Echocardiographic changes in anorexia nervosa: a pathophysiological adaptation or a disease?

Anorexia Nervosa is one of the most common form of eating disorders. Cardiac involvement occurs in approximately 80% of patients. Few reports focused on the association between body weight fluctuations and echocardiographic abnormalities, considering linear measurements. We describe echocardiographic and clinical features among male and female patients with anorexia nervosa and the effect of weight gain on these parameters. We performed a single center, retrospective study of patients followed at a dedicated multidisciplinary Unit. The study population consisted of 81 patients, mean age 25 ± 11 years, 94% female. Median body mass index was 14.4 kg/m2 (25th-75th percentile 12.7-15.6 kg/m2). Patients with body mass index below the median value had more often pericardial effusion, smaller left ventricular mass and left ventricular end-diastolic volume and thinner interventricular septum. However, when indexed to body surface area, left ventricular mass and volumes were within the normal range in 90% of population. Patients with pericardial effusion showed mitral valve abnormalities and lower values of white blood cells and platelets, although within normal limits. Presence of pericardial effusion was not related to inflammatory parameters or low plasma protein levels. In 39 patients who displayed weight gain during a median follow-up of 189 days (25th-75th percentile 47-471), increased left ventricular mass, interventricular septum thickness, white blood cells and platelet count and decreased pericardial effusion were observed. Patients with anorexia nervosa have a specific echocardiographic pattern which seems to be proportional to the body size, suggesting a pathophysiological adaptation to the lack of substrates.

Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities.

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory.

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch.

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1×10^{14} and 7.7×10^{14} electrons/cm^{3}. We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (<15 MV/m) and reach over 300 MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels.