Anisotropic behaviour of human gallbladder walls

Inverse estimation of biomechanical parameters of soft tissues from non-invasive measurements has clinical significance in patient-specific modelling and disease diagnosis. In this paper, we propose a fully nonlinear approach to estimate the mechanical properties of the human gallbladder wall muscles from in vivo ultrasound images. The iteration method consists of a forward approach, in which the constitutive equation is based on a modified Hozapfel–Gasser–Ogden law initially developed for arteries. Five constitutive parameters describing the two orthogonal families of fibres and the matrix material are determined by comparing the computed displacements with medical images. The optimisation process is carried out using the MATLAB toolbox, a Python code, and the ABAQUS solver. The proposed method is validated with published artery data and subsequently applied to ten human gallbladder samples. Results show that the human gallbladder wall is anisotropic during the passive refilling phase, and that the peak stress is 1.6 times greater than that calculated using linear mechanics. This discrepancy arises because the wall thickness reduces by 1.6 times during the deformation, which is not predicted by conventional linear elasticity. If the change of wall thickness is accounted for, then the linear model can used to predict the gallbladder stress and its correlation with pain. This work provides further understanding of the nonlinear characteristics of human gallbladder

Psychology and aggression

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68264/2/10.1177_002200275900300301.pd

Broadband single transverse-mode fluorescence sources based on ribs fabricated in pulsed laser deposited Ti:sapphire waveguides

Active rib waveguides with depths and widths varying from 3 to 5 µm and from 9 to 24 µm, respectively, have been structured by Ar+-beam etching in pulsed laser deposited Ti:sapphire layers. Losses in the channel structures were essentially at the same levels as the unstructured planar waveguide host, therefore suggesting that there is no significant additional contribution to loss from the rib-fabrication procedure. Measurements of the beam-propagation factors, Mx2 and My2, indicate single-transverse-mode fluorescence emission. The fluorescence output power was in the order of 300 µW when the structures were pumped by a 3-W multiline argon laser. These characteristics make the rib structures suitable as light sources for optical coherence tomography applications and facilitate their coupling to the optical fibre interferometers of such systems

Leiomiossarcoma pulmonar e renal em cão: relato de caso Pulmonary and renal leiomyosarcoma in dog: a case report

Este relato descreve um caso de leiomiossarcoma pulmonar e renal em cão da raça Husky Siberiano, macho, de nove anos de idade e com histórico de emagrecimento progressivo há mais de três meses. Ao exame clínico, o animal apresentava palidez discreta das mucosas e dor intensa à palpação abdominal, além de aumento de volume acentuado dos rins. No hemograma, foi evidenciada anemia discreta e na urinálise foram observados isostenúria e grumos de células do epitélio renal. Os níveis plasmáticos de uréia e creatinina estavam dentro dos limites considerados normais. O animal foi sacrificado após a confirmação de neoplasia renal bilateral por laparotomia exploratória. À necropsia, os rins apresentavam vários nódulos de 0,5 a 4cm de diâmetro, esbranquiçados e firmes. Na região do hilo e no lobo apical esquerdo dos pulmões havia aumento de volume, com 11 × 7cm de extensão, de superfície irregular e bem vascularizada, esbranquiçada e com áreas de consistência ora firmes, ora friáveis. No lobo apical direito também havia um nódulo com 1cm de diâmetro, firme e esbranquiçado. Secções histológicas dos pulmões e dos rins foram coradas pela hematoxilina-eosina, Masson e Van Gieson. Foi detectada positividade, pela imuno-histoquímica, para a vimentina e actina alfa de músculo liso. Não houve imunomarcação para citoqueratinas 1, 5, 10, 14, 8 e 7, proteína S100 e para CD68. Com base nos achados anatomopatológicos e imuno-histoquímicos foi firmado o diagnóstico de leiomiossarcoma pulmonar e renal, sem, no entanto, definir o sítio primário da neoplasia.<br>This report describes a case of pulmonary and renal leiomyosarcoma in a nine-year-old Siberian Husky male dog with a history of progressive weight loss. Clinically, the animal had mildly pale mucosae and severe abdominal pain. Kidneys enlargement also was observed. On hemogram, a mild anemia was observed. On urinalysis, isosthenuria and renal epithelial cells were detected. Urea nitrogen and creatinine levels were normal. Bilateral renal neoplasia was diagnosed by laparotomy and the animal was submitted to euthanasia. On necropsy, many whitish firm nodules ranging from 0.5 to 4cm in diameter were found in the kidneys. The region of the hilum and the left apical lobe of the lungs had a mass with 11× 7cm in area which was well vascularized and had an irregular whitish surface with either firm or friable areas. There was also a whitish firm nodule with 1cm in diameter in the right apical lobe. Histological sections were stained by hematoxilin-eosin, Masson and van Gieson. Positivity for the vimentin and smooth muscle actin were detected by immunohistochemistry. Cytokeratin 1, 5, 10, 14, 8 and 7, protein S100 and CD68 markers showed negative reactions. The anatomopathological and immunohistochemistry features allowed the diagnosis of pulmonary and renal leiomyosarcoma. However, it was not possible to determine the primary site of the neoplasia