319 research outputs found
DNA sensing by electrocatalysis with hemoglobin
Electrocatalysis offers a means of electrochemical signal amplification, yet in DNA-based sensors, electrocatalysis has required high-density DNA films and strict assembly and passivation conditions. Here, we describe the use of hemoglobin as a robust and effective electron sink for electrocatalysis in DNA sensing on low-density DNA films. Protein shielding of the heme redox center minimizes direct reduction at the electrode surface and permits assays on low-density DNA films. Electrocatalysis with methylene blue that is covalently tethered to the DNA by a flexible alkyl chain linkage allows for efficient interactions with both the base stack and hemoglobin. Consistent suppression of the redox signal upon incorporation of a single cytosine-adenine (CA) mismatch in the DNA oligomer demonstrates that both the unamplified and the electrocatalytically amplified redox signals are generated through DNA-mediated charge transport. Electrocatalysis with hemoglobin is robust: It is stable to pH and temperature variations. The utility and applicability of electrocatalysis with hemoglobin is demonstrated through restriction enzyme detection, and an enhancement in sensitivity permits femtomole DNA sampling
KH 15D: A Spectroscopic Binary
We present the results of a high-resolution spectroscopic monitoring program
of the eclipsing pre-main-sequence star KH 15D that reveal it to be a
single-line spectroscopic binary. We find that the best-fit Keplerian model has
a period P = 48.38 days, which is nearly identical to the photometric period.
Thus, we find the best explanation for the periodic dimming of KH 15D is that
the binary motion carries the currently visible star alternately above and
below the edge of an obscuring cloud. The data are consistent with the models
involving an inclined circumstellar disk, as recently proposed by Winn et al.
(2004) and Chiang & Murray-Clay (2004). We show that the mass ratio expected
from models of PMS evolution, together with the mass constraints for the
visible star, restrict the orbital eccentricity to 0.68 < e < 0.80 and the mass
function to 0.125 < Fm < 0.5 Msun.Comment: 8 pages, 4 figures, 3 tables, accepted for publication in September
AJ. Discussion of rotational velocity deferred to Hamilton, et al. (2004, in
prep). Previously reported vsini value in error; Replaced Table 3 with new
Figure 3; Added new Table 2 showing individual radial velocities w.r.t. each
reference star; Fixed typo in Figure
Weighted Sobolev spaces of radially symmetric functions
We prove dilation invariant inequalities involving radial functions,
poliharmonic operators and weights that are powers of the distance from the
origin. Then we discuss the existence of extremals and in some cases we compute
the best constants.Comment: 38 page
The Orbit and Occultations of KH 15D
The unusual flux variations of the pre-main-sequence binary star KH 15D have
been attributed to occultations by a circumbinary disk. We test whether or not
this theory is compatible with newly available data, including recent radial
velocity measurements, CCD photometry over the past decade, and photographic
photometry over the past 50 years. We find the model to be successful, after
two refinements: a more realistic motion of the occulting feature, and a halo
around each star that probably represents scattering by the disk. The occulting
feature is exceptionally sharp-edged, raising the possibility that the dust in
the disk has settled into a thin layer, and providing a tool for fine-scale
mapping of the immediate environment of a T Tauri star. However, the window of
opportunity is closing, as the currently visible star may be hidden at all
orbital phases by as early as 2008.Comment: To appear in ApJ [16 pages, 13 figures
Sequence analysis in Bos taurus reveals pervasiveness of X–Y arms races in mammalian lineages
Studies of Y Chromosome evolution have focused primarily on gene decay, a consequence of suppression of crossing-over with the X Chromosome. Here, we provide evidence that suppression of X-Y crossing-over unleashed a second dynamic: selfish X-Y arms races that reshaped the sex chromosomes in mammals as different as cattle, mice, and men. Using super-resolution sequencing, we explore the Y Chromosome o
Factors associated with positive urine cultures in cats with subcutaneous ureteral bypass system implantation
Objectives
The aims of this study were to report the postoperative incidence of subcutaneous ureteral bypass (SUB)-associated bacteriuria and risk factors in a large population of UK cats, to identify the commonly implicated isolates in these cases and to report associations of positive postoperative urine cultures with device occlusion or a need for further surgery.
Methods
Electronic clinical records were reviewed to identify cats with ureteral obstruction that underwent unilateral or bilateral SUB implantation between September 2011 and September 2019. In total, 118 client-owned cats were included in the study population. Information recorded included signalment, history, surgical and biochemical factors, urinalysis and culture results. Multivariable logistic regression was performed to identify variables associated with a positive postoperative culture.
Results
In total, 10 cats (8.5%) had a positive postoperative culture within 1 month postsurgery and 28 cats (23.7%) within 1 year postsurgery. Cats with a positive preoperative culture were significantly more likely to have a positive culture within 6 months postoperatively (odds ratio [OR] 4.09, 95% confidence interval [CI] 1.18–14.18; P = 0.026). Of the 14 cats with a positive preoperative culture, six (42.9%) returned a positive culture within 1 year postoperatively, and in four cases (66.7%) the same isolate was identified. Cats with a higher end-anaesthetic rectal temperature were significantly less likely to return a positive culture within 3 months (OR 0.398, 95% CI 0.205–0.772; P = 0.006) postsurgery. Cats culturing positive for Escherichia coli at any time point (OR 4.542, 95% CI 1.485–13.89; P = 0.008) were significantly more likely to have their implant removed or replaced.
Conclusions and relevance
Perioperative hypothermia and preoperative positive culture were independent predictors of a postoperative positive culture and this should be taken into consideration when managing these cases. Positive postoperative culture rates were higher than have previously been reported
Compactness and existence results in weighted Sobolev spaces of radial functions. Part II: Existence
We prove existence and multiplicity results for finite energy solutions to
the nonlinear elliptic equation where is a radial domain (bounded or
unbounded) and satisfies on if and as
if is unbounded. The potential may be vanishing or unbounded at
zero or at infinity and the nonlinearity may be superlinear or sublinear.
If is sublinear, the case with is also considered.Comment: 29 pages, 8 figure
Perinatal maternal antibiotic exposure augments lung injury in offspring in experimental bronchopulmonary dysplasia
Copyright © 2020 the American Physiological Society. During the newborn period, intestinal commensal bacteria influence pulmonary mucosal immunology via the gut-lung axis. Epidemiological studies have linked perinatal antibiotic exposure in human newborns to an increased risk for bronchopulmonary dysplasia, but whether this effect is mediated by the gut-lung axis is unknown. To explore antibiotic disruption of the newborn gut-lung axis, we studied how perinatal maternal antibiotic exposure influenced lung injury in a hyperoxia-based mouse model of bronchopulmonary dysplasia. We report that disruption of intestinal commensal colonization during the perinatal period promotes a more severe bronchopulmonary dysplasia phenotype characterized by increased mortality and pulmonary fibrosis. Mechanistically, metagenomic shifts were associated with decreased IL-22 expression in bronchoalveolar lavage and were independent of hyperoxia-induced inflammasome activation. Collectively, these results demonstrate a previously unrecognized influence of the gut-lung axis during the development of neonatal lung injury, which could be leveraged to ameliorate the most severe and persistent pulmonary complication of preterm birth
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