Clinical authorization of amyloid PET in France: Towards a more precise diagnosis of Alzheimer's disease

The recent clinical authorization of amyloid PET in France represents a crucial step for the nuclear medicine community involved in the diagnosis of Alzheimer's disease (AD). At the era of ATN (Amyloid, Tau, Neurodegeneration) biomarkers, amyloid PET fills a need in patients with an atypical or mixed clinical presentation, in particular young patients (<65 years old), when the lumbar puncture is contraindicated or not feasible for technical reasons. Importantly, a negative amyloid PET scan discards the diagnosis of AD. Furthermore, early phase imaging of amyloid PET allows to estimate the perfusion neuronal state, increasing the diagnostic value of such PET radiotracer. Its role could be further developed in routine care for the selection and monitoring of promising disease modifiers therapies.     

TEP/TDM au FDG et bilan initial des lymphomes : du diagnostic au pronostic

Lymphoma represents a very heterogeneous pathologic disease group and its initial assessment, treatment strategy and prognosis is closely related within each histological subtype. The diagnosis of lymphoma disease is often due to the development of a tumour mass at a lymph node area, or within an organ with or without systemic symptoms. However, all these signs remain non specific. Biopsy is the only reliable diagnostic tool, which can be carried out surgically or guided by the morphological and functional imaging. Once the histological diagnosis is determined by the WHO classification, the staging procedure aim is to provide the prognosis to assist the therapeutic decision. Morphologic imaging primarily based on CT remains the reference in exploring most cases. But in the last decade, the introduction of functional imaging using FDG-PET/CT has dramatically changed the therapeutic management of lymphoma. The additional clinical value provided by initial FDG-PET/CT could lead to an alteration of the therapeutic strategy, as well as to the optimization of radiation therapy or to the establishment of prognostic score and lead to improved lymphoma patient survival in the future.     

Epstein-Barr Virus-Induced Expression of a Novel Human Vault RNA

Non-protein-coding RNAs (ncRNAs) have recently emerged on the scene of genomic research as prominent players in the regulation of gene expression. Many functionally characterized ncRNAs have been shown to be differentially expressed in various organisms during specific environmental or developmental conditions, thus establishing regulatory networks crucial for shaping cellular life. Here, we show that the expression of vault RNAs (vtRNAs) is specifically up-regulated in human lymphocytes upon infection by γ-herpesviruses, such as the Epstein-Barr virus and Kaposi's sarcoma virus. vtRNAs are ncRNAs that are integral to the vault complex, a gigantic (13 MDa) hollow ribonucleoprotein particle with a thus far elusive biological role. Stimulation of vtRNA expression by the Epstein-Barr virus was evident for all three canonical vtRNAs (hvg1-hvg3) and also for a novel ncRNA candidate, initially termed CBL-3. This ncRNA shares clear primary- and secondary-structure similarities with the three known vtRNAs. Importantly, CBL-3 co-sediments with intact vault particles in density gradients of various human cell lines, thus strongly indicating this ncRNA as a novel, fourth vault-complex-associated RNA.     

Study on simulation models of tomato fruit quality related to cultivation environmental factors

Plant growth simulation models are valuable tools for optimizing the environmental factors and managing crop cultivation in cultural facilities. Researches presently on tomato simulation models have mainly focused on the plant growth and development, growth stages, dry matter production and distribution, however, no report on modeling of tomato fruit quality has been published yet. In this study, the method of accumulated Thermal Effectiveness and PAR (TEP) was employed to model the dynamic relationship between the major quality indicators and the environmental factors. Data of both indicators of tomato fruit quality and environmental factors, temperature and solar radiation of the cultivation environment, were collected under multiple protected structures like solar greenhouse and plastic tunnel for tomato production. The variety of simulation models were established based on the effects of temperature and solar radiation on tomato quality formation, and independently tested with the modeling data. The results show that the dynamic changes of the indicators of fruit quality after fruit set are accorded with the amount of accumulated TEP and individual indicators of fruit quality are suitable to its specific models. The fruit hardness is well accorded with a formula of generalized least squares FHi = k₁ + k₂ × TEPi + k₃ × TEPi² ; Fruit soluble sugar content is in a formula of Logistic model  . Fruit organic acid content is in a formula of generalized least squares OACi = n₁ + n₂ × TEPi + n₃ × TEPi². Fruit tannin content is in a formula of Johnson Schumacher model  . According to the established fruit hardness model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.9396, 0.9181, 0.8910 and 0.9523, respectively and values of root mean square error (RMSE) are 0.833 kg/cm², 0.942 kg/cm², 0.628 kg/cm² and 0.738 kg/cm², respectively. Based on the established fruit soluble sugar content model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.8596, 0.9420, 0.9027 and 0.9473, respectively and the values of RMSE are 1.011%, 0.710%, 0.771% and 0.608%, respectively. On the basis of the established fruit organic acid content model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.8856, 0.9025, 0.9183 and 0.8768, respectively and the values of RMSE are 0.029%, 0.030%, 0.024% and 0.023%, respectively. According to the established fruit tannin content model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.9481, 0.9219, 0.9521 and 0.8911, respectively and the values of RMSE are 13.41 mg/kg, 14.04 mg/kg, 13.92 mg/ kg and 16.78 mg/kg, respectively. All of the coefficients of determination R² are higher than 0.85, and the values of RMSE are generally smaller, which means the modeling is accurate and well accordance. This study will form a theoretic basis and provide technical support for the management of tomato production and environment control under plastic tunnel and solar greenhouse cultivation.     

Production of macroaggregates from dissolved exopolymeric substances (EPS) of bacterial and diatom origin

Exopolymeric substances (EPS) isolated from a pure culture of the marine bacterium Marinobacter sp. and the marine diatom Skeletonema costatum (axenic) were partially purified, chemically characterized and used as dissolved organic matter (DOM) for the production of macroaggregates. The role of organic particles such as transparent exopolymeric particles (TEP) and Coomassie stained particles (CSP) in the production of macroaggregates was experimentally assessed. Three experimental rolling tanks containing sterile medium with: (1) EPS, (2) EPS + live diatom cells and (3) EPS + killed bacteria, and three control tanks without any added EPS were used for macroaggregate production. Changes in abundance and average size of macroaggregates were monitored using image analysis, whereas TEP and CSP were enumerated microscopically. In the presence of microbial EPS, macroaggregates of a size of 23-35 mm(2) were produced. Aggregate size and abundance considerably varied with both time and source of EPS. No correlation was observed for macroaggregate size and abundance with either TEP or CSP. One-way ANOVA demonstrated significant differences in the variance of particle abundance and size in tanks having only EPS or EPS in combination with live diatom cells. Our data suggest that production of macroaggregates was influenced by polymer chemistry and surface properties of colliding particles, whereas TEP and CSP concentrations were influenced by molecular weight of EPS and the presence of growing cells. Interestingly, macroaggregates were formed in the near absence of TEP and CSP, highlighting the role of other unknown processes in the transformation of DOM to particulate organic matter (POM) in aquatic environments.     

A method to quantify at late imaging a release rate of 18F-FDG in tissues

This theoretical work shows that the rate constant for the (18)F-FDG release in tissues can be assessed without needing any arterial blood sampling. The method requires that the clearance of (18)F-FDG from plasma has occurred, whereas (18)F-FDG is still present in the tissue. This condition can be met dating from 3 h after (18)F-FDG injection, when hydration and/or phlorizin injection are applied after the routine static acquisition. The release rate constant can be obtained from a graphical analysis performed at the later decreasing phase of the tissue tracer activity. A two-compartment and a three-compartment model are developed, both in accordance with one another. To cite this article: E. Laffon et al., C. R. Biologies 328 (2005).     

No diagnostic impact of routinely use of respiratory gating to characterize lung nodules with 18F-FDG PET/CT

Purpose

To evaluate diagnostic impact of routinely use of respiratory gated (RG) ¹⁸FDG PET/CT to distinguish benign and malignant lung nodules.

Anomalies surrénaliennes en pratique quotidienne en TEP/TDM au 18F-FDG

Adrenal masses are common in adult population and are a daily challenge for nuclear physicians. The aim for physicians is to differentiate benign from malignant lesions when therapeutic management is impacted. 18F-FDG PET/CT combines complementary modalities, providing structural and functional information, superior to that provided by CT or PET alone. The purpose of this review is to provide some keys that will help to be familiar with the common as well as the atypical manifestations of adrenal disease.     

β-amyloid PET neuroimaging: A review of radiopharmaceutical development

Alzheimer's disease (AD) is a neurodegenerative disease characterized by deposition of amyloid-β plaques that occurs even before symptoms of brain failure are clinically detectable. Whereas previously the diagnosis of AD was only routinely based on clinical assessment, an improvement over the past few years in imaging biomarkers has now led to reconsider the core of the AD diagnostic pathway. Therefore, positron emission tomography (PET) radiotracers for the in vivo imaging of amyloid plaques have been the focus of intense research. Many chemical compounds, mostly derived from the chemistry of amyloid histological staining dyes, have permitted to obtain promising brain amyloid radiopharmaceuticals. Three of them have been approved by the FDA and European regulatory bodies. The present review focuses on the development of these compounds not only as a suitable imaging biomarker to improve AD diagnosis, but also to evaluate new potential therapy.