RESUMO
Biological cells are usually operating in conditions characterized by intercellular signaling and interaction, which are supposed to strongly influence individual cell dynamics. In this work, we study the dynamics of interacting random Boolean networks, focusing on attractor properties and response to perturbations. We observe that the properties of isolated critical Boolean networks are substantially maintained also in interaction settings, while interactions bias the dynamics of chaotic and ordered networks toward that of critical cells. The increase in attractors observed in multicellular scenarios, compared to single cells, allows us to hypothesize that biological processes, such as ontogeny and cell differentiation, leverage interactions to modulate individual and collective cell responses.
RESUMO
BACKGROUND: We evaluated the appropriateness of the prescription of echocardiography, exercise testing, Holter monitoring and vascular sonography for ambulatory patients, performed during 4 weeks in 21 outpatient laboratories in Tuscany and Umbria, Italy. METHODS: We collected the following data: the appropriateness of the prescription (according to the guidelines of the Italian Federation of Cardiology), the prescribing physician (cardiologist vs noncardiologist), the synthetic result (normal vs abnormal) and the clinical utility (useful vs useless) of each exam. RESULTS: We evaluated 5614 prescriptions (patients: 3027 males, 2587 females; mean age 63 years, range 14-96 years). The indication to the test was of class I (appropriate) in 45.3%, of class II (doubtfully appropriate) in 34.8% and of class III (inappropriate) in 19.9% of the cases. The test was abnormal in 58.3% of class I exams vs 17% of class III exams (p < 0.05). The test was useful in 72.4% of class I exams vs 17.1% of class III exams (p < 0.05). The test was prescribed by a cardiologist in 1882 cases (33.5%). Cardiologist-prescribed exams were of class I in 57.3%, of class II in 32.4% and of class III in 10.3% of the cases vs 39.2, 36.1 and 24.7% of non-cardiologist-prescribed exams (p < 0.05). Cardiologist-prescribed exams were abnormal in 53.4% of the cases vs 39% of those of non-cardiologists' (odds ratio 1.76, 95% confidence interval 1.58-1.97; p < 0.05). Cardiologist-prescribed exams were useful in 64.7% of the cases vs 44.4% of those of non-cardiologists' (odds ratio 2.26, 95% confidence interval 2.02-2.53; p < 0.05). CONCLUSIONS: In Tuscany and Umbria, Italy, less than half of the prescriptions for non-invasive diagnostic tests are appropriate: appropriately prescribed exams more often provide abnormal and useful results; cardiologist-prescribed exams are more often appropriate, abnormal and useful.
