Assessing the Usefulness of Ultrasonography for the Diagnosis and Evaluation of Intra-Orbital Lesions in Pediatric Patients: A Retrospective Analysis.

OBJECTIVES: To assess the usefulness of ultrasonography in the diagnosis and evaluation of extraocular intra-orbital lesions in pediatric patients. METHODS: Twenty-three pediatric patients with intra-orbital lesions who underwent both ultrasound and computed tomography/magnetic resonance imaging (CT/MRI) were included. The following parameters were evaluated using ultrasound: 1) lesion detection rate (presence or absence of lesions), 2) lesion characteristics, 3) lesion location (extraconal or intraconal), and 4) the lesion longest linear dimensions, and these were compared using Fisher's exact test and Mann-Whitney U test. RESULTS: Two lesions could not be detected using ultrasound; in the other 21 cases, the lesion characteristics diagnosed by ultrasound were correct. Diagnostic accuracy of detection and characteristics assessment using ultrasound were 91.3% and 91.3%, respectively. The lesion location was not significantly different between the two groups (intraconal/extraconal in those detected using ultrasound versus those in the absence on ultrasound = 7/14 versus 0/2, P > .999); however, in two cases that were not detected on ultrasound, the lesions were located at extraconal. Lesions that were small in longest linear dimensions on CT/MRI were not detected using ultrasound (the longest linear dimensions in lesions detected using ultrasound versus that in the absence of ultrasound: 29.5 ± 8.2 [range, 13-46] versus 10 and 11 mm, P = .043). CONCLUSIONS: Ultrasonography proved to be useful for visualizing and evaluating intra-orbital lesions except for lesions that were relatively small in size. Therefore, although ultrasound could not detect lesions located behind bone and bone invasion, it could be used for diagnosing and selecting treatment strategies for intra-orbital lesions.

Engineering thick cell sheets by electrochemical desorption of oligopeptides on membrane substrates.

We developed a gold-coated membrane substrate modified with an oligopeptide layer that can be used to grow and subsequently detach a thick cell sheet through an electrochemical reaction. The oligopeptide CCRRGDWLC was designed to contain a cell adhesive domain (RGD) in the center and cysteine residues at both terminals. Cysteine contains a thiol group that forms a gold-thiolate bond on a gold surface. Cells attached to gold-coated membrane substrates via the oligopeptide layer were readily and noninvasively detached by applying a negative electrical potential to cleave the gold-thiolate bond. Because of the effective oxygen supply, fibroblasts vigorously grew on the membrane substrate and the thickness of the cell sheets was ∼60 µm at 14 days of culture, which was 2.9-fold greater than that of cells grown on a conventional culture dish. The cell sheets were detached after 7 min of electrical potential application. Using this approach, five layers of cell sheets were stacked sequentially with thicknesses reaching >200 µm. This approach was also beneficial for rapidly and readily transplanting cell sheets. Grafted cell sheets secreted collagen and remained at the transplanted site for at least 2 months after transplantation. This simple electrochemical cell sheet engineering technology is a promising tool for tissue engineering and regenerative medicine applications.

Cell-adhesive and cell-repulsive zwitterionic oligopeptides for micropatterning and rapid electrochemical detachment of cells.

In this study, we describe the development of oligopeptide-modified cell culture surfaces from which adherent cells can be rapidly detached by application of an electrical stimulus. An oligopeptide, CGGGKEKEKEK, was designed with a terminal cysteine residue to mediate binding to a gold surface via a gold-thiolate bond. The peptide forms a self-assembled monolayer through the electrostatic force between the sequence of alternating charged glutamic acid (E) and lysine (K) residues. The dense and electrically neutral oligopeptide zwitterionic layer of the modified surface was resistant to nonspecific adsorption of proteins and adhesion of cells, while the surface was altered to cell adhesive by the addition of a second oligopeptide (CGGGKEKEKEKGRGDSP) containing the RGD cell adhesion motif. Application of a negative electrical potential to this gold surface cleaved the gold-thiolate bond, leading to desorption of the oligopeptide layer, and rapid (within 2 min) detachment of virtually all cells. This approach was applicable not only to detachment of cell sheets but also for transfer of cell micropatterns to a hydrogel. This electrochemical approach of cell detachment may be a useful tool for tissue-engineering applications.

Tissue engineering based on electrochemical desorption of an RGD-containing oligopeptide.

This paper describes a non-invasive approach for efficient detachment of cells adhered to a gold substrate via a specific oligopeptide. Detachment is effected by an electrical stimulus. The oligopeptide contains cysteine, which spontaneously forms a gold-thiolate bond on a gold surface. This chemical adsorption reaches > 95% equilibrium within 10 min after immersion of a gold-coated substrate in a solution containing the peptide. The peptide is reversibly desorbed from the surface within 5 min of application of a negative electrical potential. By taking advantage of this simple adsorption and desorption mechanism, cells can be grown on an oligopeptide-functionalized gold surface and can be efficiently detached as single cells or cell sheets by application of a negative electrical potential. This approach was also applied to the surface of gold-coated microrods. Capillary-like microchannels were formed in collagen gel by transferring endothelial cells to the internal surfaces of the microchannels. During subsequent perfusion culture, the enveloped endothelial cells migrated into the collagen gel and formed luminal structures, which sprouted from the microchannels. This technique has the potential to provide a fundamental tool for the engineering of thick cell sheets as well as vascularized tissues and organs.

Processing of nanolitre liquid plugs for microfluidic cell-based assays.

Plugs, i.e. droplets formed in a microchannel, may revolutionize microfluidic cell-based assays. This study describes a microdevice that handles nanolitre-scale liquid plugs for the preparation of various culture setups and subsequent cellular assays. An important feature of this mode of liquid operation is that the recirculation flow generated inside the plug promotes the rapid mixing of different solutions after plugs are merged, and it keeps cell suspensions homogeneous. Thus, serial dilutions of reagents and cell suspensions with different cell densities and cell types were rapidly performed using nanolitres of solution. Cells seeded through the plug processing grew well in the microdevice, and subsequent plug processing was used to detect the glucose consumption of cells and cellular responses to anticancer agents. The plug-based microdevice may provide a useful platform for cell-based assay systems in various fields, including fundamental cell biology and drug screening applications.

Preparation of arrays of cell spheroids and spheroid-monolayer cocultures within a microfluidic device.

This study describes a novel method for generation of an array of three-dimensional (3D) multicellular spheroids within a microchannel in patterned cultures containing one or multiple cell types. This method uses a unique property of a cross-linked albumin coated surface in which the surface can be switched from non-adhesive to cell adhesive upon electrostatic adsorption of a polycation. Introduction of a solution containing albumin and a cross-linking agent into a microchannel with an array of microwells caused the entire surface, with the exception of the interior of the microwells, to become coated with the cross-linked albumin layer. Cells that were seeded within the microchannel did not adhere to the surface of the microchannel and became entrapped in the microwells. HepG2 cells seeded in the microwells formed 3D spheroids with controlled sizes and shapes depending upon the dimensions of the microwells. When the albumin coated surface was subsequently exposed to an aqueous solution containing poly(ethyleneimine) (PEI), adhesion of secondary cells, fibroblasts, occurred in the regions surrounding the arrayed spheroids. This coculture system can be coupled with spatially controlled fluids such as gradients and focused flow generators for various biological and tissue engineering applications.