74 research outputs found
Potentiation of endogenous nitric oxide with superoxide dismutase inhibits platelet-mediated thrombosis in injured and stenotic arteries
AbstractObjectives. We tested the hypothesis that dismutation of superoxide anion increases endogenous levels of nitric oxide, resulting in inhibition of cyclic variations in blood flow in arteries that are injured and stenotic.Background. Platelet adhesion and aggregation leading to cyclic flow variations might result, in part, from generation of superoxide anion that can deplete endogenously produced nitric oxide.Methods. Spontaneous cyclic flow variations, monitored with a proximal Doppler probe, were induced in the carotid artery of anesthetized rabbits by clamping the vessel with forceps and placing a high grade stenosis at the site of injury. Bovine copper/zinc superoxide dismutase (12 mg/kg body weight, n = 5), a synthetic low molecular weight mimetic (12 mg/kg, n = 8) or buffer vehicle (n = 8) was administered intravenously as divided boluses over 45 min, and the frequency of cyclic flow variations was monitored for 4 h.Results. Cyclic flow variations remained stable for 4 h in vehicle-treated animals (15 Ā± 1 [mean Ā± SEM]/30 min at baseline and 16 Ā± 1/30 min after 4 h, n = 8) but exhibited a marked and persistent reduction in animals given copper/zinc superoxide dismutase (from 14 Ā± 1/30 min at baseline to 4 Ā± 1/30 min after 4 h) or the mimetic (from 15 Ā± 1/30 min at baseline to 3 Ā± 1/30 min after 4 h, p < 0.005). They were restored in three of four mimetic-treated animals during infusion of NG-monomethyl-l-arginine (100 mg/kg), an inhibitor of nitric oxide production. In addition, levels of cyclic guanosine 5ā²-monophosphate in platelets were elevated after administration of the mimetic (from 2.4 Ā± 0.5 fmol/106platelets at baseline to 4.9 Ā± 0.6 fmol/106platelets 45 min after the mimetic, p < 0.03, n = 6), whereas mean arterial blood pressure was decreased and flow velocity in the carotid artery was increased consistent with mediation of the effect on cyclic flow variations by increased endogenous nitric oxide.Conclusions. Dismutation of superoxide anion appears to attenuate platelet thrombus formation at a site of vessel injury by potentiation of endogenously produced nitric oxide. This approach may have utility to inhibit platelet-rich thrombosis in injured and stenotic arteries where production of superoxide anion is increased
Mediatorāinduced activation of xanthine oxidase in endothelial cells
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154271/1/fsb2003013008.pd
Recommended from our members
A Paper-Based Multiplexed Transaminase Test for Low-Cost, Point-of-Care Liver Function Testing
In developed nations, monitoring for drug-induced liver injury through serial measurements of serum transaminases [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] in at-risk individuals is the standard of care. Despite the need, monitoring for drug-related hepatotoxicity in resource-limited settings is often limited by expense and logistics, even for patients at highest risk. This article describes the development and clinical testing of a paper-based, multiplexed microfluidic assay designed for rapid, semiquantitative measurement of AST and ALT in a fingerstick specimen. Using 223 clinical specimens obtained by venipuncture and 10 fingerstick specimens from healthy volunteers, we have shown that our assay can, in 15 min, provide visual measurements of AST and ALT in whole blood or serum, which allow the user to place those values into one of three readout ābinsā [5Ć ULN, corresponding to tuberculosis/HIV treatment guidelines] with >90% accuracy. These data suggest that the ultimate point-of-care fingerstick device will have high impact on patient care in low-resource settings.Chemistry and Chemical Biolog
Pulmonary endothelial cell ATP depletion following intestinal ischemia
Multiple organ failure (MOF) is known to follow systemic inflammatory mediator activation associated with intestinal ischemia--reperfusion injury. In particular, the pulmonary microvasculature appears to be susceptible to MOF-related injury. This study was designed to evaluate the hypothesis that non-cellular plasma factors associated with intestinal ischemia without reperfusion also mediate pulmonary endothelial cell injury. Male Sprague--Dawley rats had intestinal ischemia induced by microvascular clip occlusion of the superior mesenteric artery for 30, 60, 90, or 120 min. Following each period of ischemia, plasma samples were obtained from the portal vein. Time-matched sham-operated animals served as controls. Monolayers of cultured rat pulmonary artery endothelial cells were then incubated with the plasma samples and ATP levels determined using a luciferin--luciferase assay. A 51Cr-release assay using labeled endothelial cells was performed under identical conditions to assess cytotoxicity. Endothelial cell ATP levels were 1.99 +/- 0.23 x 10-11 mole/[mu]g DNA in sham preparations. After a 4-hr incubation in plasma from the 90 and 120 min ischemia groups, cellular ATP levels fell significantly to 1.07 +/- 0.23 x 10-11 mole/[mu]g DNA, respectively (P P = NS). All animals survived 24 hr in the sham, 30, and 60 min groups. However, survival was 40 and 0% in the 90 and 120 min groups, respectively (P in vitro data with in vivo survival.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30022/1/0000390.pd
A search for technosignatures from TRAPPIST-1, LHS 1140, and 10 planetary systems in the Kepler field with the Green Bank Telescope at 1.15-1.73 GHz
As part of our ongoing search for technosignatures, we collected over three
terabytes of data in May 2017 with the L-band receiver (1.15-1.73 GHz) of the
100 m diameter Green Bank Telescope. These observations focused primarily on
planetary systems in the Kepler field, but also included scans of the recently
discovered TRAPPIST-1 and LHS 1140 systems. We present the results of our
search for narrowband signals in this data set with techniques that are
generally similar to those described by Margot et al. (2018). Our improved data
processing pipeline classified over of the 6 million detected
signals as anthropogenic Radio Frequency Interference (RFI). Of the remaining
candidates, 30 were detected outside of densely populated frequency regions
attributable to RFI. These candidates were carefully examined and determined to
be of terrestrial origin. We discuss the problems associated with the common
practice of ignoring frequency space around candidate detections in radio
technosignature detection pipelines. These problems include inaccurate
estimates of figures of merit and unreliable upper limits on the prevalence of
technosignatures. We present an algorithm that mitigates these problems and
improves the efficiency of the search. Specifically, our new algorithm
increases the number of candidate detections by a factor of more than four
compared to Margot et al. (2018).Comment: 17 pages, 9 figure
Global selective sweep of a highly inbred genome of the cattle parasite Neospora caninum
Neospora caninum, a cyst-forming apicomplexan parasite, is a leading cause of neuromuscular diseases in dogs as well as fetal abortion in cattle worldwide. The importance of the domestic and sylvatic life cycles of Neospora, and the role of vertical transmission in the expansion and transmission of infection in cattle, is not sufficiently understood. To elucidate the population genomics of Neospora, we genotyped 50 isolates collected worldwide from a wide range of hosts using 19 linked and unlinked genetic markers. Phylogenetic analysis and genetic distance indices resolved a single genotype of N. caninum. Whole-genome sequencing of 7 isolates from 2 different continents identified high linkage disequilibrium, significant structural variation, but only limited polymorphism genome-wide, with only 5,766 biallelic single nucleotide polymorphisms (SNPs) total. Greater than half of these SNPs (ā¼3,000) clustered into 6 distinct haploblocks and each block possessed limited allelic diversity (with only 4 to 6 haplotypes resolved at each cluster). Importantly, the alleles at each haploblock had independently segregated across the strains sequenced, supporting a unisexual expansion model that is mosaic at 6 genomic blocks. Integrating seroprevalence data from African cattle, our data support a global selective sweep of a highly inbred livestock pathogen that originated within European dairy stock and expanded transcontinentally via unisexual mating and vertical transmission very recently, likely the result of human activities, including recurrent migration, domestication, and breed development of bovid and canid hosts within similar proximities
Thrombospondin production and thrombospondin-mediated adhesion in U937 cells
U937 cells have low levels of surface thrombospondin (TSP) under control conditions but express higher levels after treatment for 1 day with 100 nM phorbol myristate acetate (PMA). Increased surface expression is due, in part, to increased biosynthesis. Untreated U937 cells do not adhere to TSP-coated plastic culture dishes but adhere strongly to TSP after stimulation with PMA. Untreated U937 cells also adhere weakly to endothelial cell monolayers while PMA-treated U937 cells attach strongly to monolayers of rat pulmonary artery endothelial cells. Endothelial cell adhesion appears to be mediated, in part, by TSP since antibodies to TSP partially inhibit.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29248/1/0000305.pd
- ā¦