Aortic dissection is rare in the pediatric and young adult population. We hereby present a case of a 17-year- old male patient, without any predisposing factors, who developed an aortic dissection. The initial presentation was acute abdominal pain with massive retroperitoneal hematoma. His clinical condition deteriorated rapidly, did not respond to surgical hemostasis, and died within 36 hours ...

Predisposition to Achilles tendon (AT) ruptures in middle-aged individuals may be associated with age-related changes to inherent passive biomechanical properties of the gastrocnemius-Achilles (GC-AT) muscle-tendon unit, due to known muscle-tendon structural changes in normal aging. The goal of this study was to determine whether the passive biomechanical response of the GC-AT muscle-tendon uni...

A rare condition, which generally occurs in young adults and may, simulate coronary disease, is discussed. The patients are afebrile, with low blood pressures, fast weak pulses and marked irregularities in cardiac rhythm. They are unresponsive to therapy and may survive initial attacks only to succumb to a recurrence. In the portions of the endocardium uninvolved by mural thrombi, there is mark...

Using positional data from video microscopy, we determine the elastic moduli of two-dimensional colloidal crystals as a function of temperature. The moduli are extracted from the wave-vector-dependent normal-mode spring constants in the limit q-->0 and are compared to the renormalized Young's modulus of the Kosterlitz-Thouless-Halperin-Nelson-Young theory. An essential element of this theory is...

It is known that muscular force is reduced in old age. We investigate what are the effects of this phenomenon on the mechanics of running. We hypothesized that the deficit in force would result in a lower push, causing reduced amplitude of the vertical oscillation, with smaller elastic energy storage and increased step frequency. To test this hypothesis, we measured the mechanical energy of the...

An existence result for the quasi-static evolution of incomplete damage in elastic materials is presented. The absence of gradient terms in the damage variable causes a critical lack of compactness. Therefore, the analysis is developed in the framework of Young measures, where a notion of solution is defined, presenting some improvements with respect to previous contributions. The main new feat...

Elastin, the main component of elastic fibers, is synthesized only in early life and provides the blood vessels with their elastic properties. With aging, elastin is progressively degraded, leading to arterial enlargement, stiffening, and dysfunction. Also, elastin is a key regulator of vascular smooth muscle cell proliferation and migration during development since heterozygous mutations in it...

Elastin is the prime protein in elastic tissues that contributes to elasticity of, for example, lung, aorta, and skin. Upon injury, elastic fibers are not readily replaced, which hampers tissue regeneration. Incorporation of solubilized elastin (hydrolyzed insoluble elastin fibers or elastin peptides) in biomaterials may improve regeneration, because solubilized elastin is able to promote proli...

OBJECTIVE To determine whether arterial wall hypertrophy in elastic arteries was associated with alteration in their mechanical properties in young patients with Williams syndrome. METHODS Arterial pressure and intima-media thickness, cross sectional compliance, distensibility, circumferential wall stress, and incremental elastic modulus of the common carotid artery were measured non-invasive...

A good understanding of thoracic biomechanics is important for complete examination and control of chest behaviour under conditions of physiological and pathological work, and under the impact of external forces leading to traumatic loading of the chest. The purpose of the study was to analyse the mechanical properties of human ribs obtained from individuals under the age of 25 with scoliosis d...