2D µ-Particle Image Velocimetry and Computational Fluid Dynamics Study Within a 3D Porous Scaffold

Transport properties of 3D scaffolds under fluid flow are critical for tissue development. Computational fluid dynamics (CFD) models can resolve 3D flows and nutrient concentrations in bioreactors at the scaffold-pore scale with high resolution. However, CFD models can be formulated based on assumptions and simplifications. μ-Particle image velocimetry (PIV) measurements should be performed to improve the reliability and predictive power of such models. Nevertheless, measuring fluid flow velocities within 3D scaffolds is challenging. The aim of this study was to develop a μPIV approach to allow the extraction of velocity fields from a 3D additive manufacturing scaffold using a conventional 2D μPIV system. The μ-computed tomography scaffold geometry was included in a CFD model where perfusion conditions were simulated. Good agreement was found between velocity profiles from measurements and computational results. Maximum velocities were found at the centre of the pore using both techniques with a difference of 12% which was expected according to the accuracy of the μPIV system. However, significant differences in terms of velocity magnitude were found near scaffold substrate due to scaffold brightness which affected the μPIV measurements. As a result, the limitations of the μPIV system only permits a partial validation of the CFD model. Nevertheless, the combination of both techniques allowed a detailed description of velocity maps within a 3D scaffold which is crucial to determine the optimal cell and nutrient transport properties.

Prognostic prediction ability of postoperative multifocal ERG after vitrectomy for diabetic macular edema

PURPOSE

Diabetic macular edema (DME) causes visual loss in diabetic patients. Multifocal electroretinograms (mfERGs) have been used to assess macular function pre- and postvitrectomy for DME.

METHODS

A standard three-port pars plana vitrectomy with peeling of inner limiting membrane was performed in 25 eyes of 21 patients (13 male, 8 female) with DME. For each patient, visual acuity examination, measure of retinal thickness (using optical coherence tomography), and mfERGs were performed before and 1 week, 1 month, 3 months, and 6 months after vitrectomy.

RESULTS

Mean postoperative visual acuity was significantly improved (p<0.05, t test), with mean increase of 0.17 logMAR units; mean retinal thickness was significantly (p<0.001) decreased after surgery (from 537 microm to 298 microm). The increase of normalized amplitude of central ring was not significant; the mean P1 wave-amplitude increased from 0.33 to 0.40 mV; mean P1 wave-implicit time decreased 2.88 ms. We divided the patients into two groups: Group 1 (13 eyes), in which the visual recovery was less than 0.20 logMAR, and Group 2 (12 eyes), in which the visual recovery was greater than 0.20 logMAR. ERG results were statistically significantly different between the groups (p<0.025), when we consider the response recorded from the central ring. In Group 2 there is a marked reduction in implicit time of both ERGs waves, which was statistically significant for N1 wave (p=0.01). The changes of parameters of mfERG observed 6 months after surgery were consistent with those recorded just 1 week after surgery.

CONCLUSIONS

Multifocal electroretinogram can be useful to predict functional prognosis in patients with diabetes who underwent vitrectomy for diabetic macular edema.

Workplace supports, job performance, and integration outcomes for people with psychiatric disabilities

The notion of natural workplace supports is an essential ingredient in achieving successful supported employment outcomes. This quantitative study examines the characteristics of 243 individuals with psychiatric disabilities participating in supported employment programs in the United States. Diagnoses, psychiatric symptoms, and Global Assessment of Functioning were evaluated in relation to supported employment outcomes, including social interaction, wages, and workplace supports. The results of this study indicate that social interaction and natural workplace supports improve supported employment outcomes for individuals with psychiatric disabilities.

Immunological and biochemical evidence that blepharismin is not a prosthetic group

A polyclonal, multispecific antiserum was raised against a whole 3[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate-extract of nonirradiated Blepharisma japonicum cells. It was used to reveal the composition of solutions that were hypothesized to contain the photoreceptor of the ciliate. A Bio-Gel A 1.5 m fine column chromatography of the extract allowed recovery of a single elution peak isolated by recording the 580 nm light absorbance. Fused-rocket immunoelectrophoresis of this material revealed a large number of > 300 kDa coeluted proteins. Blepharismin-rich material with a molecular mass of approximately 50 kDa, consisting of at least nine proteins was obtained when the same extract underwent preparative isoelectric focusing before column chromatography separation. Purification of the pigment obtained from light-exposed cells gave blepharismin-rich material with a molecular weight of approximately 200 kDa. Comparison of the materials obtained under the same conditions, either from the dark-kept or light-irradiated cells, by means of pore-gradient electrophoresis confirmed that proteins present in the two preparations were different. It revealed only a very small amount, if any, of proteins in the chromatography fractions with the highest absorbance at 600 nm. Results are discussed on the basis of the hypothesis that a specific blepharismin-binding protein does not exist in the protozoan.

Teaching adolescents with severe disabilities to use the public telephone

Two adolescents with severe disabilities served as participants in a study conducted to train in the use of the public telephone to call home. Participants were trained to complete a 17-step task analysis using a training package which consisted of total task presentation in conjunction with a four-level prompting procedure (i.e., independent, verbal, verbal + gesture, verbal + guidance). All instruction took place in a public setting (e.g., a shopping mall) with generalization probes taken in two alternative settings (e.g., a movie theater and a convenience store). A multiple probe across individuals design demonstrated the training package was successful in teaching participants to use the telephone to call home. In addition, newly acquired skills generalized to the two untrained settings. Implications for community-based training are discussed.