Rapid 3D printing of anatomically accurate and mechanically heterogeneous aortic valve hydrogel scaffolds.

The aortic valve exhibits complex three-dimensional (3D) anatomy and heterogeneity essential for the long-term efficient biomechanical function. These are, however, challenging to mimic in de novo engineered living tissue valve strategies. We present a novel simultaneous 3D printing/photocrosslinking technique for rapidly engineering complex, heterogeneous aortic valve scaffolds. Native anatomic and axisymmetric aortic valve geometries (root wall and tri-leaflets) with 12-22 mm inner diameters (ID) were 3D printed with poly-ethylene glycol-diacrylate (PEG-DA) hydrogels (700 or 8000 MW) supplemented with alginate. 3D printing geometric accuracy was quantified and compared using Micro-CT. Porcine aortic valve interstitial cells (PAVIC) seeded scaffolds were cultured for up to 21 days. Results showed that blended PEG-DA scaffolds could achieve over tenfold range in elastic modulus (5.3±0.9 to 74.6±1.5 kPa). 3D printing times for valve conduits with mechanically contrasting hydrogels were optimized to 14 to 45 min, increasing linearly with conduit diameter. Larger printed valves had greater shape fidelity (93.3±2.6, 85.1±2.0 and 73.3±5.2% for 22, 17 and 12 mm ID porcine valves; 89.1±4.0, 84.1±5.6 and 66.6±5.2% for simplified valves). PAVIC seeded scaffolds maintained near 100% viability over 21 days. These results demonstrate that 3D hydrogel printing with controlled photocrosslinking can rapidly fabricate anatomical heterogeneous valve conduits that support cell engraftment.

A cardioplegia circuit with versatility: the 'ReVerse' system. How to do it.

Various methods of cardioplegia administration have been used in cardiac surgery: crystalloid, blood and mixed crystalloid/blood. Each of these types of cardioplegia administration typically needs a different circuit. This may correspond to an increase in cost and the time needed to change the circuit if required. When various modifications are performed on the circuit, this also increases the risk of contamination. In order to simplify the management of differing cardioplegia circuits, we devised one circuit for all solutions in all situations by adding one modification. The ReVerse cardioplegia circuit system is a description of a two-pump cardioplegia circuit which is adaptable to either blood or crystalloid cardioplegia. The change from one mode to another requires a manoeuvre of two clamps, allowing the blood solution to travel through shunt tubing into the apposite pumphead. In our experience the versatility of this circuit is a fast, safe method to administrate all types of cardioplegia solution, saving the space taken up by storing multiple circuits.

Structural properties, conformational stability and oxygen binding properties of Penaeus monodon hemocyanin.

Hemocyanin sequences allineament shows the presence of highly invariant regions especially in the active site and in the tight intersubunits interaction sites. Comparing the aminoacids in contact regions between monomers is possible to interpret the stability of hexamers.

A simplified technique for antegrade selective cerebral perfusion.

Various methods of cerebral protection have been used during aortic arch surgery. We reviewed our experience with a modified technique for selective cerebral perfusion (SCP) administration during surgery on the thoracic aorta from October 1999. Conventionally, this technique requires an additional roller pump on the cardiopulmonary bypass (CPB) console. In order to simplify the extracorporeal circuit (ECC), the paediatric double-roller pump used for the administration of cardioplegia was utilized by adding a 'Y-connection' on the blood line of the cardioplegia circuit, upstream of the cardioplegia reservoir, to provide SCP blood flow. SCP administration with a Y-connection is both easy and fast to set up on the ECC circuit and does not create additional difficulties to the surgeon. It simplifies SCP delivery by allowing the perfusionist to use a standard ECC system set-up.

Perceived parental social support and academic achievement: an attachment theory perspective.

The study tested the extent to which parental social support predicted college grade point average among undergraduate students. A sample of 418 undergraduates completed the Social Provisions Scale--Parent Form (C.E. Cutrona, 1989) and measures of family conflict and achievement orientation. American College Testing Assessment Program college entrance exam scores (ACT; American College Testing Program, 1986) and grade point average were obtained from the university registrar. Parental social support, especially reassurance of worth, predicted college grade point average when controlling for academic aptitude (ACT scores), family achievement orientation, and family conflict. Support from parents, but not from friends or romantic partners, significantly predicted grade point average. Results are interpreted in the context of adult attachment theory.

Mechanical inventiveness: a three-phase study.

This paper focuses on mechanical inventiveness, the conception and development of new devices which require use of mechanical principles. In Phase 1 of the three-phase investigation, we studied 34 inventors who received between three and 82 agricultural and industrial patents. These inventors formed the original criterion group of mechanical inventors. Phase 2 of the investigation was the development of an inventiveness measure. From the criterion group of adult mechanical inventors, the Iowa Inventiveness Inventory (III) was developed to measure attitudes and characteristics of inventors. Subjects for Phase 3 of the study were 90 young inventors (40 males, 50 females), students (grades five to eight) who won local and regional invention contests and reached the state convention of Invent Iowa. In Phase 3, Invent Iowa state finalists in grades five to eight (n = 90) were administered the III and the Mechanical Reasoning test of the Differential Aptitude Tests. Characteristics of the young inventors, as delineated by these assessments, are provided.

Priority setting in family change and clinical practice: the Family FIRO Model.

We update a theoretical framework for understanding priority setting for the management of family change, with special emphasis on developmental change. We propose that three core dimensions of family interaction--inclusion, control, and intimacy--constitute an optimal priority sequence for managing major family change stemming from life-cycle transitions and other stressful experiences. In the next section of the article, we compare the Family FIRO Model and other models of family change. Finally, we suggest that therapists can benefit from an explicit, clinical decision-making model for setting priorities in treatment: issues of inclusion take precedence over issues of control, which in turn take precedence over issues of intimacy.