The conceptual framework of ontogenetic trajectories: parallel transport allows the recognition and visualization of pure deformation patterns.

Ontogeny is usually studied by analyzing a deformation series spanning over juvenile to adult shapes. In geometric morphometrics, this approach implies applying generalized Procrustes analysis coupled with principal component analysis on multiple individuals or multiple species datasets. The trouble with such a procedure is that it mixes intra- and inter-group variation. While MANCOVA models are relevant statistical/mathematical tools to draw inferences about the similarities of trajectories, if one wants to observe and interpret the morphological deformation alone by filtering inter-group variability, a particular tool, namely parallel transport, is necessary. In the context of ontogenetic trajectories, one should firstly perform separate multivariate regressions between shape and size, using regression predictions to estimate within-group deformations relative to the smallest individuals. These deformations are then applied to a common reference (the mean of per-group smallest individuals). The estimation of deformations can be performed on the Riemannian manifold by using sophisticated connection metrics. Nevertheless, parallel transport can be effectively achieved by estimating deformations in the Euclidean space via ordinary Procrustes analysis. This approach proved very useful in comparing ontogenetic trajectories of species presenting large morphological differences at early developmental stages.

Non-invasive assessment of functional strain lines in the real human left ventricle via speckle tracking echocardiography.

A mechanics-based analysis of data from three-dimensional speckle tracking echocardiography is proposed, aimed at investigating deformations in myocardium and at assessing shape and function of distinct strain lines corresponding to the principal strain lines of the cardiac tissue. The analysis is based on the application of a protocol of measurement of the endocardial and epicardial principal strain lines, which was already tested on simulated left ventricles. In contrast with similar studies, it is established that endocardial principal strain lines cannot be identified with any structural fibers, not even along the systolic phase and is suggested that it is due to the capacity of the endocardial surface to contrast the dilation of the left ventricle.

Evaluation of the strain-line patterns in a human left ventricle: a simulation study.

The aim of this paper is to emphasise the role of the primary strain-line patterns in a human left ventricle (LV) within the complex system that is the heart. In particular, a protocol is proposed for the measurement of the principal strain lines (PSL) in the walls of the LV; this protocol is tested by means of a computational model which resembles a human LV. When the analysis is focused on the epicardial surface, PSL can be used to derive information on the directions of muscle fibres during the entire cardiac cycle, not only the systolic phase.

Torsion of the human left ventricle: experimental analysis and computational modeling.

We set a twofold investigation: we assess left ventricular (LV) rotation and twist in the human heart through 3D-echocardiographic speckle tracking, and use representative experimental data as benchmark with respect to numerical results obtained by solving our mechanical model of the LV. We aim at new insight into the relationships between myocardial contraction patterns and the overall behavior at the scale of the whole organ. It is concluded that torsional rotation is sensitive to transmural gradients of contractility which is assumed linearly related to action potential duration (APD). Pressure-volume loops and other basic strain measures are not affected by these gradients. Therefore, realistic torsional behavior of human LV may indeed correspond to the electrophysiological and functional differences between endocardial and epicardial cells recently observed in non-failing hearts. Future investigations need now to integrate the mechanical model proposed here with minimal models of human ventricular APD to drive excitation-contraction coupling transmurally.

The watermelon stomach: long-term outcome in patients treated with Nd:YAG laser therapy.

Watermelon stomach is an unusual cause of gastrointestinal bleeding and iron deficiency anemia. Its etiology is unknown, but it has been reported to be associated with a variety of diseases, including autoimmune disorders and cirrhosis. We report on the long-term outcome of 15 patients (13 women, 2 men) treated with neodymium-yttrium-aluminum-garnet (Nd:YAG) laser therapy. The mean age of patients at presentation was 71.6 years (range, 59 to 85 years). Fourteen patients were transfusion-dependent, requiring an average of 9.6 units of blood in the 12 months preceding diagnosis and treatment. Associated diseases included scleroderma (3 patients), mixed connective tissue disease (1 patient), history of cancer (3 patients), cryptogenic cirrhosis (3 patients), and chronic renal failure (3 patients). In 7 of 9 patients who had an antinuclear antibody test, an elevated titer greater than 1:160 in a speckled pattern was noted. Nd:YAG laser coagulation therapy was administered to all patients without complications and was successful in reducing bleeding in every case. Five patients died during the course of follow-up without signs of recurrent gastrointestinal bleeding. The remaining 10 patients have had both endoscopic and hematologic improvement during a mean follow-up period of 4.4 years from the time of initial diagnosis (range, 2 to 8 years). The 10 survivors are no longer transfusion-dependent and have stable hematocrits.

Duodenal obstruction by a nondeflating Foley catheter gastrostomy tube.

We report the case of a 36-year-old mentally retarded man who presented to our emergency department after one day of vomiting and one episode of coffee-ground emesis. The Foley catheter used as his gastrostomy tube was found to be obstructing the duodenum, and the balloon could not be deflated. Removal was accomplished by rupturing the balloon by endoscopy. Our case illustrates one of many possible complications of feeding gastrostomy tubes.