Percutaneous radiologically guided gastrostomy tube placement: comparison of antegrade transoral and retrograde transabdominal approaches

PURPOSE:We aimed to compare the antegrade transoral and the retrograde transabdominal approaches for fluoroscopy-guided percutaneous gastrostomy tube (G-tube) placement.METHODS:Following institutional review board approval, all G-tubes at two academic hospitals (January 2014 to May 2015) were reviewed retrospectively. Retrograde approach was used at Hospital 1 and both antegrade and retrograde approaches were used at Hospital 2. Chart review determined type of anesthesia used during placement, dose of radiation used, fluoroscopy time, procedure time, medical history, and complications.RESULTS:A total of 149 patients (64 women, 85 men; mean age, 64.4±1.3 years) underwent G-tube placement, including 93 (62%) placed via the retrograde transabdominal approach and 56 (38%) placed via the antegrade transoral approach. Retrograde placement entailed fewer anesthesiology consultations (P < 0.001), less overall procedure time (P = 0.023), and less fluoroscopy time (P < 0.001). A comparison of approaches for placement within the same hospital demonstrated that the retrograde approach led to significantly reduced radiation dose (P = 0.022). There were no differences in minor complication rates (13%–19%; P = 0.430), or major complication rates 6%–7%; P = 0.871) between the two techniques.CONCLUSION:G-tube placement using the retrograde transabdominal approach is associated with less fluoroscopy time, procedure time, radiation exposure, and need for anesthesiology consultation with similar safety profile compared with the antegrade transoral approach. Additionally, it is hypothesized that decreased procedure time and anesthesiology consultation using the transoral approach are likely associated with reduced cost

Mismatch Repair–Independent Increase in Spontaneous Mutagenesis in Yeast Lacking Non-Essential Subunits of DNA Polymerase ε

Yeast DNA polymerase ε (Pol ε) is a highly accurate and processive enzyme that participates in nuclear DNA replication of the leading strand template. In addition to a large subunit (Pol2) harboring the polymerase and proofreading exonuclease active sites, Pol ε also has one essential subunit (Dpb2) and two smaller, non-essential subunits (Dpb3 and Dpb4) whose functions are not fully understood. To probe the functions of Dpb3 and Dpb4, here we investigate the consequences of their absence on the biochemical properties of Pol ε in vitro and on genome stability in vivo. The fidelity of DNA synthesis in vitro by purified Pol2/Dpb2, i.e. lacking Dpb3 and Dpb4, is comparable to the four-subunit Pol ε holoenzyme. Nonetheless, deletion of DPB3 and DPB4 elevates spontaneous frameshift and base substitution rates in vivo, to the same extent as the loss of Pol ε proofreading activity in a pol2-4 strain. In contrast to pol2-4, however, the dpb3Δdpb4Δ does not lead to a synergistic increase of mutation rates with defects in DNA mismatch repair. The increased mutation rate in dpb3Δdpb4Δ strains is partly dependent on REV3, as well as the proofreading capacity of Pol δ. Finally, biochemical studies demonstrate that the absence of Dpb3 and Dpb4 destabilizes the interaction between Pol ε and the template DNA during processive DNA synthesis and during processive 3′ to 5′exonucleolytic degradation of DNA. Collectively, these data suggest a model wherein Dpb3 and Dpb4 do not directly influence replication fidelity per se, but rather contribute to normal replication fork progression. In their absence, a defective replisome may more frequently leave gaps on the leading strand that are eventually filled by Pol ζ or Pol δ, in a post-replication process that generates errors not corrected by the DNA mismatch repair system

Sgs1 and Exo1 Redundantly Inhibit Break-Induced Replication and De Novo Telomere Addition at Broken Chromosome Ends

In budding yeast, an HO endonuclease-inducible double-strand break (DSB) is efficiently repaired by several homologous recombination (HR) pathways. In contrast to gene conversion (GC), where both ends of the DSB can recombine with the same template, break-induced replication (BIR) occurs when only the centromere-proximal end of the DSB can locate homologous sequences. Whereas GC results in a small patch of new DNA synthesis, BIR leads to a nonreciprocal translocation. The requirements for completing BIR are significantly different from those of GC, but both processes require 5′ to 3′ resection of DSB ends to create single-stranded DNA that leads to formation of a Rad51 filament required to initiate HR. Resection proceeds by two pathways dependent on Exo1 or the BLM homolog, Sgs1. We report that Exo1 and Sgs1 each inhibit BIR but have little effect on GC, while overexpression of either protein severely inhibits BIR. In contrast, overexpression of Rad51 markedly increases the efficiency of BIR, again with little effect on GC. In sgs1Δ exo1Δ strains, where there is little 5′ to 3′ resection, the level of BIR is not different from either single mutant; surprisingly, there is a two-fold increase in cell viability after HO induction whereby 40% of all cells survive by formation of a new telomere within a few kb of the site of DNA cleavage. De novo telomere addition is rare in wild-type, sgs1Δ, or exo1Δ cells. In sgs1Δ exo1Δ, repair by GC is severely inhibited, but cell viaiblity remains high because of new telomere formation. These data suggest that the extensive 5′ to 3′ resection that occurs before the initiation of new DNA synthesis in BIR may prevent efficient maintenance of a Rad51 filament near the DSB end. The severe constraint on 5′ to 3′ resection, which also abrogates activation of the Mec1-dependent DNA damage checkpoint, permits an unprecedented level of new telomere addition

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Seismic Performance Of Precast Columns With Mechanically Spliced Column-Footing Connections

This paper presents the results from a large-scale experimental study that was conducted at the University of Nevada, Reno, NV. Five half-scale bridge column models were constructed and tested under reversed slow cyclic loading. The study focused on developing four new moment connections at column-footing joints for accelerated bridge construction in regions of high seismicity. The new connections were employed in precast columns, each using mechanical splices to create connectivity with reinforcing bars in a cast-in-place footing. Two different mechanical splices were studied: an upset headed coupler and a grout-filled sleeve coupler. Along with the splice type, the location of couplers within the plastic hinge zone was also a test variable. All precast models were designed with the intent to emulate conventional cast-in-place construction and, thus, were compared with a conventional cast-inplace test model. Results indicate the behavior of these new connections was similar to that of conventional cast-in-place construction with respect to key response parameters, although the plastic hinge mechanism could be significantly affected by the couplers. © 2014, American Concrete Institute

Testing And Analysis Of Precast Columns With Grouted Sleeve Connections And Shifted Plastic Hinging

Prefabricated reinforced concrete column connections employing grouted sleeve (GS) splices enable rapid construction, are familiar to contractors, and their detailing resembles cast-in-place (CIP) construction. Previous studies showed disrupted plastic hinge formation in the stiff sleeve region. The proposed design method shifts the plastic hinge location above the sleeve region, which effectively increases the plastic rotation capacity and ductility. Plastic hinge shifting was realized by using transition splicing and high-strength steel reinforcement in the connecting element (footing). The proposed method was investigated experimentally using two 0.42-scale column tests under slow cyclic loading and a series of uniaxial tensile tests. Results indicate that good ductility can be achieved compared with conventional CIP construction and previously tested GS connections details. Experimental and analytical moment-curvature results were used to support discussion of design considerations and of an approximate method for calculating the displacement ductility of precast columns with GS connections and shifted plastic hinging

Shifted Plastic Hinging For Grouted Sleeve Column Connections

Accelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. For bridge substructure elements, ABC typically requires connections, such as mechanical couplers, between prefabricated elements where moment demands are largest. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast concrete elements. Therefore, they have gained interest for use in ABC in seismic regions. Large-scale precast column models using GS splices were designed and tested using a shifted plastic hinge (SPH) concept to minimize the damage in the footing and retain the column ductility. The testing matrix considered aspect ratio, moment gradient, and splicing details. Results showed that SPH can be used for flexural and flexural-shear columns; plastic hinging formed above the sleeve region and footing dowels remained elastic to minimize footing damage. Each precast column exhibited good ductility and energy dissipation, and formed slightly shorter SPH length compared with conventional columns

Predictors of Active Extravasation and Complications after Conventional Angiography for Acute Intraabdominal Bleeding

Conventional angiography is used to evaluate and treat possible sources of intraabdominal bleeding, though it may cause complications such as contrast-induced nephropathy (CIN). The study’s purpose was to identify factors predicting active extravasation and complications during angiography for acute intraabdominal bleeding. All conventional angiograms for acute bleeding (January 2013–June 2015) were reviewed retrospectively, including 75 angiograms for intraabdominal bleeding in 70 patients. Demographics, comorbidities, vital signs, complications within one month, and change in hematocrit (ΔHct) and fluids and blood products administered over the 24 h prior to angiography were recorded. Of 75 exams, 20 (27%) demonstrated extravasation. ΔHct was the only independent predictor of extravasation (p = 0.017), with larger ΔHct (−17%) in patients with versus those without extravasation (–1%) (p = 0.01). CIN was the most common complication, occurring in 10 of 66 angiograms (15%). Glomerular filtration rate (GFR) was the only independent predictor (p = 0.03); 67% of patients with GFR &lt; 30, 29% of patients with GFR 30–60, and 8% of patients with GFR &gt; 60 developed CIN. For patients with intraabdominal bleeding, greater ΔHct decrease over 24 h before angiography predicts active extravasation. Pre-existing renal impairment predicts CIN. Patients with large hematocrit declines should be triaged for rapid angiography, though benefits can be weighed with the risk of renal impairment

Break-induced replication requires all essential DNA replication factors except those specific for pre-RC assembly

Break-induced replication (BIR) is an efficient homologous recombination (HR) pathway employed to repair a DNA double-strand break (DSB) when homology is restricted to one end. All three major replicative DNA polymerases are required for BIR, including the otherwise nonessential Pol32 subunit. Here we show that BIR requires the replicative DNA helicase (Cdc45, the GINS, and Mcm2–7 proteins) as well as Cdt1. In contrast, both subunits of origin recognition complex (ORC) and Cdc6, which are required to create a prereplication complex (pre-RC), are dispensable. The Cdc7 kinase, required for both initiation of DNA replication and post-replication repair (PRR), is also required for BIR. Ubiquitination and sumoylation of the DNA processivity clamp PCNA play modest roles; in contrast, PCNA alleles that suppress pol32Δ's cold sensitivity fail to suppress its role in BIR, and are by themselves dominant inhibitors of BIR. These results suggest that origin-independent BIR involves cross-talk between normal DNA replication factors and PRR