The
p
̄
Ne
annihilation cross section is measured for the first time in the momentum interval (53÷63) MeV/c. About 9000 pictures collected by the Streamer Chamber Collaboration (PS179) at LEAR-CERN ...have been scanned. Four events are found, corresponding to
σ
ann=2210±1105 mb. The result is compared to the set of measurements presently available in the region of low p̄ momentum.
The ratio of the total exclusive production cross sections for
η' and
η mesons has been measured in the
pp reaction at
p
beam=3.67 GeV/
c. The observed
η
′/
η ratio is (0.83±0.11
+0.23
−0.18)×10
−2 ...from which the exclusive
η
′ meson production cross section is determined to be (1.12±0.15
+0.42
−0.31) μb. Differential cross section distributions have been measured. Their shape is consistent with isotropic
η
′ meson production.
The ability to identify and quantify brain β-amyloid could increase the accuracy of a clinical diagnosis of Alzheimer disease.
To determine if florbetapir F 18 positron emission tomographic (PET) ...imaging performed during life accurately predicts the presence of β-amyloid in the brain at autopsy.
Prospective clinical evaluation conducted February 2009 through March 2010 of florbetapir-PET imaging performed on 35 patients from hospice, long-term care, and community health care facilities near the end of their lives (6 patients to establish the protocol and 29 to validate) compared with immunohistochemistry and silver stain measures of brain β-amyloid after their death used as the reference standard. PET images were also obtained in 74 young individuals (18-50 years) presumed free of brain amyloid to better understand the frequency of a false-positive interpretation of a florbetapir-PET image.
Correlation of florbetapir-PET image interpretation (based on the median of 3 nuclear medicine physicians' ratings) and semiautomated quantification of cortical retention with postmortem β-amyloid burden, neuritic amyloid plaque density, and neuropathological diagnosis of Alzheimer disease in the first 35 participants autopsied (out of 152 individuals enrolled in the PET pathological correlation study).
Florbetapir-PET imaging was performed a mean of 99 days (range, 1-377 days) before death for the 29 individuals in the primary analysis cohort. Fifteen of the 29 individuals (51.7%) met pathological criteria for Alzheimer disease. Both visual interpretation of the florbetapir-PET images and mean quantitative estimates of cortical uptake were correlated with presence and quantity of β-amyloid pathology at autopsy as measured by immunohistochemistry (Bonferroni ρ, 0.78 95% confidence interval, 0.58-0.89; P <.001) and silver stain neuritic plaque score (Bonferroni ρ, 0.71 95% confidence interval, 0.47-0.86; P <.001). Florbetapir-PET images and postmortem results rated as positive or negative for β-amyloid agreed in 96% of the 29 individuals in the primary analysis cohort. The florbetapir-PET image was rated as amyloid negative in the 74 younger individuals in the nonautopsy cohort.
Florbetapir-PET imaging was correlated with the presence and density of β-amyloid. These data provide evidence that a molecular imaging procedure can identify β-amyloid pathology in the brains of individuals during life. Additional studies are required to understand the appropriate use of florbetapir-PET imaging in the clinical diagnosis of Alzheimer disease and for the prediction of progression to dementia.
Summary Background Results of previous studies have shown associations between PET imaging of amyloid plaques and amyloid-β pathology measured at autopsy. However, these studies were small and not ...designed to prospectively measure sensitivity or specificity of amyloid PET imaging against a reference standard. We therefore prospectively compared the sensitivity and specificity of amyloid PET imaging with neuropathology at autopsy. Methods This study was an extension of our previous imaging-to-autopsy study of participants recruited at 22 centres in the USA who had a life expectancy of less than 6 months at enrolment. Participants had autopsy within 2 years of PET imaging with florbetapir (18 F). For one of the primary analyses, the interpretation of the florbetapir scans (majority interpretation of five nuclear medicine physicians, who classified each scan as amyloid positive or amyloid negative) was compared with amyloid pathology (assessed according to the Consortium to Establish a Registry for Alzheimer's Disease standards, and classed as amyloid positive for moderate or frequent plaques or amyloid negative for no or sparse plaques); correlation of the image analysis results with amyloid burden was tested as a coprimary endpoint. Correlation, sensitivity, and specificity analyses were also done in the subset of participants who had autopsy within 1 year of imaging as secondary endpoints. The study is registered with ClinicalTrials.gov , number NCT 01447719 (original study NCT 00857415 ). Findings We included 59 participants (aged 47–103 years; cognitive status ranging from normal to advanced dementia). The sensitivity and specificity of florbetapir PET imaging for detection of moderate to frequent plaques were 92% (36 of 39; 95% CI 78–98) and 100% (20 of 20; 80–100%), respectively, in people who had autopsy within 2 years of PET imaging, and 96% (27 of 28; 80–100%) and 100% (18 of 18; 78–100%), respectively, for those who had autopsy within 1 year. Amyloid assessed semiquantitatively with florbetapir PET was correlated with the post-mortem amyloid burden in the participants who had an autopsy within 2 years (Spearman ρ=0·76; p<0·0001) and within 12 months between imaging and autopsy (0·79; p<0·0001). Interpretation The results of this study validate the binary visual reading method approved in the USA for clinical use with florbetapir and suggest that florbetapir could be used to distinguish individuals with no or sparse amyloid plaques from those with moderate to frequent plaques. Additional research is needed to understand the prognostic implications of moderate to frequent plaque density. Funding Avid Radiopharmaceuticals.
Today, important fisheries have become commercially extinct and others are threatened. The dominant presence of this scientific uncertainty indicates the need to rethink the existing fishery ...management system. This book examines in detail the underlying root causes of our failure to successfully manage the fishery resources of the world's oceans and offers alternative solutions that will allow human society to maximize the long term benefits form ocean resources. This monograph will be of great interest to academics in economics, business, environmental sciences and sociology, in addition to the core market of natural resources management, environmental policy, resource conservation, economic development and geography. In addition, it is relevant for those working in fisheries management for government bodies and NGOs.
The total cross section of the reaction
pp→
ppK
+
K
− has been determined for proton–proton reactions with
p
beam
=3.67
GeV/c
. This represents the first cross section measurement of the
pp→
ppK
−
K
...+ channel near threshold, and is equivalent to the inclusive
pp→
ppK
−
X cross section at this beam momentum. The cross section determined at this beam momentum is about a factor 20 lower than that for inclusive
pp→
ppK
+
X meson production at the same CM energy above the corresponding threshold. This large difference in the
K
+ and
K
− meson inclusive production cross sections in proton-proton reactions is in strong contrast to cross sections measured in sub-threshold heavy ion collisions, which are similar in magnitude at the same energy per nucleon below the respective thresholds.
The
p̄
3He annihilation cross section is measured for the first time in the momentum interval (50÷60) MeV/
c. About 9000 pictures collected by the Streamer Chamber Collaboration (PS179) at LEAR–CERN ...have been scanned. Six events are found, corresponding to
σ
ann=1850±700 mb. The result is compared to the set of measurements presently available in the region of low
p̄ momentum.
To examine the association between regional brain uptake of a novel amyloid positron emission tomography (PET) tracer florbetapir F 18 ((18)F-AV-45) and cognitive performance in a pilot study.
...Cross-sectional comparison of (18)F-AV-45 in AD patients versus controls.
Three specialty memory clinics.
Eleven participants with probable Alzheimer disease (AD) by NINDS/ADRDA criteria and 15 healthy comparison (HC) participants.
Participants underwent PET imaging following a 370 MBq (10 mCi) intravenous administration of (18)F-AV-45. Regional/cerebellar standardized uptake value ratios (SUVRs) were calculated. Cognition was assessed using Mini-Mental State Examination, Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog), Wechsler Logical Memory IA (immediate recall) test (LMIA), and verbal category fluency.
Greater (18)F-AV-45 SUVR was associated with poorer performance on all cognitive tests. In the HC group, occipital, parietal, precuneus, temporal, and cortical average SUVR was associated with greater ADAS-Cog, and greater anterior cingulate SUVR was associated with lower LMIA. Two HC participants had (18)F-AV-45 cortical/cerebellar SUVR greater than 1.5, one of whom had deficits in episodic recall and on follow-up met criteria for amnestic mild cognitive impairment.
(18)F-AV-45 SUVR in several brain regions was associated with worse global cognitive performance particularly in HC, suggesting its potential as a marker of preclinical AD.
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