Viscoelastic computational modeling of the human head-neck system: Eigenfrequencies and time-dependent analysis.

A subject-specific 3-dimensional viscoelastic finite element model of the human head-neck system is presented and investigated based on computed tomography and magnetic resonance biomedical images. Ad hoc imaging processing tools are developed for the reconstruction of the simulation domain geometry and the internal distribution of bone and soft tissues. Material viscoelastic properties are characterized point-wise through an image-based interpolating function used then for assigning the constitutive prescriptions of a heterogenous viscoelastic continuum model. The numerical study is conducted both for modal and time-dependent analyses, compared with similar studies and validated against experimental evidences. Spatiotemporal analyses are performed upon different exponential swept-sine wave-localized stimulations. The modeling approach proposes a generalized, patient-specific investigation of sound wave transmission and attenuation within the human head-neck system comprising skull and brain tissues. Model extensions and applications are finally discussed.

Modelling far field pacing for terminating spiral waves pinned to ischaemic heterogeneities in cardiac tissue.

In cardiac tissue, electrical spiral waves pinned to a heterogeneity can be unpinned (and eventually terminated) using electric far field pulses and recruiting the heterogeneity as a virtual electrode. While for isotropic media the process of unpinning is much better understood, the case of an anisotropic substrate with different conductivities in different directions still needs intensive investigation. To study the impact of anisotropy on the unpinning process, we present numerical simulations based on the bidomain formulation of the phase I of the Luo and Rudy action potential model modified due to the occurrence of acute myocardial ischaemia. Simulating a rotating spiral wave pinned to an ischaemic heterogeneity, we compare the success of sequences of far field pulses in the isotropic and the anisotropic case for spirals still in transient or in steady rotation states. Our results clearly indicate that the range of pacing parameters resulting in successful termination of pinned spiral waves is larger in anisotropic tissue than in an isotropic medium.This article is part of the themed issue 'Mathematical methods in medicine: neuroscience, cardiology and pathology'.

[Effects of dose of erythropoiesis stimulating agents on cardiovascular outcomes, quality of life and costs of haemodialysis. the clinical evaluation of the DOSe of erythropoietins (C.E. DOSE) Trial]. / Effetti della dose degli agenti stimolanti l'eritropoiesi su esiti cardio-cerebrovascolari, qualità di vita e costi in emodialisi.

BACKGROUND: Anaemia is a risk factor for death, adverse cardiovascular outcomes and poor quality of life in patients with chronic kidney disease (CKD). Erythropoietin Stimulating Agents (ESA) are the most used treatment option. In observational studies, higher haemoglobin (Hb) levels (around 11-13 g/dL) are associated with improved survival and quality of life compared to Hb levels around 9-10 g/dL. Randomized studies found that targeting higher Hb levels with ESA causes an increased risk of death, mainly due to adverse cardiovascular outcomes. It is possible that this is mediated by ESA dose rather than haemoglobin concentration, although this hypothesis has never been formally tested. METHODS: We present the protocol of the Clinical Evaluation of the Dose of Erythropoietins (C.E. DOSE) trial, which will assess the benefits and harms of a high versus a low ESA dose therapeutic strategy for the management of anaemia of end stage kidney disease (ESKD). This is a randomized, prospective open label blinded end-point (PROBE) design trial due to enroll 900 haemodialysis patients. Patients will be randomized 1:1 to 4000 UI/week i. v. versus 18000 UI/week i. v. of epoetin alfa, beta or any other epoetin in equivalent doses. The primary outcome of the trial is a composite of cardiovascular events. In addition, quality of life and costs of these two strategies will be assessed. The study has been approved and funded by the Italian Agency of Drugs (Agenzia Italiana del Farmaco (AIFA)) within the 2006 funding plan for independent research on drugs (registered at www.clinicaltrials.gov (NCT00827021)).

[Patient satisfaction in hemodialysis: a pilot cross-sectional analysis and a review]. / Valutazione del grado di soddisfazione da trattamento nel paziente in emodialisi: metologia di ricerca, strumenti, limiti e studio pilota trasversale.

BACKGROUND: Assessment of patient satisfaction is not performed routinely in many healthcare institutions. In this review, we discuss methodological aspects of assessment of patient satisfaction in hemodialysis. We also present a pilot study conducted in the Gambro Healthcare Italy dialysis clinics network. METHODS: Patient satisfaction was assessed in a network of hemodialysis units by using an internally validated Italian translation of the Choices for Healthy Outcomes in Caring for ESRD (CHOICE) questionnaire. A cross-sectional analytic study design was used and data analysed with univariate and multivariate hierarchical logistic regression to explore correlates of the risk of being unsatisfied with dialysis treatment. Covariates which were considered include a series of over 20 clinical, demographic, organizational and structural aspects. In addition, unexplained inter-centre residual variability due to 'case-mix' was explored and plotted. RESULTS: Seventeen dialysis units participated in this cross-sectional analysis and 758/1001 (75.7%) provided answers to the questionnaires. There was a statistically significant association on multivariate hierarchical analysis between the risk of being unsatisfied with dialysis treatment and interdialysis body weight gain (unit of increase: 1 kg, p=0.004). On the contrary, the risk of unsatisfaction with dialysis treatment was significantly lower in patients with higher dry weight (unit of increase: 1 kg, p=0.002). Our multivariate hierarchical analysis identified some residual variability between dialysis units (n=6 outliers) which may not be explained by any of over 20 potential confounding covariates which were explored. CONCLUSIONS: Assessment of ''customer satisfaction'' is standard practice in private for profit product companies in general but needs to be increasingly recognized as a standard in both public and private providers of healthcare services. Social research methods, which are used for this type of analysis, need to be fine tuned and actively implemented in order to better understand how we may influence the quality of service we provide to our patients and the level at which they rate it.

Long-term zinc and iron supplementation in children of short stature: effect of growth and on trace element content in tissues.

We evaluated the effect of one year of supplementation with iron plus zinc (12 mg/day of Fe+++ and 12.5 mg/day of Zn++), zinc alone (12.5 mg/day of Zn++) and placebo on growth and on the iron, zinc, copper and selenium tissue contents in 30 well-selected children of short stature (16 M and 14 F; 4-11 years old). Before and after supplementation, we measured the concentrations of iron, transferrin, ferritin, zinc and copper in serum, of zinc in erythrocytes and leukocytes, and of zinc, copper and selenium in hair, as well as glutathione peroxidase activity in erythrocytes. Before supplementation, ferritin and serum, erythrocyte and hair zinc contents were significantly lower than in age-matched controls, while the other measured indices were in the normal range. Iron plus zinc supplementation caused an improvement in growth rate in all subjects, i.e., the median Z-score increased from -2.22 +/- 0.45 to -0.64 +/- 0.55; (p < 0.01). In the zinc-supplemented group, only the subjects whose ferritin levels were higher than 20 ng/L before supplementation showed a similar improvement of growth rate. Iron plus zinc supplementation could be a reasonable treatment in short, prepubertal children affected by marginal zinc and iron deficiency.

Reseña de legislación y administración comparadas sobre contaminación hídrica

Señala la importancia de la contaminación del agua. Plantea una serie de detalles que evidencian la alta significación que se está tomando para la prevención y control de la contaminación de los recursos hídricos. Enumera los componentes del derecho comparado versados en la definición del hecho de la contaminación de las aguas, sistema de legislación y por último en la legislación argentina