Precision and accuracy of an artificial anterior chamber system in obtaining corneal lenticules for lamellar keratoplasty.

PURPOSE: To determine the precision and accuracy of an artificial anterior chamber and a manual microkeratome in obtaining corneal lenticules for lamellar keratoplasty. SETTING: Department of Ophthalmology, Cornea, External Diseases and Refractive Surgery Service, University of California Irvine, Irvine, California, USA. METHODS: A lamellar keratectomy was performed in 47 human corneoscleral rims. Three lenticule thicknesses (180, 300, and 360 microm heads) and 3 diameters (7.0, 8.0, and 9.0 mm) were attempted. Diameters and thicknesses were measured by planimetry and pachymetry, respectively. RESULTS: Peripheral lenticule thickness was more likely to be within +/-50 microm of the intended depth in thinner cuts (180 microm, 9/15 corneas, 60%; 300 microm, 6/16 corneas, 40%; 360 microm, 3/12 corneas, 33.3%) (P = .045). Eighty percent (32/40 corneas) were within +/-0.5 mm of the expected diameter. Accuracy was best in the 8.0 mm group, with 47.1% (8/17 corneas) within +/-0.2 mm of the expected diameter. A thickness/diameter correlation was not observed (r(s) < or = 0.28). CONCLUSIONS: The precision and accuracy of this system varied according to the attempted thickness and diameter.

Re-epithelialization in cornea organ culture after chemical burns and excimer laser treatment.

OBJECTIVE: To describe the epithelial healing rates observed in freshly cultured rabbit corneas chemically burned with high-concentration hydrochloric acid (HCl) and sodium hydroxide (NaOH) and subsequently treated with phototherapeutic keratectomy (PTK). METHODS: We obtained 126 fresh corneoscleral rims from cadaveric New Zealand white rabbits. Each cornea was exposed to 4-mm cellulose sponges soaked in a solution of topical 0.9% isotonic sodium chloride solution, 2M HCl, or 0.5M NaOH. A transepithelial PTK (6-mm zone; 100-microm ablation depth) was then performed using the excimer laser (150-mJ/cm(2) energy pulse; 20 nanosecond duration; and 10-Hz frequency). Corneas were placed in tissue culture, and 1 cornea from each group was taken out of culture each day after treatment. Re-epithelialization was monitored by means of fluorescein staining, slitlamp photography, and histopathological analysis. RESULTS: Corneas treated with HCl and NaOH exhibited immediate epithelial defects that slowly healed over time. In PTK-treated corneas, the re-epithelialization rate was accelerated compared with that of controls (P =.003 for the HCl group, and P<.001 for the NaOH group). The new epithelial layers were smoother in PTK-treated corneas, as confirmed by results of histopathological analysis. CONCLUSION: Corneal damage caused by HCl and NaOH may be modulated in vitro by PTK in this rabbit model. CLINICAL RELEVANCE: After corneal chemical damage, 193-nm excimer laser PTK accelerates epithelial wound healing.

Simple organ cornea culture model for re-epithelialization after in vitro excimer laser ablation.

BACKGROUND AND OBJECTIVE: Most of the in vitro work to characterize the effects of clinical laser surgery on corneal tissues has concentrated on the effects on stromal keratocytes and endothelium with little attention being paid to corneal epithelium. Our purpose is to describe the epithelial healing rates observed in freshly cultured rabbit corneas treated with phototherapeutic keratectomy (PTK). STUDY DESIGN/MATERIALS AND METHODS: Corneas were placed in a simple organ culture system, with media change every 2 days. A clinical excimer laser was used to perform a 6 mm diameter, 100 microm depth transepithelial PTK on 24 cultured rabbit corneas, 1 day after culture initiation. For each post-treatment day, one experimental and one control cornea were removed from culture and stained with fluorescein, photographed, and fixed for histology. Epithelial defect area was measured with digital imaging software and analyzed statistically to assess the re-epithelialization rate. RESULTS: Control corneas, maintained in culture for 1-4 days, had no epithelial defects. Those corneas treated with PTK exhibited an immediate epithelial defect that slowly healed over 3 days. This was confirmed on histopathological analysis. A significant linear trend in re-epithelialization across the time points studied was found (F = 80.48, P = 0.0029). The slope of the linear regression model showed an estimate rate of re-epithelialization of -6.70 over the 3 days. CONCLUSION: We have described the development of a simple, whole organ, rabbit cornea culture model for re-epithelialization after PTK. Our rates of epithelial healing resemble those found in the literature in live rabbit models. Therefore, this model may possibly be used to monitor epithelial wound healing in different corneal diseases or injuries.

Direct interaction in T-cells between thetaPKC and the tyrosine kinase p59fyn.

The protein kinase C (PKC) family has been clearly implicated in T-cell activation as have several nonreceptor protein-tyrosine kinases associated with the T-cell receptor, including p59fyn. This report demonstrates that thetaPKC and p59fyn specifically interact in vitro, in the yeast two-hybrid system, and in T-cells. Further indications of direct interaction are that p59fyn potentiates thetaPKC catalytic activity and that thetaPKC is a substrate for tyrosine phosphorylation by p59fyn. This interaction may account for the localization of thetaPKC following T-cell activation, pharmacological disruption of which results in specific cell-signaling defects. The demonstration of a physical interaction between a PKC and a protein-tyrosine kinase expands the class of PKC-anchoring proteins (receptors for activated C kinases (RACKs)) and demonstrates a direct connection between these two major T-cell-signaling pathways.

Naturally occurring insulin autoantibodies in neonates of normal pregnancies and their relationship to insulinemia and birth weight.

OBJECTIVE: The objectives of this study were to determine whether insulin autoantibodies are present in umbilical cord blood from normal pregnancies, determine whether cord blood insulin autoantibody levels correlate with respective maternal levels at delivery, determine whether cord blood insulin autoantibody levels are related to cord blood or maternal insulin levels, and to determine what relationship neonatal birth weight has with either cord blood insulin autoantibody and insulin levels or maternal insulin autoantibody and insulin levels. STUDY DESIGN: Paired umbilical cord and maternal serum samples were taken from 70 normal subjects at delivery. Measurements of serum insulin autoantibody (competitive charcoal radiobinding assay) and insulin (radioimmune inhibition assay) levels were performed. Multiple linear regression analysis and paired t tests were used for data analyses. RESULTS: Neonatal insulin autoantibody levels (120 nU/ml) were more than two times higher than maternal levels (49 nU/ml) (p < 0.001). No correlation was observed between neonatal and maternal insulin autoantibody levels (r = 0.14, p = 0.25). A positive correlation of both neonatal and maternal insulin with birth weight was observed (r = 0.28, p < 0.02; and r = 0.36, p < 0.01, respectively). CONCLUSIONS: These results suggest that the insulin autoantibody levels in fetal cord blood are not related to maternal levels in normal uncomplicated pregnancies. In addition, insulin levels in both maternal and neonatal circulations were positively correlated with increased birth weight in the normal pregnancies studied.