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Annals of emergency medicine 07/2012; 60(1):135. · 4.23 Impact Factor
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ABSTRACT: Recent-onset atrial fibrillation, defined as a first detected or recurrent episode of atrial fibrillation lasting less than 48 hours, is a commonly encountered dysrhythmia in the emergency department (ED). Cardioversion of stable patients in the ED with recent-onset atrial fibrillation without antecedent anticoagulation would allow for these patients to be discharged directly to home. We searched the literature to determine whether any studies have investigated the safety of this management strategy and identified five that addressed this question. These studies are reviewed herein; importantly, not one ED patient who was cardioverted in any of the five studies suffered a thromboembolic event - the feared complication responsible for most of the controversy surrounding the ED management of atrial fibrillation. According to the available evidence, we conclude that it would be within the standard of care to discharge home stable patients with recent-onset atrial fibrillation after cardioversion in the ED with adequate follow-up. It should be noted that although this strategy is safe and effective, the return visit rate for relapsed atrial fibrillation is 3% to 17%, and patients should be made aware of this possibility.
Annals of emergency medicine 12/2011; 58(6):517-20. · 4.23 Impact Factor
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ABSTRACT: In flowering plants, sperm cells develop in the pollen cytoplasm and are transported through floral tissues to an ovule by a pollen tube, a highly polarized cellular extension. After targeting an ovule, the pollen tube bursts, releasing two sperm that fertilize an egg and a central cell. Here, we identified the gene encoding Arabidopsis HAP2, demonstrating that it is allelic to GCS1. HAP2 is expressed only in the haploid sperm and is required for efficient pollen tube guidance to ovules. We identified an insertion (hap2-1) that disrupts the C-terminal portion of the protein and tags mutant pollen grains with the beta-glucuronidase reporter. By monitoring reporter expression, we showed that hap2-1 does not diminish pollen tube length in vitro or in the pistil, but it reduces ovule targeting by twofold. In addition, we show that the hap2 sperm that are delivered to ovules fail to initiate fertilization. HAP2 is predicted to encode a protein with an N-terminal secretion signal, a single transmembrane domain and a C-terminal histidine-rich domain. These results point to a dual role for HAP2, functioning in both pollen tube guidance and in fertilization. Moreover, our findings suggest that sperm, long considered to be passive cargo, are involved in directing the pollen tube to its target.
Development 01/2007; 133(23):4761-9. · 6.60 Impact Factor
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ABSTRACT: In flowering plants, the egg develops within a haploid embryo sac (female gametophyte) that is encased within the pistil. The haploid pollen grain (male gametophyte) extends a pollen tube that carries two sperm cells within its cytoplasm to the embryo sac. This feat requires rapid, precisely guided, and highly polarized growth through, between, and on the surface of the cells of the stigma, style, and ovary. Pollen tube migration depends on a series of long-range signals from diploid female cells as well as a short-range attractant emitted by the embryo sac that guides the final stage of tube growth. We developed a genetic screen in Arabidopsis thaliana that tags mutant pollen with a cell-autonomous marker carried on an insertion element. We found 32 haploid-disrupting (hapless) mutations that define genes required for pollen grain development, pollen tube growth in the stigma and style, or pollen tube growth and guidance in the ovary. We also identified genomic DNA flanking the insertion element for eleven hap mutants and showed that hap1 disrupts AtMago, a gene whose ortholog is important for Drosophila cell polarity.
Genetics 10/2004; 168(2):971-82. · 4.01 Impact Factor
