Comparative metagenomic, phylogenetic and physiological analyses of soil microbial communities across nitrogen gradients

Terrestrial ecosystems are receiving elevated inputs of nitrogen (N) from anthropogenic sources and understanding how these increases in N availability affect soil microbial communities is critical for predicting the associated effects on belowground ecosystems. We used a suite of approaches to analyze the structure and functional characteristics of soil microbial communities from replicated plots in two long-term N fertilization experiments located in contrasting systems. Pyrosequencing-based analyses of 16S rRNA genes revealed no significant effects of N fertilization on bacterial diversity, but significant effects on community composition at both sites; copiotrophic taxa (including members of the Proteobacteria and Bacteroidetes phyla) typically increased in relative abundance in the high N plots, with oligotrophic taxa (mainly Acidobacteria) exhibiting the opposite pattern. Consistent with the phylogenetic shifts under N fertilization, shotgun metagenomic sequencing revealed increases in the relative abundances of genes associated with DNA/RNA replication, electron transport and protein metabolism, increases that could be resolved even with the shallow shotgun metagenomic sequencing conducted here (average of 75 000 reads per sample). We also observed shifts in the catabolic capabilities of the communities across the N gradients that were significantly correlated with the phylogenetic and metagenomic responses, indicating possible linkages between the structure and functioning of soil microbial communities. Overall, our results suggest that N fertilization may, directly or indirectly, induce a shift in the predominant microbial life-history strategies, favoring a more active, copiotrophic microbial community, a pattern that parallels the often observed replacement of K-selected with r-selected plant species with elevated N

An analysis of medical students' residency and specialty choices

The contemporary geographic maldistribution of physicians and shortages in some specialty areas is a persistent problem facing United States federal and state wide health planners. This paper attempts to illustrate some of the formal and informal processes of the selection of specialties and recidency programs based on a survey of senior students of 37 selected American medical schools at the time of the National Residency Matching Program in 1982. Results of a factor analysis on influences on specialty choice produced two major clusters of medical students; those predominantly influenced in specialty choice by the faculty and other senior physicians (sponsorship), and those predominantly influenced by the social dimension of the physicians' role (social responsibility). These medical specialty choice orientations were also systematically related to either choice of specialty vs primary care medicine, to a life-style or status related choice of residency program, and to students' perceptions regarding a program's evaluation of a candidate. The results of the survey suggested that students who chose primary care were more apt to be influenced by sources outside of the medical school. These findings raise questions regarding the efficacy of medical school curriculum in motivating career choices in primary care. This is particularly important in view of the stated need to increase the proportion of medical school graduates choosing primary care careers.medical education postgraduate training specialty choice residency choice

Which anesthetic should be used in the treatment of refractory status epilepticus?

While the treatment of refractory status epilepticus (SE) relies on the use of anesthetic agents, mostly barbiturates, propofol, or midazolam, the study of the available literature discloses that the evidence level is low. Therapeutic coma induction appears straightforward for generalized convulsive or subtle SE, but this approach is debated for complex partial SE. Each anesthetic has its own advocates, and specific advantages and risks; furthermore, several different protocols have been reported regarding the duration and depth of sedation. However, it seems that the biological background of the patient (especially the etiology) remains the main prognostic determinant in SE. There is a clear need of controlled trials regarding this topic