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Hosseinzadeh, Z.

Publications and source records attributed to Hosseinzadeh, Z..

2 recordsLinked to original sources

Adaptation of visual responses in degenerating rd10 and healthy mouse retinas during ongoing electrical stimulation.

ObjectiveVisual adaptation is a physiological and perceptual process by which the visual system adjusts to changes in the environment or visual stimuli. This process is fundamental to how we perceive the world around us and allows our visual system to efficiently encode and process visual information. The retina incorporates adaptaion with its dozens of functionally distinct retinal ganglion cell types. Meanwhile, the field of retinal prostheses is increasing its understanding of electrical adaptation and cell-specific stimulation. However, very little is known about the interaction of visual and electrical stimulation on the adaptation of retinal ganglion cell types. Methods/ApproachRecording with a microelectrode array (MEA), we presented an ON and OFF full-field, visual stimulus to characterize various visual response parameters in healthy and degenerating rd10 mouse retinas. We then evaluated visual response changes before and after blocks of monophasic voltage-controlled electrical pulse stimulation. Main ResultsA history of electrical stimulation strengthened visual responses in WT retina, even when changes attributable to in vitro visual adaptation were taken into account. In rd10 retinas, electrical adaptation counteracted the baseline in vitro visual adaptation. In all cases, adaptation often affected the ON and OFF visual response components differentially. Consequently, the ON/OFF classification of indiviual cells changed as a result of adaptation. SignificanceElectrical stimulation-induced changes in the retina should be considered in the encoding of visual stimuli by retinal prosthetic devices. In vitro investigations for bionic vision should strive to probe electrical responsiveness after adaptation to ongoing electrical stimulation has achieved a steady-state.

neuroscience↗

Investigation of co-encapsulation of pancreatic beta cells and curcumin within alginate microcapsules

1.Cell encapsulation is an ideal approach for the replacement of pancreatic function in Type 1 diabetes. Poor biocompatibility of microcapsules generates an inflammatory response in the implantation site and induces fibrosis infiltration, which causes microencapsulated cell death and graft failure. To prevent inflammation after implantation, composite microcapsules which exhibit anti-inflammatory properties were designed. This study is about co-encapsulating beta cells and curcumin within 1.5% alginate by the jet-breaking regime of the syringe pump. The microcapsules size distribution and rate of the alginate solution were characterized to find uniform particles. Micro-size particles were attained at a rate of 25 ml/min. Uniform spherical microcapsules (200-300 m) were created in large amounts in a short period. Microcapsule breakage was less than 3% during 7 days and demonstrated the stability of the encapsulation method. Insulin secretion and cell viability assays were performed 1, 3, and 7 days after microencapsulation by GSIS and MTT assays. No significant differences in the amount of insulin secretion and beta cell viability were observed among free cells, alginate microcapsules, and curcumin-alginate microcapsules during 7 days (P > 0.05). Therefore, curcumin and alginate membrane did not show any harmful impacts on the function and survival of the beta cells.

bioengineering↗