Fabrication using a rapid prototyping system and in vitro characterization of PEG-PCL-PLA scaffolds for tissue engineering

In the field of tissue engineering new polymers are needed to fabricate scaffolds with specific properties depending on the targeted tissue. This work aimed at designing and developing a 3D scaffold with variable mechanical strength, fully interconnected porous network, controllable hydrophilicity and degradability. For this, a desktop-robot-based melt-extrusion rapid prototyping technique was applied to a novel tri-block co-polymer, namely poly(ethylene glycol)-block-poly(epsilon-caprolactone)-block-poly(DL-lactide), PEG-PCL-P(DL)LA. This co-polymer was melted by electrical heating and directly extruded out using computer-controlled rapid prototyping by means of compressed purified air to build porous scaffolds. Various lay-down patterns (0/30/60/90/120/150 degrees, 0/45/90/135 degrees, 0/60/120 degrees and 0/90 degrees) were produced by using appropriate positioning of the robotic control system. Scanning electron microscopy and micro-computed tomography were used to show that 3D scaffold architectures were honeycomb-like with completely interconnected and controlled channel characteristics. Compression tests were performed and the data obtained agreed well with the typical behavior of a porous material undergoing deformation. Preliminary cell response to the as-fabricated scaffolds has been studied with primary human fibroblasts. The results demonstrated the suitability of the process and the cell biocompatibility of the polymer, two important properties among the many required for effective clinical use and efficient tissue-engineering scaffolding.

Predictors of first lifetime episodes of major depression in midlife women

BACKGROUND

Little is known about factors that predict first lifetime episodes of major depression in middle-aged women. It is not known whether health-related factors and life stress pose more or less of a risk to the onset of clinical depression than does the menopausal transition.

METHOD

The Structured Clinical Interview for DSM-IV Axis I Disorders (SCID) was used to assess diagnoses of lifetime, annual and current major depression in a community-based sample of premenopausal or early perimenopausal African American and White women. Menstrual cycle characteristics, psychosocial and health-related factors, and blood samples for assay of reproductive hormones were obtained annually. Two hundred and sixty-six women without a history of major depression at baseline constituted the cohort for the current analyses.

RESULTS

Over 7 years of follow-up, 42 (15.8%) women met criteria for a diagnosis of major depression. Frequent vasomotor symptoms (VMS; hot flashes and/or night sweats) (HR 2.14, p=0.03) were a significant predictor of major depression in univariate analyses. After simultaneous adjustment for multiple predictors in Cox proportional hazards analyses, frequent VMS were no longer significant; lifetime history of an anxiety disorder (HR 2.20, p=0.02) and role limitations due to physical health (HR 1.88, p=0.07) at baseline and a very stressful life event (HR 2.25, p=0.04) prior to depression onset predicted a first episode of major depression.

CONCLUSIONS

Both earlier (e.g. history of anxiety disorders) and more proximal factors (e.g. life stress) may be more important than VMS in contributing to a first episode of major depression during midlife.