11 research outputs found
Differences in IV alcohol-induced dopamine release in the ventral striatum of social drinkers and nontreatment-seeking alcoholics
Background
Striatal dopamine (DA) has been implicated in alcohol use disorders, but it is still unclear whether or not alcohol can induce dopamine release in social drinkers. Furthermore, no data exist on dopamine responses to alcohol in dependent drinkers. We sought to characterize the DA responses to alcohol intoxication in moderately large samples of social drinkers (SD) and nontreatment-seeking alcoholics (NTS).
Methods
Twenty-four SD and twenty-one NTS received two [11C]raclopride (RAC) PET scans; one at rest, and one during an intravenous alcohol infusion, with a prescribed ascent to a target breath alcohol concentration (BrAC), at which it was then âclamped.â The alcohol clamp was started 5 min after scan start, with a linear increase in BrAC over 15 min to the target of 80 mg%, the legal threshold for intoxication. Target BrAC was maintained for 30 min. Voxel-wise binding potential (BPND) was estimated with MRTM2.
Results
IV EtOH induced significant increases in DA in the right ventral striatum in NTS, but not SD. No decreases in DA were observed in either group.
Conclusions
Alcohol intoxication results in distinct anatomic profiles of DA responses in SD and NTS, suggesting that in NTS, the striatal DA system may process effects of alcohol intoxication differently than in SD
Pseudo-reference regions for glial imaging with (11)C-PBR28:investigation in two clinical cohorts
none14The translocator protein (TSPO) is a commonly used imaging target to investigate neuroinflammation. While TSPO imaging demonstrates great promise, its signal exhibits substantial interindividual variability, which needs to be accounted for to uncover group effects that are truly reflective of neuroimmune activation. Recent evidence suggests that relative metrics computed using pseudo-reference approaches can minimize within-group variability, and increase sensitivity to detect physiologically meaningful group differences. Here, we evaluated various ratio approaches for TSPO imaging and compared them with standard kinetic modeling techniques, analyzing two different disease cohorts. Patients with chronic low back pain (cLBP) or amyotrophic lateral sclerosis (ALS) and matching healthy controls received (11)C-PBR28 PET scans. Occipital cortex, cerebellum and whole brain were first evaluated as candidate pseudo-reference regions by testing for the absence of group differences in Standardized Uptake Value (SUV) and distribution volume (VT) estimated with an arterial input function (AIF). SUV from target regions (cLBP study - thalamus; ALS study - precentral gyrus) was normalized with SUV from candidate pseudo-reference regions to obtain SUVRoccip, SUVRcereb, and SUVRWB The sensitivity to detect group differences in target regions was compared using various SUVR approaches, as well as distribution volume ratio (DVR) estimated with (blDVR) or without AIF (refDVR), and VT Additional voxelwise SUVR group analyses were performed. We observed no significant group differences in pseudo-reference VT or SUV, excepting whole-brain VT, which was higher in cLBP patients than controls. Target VT elevations in patients (P = 0.028 and 0.051 in cLBP and ALS, respectively) were similarly detected by SUVRoccip and SUVRWB, and by refDVR and blDVR (less reliably by SUVRcereb). In voxelwise analyses, SUVRoccip, but not SUVRcereb, identified regional group differences initially observed with SUVRWB, and in additional areas suspected to be affected in the pathology examined. All ratio metrics were highly cross-correlated, but generally were not associated with VT While important caveats need to be considered when using relative metrics, ratio analyses appear to be similarly sensitive to detect pathology-related group differences in (11)C-PBR28 signal as classic kinetic modeling techniques. Occipital cortex may be a suitable pseudo-reference region, at least for the populations evaluated, pending further validation in larger cohorts.noneAlbrecht, Daniel Strakis; Normandin, Marc David; Shcherbinin, Sergey; Wooten, Dustin W; Schwarz, Adam J; Zurcher, Nicole R; Barth, Vanessa N; Guehl, Nicolas J; Johnson-Akeju, Oluwaseun; Atassi, Nazem; Veronese, Mattia; Turkheimer, Federico; Hooker, Jacob M; Loggia, Marco LucianoAlbrecht, Daniel Strakis; Normandin, Marc David; Shcherbinin, Sergey; Wooten, Dustin W; Schwarz, Adam J; Zurcher, Nicole R; Barth, Vanessa N; Guehl, Nicolas J; Johnson-Akeju, Oluwaseun; Atassi, Nazem; Veronese, Mattia; Turkheimer, Federico; Hooker, Jacob M; Loggia, Marco Lucian
Glossaire illustrĂ© sur les formes dâaltĂ©ration de la pierre
The ICOMOS International Scientific Committee for
Stone (ISCS) is providing a forum for the interchange of
experience, ideas, and knowledge in the field of stone
conservation. ISCS aims at facilitating the publication,
dissemination and presentation of state of the art
reviews on pre-identified issues. Simplification and
demystification of scientific information for practitioners are also part of the main goals of the group.
In studies on stone deterioration and conservation, terminological confusions lead to major communication
problems between scientists, conservators and practitioners. In this context, it is of primary importance to set
up a common language; if degradation patterns can be
shown, named and described, then they can be recognised and compared with similar ones in a more accurate
way in further investigations.
The ISCS glossary constitutes an important tool for
scientific discussions on decay phenomena and processes. It is also an excellent basis for tutorials on stone
deterioration. It is based on the careful examination of
pre-existing glossaries of English terms. It does not aim
at replacing these glossaries, often set up originally in a
language other than English, and for most of them done
to a high standard.
As President of ICOMOS I would like to congratulate the
International Scientific Committee for Stone and its
President VĂ©ronique Verges-Belmin for the results of
years of research presented in this publication. Stone
conservation is a crucial topic in monument conservation and many of our National Committees all over the
world hope for advice and help from the specialists
familiar with traditional and modern methods of
conservation. The Illustrated Glossary on Stone
Deterioration Patterns offers a wide range of suggestions and practical advice. Probably, after the English-French version becomes available the Glossary will also
be translated into other languages. In view of the accelerating decay of our stone monuments worldwide this
is an exemplary contribution which will promote the
international cooperation so important in this field.peer-reviewe
Estimation of neurotransmitter kinetics from dynamic positron emission tomography data
Positron emission tomography (PET) has been used previously to measure the spatial distribution of neuroreceptors and to detect acute neurotransmitter fluctuations in vivo. Conventional data analysis procedures are unable to characterize the temporal pattern of neurotransmitter release. The time course of neurotransmitter concentration may encode pertinent information about brain function and dysfunction, such as learning and memory or drug addiction and abuse liability. We have developed mathematical techniques â collectively called ntPET (neurotransmitter PET) â for the purpose of extracting neurotransmitter kinetics from dynamic PET data. The first of these methods, p-ntPET (parametric ntPET), relies on an enhanced compartmental model and constrained non-linear parameter estimation to simultaneously analyze data from two PET scans (baseline and activation conditions). The p-ntPET model was thoroughly scrutinized by application to realistic simulated data. The results show that p-ntPET is robust to plausible model violations and capable of estimating neurotransmitter release profiles with approximately three minute precision. Analyses of PET data acquired in rats receiving methamphetamine with concurrent microdialysis (direct sampling of extracellular fluid in brain) indicate excellent correspondence between p-ntPET predictions and microdialysis measurements of dopamine release. The second method, lp-ntPET (linear parametric ntPET), is in essence a linearization of the p-ntPET model that utilizes a basis function approach to achieve computational efficiency. Simulation results indicate that lp-ntPET performs similarly to p-ntPET while reducing computational burden by several orders of magnitude. Analyses of baseline-challenge data from rats receiving methamphetamine and single-scan data from a human performing a motor learning task yielded activation profiles that were in good agreement with expected responses. The efficiency of the algorithm will facilitate parametric analysis at each image voxel. Lastly, we demonstrate a method to account for statistical uncertainties in the measured input function. This optimization strategy improves the quantitation of receptor density with standard analysis techniques and may also benefit the performance of the ntPET models. The developments described here enhance the quality of conventional outcome metrics and offer the ability to extract previously unavailable information about the functioning brain
Pseudoreference Regions for Glial Imaging with 11
The translocator protein (TSPO) is a commonly used imaging target to investigate neuroinflammation. While TSPO imaging demonstrates great promise, its signal exhibits substantial interindividual variability, which needs to be accounted for to uncover group effects that are truly reflective of neuroimmune activation. Recent evidence suggests that relative metrics computed using pseudo-reference approaches can minimize within-group variability, and increase sensitivity to detect physiologically meaningful group differences. Here, we evaluated various ratio approaches for TSPO imaging and compared them with standard kinetic modeling techniques, analyzing two different disease cohorts. Patients with chronic low back pain (cLBP) or amyotrophic lateral sclerosis (ALS) and matching healthy controls received (11)C-PBR28 PET scans. Occipital cortex, cerebellum and whole brain were first evaluated as candidate pseudo-reference regions by testing for the absence of group differences in Standardized Uptake Value (SUV) and distribution volume (VT) estimated with an arterial input function (AIF). SUV from target regions (cLBP study - thalamus; ALS study - precentral gyrus) was normalized with SUV from candidate pseudo-reference regions to obtain SUVRoccip, SUVRcereb, and SUVRWB The sensitivity to detect group differences in target regions was compared using various SUVR approaches, as well as distribution volume ratio (DVR) estimated with (blDVR) or without AIF (refDVR), and VT Additional voxelwise SUVR group analyses were performed. We observed no significant group differences in pseudo-reference VT or SUV, excepting whole-brain VT, which was higher in cLBP patients than controls. Target VT elevations in patients (P = 0.028 and 0.051 in cLBP and ALS, respectively) were similarly detected by SUVRoccip and SUVRWB, and by refDVR and blDVR (less reliably by SUVRcereb). In voxelwise analyses, SUVRoccip, but not SUVRcereb, identified regional group differences initially observed with SUVRWB, and in additional areas suspected to be affected in the pathology examined. All ratio metrics were highly cross-correlated, but generally were not associated with VT While important caveats need to be considered when using relative metrics, ratio analyses appear to be similarly sensitive to detect pathology-related group differences in (11)C-PBR28 signal as classic kinetic modeling techniques. Occipital cortex may be a suitable pseudo-reference region, at least for the populations evaluated, pending further validation in larger cohorts
Pancreatic Beta Cell Mass PET Imaging and Quantification with [11C]DTBZ and [18F]FP-(+)-DTBZ in Rodent Models of Diabetes
Differences in IV alcohol-induced dopamine release in the ventral striatum of social drinkers and nontreatment-seeking alcoholics
Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO
International audienceDuring their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100ââMâ, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93ââGpcâ3âyrâ1 in comoving units at the 90%Â confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits
First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data
International audienceWe report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100Â Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7ââ[1/Hz]. At the frequency of best strain sensitivity, near 100Â Hz, we set 90% confidence upper limits of 1.8Ă10-25. At the low end of our frequency range, 20Â Hz, we achieve upper limits of 3.9Ă10-24. At 55Â Hz we can exclude sources with ellipticities greater than 10-5 within 100Â pc of Earth with fiducial value of the principal moment of inertia of 1038ââkgâm2