Modeling [F-18]MPPF positron emission tomography kinetics for the determination of 5-hydroxytryptamine(1A) receptor concentration with multiinjection

peer reviewedThe selectivity of [F-18]MPPF (fluorine-18-labeled 4-(2'-methoxyphenyl)-1-[2'-(N-2"-pirydynyl)-p-fluorobenzamido]ethylpiperazine) for serotonergic 5-hydroxytryptamine(1A) (5-HT1A) receptors has been established in animals and humans. The authors quantified the parameters of ligand-receptor exchanges using a double-injection protocol. After injection of a tracer and a coinjection dose of [F-18]MPPF, dynamic positron emission tomography (PET) data Were acquired during a 160-minute session in five healthy males. These PET and magnetic resonance imaging data were coregistered for anatomical identification. A three-compartment model was used to determine six parameters: F-v (vascular fraction). K-1, k(2) (plasma/free compartment exchange rate). k(off). k(on)/V-r (association and dissociation rate), B-max (receptor concentration), and to deduce K-d (apparent equilibrium dissociation rate). The model was fitted with regional PET kinetics and arterial input function corrected for metabolites. Analytical distribution volume and binding potential Were compared With indices generated by Logan-Patlak graphical analysis. The 5HT(1A) specificity for MPPF was evidenced. A B-max of 2.9 pmol/mL and a K-d of 2.8 nmol/L were found in hippocampal regions, K-d and distribution volume in the free compartment were regionally stable. and the Logan binding potential was linearly correlated to B-max. This study confirms the value of MPPF in the investigation of normal and pathologic systems involving the limbic network and 5-HT1A receptors. Standard values can be used for the simulation of simplified protocols

On the visual detection of non-natural records in streamflow time series: challenges and impacts

Large datasets of long-term streamflow measurements are widely used to infer and model hydrological processes. However, streamflow measurements may suffer from what users can consider anomalies, i.e. non-natural records that may be erroneous streamflow values or anthropogenic influences that can lead to misinterpretation of actual hydrological processes. Since identifying anomalies is time consuming for humans, no study has investigated their proportion, temporal distribution, and influence on hydrological indicators over large datasets. This study summarizes the results of a large visual inspection campaign of 674 streamflow time series in France made by 43 evaluators, who were asked to identify anomalies falling under five categories, namely, linear interpolation, drops, noise, point anomalies, and other. We examined the evaluators' individual behaviour in terms of severity and agreement with other evaluators, as well as the temporal distributions of the anomalies and their influence on commonly used hydrological indicators. We found that inter-evaluator agreement was surprisingly low, with an average of 12 % of overlapping periods reported as anomalies. These anomalies were mostly identified as linear interpolation and noise, and they were more frequently reported during the low-flow periods in summer. The impact of cleaning data from the identified anomaly values was higher on low-flow indicators than on high-flow indicators, with change rates lower than 5 % most of the time. We conclude that the identification of anomalies in streamflow time series is highly dependent on the aims and skills of each evaluator, which raises questions about the best practices to adopt for data cleaning.</p

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Prognostic et traitement de l'endocardite bacterienne. Revue de 70 cas

The long term results of medical and surgical treatments have been reviewed in 70 cases examined during the last 8 years. In 24 of them, bacterial endocarditis developed after valvular replacement. Antibiotic treatment was administered during at least 6 weeks. Determinations of the minimum inhibitory concentration of the antibiotic and of the bactericidal power of the serum were considered as the most important laboratory controls. In the post-operative cases with prosthetic valves, numerous pathogenic organisms were found, including gram (minus) bacilli and monilia, which may partly account for the high mortality in this group. Despite surgical reinterventions, 20 of the 24 patients died. For the gram (+) cocci, prognosis is however statistically worse (at the 99% confidence limit) when prosthetic valves are present. Out of the 46 patients without prosthetic valves, 31 (68%) had a favourable bacteriological and haemodynamic evolution; in this group, gram (minus) bacilli and monilia were never found to be the pathogenic organisms. For streptococci infections, recovery was obtained in 73% of the cases (24 out of 33). Percentages of long term recovery are very similar in mitral (67%) and aortic (69%) valvular involvment, but the frequency of surgical indication was very different in either group. In cases of aortic valvular disease, valvular replacement was indicated for bacteriological or haemodynamic reasons in 19 of the 20 patients who recovered. Amongst the 9 patients who died, 6 were not operated upon. Valvular replacement is by far less frequently necessary in cases of bacterial endocarditis on the mitral valve : one prosthetic valve amongst 8 patients who recovered. Finally, the authors discuss the place of surgery in the treatment of bacterial endocarditis. According to their experience, recent improvement in the prognosis of the disease seems to depend more on the surgical approach of the problem than on the discovery of new antibiotics