National Autonomous University of Mexico

About: National Autonomous University of Mexico is a education organization based out in Mexico City, Distrito Federal, Mexico. It is known for research contribution in the topics: Population & Galaxy. The organization has 72868 authors who have published 127797 publications receiving 2285543 citations. The organization is also known as: UNAM & Universidad Nacional Autónoma de México.

Sulfur assimilation and glutathione metabolism under cadmium stress in yeast, protists and plants.

Abstract: Glutathione (γ-glu-cys-gly; GSH) is usually present at high concentrations in most living cells, being the major reservoir of non-protein reduced sulfur. Because of its unique redox and nucleophilic properties, GSH serves in bio-reductive reactions as an important line of defense against reactive oxygen species, xenobiotics and heavy metals. GSH is synthesized from its constituent amino acids by two ATP-dependent reactions catalyzed by γ-glutamylcysteine synthetase and glutathione synthetase. In yeast, these enzymes are found in the cytosol, whereas in plants they are located in the cytosol and chloroplast. In protists, their location is not well established. In turn, the sulfur assimilation pathway, which leads to cysteine biosynthesis, involves high and low affinity sulfate transporters, and the enzymes ATP sulfurylase, APS kinase, PAPS reductase or APS reductase, sulfite reductase, serine acetyl transferase, O-acetylserine/O-acetylhomoserine sulfhydrylase and, in some organisms, also cystathionine β-synthase and cystathionine γ-lyase. The biochemical and genetic regulation of these pathways is affected by oxidative stress, sulfur deficiency and heavy metal exposure. Cells cope with heavy metal stress using different mechanisms, such as complexation and compartmentation. One of these mechanisms in some yeast, plants and protists is the enhanced synthesis of the heavy metal-chelating molecules GSH and phytochelatins, which are formed from GSH by phytochelatin synthase (PCS) in a heavy metal-dependent reaction; Cd2+ is the most potent activator of PCS. In this work, we review the biochemical and genetic mechanisms involved in the regulation of sulfate assimilation-reduction and GSH metabolism when yeast, plants and protists are challenged by Cd2+.

Payments for ecosystem services and the fatal attraction of win-win solutions

Abstract: In this commentary we critically discuss the suitability of payments for ecosystem services and the most important challenges they face. While such instruments can play a role in improving environmental governance, we argue that over-reliance on payments as win-win solutions might lead to ineffective outcomes, similar to earlier experience with integrated conservation and development projects. Our objective is to raise awareness, particularly among policy makers and practitioners, about the limitations of such instruments and to encourage a dialogue about the policy contexts in which they might be appropriate.

Tocilizumab Inhibits Structural Joint Damage in Rheumatoid Arthritis Patients With Inadequate Responses to Methotrexate: Results From the Double-Blind Treatment Phase of a Randomized Placebo-Controlled Trial of Tocilizumab Safety and Prevention of Structural Joint Damage at One Year

Abstract: Objective To assess the efficacy and safety of tocilizumab plus methotrexate (MTX) versus MTX alone in preventing structural joint damage and improving physical function and disease activity in patients with moderate-to-severe rheumatoid arthritis and inadequate responses to MTX Methods A total of 1,196 patients were enrolled in a 2-year, randomized, double-blind, placebo-controlled trial Patients received tocilizumab (8 mg/kg or 4 mg/kg) or placebo every 4 weeks plus MTX Rescue treatment was available from week 16 Results from year 1 are presented Results Mean change in the total Genant-modified Sharp score was 029 and 034 with tocilizumab 8 mg/kg plus MTX and 4 mg/kg plus MTX, respectively, versus 113 with placebo plus MTX (P < 00001 for both comparisons) Analysis of variance of the area under the curve for change from baseline in the disability index of the Health Assessment Questionnaire showed greater decreases with tocilizumab 8 mg/kg and 4 mg/kg (−1441 and −1284 units, respectively) than with placebo (−581 units; P < 00001 for both comparisons) Proportions of patients with American College of Rheumatology 20%, 50%, and 70% improvement and with Disease Activity Score in 28 joints remission were higher in those receiving 8 mg/kg tocilizumab than in those receiving placebo (P < 00001 for all comparisons) The safety profile of tocilizumab was consistent with the profiles in previous studies Infections were the most common adverse and serious adverse events Conclusion The findings of this study show that tocilizumab plus MTX results in greater inhibition of joint damage and improvement in physical function than does MTX alone Tocilizumab has a well-characterized safety profile