The 4,639,221-base pair sequence of Escherichia coli K-12 is presented. Of 4288 protein-coding genes annotated, 38 percent have no attributed function. Comparison with five other sequenced microbes reveals ubiquitous as well as narrowly distributed gene families; many families of similar genes within E. coli are also evident. The largest family of paralogous proteins contains 80 ABC transporters. The genome as a whole is strikingly organized with respect to the local direction of replication; guanines, oligonucleotides possibly related to replication and recombination, and most genes are so oriented. The genome also contains insertion sequence (IS) elements, phage remnants, and many other patches of unusual composition indicating genome plasticity through horizontal transfer.

The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome. Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States. The severity of disease, the lack of effective treatment and the potential for large-scale outbreaks from contaminated food supplies have propelled intensive research on the pathogenesis and detection of E. coli O157:H7 (ref. 4). Here we have sequenced the genome of E. coli O157:H7 to identify candidate genes responsible for pathogenesis, to develop better methods of strain detection and to advance our understanding of the evolution of E. coli, through comparison with the genome of the non-pathogenic laboratory strain E. coli K-12 (ref. 5). We find that lateral gene transfer is far more extensive than previously anticipated. In fact, 1,387 new genes encoded in strain-specific clusters of diverse sizes were found in O157:H7. These include candidate virulence factors, alternative metabolic capacities, several prophages and other new functions--all of which could be targets for surveillance.

Using a South Los Angeles charter school of approximately 500 students operated by a non-profit charter management organization (CMO) as the primary field site, this two-year, ethnographic dissertation project examines the implementation of a one-to-one tablet computer program in a public high school. This poster examines the variety of ways that information and communication technology (ICT) functions in everyday life within the institution -including classroom instruction, school discipline, and evaluation -through qualitative methods, primarily class observations, photographs, and interviews with teachers, students, and administrators as the program evolved over two consecutive school years. This project contributes needed empirical context to questions of technological innovation in public education, providing the first-ever multi-year study of a one-to-one tablet computer program in a California public school.

A system of versatile insertion plasmids was constructed that permits efficient delivery of the target sites of an ultra-rare-cutting endonuclease and the recombinase FLP into preselected sites of the bacterial genome. With the help of this system, the pathogenicity island LEE of the Escherichia coli O157:H7 genome was excised and isolated in vitro, deleted in vivo, rescued as a plasmid, and transferred into another strain.Characterization and manipulation of bacterial genomes can be facilitated by creating genomic insertions with ultrarare restriction sites and recognition sites for specific recombinases. These insertions can serve as "landmarks" in physical mapping and strain comparisons (12), allow direct isolation of preselected chromosomal segments for sequencing (2,11,14), provide a means for obtaining precise genomic deletions, and permit plasmid rescue of a genomic segment. Suicide plasmids are appropriate vehicles for delivery of such insertions into the chromosome (7). However, efficient introduction of plasmids into the target cell is frequently hindered by restriction, methylation sensitivity, plasmid incompatibility, and other factors.We constructed two sets of small, suicidal insertion plasmids that combine several useful features: rare and ultrarare restriction sites (NotI and I-SceI), the target site (FRT) for the recombinase FLP, the T7 and SP6 phage promoters, a choice of three antibiotic resistance genes (ampicillin [Ap], kanamycin [Kn], and chloramphenicol [Cm], and either of two conditional replication systems (R6K or pSC101 ts ). The plasmids can be recombined by a single crossover into preselected sites of the genome with the aid of DNA fragments that are cloned into them and are homologous to the targeted sites. Such homologous fragments can be obtained by PCR with available sequence information from the target cell or from related organisms. The two sets of suicide plasmids permit two insertions to be obtained sequentially in the same genome. The genomic segment flanked by these insertions can then be excised by I-SceI in vitro and can be isolated directly from a pulsed-field gel. In vivo deletion or inversion of the segment, depending on the relative orientation of the FRT sites, can also be achieved by expressing FLP from a helper plasmid. Since FLP-mediated deletion is a very effective process, no direct selection of the clone carrying the deletion is necessary. In addition, the chromosomal segment, excised and circularized by FLP, can be isolated as a plasmid and transformed into another host, where it can be either maintained as a plasmid or inserted into the genome.The insertion plasmids are introduced into the target cell by electroporation. If the transformation efficiency is sufficiently high and a large number of transformants can be obtained, the plasmids are used in "direct suicide" (nonreplicating) mode, and recombinants are selected by their antibiotic resistance. In strains that are difficult to transform, the plasmids are used in "conditional suicide" mode (6). In this ap...

Burnout among physicians and physicians-in-training is well established as a potential threat to the health and well-being of health care providers and patients. However, there are myriad problems with current burnout research and its ongoing measurement that threaten the validity of the conclusions. For example, researchers have used differing ways of defining and measuring burnout. Those who have used the Maslach Burnout Inventory vary in recommended use of the instrument and cutoff scores. As a result, the authors suggest that the term "burnout" may be misused and recommend some reconsideration of the meaning of burnout. The measurement and discussion of burnout have strong implications for interventions and policy alike. In this article, the authors review the problems with burnout research and ask important questions about the future directions of research efforts. The authors recommend a consistent measurement approach and perhaps moving toward a focus on physician wellness from a positive psychology perspective.

Post-traumatic stress disorder (PTSD) is one of the few mental disorders in which the cause is readily identifiable. In this article, we review the new Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnostic criteria, prevalence, and presentation of patients with PTSD in primary care. The purpose of this article is to review current literature regarding theory, etiology, and treatment effectiveness. Key findings in terms of neurobiological underpinnings with implications for future treatment are discussed. Recommendations regarding effective psychotherapy and pharmacotherapy, emerging treatment, and management issues in primary care settings are offered.

A sense of career meaning and accomplishment, along with a lack of distress, are important factors in determining physician happiness. The number of hours a physician works is not related to happiness, but the perceived ability to manage workload was significantly related to happiness. Wellness-promotion efforts could focus on assisting physicians with skills to manage the workload by eliminating unnecessary tasks or sharing workload among team members, improving feelings of work accomplishment, improving career satisfaction and meaning, and managing distress related to patient care.

To understand more clearly how recent infusions of technology into the schools have affected students, the authors undertook a yearlong investigation into technology use at two San Francisco Bay Area high schools. They share their findings here and measure them against the dreams of the techno-promoters.