[en] To further validate its use in positron emission tomography (PET), we studied the binding of [¹⁸F]altanserin, a specific 5HT₂ radioligand, in the rat brain using in vivo autoradiography. Distribution of [¹⁸F]altanserin binding was comparable to the in vitro mapping of 5HT₂ receptors reported in the literature. Selective displacers were used to test the reversibility and the selectivity of this radioligand. Specific binding of [¹⁸F]altanserin in the rat frontal cortex was quantified by direct counting with an electronic imaging system and by quantification on digitalized autoradiograms. Close results of about 30 pmol/g were obtained with both methods. Our data confirmed that [¹⁸F]altanserin is a valid tracer for 5HT₅ receptors binding studies

[en] Short communication

[en] During the past decade, microwave technology has received considerable attention in organic synthesis and in radiochemistry primarily due to substantial rate increase and time gain. Most of the examples described are reactions done with domestic microwave ovens. Space and shielding requirements, difficulties in integrating them in an automated synthesis system, and poor reproducibility were the major concerns for their use in radiochemistry. The authors describe their microwave cavity system and present potential applications for labelling with nucleophilic [¹⁸F]fluoride. [¹⁸F]FDG and [¹⁸F]altanserin synthesis are discussed in terms of radiochemical yields, synthesis time, and reliability

[en] The center, opened in November 1990 and entirely dedicated to PET programs, is equipped with an IBA CYCLONE-30 (proton 15-30 MeV, 6 ports) with targets and automated chemistry modules for routine production of ¹⁵O-, ¹¹C-, ¹⁸F-compounds. We report here our first year experience with the production of [¹⁸F]FDG and [¹³N]NH₄. (author) 2 figs., 4 refs

[en] Short communication

[en] Companies specialized in the development and installation of accelerator-based systems dedicated to the medical applications brought on the market cyclotrons well fitted to the requests of the industrial community or universities and so covering every segment of the market. These machines are fully automatic, and need reduced maintenance; they are highly specialized for defined tasks. They can produce high beam intensity and realize dual beam irradiation. Also the prices are reducing considerably. The targets and the automatic system follow the same trend. Unfortunately, the flexibility of these devices for new area of research and development has been dramatically reduced. The growing number of PET cameras has increased the popularity of PET tracers used for nuclear imaging. Consequently, there is a growing demand for these radiopharmaceuticals compounds labeled with short-lived radioisotopes for clinical applications. From a research and development tool in the eighties, PET has now grown up to a clinical tool. Moreover, depending of the social welfare, reimbursement of some PET examinations is granted, which accelerates the trend for an extended use of PET tracers. Regulatory affairs try to establish and standardize the control on these radiopharmaceutical compounds produced in a growing number of local radio pharmacies owning a baby cyclotron. On the other hand, the attention of equipment suppliers was brought in the setting up of a total quality control follow up. These efforts were successively achieved by getting for instance the ISO 9001 certificate

[en] PeakForce^TM quantitative nanomechanical mapping (QNM^TM) is a new atomic force microscopy technique for measuring Young's modulus of materials with high spatial resolution and surface sensitivity by probing at the nanoscale. In this work, modulus results from PeakForce(TM) QNM(TM) using three different probes are presented for a number of different polymers with a range of Young's moduli that were measured independently by instrumented (nano) indentation testing (IIT). The results from the diamond and silicon AFM probes were consistent and in reasonable agreement with IIT values for the majority of samples. It is concluded that the technique is complementary to IIT; calibration requirements and potential improvements to the technique are discussed

[en] Serotoninergic type 2 (5HT₂) receptors have been implicated in the regulation of many brain functions in humans and may play a role in several neurological and psychiatric diseases. Fluorine-18 altanserin has been proposed as a new radiotracer for the study of 5HT₂ receptors by PET because of its high affinity for 5HT₂ receptors (Ki: 0.13 nM) and its good specificity in in vitro studies. Dynamic PET studies were carried out in 12 healthy volunteers after intravenous injection of 0.1 mCi/kg [¹⁸F] altanserin. Ninety minutes after injection, we observed mainly cortical binding. Basal ganglia and cerebellum showed very low uptake and the frontal cortex to cerebellum ratio was about 3. To evaluate the quantitative distribution of this ligand in the brain, we used two different methods of data analysis: a four-compartment model was used to achieve quantitative evaluation of rate constants (K₁ and k₂ through k₆) by non-linear regression, and a multiple-time graphical analysis technique for reversible binding was employed for the measurement of k₁/k₂ and k₃/k₄ ratios. Using both methods, we found significant differences in binding capacity (estimated by k₃/k₄ = B_max/K_d) between regions, the values increasing as follows: occipital, limbic, parietal, frontal and temporal cortex. After correction of values obtained by the graphical method for the existence of non-specific binding, results generated by the two methods were consistent. (orig.)