Cardiovascular Responses During Resistance Exercise in Patients with Parkinson Disease

Background: Patients with Parkinson disease (PD) present cardiovascular autonomic dysfunction which impairs blood pressure control. However, cardiovascular responses during resistance exercise are unknown in these patients. Objective: Investigate the cardiovascular responses during resistance exercise performed with different muscle masses, in patients with PD. Design: Two groups, repeated-measures design. Setting: Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of São Paulo. Participants: Thirteen patients with PD (4 women, 62.7±1.3 years, stages 2-3 of modified Hoehn and Yahr scale; "on" state of medication) and thirteen paired controls without PD (7 women, 66.2±2.0years) Interventions: Both groups performed, in a random order, bilateral and unilateral knee extension exercises (2 sets, 10–12 RM, 2 min of interval). Main Outcome Measurements: Systolic blood pressure (SBP) and heart rate (HR) were assessed before (pre) and during the exercises. Results: Independent of set and exercise type, SBP and HR increases were significantly lower in PD than the control group (combined values: +45±2 vs. +73±4 mmHg and +18±1 vs. +31±2 bpm, P =.003 and .007, respectively). Independently of group and set, the SBP increase was greater in the bilateral than the unilateral exercise (combined values: +63±4 vs +54±3 mmHg, P=.002), while the HR increase was similar. In addition, independently of group and exercise type, the SBP increase was higher in the 2nd than the 1st set (combined values: +56±4 vs +61±4 mmHg, P=.04), while the HR increases were similar. Conclusions: Patients with PD present attenuated 25 increases in SBP and HR during resistance exercise in comparison with healthy subjects. These results support that resistance exercise is safe and well tolerated for patients with PD from a cardiovascular point of view supporting its recommendation for this population

Application of Silicon Photomultipliers to Positron Emission Tomography

Historically, positron emission tomography (PET) systems have been based on scintillation crystals coupled to photomultipliers tubes (PMTs). However, the limited quantum efficiency, bulkiness, and relatively high cost per unit surface area of PMTs, along with the growth of new applications for PET, offers opportunities for other photodetectors. Among these, small-animal scanners, hybrid PET/MRI systems, and incorporation of time-of-flight information are of particular interest and require low-cost, compact, fast, and magnetic field compatible photodetectors. With high quantum efficiency and compact structure, avalanche photodiodes (APDs) overcome several of the drawbacks of PMTs, but this is offset by degraded signal-to-noise and timing properties. Silicon photomultipliers (SiPMs) offer an alternative solution, combining many of the advantages of PMTs and APDs. They have high gain, excellent timing properties and are insensitive to magnetic fields. At the present time, SiPM technology is rapidly developing and therefore an investigation into optimal design and operating conditions is underway together with detailed characterization of SiPM-based PET detectors. Published data are extremely promising and show good energy and timing resolution, as well as the ability to decode small scintillator arrays. SiPMs clearly have the potential to be the photodetector of choice for some, or even perhaps most, PET systems

Characterization of Si pixel detectors of different thickness

Tests on silicon pixel detector in the mammographic energy range have shown good imaging performances so, in order to improve the efficiency in this energy range, we have designed thicker detectors of the p(+) /n type. The detectors have been fabricated by ITC-IRST (Trento, Italy) in high resistivity silicon substrates (300 and 525 mum thick). A TCAD simulation work has been carried out to optimize the electric field distribution and to enhance the breakdown voltage. Very low leakage current and high breakdown voltage characteristics have been measured on detectors in preliminary on-wafer tests. After that, detectors have been bump-bonded to a dedicated VLSI electronic chips, realizing an assembly. Choosing the best set-up condition and using a standard marnmographic tube, we have acquired a large area image (8 x 8 cm(2)) of the RMI 156 phantom, recommended for mammographic quality checks. In order to cover the whole surface, we have acquired different images translating the phantom over the assembly. We present some selected results for these assemblies both for the electrical characteristics and for the imaging performances. (C) 2003 Elsevier B.V. All rights reserved