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The search for an effective cure for type I diabetes from the transplantation of encapsulated pancreatic β-cell clusters has so far produced sub-optimal clinical outcomes. Previous efforts have not controlled the size of transplanted clusters, a parameter implicated in affecting long-term viability and the secretion of therapeutically sufficient insulin. Here we demonstrate a method based on covalent attachment of patterned laminin for fabricating uniformly size-controlled insulin-secreting cell clusters. We show that cluster size within the range 40-120μm in diameter affects a variety of therapeutically relevant cellular responses including insulin expression, content and secretion. Our studies elucidate two size-dependent phenomena: (1) as the cluster size increases from 40μm to 60μm, glucose stimulation results in a greater amount of insulin produced per cell; and (2) as the cluster size increases beyond 60μm, sustained glucose stimulation results in a greater amount of insulin secreted per cell. Our study describes a method for producing uniformly sized insulin-secreting cell clusters, and since larger cluster sizes risk nutrient availability limitations, our data suggest that 100-120μm clusters may provide optimal viability and efficacy for encapsulated β-cell transplants as a treatment for type I diabetes and that further in vivo evaluation is warranted., (Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Pancreatic β-cells function optimally when clustered in islet-like structures. However, nutrient and oxygen deprivation limits the viability of cells at the core of excessively large clusters. Hence, production of functional β-cells from human embryonic stem cells (hESCs) for patients with diabetes would benefit from the growth and differentiation of these cells in size-controlled aggregates. In this study, we controlled cluster size by seeding hESCs onto glass cover slips patterned by the covalent microcontact-printing of laminin in circular patches of 120 μm in diameter. These were used as substrates to grow and differentiate hESCs first into SOX17-positive/SOX7-negative definitive endoderm, after which many clusters released and formed uniformly sized three-dimensional clusters. Both released clusters and those that remained attached differentiated into HNF1β-positive primitive gut tube-like cells with high efficiency. Further differentiation yielded pancreatic endoderm-like cells that co-expressed PDX1 and NKX6.1. Controlling aggregate size allows efficient production of uniformly-clustered pancreatic endocrine precursors for in vivo engraftment or further in vitro maturation., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Cluster-size dependent behavior of pancreatic beta-cells has direct implications in islet transplantation therapy for type I diabetes treatment. Control over the cluster size enables evaluation of cluster-size-dependent function, ultimately leading to the production of beta-cell clusters with improved transplant efficacy. This work for the first time demonstrates the use of microcontact-printing-based cell patterning of discrete two- and three-dimensional clusters of pancreatic beta-cells. Both single and multiple cell layers are confined to a 2D area by attaching to patterns of covalently linked laminin and not adhering to surrounding polyethylene glycol. Cell clusters were successfully formed within 24 h for printed patterns in the range 40-120 microm, and simple modulation of the initial cell seeding density leads to the formation of multiple cell layers. Semiquantitative fluorescence microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to extensively characterize the surface chemistry. This technique offers exceptional control over cell cluster shape and size, and not only provides an effective tool to study the cluster-size-dependent behavior of pancreatic beta-cells but also has potential applicability to numerous other cell lines.

In this study, TiO(2) nanotubes of various dimensions were used to elute albumin, a large protein molecule, as well as sirolimus and paclitaxel, common small molecule drugs. The nanotubes controlled small molecule diffusion for weeks and large molecule diffusion for a month. Drug eluted from the nanotubes was bioactive and decreased cell proliferation in vitro. Elution kinetics was most profoundly affected by tube height. This study demonstrates that TiO(2) nanotubes may be a promising candidate for a drug-eluting implant coating.

Clinical and laboratory findings of 47 patients with ocular infections secondary to Neisseria gonorrhoeae during a 5 1/2-year period were reviewed. In 16 patients (34%), corneal involvement was noted. Six of these patients had a severe ulcerative keratitis resulting in permanent visual loss and five required surgery for a corneal perforation. Patients with corneal involvement were older and presented later in the course of their disease than patients with isolated conjunctival involvement (P less than 0.005). An out-patient regimen of intramuscular antibiotics (either penicillin, cephalosporin, or spectinomycin [Trobicin]) appeared to be effective for infections limited to the conjunctiva in adults. If a topical antibiotic ointment is used in addition to parenteral antimicrobial agents, the authors' laboratory sensitivities suggest that erythromycin may be the drug of choice.

A 65-year-old man developed unilateral nonrubeotic secondary angle-closure glaucoma after central retinal vein occlusion. Therapy was nonsurgical and included medical control of the intraocular pressure. The anterior chamber eventually deepened and panretinal photocoagulation was later necessary because of developing rubeosis iridis and neovascularization of the optic disk. Secondary nonrubeotic angle-closure glaucoma from central retinal vein occlusion must be distinguished from rubeotic glaucoma or pupillary-block glaucoma so that inappropriate medical or surgical treatment can be avoided.

Rabbits rendered hypercholesterolemic on a high cholesterol diet while subjected to corneal suture placement to induce neovascularization made useful models for qualitatively and quantitatively studying lipid keratopathy. Forty rabbit eyes were subjected to placement of four sutures located between 1 and 4 mm from the limbus. The neovasculature grew at a constant rate of 0.24 mm/day, unaffected by serum cholesterol levels. Rabbits fed cholesterol prior to surgery were the earliest to display lipid keratopathy, followed by those who began cholesterol feedings on the day of surgery, and last by rabbits who began receiving high cholesterol food seven days following suture placement. A description of the corneal neovascularization process and histopathological and biochemical analyses of the induced lipid keratopathy are presented.

Argon laser photocoagulation was performed on rabbit eyes with lipid keratopathy. The lipid keratopathy was induced by rendering 30 rabbits hypercholesterolemic and inciting neovascularization by insertion of corneal sutures. The number of laser shots required to occlude corneal vessels increased with the suture residence time, whereas the number of limbal shots remained essentially constant. Corneal opacification and cholesterol content increased as a result of greater suture residence time and unexpectedly from the laser applications which were administered in a single treatment session.

A healthy-appearing male patient presented with signs of unilateral fibrinous iritis, necrotizing retinitis, retinal vasculitis, and vitritis, suggestive of a herpesvirus retinitis or acute retinal necrosis syndrome (ARN). The patient, an active homosexual, withheld the details of his sexual history, portraying himself as exclusively heterosexual. With the exception of a positive VDRL and FTA-ABS, the workup was negative. Examination of the cerebrospinal fluid confirmed the presence of neurosyphilis. The patient was successfully treated with intravenous penicillin, which resulted in a complete visual recovery. Syphilitic retinitis must be considered in evaluating patients with necrotizing retinitis.

The photochemical interaction between intravenously injected rose bengal dye and 514.5-nm argon laser irradiation was employed to initiate permanent thrombotic occlusions in the corneal neovasculature of rabbit eyes with experimentally induced lipid keratopathy. This photothrombotic procedure did not produce corneal edema or polymorphonuclear leukocyte infiltration, as was found in previous studies employing laser-induced photocoagulation. Thus, by means of the new technique, we avoided the formation of additional neovascularization and lipid deposition. Vascular occlusion by photothrombosis, effected with 8.5 times less incident intensity and 27.5 times less total light exposure than with photocoagulation, yielded an average reduction of corneal cholesterol content of 36% as opposed to an increase of 24% found with previous argon laser photocoagulation.

Currently employed techniques utilizing a continuous wave argon laser for the production of peripheral iridotomies in the treatment of angle-closure glaucoma are successful in producing patient iridotomies; however, complications such as corneal, lenticular, and retinal burns have been experienced. We found that a combination of low energy, much shorter exposures and an overlapping stretch pattern also gave a high success ratio in terms of formation of a patent iridotomy while reducing the number of complications for both black and white patients. Highly encouraging was the absence of corneal edema of a severity sufficient to cause an interruption in the treatment.

A comparison was made of the accuracy of the Tono-Pen, Pneumatonometer, and Perkins hand-held tonometers by measuring the hydrostatically controlled intracular pressure from 10 to 50 mm Hg in human eye bank eyes. The open stopcock method was used in which the cannulated eye, the hydrostatic pressure controlling column, and a manometer were continuously open to each other. The Pneumatonometer gave accurate results at 50 mm Hg but overestimated the lower intraocular pressures; whereas, the Perkins gave satifactory results at 10 and 20 mm Hg but underestimated higher intraocular pressures. The Tono-Pen displayed the least deviation from the controlled pressure over the entire range studied. Another aspect of this study involved determining that a therapeutic soft contact lens did not have any noticeably adverse effect on the accuracy of the Pneumatonometer and Tono-Pen tonometers.

By scanning electron microscopy, we studied eight lenses from eyes that had received a neodymium-YAG laser iridotomy one day prior to elective intracapsular cataract extraction. In some of these cases, pitting lesions were found on the anterior-equatorial lens surface, thereby showing that lenticular damage may occur following this procedure if the iridotomy is applied too centrally. It is recommended that care be taken to ensure that the iridotomy be placed at a site peripheral to the outer circumference of the lens.

Corneal and plasma lipids were studied in a rabbit model to gain insight into the pathogenesis of secondary lipid keratopathy. Rabbits were divided into four groups in which a high cholesterol diet and corneal suture placement were varied to produce lipid keratopathy. In rabbits with lipid keratopathy, quantitative thin layer chromatography revealed that cholesterol esters comprised most of the deposited lipid, with free cholesterol being deposited as well. The ratio of accumulated cholesterol ester to free cholesterol corresponded closely to the same ratio in hypercholesterolemic plasma total low and very low density lipoprotein (TLDL). Furthermore, gas chromatography showed that the cholesterol ester composition in the corneas with lipid keratopathy resembled that seen in hypercholesterolemic plasma TLDL but was different from the pattern observed in the normal cornea. These studies suggest that the direct source of the deposited cholesterol ester is primarily the plasma TLDL. Since phospholipids and triglycerides did not show a significant increase in the experimental corneas, they are presumably metabolized by the keratocytes after the uptake of TLDL. However, the amount of cholesterol ester carried by the lipoprotein exceeds the capacity of the cell for use and excretion and the lipid accumulates in the cornea.