Control group To allow group analysis and evaluation of the inter- and intraindividual variations of cerebral perfusion, a control group of 12 healthy volunteers was included in the study. Within
this group of twelve healthy volunteers (low consumers of 0 to 2 cups of coffee daily) not receiving any drink before the two SPECT examinations, eight and six were randomly selected for comparison with the LC and HC caffeine group, respectively, while the whole caffeine-consuming group was compared with the totality of the control group. Inhibitors,research,lifescience,medical SPECT procedure The caffeine groups subjects were subjected to two separate morning examinations upon arrival at the hospital: (i) one SPECT study after the placebo beverage; and (ii) one SPECT study after the caffeine containing beverage. Inhibitors,research,lifescience,medical The two beverages were given on two different days at 7-day interval, in a double-blind randomized counterbalanced design. Upon arrival at the clinic, the subjects were invited to relax in a comfortable armchair in a quiet and pleasant room. A venous catheter for tracer injection was immediately inserted into the left Inhibitors,research,lifescience,medical arm, and a first blood sample was taken to measure caffeine levels to check for
compliance to 12 h caffeine selleck products abstinence. Heart rate and blood pressure measurements were then performed and the subjects filled in the STAI questionnaire. Then, subjects received the caffeine or placebo drink and were asked to rest in the same surrounding for 45 min. This time was chosen since caffeine reaches peak values in the brain between 45 and 60 min postingestion.3 Thereafter, the subjects underwent the same procedure for the measurement of plasma caffeine levels, cardiovascular parameters, and filled in the STAI Inhibitors,research,lifescience,medical questionnaire again. Immediately afterwards, the tracer, 640-925 MBq99mTc-ethyl cysteinate dimer (ECD, Neurolite, Bristol-Myers Squibb Medical Imaging), was injected into the already inserted venous catheter. The subjects were not allowed to read, write, or talk for 5 min, including the fixation period of
Inhibitors,research,lifescience,medical the radiotracer. The control group subjects were also subjected Thiamine-diphosphate kinase to two separate morning SPECT examinations at 7-day intervals, in the same conditions, without any beverage. This procedure was used to evaluate the intrasubject variability between two examinations and to avoid the consequences of variable spontaneous mental activity and/or possible perfusion changes induced by the stressful environment related to SPECT examination. SPECT imaging studies were realized with a low-energy, high-resolution, double-head camera (Helix, Elscint). The camera was operated in the “stop and shoot” mode, with acquisitions at 3° intervals and a total acquisition time of 25 min (120 projections, 642 matrix). The total number of counts was superior to 6 million. Slices were reconstructed by filtered back-projection using a Metz filter (FWMH of 8 mm). Slices were acquired 30 min after the injection of ECD.