2,449 research outputs found
Acute neuroinflammation induces AIS structural plasticity in a NOX2-dependent manner
Background Chronic microglia-mediated inflammation and oxidative stress are well-characterized underlying factors in neurodegenerative disease, whereby reactive inflammatory microglia enhance ROS production and impact neuronal integrity. Recently, it has been shown that during chronic inflammation, neuronal integrity is compromised through targeted disruption of the axon initial segment (AIS), the axonal domain critical for action potential initiation. AIS disruption was associated with contact by reactive inflammatory microglia which wrap around the AIS, increasing association with disease progression. While it is clear that chronic microglial inflammation and enhanced ROS production impact neuronal integrity, little is known about how acute microglial inflammation influences AIS stability. Here, we demonstrate that acute neuroinflammation induces AIS structural plasticity in a ROS-mediated and calpain-dependent manner. Methods C57BL/6J and NOX2â/â mice were given a single injection of lipopolysaccharide (LPS; 5 mg/kg) or vehicle (0.9% saline, 10 mL/kg) and analyzed at 6 hâ2 weeks post-injection. Anti-inflammatory Didox (250 mg/kg) or vehicle (0.9% saline, 10 mL/kg) was administered beginning 24 h post-LPS injection and continued for 5 days; animals were analyzed 1 week post-injection. Microglial inflammation was assessed using immunohistochemistry (IHC) and RT-qPCR, and AIS integrity was quantitatively analyzed using ankyrinG immunolabeling. Data were statistically compared by one-way or two-way ANOVA where mean differences were significant as assessed using Tukeyâs post hoc analysis. Results LPS-induced neuroinflammation, characterized by enhanced microglial inflammation and increased expression of ROS-producing enzymes, altered AIS protein clustering. Importantly, inflammation-induced AIS changes were reversed following resolution of microglial inflammation. Modulation of the inflammatory response using anti-inflammatory Didox, even after significant AIS disruption occurred, increased the rate of AIS recovery. qPCR and IHC analysis revealed that expression of microglial NOX2, a ROS-producing enzyme, was significantly increased correlating with AIS disruption. Furthermore, ablation of NOX2 prevented inflammation-induced AIS plasticity, suggesting that ROS drive AIS structural plasticity. Conclusions In the presence of acute microglial inflammation, the AIS undergoes an adaptive change that is capable of spontaneous recovery. Moreover, recovery can be therapeutically accelerated. Together, these findings underscore the dynamic capabilities of this domain in the presence of a pathological insult and provide evidence that the AIS is a viable therapeutic target
COMPTEL solar flare observations
COMPTEL as part of a solar target of opportunity campaign observed the sun during the period of high solar activity from 7-15 Jun. 1991. Major flares were observed on 9 and 11 Jun. Although both flares were large GOES events (greater than or = X10), they were not extraordinary in terms of gamma-ray emission. Only the decay phase of the 15 Jun. flare was observed by COMPTEL. We report the preliminary analysis of data from these flares, including the first spectroscopic measurement of solar flare neutrons. The deuterium formation line at 2.223 MeV was present in both events and for at least the 9 Jun. event, was comparable to the flux in the nuclear line region of 4-8 MeV, consistent with Solar-Maximum Mission (SSM) Observations. A clear neutron signal was present in the flare of 9 Jun. with the spectrum extending up to 80 MeV and consistent in time with the emission of gamma-rays, confirming the utility of COMPTEL in measuring the solar neutron flux at low energies. The neutron flux below 100 MeV appears to be lower than that of the 3 Jun. 1982 flare by more than an order of magnitude. The neutron signal of the 11 Jun. event is under study. Severe dead time effects resulting from the intense thermal x-rays require significant corrections to the measured flux which increase the magnitude of the associated systematic uncertainties
Epidemiology of coagulase-negative staphylococci intramammary infection in dairy cattle and the effect of bacteriological culture misclassification
Response to Comment on: Luijf et al. Premeal Injection of Rapid-Acting Insulin Reduces Postprandial Glycemic Excursions in Type 1 Diabetes. Diabetes Care 2010;33:2152â2155
Escape Behavior of Quantum Two-Particle Systems with Coulomb Interactions
Quantum escapes of two particles with Coulomb interactions from a confined
one-dimensional region to a semi-infinite lead are discussed by the probability
of particles remaining in the confined region, i.e. the survival probability,
in comparison with one or two free particles. For free-particle systems the
survival probability decays asymptotically in power as a function of time. On
the other hand, for two-particle systems with Coulomb interactions it shows an
exponential decay in time. A difference of escape behaviors between Bosons and
Fermions is considered as quantum effects of identical two particles such as
the Pauli exclusion principle. The exponential decay in the survival
probability of interacting two particles is also discussed in a viewpoint of
quantum chaos based on a distribution of energy level spacings.Comment: 10 pages, 7 figure
Signals from the Noise: Image Stacking for Quasars in the FIRST Survey
We present a technique to explore the radio sky into the nanoJansky regime by
employing image stacking using the FIRST survey. We first discuss the
non-intuitive relationship between the mean and median values of a distribution
that is dominated by noise, followed by an analysis of the systematic effects
present in FIRST's 20cm VLA snapshot images. Image stacking allows us to
recover the properties of source populations with fluxes a factor of 30 or more
below the rms noise level. Mean estimates of radio flux density, luminosity,
etc., are derivable for any source class having arcsecond positional accuracy.
We use this technique to compute the mean radio properties for 41,295 quasars
from the SDSS DR3 catalog. There is a tight correlation between optical and
radio luminosity, with the radio luminosity increasing as the 0.85 power of
optical luminosity. This implies declining radio-loudness with optical
luminosity: the most luminous objects (M=-28.5) have average radio-to-optical
ratios 3 times lower than the least luminous objects (M=-20). There is also a
striking correlation between optical color and radio loudness: quasars that are
either redder or bluer than the norm are brighter radio sources, with objects
0.8 magnitudes redder than the SDSS composite spectrum having radio-loudness
ratios that are higher by a factor of 10. We explore the longstanding question
of whether a radio-loud/radio-quiet dichotomy exists in quasars, finding that
optical selection effects probably dominate the distribution function of radio
loudness, which has at most a modest (~20%) inflection between the radio-loud
and radio-quiet ends of the distribution. We also find, surprisingly, that
broad absorption line quasars have higher mean radio flux densities, with the
greatest disparity arising in the rare low-ionization BAL subclass.Comment: 17 pages, 19 figures, accepted by ApJ; corrected error in absolute
magnitude
Contact frequency determines outcome of basal insulin initiation trials in type 2 diabetes
Aims/hypothesis The aim of the present study was to investigate whether predetermined contact frequency with the study teamand endpoint insulin dose are associated with study outcomes in basal insulin initiation trials in type 2 diabetes. Methods A systematic Medline search was performed. Using data from the selected studies, contact frequency was plotted against HbA(1c) reduction and endpoint insulin dose. The importance of face-to-face vs telephone contact was also analysed. Insulin dose was plotted against HbA(1c) reduction, hypoglycaemia rate and weight gain. To investigate non-specific study effects, the relationship between contact frequency and HbA(1c) was also assessed in dipeptidyl peptidase-4 (DPP-4) inhibitor trials. Results The reduction in HbA(1c) was highly correlated with contact frequency and endpoint insulin dose (r(2)=0.751, p<0.001 and r(2)=0.433, p=0.008, respectively). However, after adjusting for contact frequency, the relationship between insulin dose and HbA(1c) reduction was no longer significant (p=0.270). The frequency of both clinical and telephone contacts were independent predictors of HbA(1c) improvement (p=0.010 and p<0.001, respectively). We found no dose response relationship between end-of-study insulin dose and hypoglycaemia or weight gain. In DPP-4 inhibitor studies, contact frequency was not positively associated with HbA(1c). Conclusions/interpretation The frequency of contact with the study team is highly correlated with the improvement in HbA(1c) achieved in basal insulin initiation trials in type 2 diabetic patients. This has important implications for trial design and interpretation, as well as for clinical car
Effects of light at night on laboratory animals and research outcomes
Light has substantial influences on the physiology and behavior of most laboratory animals. As such, lighting conditions within animal rooms are potentially significant, and often underappreciated variables within experiments. Disruption of the light/dark cycle, primarily by exposing animals to light at night (LAN), disturbs biological rhythms and has widespread physiological consequences due to mechanisms such as melatonin suppression, sympathetic stimulation, and altered circadian clock gene expression. Thus, attention to the lighting environment of laboratory animals and maintaining consistency of a light/dark cycle is imperative for study reproducibility. Light intensity as well as wavelength, photoperiod, and timing are all important variables. Although modern rodent facilities are designed to facilitate appropriate light cycling, there are simple ways to modify rooms to prevent extraneous light exposure during the dark period. Attention to lighting conditions of laboratory animals by both researchers and research care staff ensures best practices for maintaining animal welfare, as well as reproducibility of research results
Relativistic and Radiative Energy Shifts for Rydberg States
We investigate relativistic and quantum electrodynamic effects for
highly-excited bound states in hydrogenlike systems (Rydberg states). In
particular, hydrogenic one-loop Bethe logarithms are calculated for all
circular states (l = n-1) in the range 20 <= n <= 60 and successfully compared
to an existing asymptotic expansion for large principal quantum number n. We
provide accurate expansions of the Bethe logarithm for large values of n, for
S, P and circular Rydberg states. These three expansions are expected to give
any Bethe logarithms for principal quantum number n > 20 to an accuracy of five
to seven decimal digits, within the specified manifolds of atomic states.
Within the numerical accuracy, the results constitute unified, general formulas
for quantum electrodynamic corrections whose validity is not restricted to a
single atomic state. The results are relevant for accurate predictions of
radiative shifts of Rydberg states and for the description of the recently
investigated laser-dressed Lamb shift, which is observable in a strong
coherent-wave light field.Comment: 8 pages; RevTeX
A Decrease in Glucose Variability Does Not Reduce Cardiovascular Event Rates in Type 2 Diabetic Patients After Acute Myocardial Infarction: A reanalysis of the HEART2D study
To assess the effect of intraday glucose variability (GV) on cardiovascular outcomes in a reanalysis of Hyperglycemia and Its Effect After Acute Myocardial Infarction on Cardiovascular Outcomes in Patients With Type 2 Diabetes Mellitus (HEART2D) study data. Type 2 diabetic patients after acute myocardial infarction were randomized to an insulin treatment strategy targeting postprandial (PRANDIAL; n = 557) or fasting/interprandial (BASAL; n = 558) hyperglycemia. GV was calculated as mean amplitude of glycemic excursions (MAGE), mean absolute glucose (MAG) change, and SD. The PRANDIAL strategy resulted in an 18% lower MAG than BASAL (mean [SEM] difference 0.09 [0.04] mmol/L/h, P = 0.02). In addition, MAGE and SD were lower in the PRANDIAL group, however, not significantly. HbA(1c) levels and cardiovascular event rates were comparable between groups. A PRANDIAL strategy demonstrated lower intraday GV vs. a BASAL strategy with similar overall glycemic control but did not result in a reduction in cardiovascular outcomes. This does not support the hypothesis that targeting GV would be beneficial in reducing subsequent secondary cardiovascular event
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