Reversion of Sulfenamide Prodrugs in the Presence of Free Thiol Containing Proteins

The purpose of this work was to study the reaction kinetics between two model sulfenamide prodrugs of linezolid, N-(phenylthio)linezolid and N-((2-ethoxycarbonyl)ethylthio)linezolid, with free thiol containing proteins; human serum albumin (HSA); a constitutively active mutant of theprotein tyrosine phosphatase PRL-1, PRL-1-C170-171S, a model protein; and diluted fresh human plasma. The reaction was followed by HPLC, both for the loss of prodrug and appearance of linezolid, and at different pH values with molar excess of the proteins relative to the prodrugs. Pseudo first-order kinetics were observed. Consistent with earlier findings for the reaction between similar sulfenamides and small molecule thiols, the reaction kinetics appeared to be consistent with thiolate attack at the sulfenamide bond to release the parent drug. The proteins reacted significantly slower on a molar basis than their small molecule counterparts. It appears that proteins such as HSA may play a role in the in vivo conversion of sulfenamide prodrugs to their parent drug

Consumo de Savia por Melanerpes cactorum y su Rol en la Estructuración de Ensambles de Aves en Bosques Secos

The White-fronted Woodpecker (Melanerpes cactorum) drills holes in branches and trunks to feed on sap flows, providing an energy-rich food resource for other birds. Here we describe ecological and behavioral traits of the White-fronted Woodpecker related to its sap-feeding habits in the semiarid Chaco of Argentina and explore the structure of the avian assemblage in relation to the sap resource. Sap consumption by the White-fronted Woodpecker and other sap-feeding species was strongly seasonal and positively associated with periods of resource scarcity. The White-fronted Woodpecker actively defended the sap wells from smaller birds. Specialist and facultative nectarivores that assimilate sucrose at a high rate represented an important proportion of sap-feeding birds. In this system of woodpecker, sap, and other sap-feeding species, each species’ consumption depends on its physiological and behavioral characteristics as well as on the availability of other food in the surrounding environment.Melanerpes cactorum perfora ramas y troncos de árboles y arbustos para consumir la savia que fluye de las perforaciones, posibilitando a otras especies de aves el acceso a un recurso de alto contenido energé- tico. En este estudio describimos rasgos de la historia natural de M. cactorum relacionados con su alimentación en el Chaco semiárido de Argentina e investigamos la estructuración de ensambles de aves en torno al recurso savia. Para M. cactorum y las especies de aves que consumieron savia, el consumo de savia fue marcadamente estacional, posiblemente asociado a periodos de escasez de recursos. Melanerpes cactorum defendió activamente las perforaciones ante algunas especies de aves cuya masa corporal fue menor a la de los carpinteros. Las especies nectarívoras especialistas y facultativas con alta tasa de asimilación de sacarosa representaron una importante proporción de las aves que consumieron savia. En el sistema carpinteros–savia–aves consumidoras de savia, el consumo de este recurso depende de características fisiológicas y comportamentales de las especies, como así también de la disponibilidad de otros recursos alimenticios en los ambientes que habitan.Fil: Nuñez Montellano, Maria Gabriela. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Macchi, Leandro. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentin

The Collective Action Problem: Within-Group Cooperation and Between-Group Competition in a Repeated Rent-Seeking Game

This paper analyzes the ability of group members to cooperate in rent-seeking activities in a context of between-group competition. For this purpose, we develop an infinitely repeated rent-seeking game between two groups of different size. We first investigate Nash reversion strategies to support cooperative behavior in a given group before analyzing double-edge trigger strategies which have the property that cheating on the cooperative agreement in a given group is followed by non-cooperation in this group and cooperation in the rival group. The main conclusion is that the set of parameters for which cooperation can be sustained within the larger group as a subgame perfect outcome is as large as that for which cooperation can be sustained in the smaller group. Hence, in contrast with Olson’s (1965) celebrated thesis but in accordance with many informal and formal observations, the larger group is as effective as the smaller group in furthering its interest

Population-Based Rates of Revision of Primary Total Hip Arthroplasty: A Systematic Review

Background: Most research on failure leading to revision total hip arthroplasty (THA) is reported from single centers. We searched PubMed between January 2000 and August 2010 to identify population- or community-based studies evaluating ten-year revision risks. We report ten-year revision risk using the Kaplan-Meier method, stratifying by age and fixation technique. Results: Thirteen papers met the inclusion criteria. Cemented prostheses had Kaplan-Meier estimates of revision-free implant survival of ten years ranging from 88 % to 95%; uncemented prostheses had Kaplan-Meier estimates from 80 % to 85%. Estimates ranged from 72 % to 86 % in patients less than 60 years old and from 90 to 96 % in older patients. Conclusion: Data reported from national registries suggest revision risks of 5 to 20 % ten years following primary THA. Revision risks are lower in older THA recipients. Uncemented implants may have higher ten-year rates of revision, regardless of age

Review: Time use as an explanation for the agri-nutrition disconnect? Evidence from rural areas in low and middle income countries

Time is a vital input into nutritional outcomes, as it is necessary for the production, procurement and preparation of food, child feeding and childcare. Thus, agricultural interventions may fail to improve nutritional outcomes if they do not take account of time constraints, particularly of rural women who spend a considerable portion of their time in agriculture. Given the potential trade-offs pertaining to time in productive vs. reproductive activities and its implications for maternal and child nutrition, the goal of this review is to systematically map and assess the available evidence, both qualitative and quantitative studies, agriculture-time use-nutrition pathway. Through an analysis of 89 studies, identified through a systematic search, on rural areas of low and middle-income countries, we observe three findings. First, women play a key role in agriculture, as reflected in their time commitments. Second, evidence from a very limited set of studies suggests that agricultural interventions tend to increase time commitments in agriculture of the household members for whom impact is measured. Third, while changing time use tends to change nutritional outcomes, it does so in a range of complex ways and there is no agreement on the impact. Nutritional impacts are varied because households and household members respond to increased time burden and workload in different ways