The catalytic group-I introns of the psbA gene of Chlamydomonas reinhardtii : core structures, ORFs and evolutionary implications

The sequences and predicted secondary structures of the four catalytic group-I introns in the psbA gene of Chlamydomonas reinhardtii, Cr.psbA-1–Cr.psbA-4, have been determined. Cr.psbA-1 and Cr.psbA-4 are subgroup-IA1 introns and have similar secondary structures, except at the 3′ end where Cr.psbA-1 contains a large inverted-repeat domain. Cr.psbA-4 is closely related to intron 1 of the Chlamydomonas moewusii psbA gene, with which it shares the same location, high nucleotide identity in the core, and an identically placed ORF that shows 58% amino-acid identity. Cr.psbA-2 is a subgroup-IA3 intron, and shows similarities to the Chlamydomonas eugametos rRNA intron, Ce.LSU-1. Cr.psbA-3 is a subgroup-IA2 intron, and is remarkably similar to the T4 phage intron, sunY. Interestingly, a degenerate version of Cr.psbA-3 is located in the intergenic region between the chloroplast petA and petD genes. All four introns contain ORFs, which potentially code for basic proteins of 11–38 kDa. The ORFs in introns 2 and 3 contain variants of the GIY-YIG motif; however, the Cr.psbA-2 ORF is free-standing, whereas the Cr.psbA-3 ORF is contiguous and in-frame with the upstream exon. The Cr.psbA-4 ORF contains an H-N-H motif, and possibly a GIY-YIG motif. These data indicate that the C. reinhardtiipsbA introns have multiple origins, and illustrate some of the evolutionary DNA dynamics associated with group-I introns in Chlamydomonas. Received: 24 November 1998 / 23 March 1999     

Local and systemic effects of orally applied sodium salts

This study determines whether the oral application of a baking soda-3% hydrogen peroxide dentifrice and a nearly saturated sodium chloride mouthwash, as a home care method for treating periodontal disease, creates a sodium burden for human subjects. The dietary intake and urinary excretion of sodium and potassium were monitored in participating subjects. Urinary sodium did not increase in subjects using the method. Desquamative gingival lesions, however, were seen in all treated subjects. Further study is needed to determine safe salt concentrations for this home care regimen.     

The executive master of science in nursing program: competencies and learning experiences

This is the first in a 3-part series describing an executive master of science in nursing program. Part 1 describes program development built on the American Organization of Nurse Executives' competencies and distinct features of the students' online and on-site learning experiences. Part 2 will discuss how the 14 Forces of Magnetism are integrated across the curriculum and the unique criteria for program admission. Finally, Part 3 will describe the use of the Robert Wood Johnson Executive Nurse Fellows Program as the model for learning activity and Benner's Novice to Expert theory for program evaluation.     

Medical messages in the media – barriers and solutions to improving medical journalism

Context Medical issues are widely reported in the mass media. These reports influence the general public, policy makers and health‐care professionals. This information should be valid, but is often criticized for being speculative, inaccurate and misleading. An understanding of the obstacles medical reporters meet in their work can guide strategies for improving the informative value of medical journalism. Objective To investigate constraints on improving the informative value of medical reports in the mass media and elucidate possible strategies for addressing these. Design We reviewed the literature and organized focus groups, a survey of medical journalists in 37 countries, and semi‐structured telephone interviews. Results We identified nine barriers to improving the informative value of medical journalism: lack of time, space and knowledge; competition for space and audience; difficulties with terminology; problems finding and using sources; problems with editors and commercialism. Lack of time, space and knowledge were the most common obstacles. The importance of different obstacles varied with the type of media and experience. Many health reporters feel that it is difficult to find independent experts willing to assist journalists, and also think that editors need more education in critical appraisal of medical news. Almost all of the respondents agreed that the informative value of their reporting is important. Nearly everyone wanted access to short, reliable and up‐to‐date background information on various topics available on the Internet. A majority (79%) was interested in participating in a trial to evaluate strategies to overcome identified constraints. Conclusion Medical journalists agree that the validity of medical reporting in the mass media is important. A majority acknowledge many constraints. Mutual efforts of health‐care professionals and journalists employing a variety of strategies will be needed to address these constraints.