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Biomedical subjects

A Previti

Publications and source records attributed to A Previti.

6 recordsLinked to original sources
PubMed2004

Microfabricated fractal branching networks.

In this article, we demonstrate how a combination of engineering and biological techniques could lead to the realization of branched microstructures that can be used for the repair of damaged vascularized tissue. Recursive "treelike" networks were first generated by using fractal algorithms based on Murray's equation for vascular branching as well as allometric scaling rules. Two- and three-dimensional branching patterns with different levels of complexity were then microfabricated from poly-lactide-co-glycolide (PLGA) by using the pressure-assisted microsyringe (PAM) system developed in our laboratory. Human endothelial cells isolated from umbilical cords were seeded on the microfabricated branched scaffolds to evaluate their effectiveness in supporting site-specific cell adhesion. The results show that cell densities on the networks increase with complexity up to the sixth level and are then constant independent of branching level. The implications of this finding are discussed in terms of contact inhibition of "capillaries."

Algorithms↗
PubMed2002

Microsyringe-based deposition of two-dimensional and three-dimensional polymer scaffolds with a well-defined geometry for application to tissue engineering.

A technique for controlled deposition of biomaterials and cells in specific and complex architectures is described. It employs a highly accurate three-dimensional micropositioning system with a pressure-controlled syringe to deposit biopolymer structures with a lateral resolution of 5 microm. The pressure-activated microsyringe is equipped with a fine-bore exit needle and a wide variety of two- and three-dimensional patterns on which cells to be deposited can adhere. The system has been characterized in terms of deposition parameters such as applied pressure, motor speed, line width and height, and polymer viscosity, and a fluid dynamic model simulating the deposition process has been developed, allowing an accurate prediction of the topological characteristics of the polymer structures.

Biocompatible Materials↗
PubMed2000

Usefulness of transesophageal echocardiography during open heart surgery of mitral stenosis.

BACKGROUND: The aim of this study was to verify if the use of intraoperative transesophageal echocardiography (TEE), by detecting mitral insufficiency or residual stenosis during surgery, may improve medium term results in patients with severe mitral stenosis who undergo open heart valvuloplasty. METHODS: This prospective study included twenty-two patients (20 women and 2 men) with a mean age of 49+/-13 years with severe mitral stenosis. Mean follow-up was 32 months (range 12-55 months). All the patients underwent transthoracic echocardiography (TrE) before surgery and intraoperative TEE. Before surgery the mean transmitral gradient was 11+/-6.8 mmHg, the mean pressure half time (PHT) area was 0.89+/-0.19 cm2, the mean echo score was 8.9+/-2.2. Intraoperative TEE before the repair showed a mean echo score of 7.9+/-1.8. RESULTS: Two patients with unsatisfactory repair at TEE underwent immediate valve replacement. In the remaining patients, mean transmitral gradient and PHT valve area before discharge was 5.2+/-3 mmHg and 2.5 cm2. No patients had more than trivial mitral regurgitation. During the follow-up two patients had to be reoperated. Patients with poor immediate (2 patients) or medium term results (2 patients), had a mean echocardiographic score of 12.24, while patients with a satisfactory medium term outcome had a mean score of 7.27 (p<0.001). CONCLUSIONS: Intraoperative TEE may guide the surgeon in the assessment of valvuloplasty. However the absence of mitral regurgitation after repair and at discharge cannot predict the medium term results, which are related to the degree of the disease of the mitral valve.

Adult↗