Is the Fast Evolution Scenario for Virialized Compact Groups Really Compelling? The Role of a Dark Massive Group Halo

We report on results of N-body simulations aimed at testing the hypothesis that galaxies in X-ray emitting (i.e., virialized) Compact Groups are not tidally stripped when they are embedded in a common, massive, quiescent dark matter halo. To disentangle the effects of interactions from spurious effects due to an incorrect choice of the initial galaxy model configurations, these have been chosen to be tidally-limited King spheres, representing systems in quasi-equilibrium within the tidal field of the halo. The potential of the halo has been assumed to be frozen and the braking due to dynamical friction neglected. Our results confirm the hypothesis of low rates of tidal stripping and suggest a scenario for virialized Compact Group evolution in their quiescent phases with only very moderate tidally induced galaxy evolution can be generally expected. This implies the group stability, provided that the dynamical friction timescales in these systems are not much shorter than the Hubble time. We discuss briefly this possibility, in particular taking account of the similarity between the velocity dispersions of a typical virialized Compact Groups and the internal velocity dispersion of typical member galaxies. A number of puzzling observational data on Compact Groups can be easily explained in this framework. Other observations would be better understood as the result of enhanced merging activity in the proto-group environment, leading to virialized Compact Group formation through mergers of lower mass halos, as predicted by hierarchical scenarios of structure formation.Comment: 18 pages, 1 postscript file, 2 tables, to be published in ApJLet

Assessment of cognitive function in patients with essential hypertension treated with lercanidipine

J Tisaire-Sánchez1, J Roma2, Ignacio Camacho-Azcargorta3, J Bueno-Gómez1, J Mora-Maciá4, Angel Navarro51Fundación para la Investigación de la Hipertensión Arterial, Zaragoza, Spain; 2Fundació per l’Estudi de la Hipertensió Arterial als Hospitals Comarcals de Catalunya, Barcelona, Spain; 3Servicio de Cardiología, Clínica San José, Valencia, Spain; 4Unidad de Hipertensión Arterial, Instituto Médico Tecnológico, Barcelona, Spain; 5Recordati España, Madrid, SpainObjectives: The aim of this longitudinal, open-label, comparative, multicenter study was to assess cognitive function in hypertensive patients receiving mid-term treatment with lercanidipine.Methods: Hypertensive patients aged 40 years or older were treated with lercanidipine (10 mg daily) after 7–10 days washout period. The duration of the study was 6 months. Blood pressure (BP) was measured every 4 weeks (JNC 6th report). In patients with inadequate BP control, doxazosin was added and up-titrated. At baseline and after 6 months of treatment, cognitive function was evaluated using the Spanish validated version of the Mini-Mental State Examination (MMSE) and the Trail Making Test (TMT). Results: In the study population of 467 patients, BP decreased from 154.4/95.3 mmHg at baseline to 134.8/80.7 mmHg at 6 months. At the end of the study, 98% of patients were receiving lercanidipine, 20% an angiotensin-converting enzyme inhibitor, and 6% doxazosin. Adequate BP control was obtained in 68% of patients. The mean (standard deviation) MMSE scores improved from 32.35 (2.59) to 33.25 (2.36) (p<0.0001). Patients with good BP control scored significantly better than those with inadequate BP control (p<0.05), which was already observed at the first month. Conclusions: The third-generation calcium channel antagonist, lercanidipine, improved cognitive function after 6 months of treatment especially in patients with good BP control, suggesting that improvements in cognitive function may be associated with a decrease in BP. Keywords: lercanidipine, hypertension, cognitive functio