Effect of glutaraldehyde based cross-linking on the viscoelasticity of mitral valve basal chordae tendineae.

BACKGROUND: Mitral valve failure can require repair or replacement. Replacement bioprosthetic valves are treated with glutaraldehyde prior to implantation. The aim of this study was to determine the changes in mechanical properties following glutaraldehyde fixation of mitral valve chordae. METHODS: To investigate the impact of glutaraldehyde on mitral valve chordae, 24 basal chordae were dissected from four porcine hearts. Anterior and posterior basal (including strut) chordae were used. All 24 chordae were subjected to a sinusoidally varying load (mean level 2N, dynamic amplitude 2N) over a frequency range of 0.5-10 Hz before and after glutaraldehyde treatment. RESULTS: The storage and loss modulus of all chordal types decreased following glutaraldehyde fixation. The storage modulus ranged from: 108 to 119 MPa before fixation and 67.3-87.4 MPa following fixation for basal chordae; 52.3-58.4 MPa before fixation and 47.9-53.5 MPa following fixation for strut chordae. Similarly, the loss modulus ranged from: 5.47 to 6.25 MPa before fixation and 3.63-4.94 MPa following fixation for basal chordae; 2.60-2.97 MPa before fixation and 2.31-2.93 MPa following fixation for strut chordae. CONCLUSION: The viscoelastic properties of mitral valve chordae are affected by glutaraldehyde fixation; in particular, the reduction in storage moduli decreased with an increase in chordal diameter.

A numerical analysis of the aortic blood flow pattern during pulsed cardiopulmonary bypass.

In the modern era, stroke remains a main cause of morbidity after cardiac surgery despite continuing improvements in the cardiopulmonary bypass (CPB) techniques. The aim of the current work was to numerically investigate the blood flow in aorta and epiaortic vessels during standard and pulsed CPB, obtained with the intra-aortic balloon pump (IABP). A multi-scale model, realized coupling a 3D computational fluid dynamics study with a 0D model, was developed and validated with in vivo data. The presence of IABP improved the flow pattern directed towards the epiaortic vessels with a mean flow increase of 6.3% and reduced flow vorticity.

Characterization of the anisotropic mechanical behaviour of colonic tissues: experimental activity and constitutive formulation.

The aim was to investigate the biomechanical behaviour of colonic tissues by a coupled experimental and numerical approach. The wall of the colon is composed of different tissue layers. Within each layer, different fibre families are distributed according to specific spatial orientations, which lead to a strongly anisotropic configuration. Accounting for the complex histology of the tissues, mechanical tests must be planned and designed to evaluate the behaviour of the colonic wall in different directions. Uni-axial tensile tests were performed on tissue specimens from 15 fresh pig colons, accounting for six different loading directions (five specimens for each loading direction). The next step of the investigation was to define an appropriate constitutive framework and develop a procedure for identification of the constitutive parameters. A specific hyperelastic formulation was developed that accounted for the multilayered conformation of the colonic wall and the fibre-reinforced configuration of the tissues. The parameters were identified by inverse analyses of the mechanical tests. The comparison of model results with experimental data, together with the evaluation of satisfaction of material thermomechanics principles, confirmed the reliability of the analysis developed. This work forms the basis for more comprehensive activities that aim to provide computational tools for the interpretation of surgical procedures that involve the gastrointestinal tract, considering the specific biomedical devices adopted.

Composite intestinal-type adenocarcinoma and small cell carcinoma of sinonasal tract.

BACKGROUND AND AIMS: Sinonasal intestinal-type adenocarcinomas (ITACs) are rare neoplasms resembling intestinal adenocarcinomas. Although several studies have documented neuroendocrine differentiation in ITACs, the combination of ITAC and small cell carcinoma has not been previously described in detail. The aim of this report is to detail the histopathological and immunohistochemical characteristics of two cases of composite ITAC with small cell carcinoma. METHODS: Two cases of composite ITAC with small cell carcinoma were routinely processed, and representative sections were stained with CAM5.2, AE1:AE3, keratin 7, keratin 20, keratin 19, CDX-2, p63, villin, chromogranin, synaptophysin and CD56. RESULTS: One tumour consisted of a mixed-type ITAC showing colonic-type and poorly differentiated adenocarcinoma with foci of "signet-ring" cells combined with small cell carcinoma. Both components stained positively with CAM5.2, AE1:AE3, CK7, CK20 and CK19, whereas only the small cell carcinoma expressed synaptophysin and CD56. Both components stained negatively with CDX-2, villin, CD99 and p63. The "signet-ring" cells stained positively with chromogranin and synaptophysin. The second tumour showed a papillary-type ITAC combined with a small cell carcinoma. The adenocarcinoma and small cell carcinoma stained positively with CAM5.2, AE1:AE3, CK7, CK19 and CK20. Only the adenocarcinoma was CDX-2 positive, whereas the small cell carcinoma expressed CD56 and synaptophysin. CONCLUSIONS: The two components of the combined ITACs and neuroendocrine small cell carcinoma show significant immunohistochemical overlap, supporting a common origin. The occurrence of a distinct neuroendocrine carcinoma combined with ITACs expands the histopathological spectrum of these tumours.

Utilidad de la ecografía en el diagnóstico de enfermedades del bazo / Usefulness of ultrasonography in the diagnosis of spleen disorders

Se valoró la utilidad de la utrasonografía en la detección de alteraciones esplénicas en pacientes pediátricos, como método de diagnóstico por imágenes de baja complejidad, que permitió detectar diferentes patologías basándose en alteraciones de la ecoestructura del parénquima esplénico.Se seleccionaron de la base de datos Epi Info del servicio de Ecografía 42 pacientes que concurrieron al mismo durante el período 1994-1998 a los que se lesdetectó patología esplénica, no se incluyeron las esplenomegalias inespecíficas. Las enfermedades infecciosas fueron la causa más frecuente de patología esplénica de la muestra (33 por ciento), seguida de la patología malformativa (24 por ciento). No fue despreciable el compromiso tumoral, en su mayoría secundario (19por ciento). Menos frecuente fueron los quistes esplénicos (7 por ciento) y la patología secundaria a traumatismos (5 por ciento). El resto se agrupó en enfermedad esplénica, no infecciosa, no traumática (12 por ciento). La ultrasonografíaes un método de diagnóstico altamente confiable en la detección precoz de patología que altera la estructura del bazo en pediatría. La misma es, en su mayoría,una manifestación asociada o secundaria a enfermedades en otros órganos o sistemas. (AU)

Utilidad de la ecografía en el diagnóstico de enfermedades del bazo / Usefulness of ultrasonography in the diagnosis of spleen disorders

Se valoró la utilidad de la utrasonografía en la detección de alteraciones esplénicas en pacientes pediátricos, como método de diagnóstico por imágenes de baja complejidad, que permitió detectar diferentes patologías basándose en alteraciones de la ecoestructura del parénquima esplénico.Se seleccionaron de la base de datos Epi Info del servicio de Ecografía 42 pacientes que concurrieron al mismo durante el período 1994-1998 a los que se lesdetectó patología esplénica, no se incluyeron las esplenomegalias inespecíficas. Las enfermedades infecciosas fueron la causa más frecuente de patología esplénica de la muestra (33 por ciento), seguida de la patología malformativa (24 por ciento). No fue despreciable el compromiso tumoral, en su mayoría secundario (19por ciento). Menos frecuente fueron los quistes esplénicos (7 por ciento) y la patología secundaria a traumatismos (5 por ciento). El resto se agrupó en enfermedad esplénica, no infecciosa, no traumática (12 por ciento). La ultrasonografíaes un método de diagnóstico altamente confiable en la detección precoz de patología que altera la estructura del bazo en pediatría. La misma es, en su mayoría,una manifestación asociada o secundaria a enfermedades en otros órganos o sistemas.