Charges, outcomes, and complications: a comparison of magnetic sphincter augmentation versus laparoscopic Nissen fundoplication for the treatment of GERD.

BACKGROUND: Magnetic sphincter augmentation (MSA) is approved for uncomplicated GERD. Multiple studies have shown MSA to compare favorably to laparoscopic Nissen fundoplication (LNF) in terms of symptom control with results out to 5 years. The MSA device itself, however, is an added cost to an anti-reflux surgery, and direct cost comparison studies have not been done between MSA and LNF. The aim of the study was to compare charges, complications, and outcome of MSA versus LNF at 1 year. METHODS: This is a retrospective analysis of all patients who underwent MSA or LNF for the treatment of GERD between January 2010 and June 2013. Patient charges were collected for the surgical admission. We also collected data on 30-day complications and symptom control at 1 year assessed by GERD-HRQL score and PPI use. RESULTS: There were 119 patients included in the study, 52 MSA and 67 LNF. There was no significant difference between the mean charges for MSA and LNF ($48,491 vs. $50,111, p = 0.506). There were significant differences in OR time (66 min MSA vs. 82 min LNF, p < 0.01) and LOS (17 h MSA vs. 38 h LNF, p < 0.01). At 1-year follow-up, mean GERD-HRQL was 4.3 for MSA versus 5.1 for LNF (p = 0.47) and 85 % of MSA patients versus 92 % of LNF patients were free from PPIs (p = 0.37). MSA patients reported less gas bloat symptoms (23 vs. 53 %, p ≤ 0.01) and inability to belch (10 vs. 36 %, p ≤ 0.01) and vomit (4 vs. 19 %, p ≤ 0.01). CONCLUSION: The side effect profile of MSA is better than LNF as evidenced by less gas bloat and increase ability to belch and vomit. LNF and MSA are comparable in symptom control, safety, and overall hospital charges. The charge for the MSA device is offset by less charges in other categories as a result of the shorter operative time and LOS.

A new topology of the HK97-like fold revealed in Bordetella bacteriophage by cryoEM at 3.5 A resolution.

Bacteriophage BPP-1 infects and kills Bordetella species that cause whooping cough. Its diversity-generating retroelement (DGR) provides a naturally occurring phage-display system, but engineering efforts are hampered without atomic structures. Here, we report a cryo electron microscopy structure of the BPP-1 head at 3.5 Å resolution. Our atomic model shows two of the three protein folds representing major viral lineages: jellyroll for its cement protein (CP) and HK97-like ('Johnson') for its major capsid protein (MCP). Strikingly, the fold topology of MCP is permuted non-circularly from the Johnson fold topology previously seen in viral and cellular proteins. We illustrate that the new topology is likely the only feasible alternative of the old topology. ß-sheet augmentation and electrostatic interactions contribute to the formation of non-covalent chainmail in BPP-1, unlike covalent inter-protein linkages of the HK97 chainmail. Despite these complex interactions, the termini of both CP and MCP are ideally positioned for DGR-based phage-display engineering. DOI: http://dx.doi.org/10.7554/eLife.01299.001.

Target site recognition by a diversity-generating retroelement.

Diversity-generating retroelements (DGRs) are in vivo sequence diversification machines that are widely distributed in bacterial, phage, and plasmid genomes. They function to introduce vast amounts of targeted diversity into protein-encoding DNA sequences via mutagenic homing. Adenine residues are converted to random nucleotides in a retrotransposition process from a donor template repeat (TR) to a recipient variable repeat (VR). Using the Bordetella bacteriophage BPP-1 element as a prototype, we have characterized requirements for DGR target site function. Although sequences upstream of VR are dispensable, a 24 bp sequence immediately downstream of VR, which contains short inverted repeats, is required for efficient retrohoming. The inverted repeats form a hairpin or cruciform structure and mutational analysis demonstrated that, while the structure of the stem is important, its sequence can vary. In contrast, the loop has a sequence-dependent function. Structure-specific nuclease digestion confirmed the existence of a DNA hairpin/cruciform, and marker coconversion assays demonstrated that it influences the efficiency, but not the site of cDNA integration. Comparisons with other phage DGRs suggested that similar structures are a conserved feature of target sequences. Using a kanamycin resistance determinant as a reporter, we found that transplantation of the IMH and hairpin/cruciform-forming region was sufficient to target the DGR diversification machinery to a heterologous gene. In addition to furthering our understanding of DGR retrohoming, our results suggest that DGRs may provide unique tools for directed protein evolution via in vivo DNA diversification.