Simultaneous determination of natural and synthetic steroid estrogens and their conjugates in aqueous matrices by liquid chromatography / mass spectrometry

An analytical method for the simultaneous determination of nine free and conjugated steroid estrogens was developed with application to environmental aqueous matrices. Solid phase extraction (SPE) was employed for isolation and concentration, with detection by liquid chromatography/mass spectrometry (LC/MS) using electrospray ionisation (ESI) in the negative mode. Method recoveries for various aqueous matrices (wastewater, lake and drinking water) were determined, recoveries proving to be sample dependent. When spiked at 50 ng/l concentrations in sewage influent, recoveries ranged from 62-89 % with relative standard deviations (RSD) < 8.1 %. In comparison, drinking water spiked at the same concentrations had recoveries between 82-100 % with an RSD < 5%. Ion suppression is a known phenomenon when using ESI; hence its impact on method recovery was elucidated for raw sewage. Both ion suppression from matrix interferences and the extraction procedure has bearing on the overall method recovery. Analysis of municipal raw sewage identified several of the analytes of interest at ng/l concentrations, estriol (E3) being the most abundant. Only one conjugate, estrone 3-sulphate (E1-3S) was observe

Analysing intermediary organisations and their influence on upgrading in emerging agricultural clusters

This paper analyses intermediary organisations in developing economy agricultural clusters. The paper critically engages with a growing narrative in studies of intermediaries that have stressed the ownership structure of intermediaries as a key driver for enabling knowledge transfer, inter-firm learning and upgrading of small producers in clusters. Two case studies of Latin American clusters are presented and discussed. The study suggests that in addition to ownership structure, cluster governance and the embeddedness of intermediaries in clusters are critical factors that need to be taken into account in understanding the influence of intermediaries in the upgrading of small producers in clusters

Optimization of Time-Course Experiments for Kinetic Model Discrimination

Systems biology relies heavily on the construction of quantitative models of biochemical networks. These models must have predictive power to help unveiling the underlying molecular mechanisms of cellular physiology, but it is also paramount that they are consistent with the data resulting from key experiments. Often, it is possible to find several models that describe the data equally well, but provide significantly different quantitative predictions regarding particular variables of the network. In those cases, one is faced with a problem of model discrimination, the procedure of rejecting inappropriate models from a set of candidates in order to elect one as the best model to use for prediction

Assessment of cognitive status in patients with type 2 diabetes through the mini-mental status examination: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Diabetes is considered an independent risk factor for cognitive impairment and some studies observed through neuropsychological tests that cognitive disfunction affects both elderly and younger patients with diabetes. The aims of this study were to evaluate the cognitive status of outpatients with type 2 diabetes and to evaluate factors associated with impaired function.</p> <p>Methods</p> <p>A cross-sectional study was conducted in a group of type 2 diabetic outpatients. They were asked to undergo the Mini-Mental State Examination (MMSE) during routine ambulatory visits between April 2006 and January 2007, with the highest pontuation of the test being 30 points. Patients were classified as having possible dementia according to years of study. Exclusion criteria were blindness, illiterately, stroke, Alzheimer disease and psychiatric disorder. Results are presented as median (interquartile range) or mean ± SD.</p> <p>Results</p> <p>The study group was composed of 346 type 2 diabetic outpatients (216 females), aged 58,6 ± 12,1 years and with duration of diabetes of 12,3 ± 9,1 years. Hypertension was present in 77,2%. The total MMSE score achieved was 26 points (16 - 30) and was correlated with years of study (R²= 0,39, p < 0,001) and 'per capita' income (R²= 0,22, p < 0,0001) and duration of diabetes (R2 = - 0,13, p = 0,01). Patients who needed help to take their medications obtained worst performance in the MMSE (23,16 ± 3,55 <it>vs </it>25,7 ± 2,84, p < 0,01) and were more likely to present possible dementia (p < 0,01). Forty two subjects (12.1%) had diagnosis of possible dementia and this was also associated with years of study (p = 0,045). No association was observed between possible dementia and total MMSE scores with A1C levels.</p> <p>Conclusions</p> <p>We conclude that patients with type 2 diabetes should be regularly evaluated for their cognitive function, because duration of disease could be associated with decline in cognition. The early implementation of mini mental which is a simple method of execution can be done to detect early stages of dementia. This test could be an important tool to access the ability of patient to understand their disease and treatment.</p

Does Sex-Selective Predation Stabilize or Destabilize Predator-Prey Dynamics?

Background: Little is known about the impact of prey sexual dimorphism on predator-prey dynamics and the impact of sexselective harvesting and trophy hunting on long-term stability of exploited populations. Methodology and Principal Findings: We review the quantitative evidence for sex-selective predation and study its longterm consequences using several simple predator-prey models. These models can be also interpreted in terms of feedback between harvesting effort and population size of the harvested species under open-access exploitation. Among the 81 predator-prey pairs found in the literature, male bias in predation is 2.3 times as common as female bias. We show that long-term effects of sex-selective predation depend on the interplay of predation bias and prey mating system. Predation on the ‘less limiting’ prey sex can yield a stable predator-prey equilibrium, while predation on the other sex usually destabilizes the dynamics and promotes population collapses. For prey mating systems that we consider, males are less limiting except for polyandry and polyandrogyny, and male-biased predation alone on such prey can stabilize otherwise unstable dynamics. On the contrary, our results suggest that female-biased predation on polygynous, polygynandrous or monogamous prey requires other stabilizing mechanisms to persist. Conclusions and Significance: Our modelling results suggest that the observed skew towards male-biased predation might reflect, in addition to sexual selection, the evolutionary history of predator-prey interactions. More focus on these phenomena can yield additional and interesting insights as to which mechanisms maintain the persistence of predator-prey pairs over ecological and evolutionary timescales. Our results can also have implications for long-term sustainability of harvesting and trophy hunting of sexually dimorphic species

Novel Primate-Specific Genes, RMEL 1, 2 and 3, with Highly Restricted Expression in Melanoma, Assessed by New Data Mining Tool

Melanoma is a highly aggressive and therapy resistant tumor for which the identification of specific markers and therapeutic targets is highly desirable. We describe here the development and use of a bioinformatic pipeline tool, made publicly available under the name of EST2TSE, for the in silico detection of candidate genes with tissue-specific expression. Using this tool we mined the human EST (Expressed Sequence Tag) database for sequences derived exclusively from melanoma. We found 29 UniGene clusters of multiple ESTs with the potential to predict novel genes with melanoma-specific expression. Using a diverse panel of human tissues and cell lines, we validated the expression of a subset of three previously uncharacterized genes (clusters Hs.295012, Hs.518391, and Hs.559350) to be highly restricted to melanoma/melanocytes and named them RMEL1, 2 and 3, respectively. Expression analysis in nevi, primary melanomas, and metastatic melanomas revealed RMEL1 as a novel melanocytic lineage-specific gene up-regulated during melanoma development. RMEL2 expression was restricted to melanoma tissues and glioblastoma. RMEL3 showed strong up-regulation in nevi and was lost in metastatic tumors. Interestingly, we found correlations of RMEL2 and RMEL3 expression with improved patient outcome, suggesting tumor and/or metastasis suppressor functions for these genes. The three genes are composed of multiple exons and map to 2q12.2, 1q25.3, and 5q11.2, respectively. They are well conserved throughout primates, but not other genomes, and were predicted as having no coding potential, although primate-conserved and human-specific short ORFs could be found. Hairpin RNA secondary structures were also predicted. Concluding, this work offers new melanoma-specific genes for future validation as prognostic markers or as targets for the development of therapeutic strategies to treat melanoma