplasts is degraded by a CDC48- and vacuole-independent mechanism
The B chain of ricin was expressed and delivered to the endoplasmic
reticulum of tobacco protoplasts where it disappeared
with time in a manner consistent with degradation. This turnover
did not occur in the vacuoles or upon secretion. Indeed,
several lines of evidence indicate that, in contrast to the turnover
of endoplasmic reticulum-targeted ricin A chain in the
cytosol, the bulk of expressed ricin B chain was degraded in the
secretory pathway
The role of CDC48 in the retro-translocation of non-ubiquitinated toxin substrates in plant cells
When the catalytic A subunits of the castor
bean toxins ricin and Ricinus communis
agglutinin (denoted as RTA and RCA A,
respectively) are delivered into the
endoplasmic reticulum (ER) of tobacco
protoplasts, they become substrates for ER-associated
protein degradation (ERAD). As
such, these orphan polypeptides are retro-translocated
to the cytosol, where a significant
proportion of each protein is degraded by
proteasomes. Here we begin to characterise
the ERAD pathway in plant cells, showing
that retro-translocation of these lysine-deficient
glycoproteins requires the ATPase
activity of cytosolic CDC48. Lysine
polyubiquitination is not obligatory for this
step. We also show that while RCA A is found
in a mannose-untrimmed form prior to its
retro-translocation, a significant proportion of
newly synthesised RTA cycles via the Golgi
and becomes modified by downstream
glycosylation enzymes. Despite these
differences, both proteins are similarly retro-translocated
The Compartmentalisation of Phosphorylated Free Oligosaccharides in Cells from a CDG Ig Patient Reveals a Novel ER-to-Cytosol Translocation Process
BACKGROUND: Biosynthesis of the dolichol linked oligosaccharide (DLO) required for protein N-glycosylation starts on the cytoplasmic face of the ER to give Man(5)GlcNAc(2)-PP-dolichol, which then flips into the ER for further glycosylation yielding mature DLO (Glc(3)Man(9)GlcNAc(2)-PP-dolichol). After transfer of Glc(3)Man(9)GlcNAc(2) onto protein, dolichol-PP is recycled to dolichol-P and reused for DLO biosynthesis. Because de novo dolichol synthesis is slow, dolichol recycling is rate limiting for protein glycosylation. Immature DLO intermediates may also be recycled by pyrophosphatase-mediated cleavage to yield dolichol-P and phosphorylated oligosaccharides (fOSGN2-P). Here, we examine fOSGN2-P generation in cells from patients with type I Congenital Disorders of Glycosylation (CDG I) in which defects in the dolichol cycle cause accumulation of immature DLO intermediates and protein hypoglycosylation. METHODS AND PRINCIPAL FINDINGS: In EBV-transformed lymphoblastoid cells from CDG I patients and normal subjects a correlation exists between the quantities of metabolically radiolabeled fOSGN2-P and truncated DLO intermediates only when these two classes of compounds possess 7 or less hexose residues. Larger fOSGN2-P were difficult to detect despite an abundance of more fully mannosylated and glucosylated DLO. When CDG Ig cells, which accumulate Man(7)GlcNAc(2)-PP-dolichol, are permeabilised so that vesicular transport and protein synthesis are abolished, the DLO pool required for Man(7)GlcNAc(2)-P generation could be depleted by adding exogenous glycosylation acceptor peptide. Under conditions where a glycotripeptide and neutral free oligosaccharides remain predominantly in the lumen of the ER, Man(7)GlcNAc(2)-P appears in the cytosol without detectable generation of ER luminal Man(7)GlcNAc(2)-P. CONCLUSIONS AND SIGNIFICANCE: The DLO pools required for N-glycosylation and fOSGN2-P generation are functionally linked and this substantiates the hypothesis that pyrophosphatase-mediated cleavage of DLO intermediates yields recyclable dolichol-P. The kinetics of cytosolic fOSGN2-P generation from a luminally-generated DLO intermediate demonstrate the presence of a previously undetected ER-to-cytosol translocation process for either fOSGN2-P or DLO
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