1,312 research outputs found
Cold snare piecemeal resection of colonic and duodenal polyps ≥1 cm
BACKGROUND: Endoscopic removal of duodenal and colorectal adenomas is currently considered to be the standard of care for prevention of adenocarcinoma. The use of cautery carries a risk of delayed bleeding, post-polypectomy syndrome, and perforation. We examined the safety and feasibility of removing colonic and duodenal polyps ≥ 1 cm using a piecemeal cold snare polypectomy technique.
PATIENTS: The study included 15 patients with duodenal polyps ≥ 1 cm and 15 patients with colonic polyps ≥ 1 cm.
MAIN OUTCOME MEASUREMENTS: Bleeding, perforation, abdominal pain, or hospitalization occurring within 2 weeks of polypectomy.
RESULTS: Between 24 August 2011 and 29 April 2013, 15 patients had removal of duodenal polyps ≥ 1 cm. Mean patient age was 64 years and 9/15 patients were male. The mean polyp size was 24 mm (10 - 60 mm). All polyps were removed with a cold snare and some required cold biopsy forceps. One patient required hospitalization for gastrointestinal blood loss 7 days post-polypectomy; this patient was using Coumadin. Between 27 February 2012 and 30 May 2013, 15 patients underwent resection of a ≥ 1 cm colonic polyp. Mean patient age was 68 years and 9/15 were male. The mean polyp size was 20 mm (10 - 45 mm). All polyps were primarily removed with a cold snare. None of the patients required hemostatic clips for control of immediate bleeding. One patient presented to the emergency department with abdominal pain 1 day after initial endoscopy. CT scan showed no abnormalities and the patient was discharged.
CONCLUSIONS: Cold snare polypectomy for large duodenal and colonic polyps is technically feasible and may have a favorable safety profile compared to standard electrocautery-based endoscopic resection. Comparative trials are required to determine the relative safety and efficacy of cold snare techniques for complete and durable resection of large polyps compared to standard hot snare methods
U-Pb Studies of Zircon Cores and Overgrowths, and Monazite: Implications for Age and Petrogenesis of the Northeastern Idaho Batholith
U/Pb isotopic studies of zircons, many containing xenocrystic cores with euhedral overgrowths, and monazite from igneous rocks and metasedimentary inclusions of the northeastern Idaho batholith yield linear arrays on concordia diagrams. We interpret these as mixing lines between an old component (cores) and a young component (overgrowths and zircons without cores). The lower intercept of such arrays with concordia may yield the minimum age of the rocks if the overgrowths and zircons without cores are discordant, or the crystallization age if they are concordant. Monazites yield apparently concordant ages either equal or less than the lower intercept zircon ages. The samples studied yield lower intercept ages ranging from 73.5+ or -6 Ma (foliated quartz diorite) to 46.5+ or -1 Ma (feldspar megacryst granite); ages obtained are consistent with crosscutting relations observed in the field. Upper intercepts yield ages of 1700 to 2349 Ma. These are interpreted to indicate the mean age of xenocrystic zircon. Studies of zircons from xenolith suites indicate that they could represent the source of the old zircon component. The zircon and monazite results, the generally high initial 87Sr/86Sr ratios of the igneous rocks, and the isotopic composition of Pb in feldspar indicate that the magmas were derived anatectically from a continental crustal source or were extensively mixed with such old crust prior to or during emplacement
Central spindle self-organization and cytokinesis in artificially activated sea urchin eggs
Author Posting. © Marine Biological Laboratory, 2016. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 230, no.2 (2016): 85-95.The ability of microtubules of the mitotic apparatus
to control the positioning and initiation of the cleavage
furrow during cytokinesis was first established from
studies on early echinoderm embryos. However, the identity
of the microtubule population that imparts cytokinetic signaling
is unclear. The two main––and not necessarily mutually
exclusive–– candidates are the central spindle and the
astral rays. In the present study, we examined cytokinesis in
ammonia-activated sea urchin eggs, which lack paternally
derived centrosomes and undergo mitosis mediated by unusual
anastral, bipolar mini-spindles. Live cell imaging and
immunolabeling for microtubules and the centralspindlin
constituent and kinesin-related protein, MKLP1, demonstrated
that furrowing in ammonia-activated eggs was associated
with aligned arrays of centralspindlin-linked, opposed
bundles of antiparallel microtubules. These autonomous, zipper-
like arrays were not associated with a mitotic apparatus,
but did possess characteristics similar to the central spindle
region of control, fertilized embryos. Our results highlight the
self-organizing nature of the central spindle region and its
ability to induce cytokinesis-like furrowing, even in the absence
of a complete mitotic apparatus.This research was
supported by student/faculty summer research grants from
the Dickinson College Research and Development Committee
to JHH; Laura and Arthur Colwin Summer Research
Fellowships from the MBL to JHH and CBS; a National
Science Foundation Major Research Instrumentation grant
to JHH (MRI-0320606); and a NSF collaborative research
grant to JHH (MCB-1412688) and to CBS (MCB-
1412734)
Spontaneous symmetry breaking in strong-coupling lattice QCD at high density
We determine the patterns of spontaneous symmetry breaking in strong-coupling
lattice QCD in a fixed background baryon density. We employ a
next-nearest-neighbor fermion formulation that possesses the SU(N_f)xSU(N_f)
chiral symmetry of the continuum theory. We find that the global symmetry of
the ground state varies with N_f and with the background baryon density. In all
cases the condensate breaks the discrete rotational symmetry of the lattice as
well as part of the chiral symmetry group.Comment: 10 pages, RevTeX 4; added discussion of accidental degeneracy of
vacuum after Eq. (35
A chiral crystal in cold QCD matter at intermediate densities?
The analogue of Overhauser (particle-hole) pairing in electronic systems
(spin-density waves with non-zero total momentum ) is analyzed in
finite-density QCD for 3 colors and 2 flavors, and compared to the
color-superconducting BCS ground state (particle-particle pairing, =0). The
calculations are based on effective nonperturbative four-fermion interactions
acting in both the scalar diquark as well as the scalar-isoscalar quark-hole
('') channel. Within the Nambu-Gorkov formalism we set up the coupled
channel problem including multiple chiral density wave formation, and evaluate
the resulting gaps and free energies. Employing medium-modified
instanton-induced 't Hooft interactions, as applicable around
GeV (or 4 times nuclear saturation density), we find the 'chiral crystal phase'
to be competitive with the color superconductor.Comment: 14 pages ReVTeX, including 11 ps-/eps-figure
Revised Phase Diagram of the Gross-Neveu Model
We confirm earlier hints that the conventional phase diagram of the discrete
chiral Gross-Neveu model in the large N limit is deficient at non-zero chemical
potential. We present the corrected phase diagram constructed in mean field
theory. It has three different phases, including a kink-antikink crystal phase.
All transitions are second order. The driving mechanism for the new structure
of baryonic matter in the Gross-Neveu model is an Overhauser type instability
with gap formation at the Fermi surface.Comment: Revtex, 12 pages, 15 figures; v2: Axis labelling in Fig. 9 correcte
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