Viability of limbal epithelium after anterior lamellar harvesting using a microkeratome

OBJECTIVE: To determine the viability in cold eye bank storage of different layers of central and limbal corneal epithelium, including the limbal basal stem cell population, on days 0, 3, 6, and 9 after harvest using a large diameter microkeratome system. METHODS: Twenty-two human whole globes not suitable for transplantation were obtained from an eye bank (San Diego Eye Bank, San Diego, California) and used for study. Large-diameter anterior corneal discs were prepared using a large diameter microkeratome and stained with calcein AM and an ethidium homodimer to differentiate live from dead cells, respectively. A laser confocal microscope and digital imaging were used to distinguish live (green) from dead (red) cells. Central and limbal epithelial regions were isolated and the middle and basal epithelial sections were cell counted by 3 independent observers. These sections were stored up to 9 days at 4 degrees C in an eye bank corneal storage medium. Differences were tested using nonparametric methods. MAIN OUTCOME MEASURES: The percentage of live cells in each of these epithelial layers was determined for up to 9 days in cold eye bank corneal storage medium. RESULTS: At all time points studied, the better protected basal epithelial layers displayed greater mean viability than the overlying middle epithelial layers. However, the difference was not statistically significant on all days. When comparing the basal epithelial viability of the limbal and central regions, after day 0 in 4 degrees C cold organ culture, the observed viability of the limbal basal epithelium, the purported location of the limbal epithelial stem cell region, was significantly greater than that of the central epithelium. On day 0, median limbal basal versus central basal epithelial viability were 100% (range, 71.7-100%) versus 98.4% (range, 88.9-100%) (P>0.05); on day 3, 100% (range, 64.3-100%) versus 63.4% (range, 13.6-95.5%) (P<0.0005); on day 6, 95.0% (range, 35.0-100%) versus 28.0% (range, 0-92.0%) (P<0.0005); and on day 9, 95.0% (range, 3.7-100%) versus 68.6% (range, 0-100%) (P<0.0005). CONCLUSIONS: After microkeratome harvesting, the limbal basal epithelium is significantly longer lived in cold eye bank storage than central basal epithelium and the middle layers of limbal and central epithelium. This longevity not only bodes well for organ storage of limbal grafts, but also confirms the hardiness of the stem cell region.     

A portable microkeratome for harvesting the human anterior corneal surface

A portable, gas-driven turbine microkeratome device capable of harvesting the entire anterior corneal surface for lamellar transplantation on human donor globes was evaluated. The device consisted of a modified LASIK microkeratome with an enlarged suction ring, head, and blade. Vacuum was achieved by a simple hand pump. Lamellar keratectomy was performed on 5 fresh human donor globes. Lenticule dimensions were measured on days 0, 3, 6, and 9 after storage in preservation media at 4 degrees C. On day 0, the obtained lenticules were 13.9 +/- 0.9 mm and 13.5 +/- 0.4 mm, vertical and horizontal diameters, respectively. The average central lenticule thickness was 152.2 +/- 52 microm. Each lenticule was uniform in thickness over 5 measurement points (P = 0.74). Repeat measurements of corneal thickness over the 9 days showed no statistically significant difference (P = 0.51). On day 9 lenticules were 14.6 +/- 0.3 mm and 14.6 +/- 0.4 mm, vertical and horizontal diameters, respectively. When day 0 was compared to day 9, vertical diameter also showed no statistically significant difference (P = 0.16), whereas horizontal diameter was significantly different (P < 0.001). This device proves to be an economical alternative to electric-powered systems for the harvest of transplantable corneal sections.     

Dyslipidemia in HIV patients

Thanks to antiretroviral therapy, people with human immunodeficiency virus (HIV) infection are living longer, but as they do, non-HIV medical problems become more relevant. In particular, dyslipidemia, an important reversible risk factor for cardiovascular disease, has been linked to HIV infection and its treatment. Although controversy remains as to whether people with HIV infections will develop premature coronary heart disease, it seems prudent to manage dyslipidemia in these patients just as we do in our HIV-negative patients. Interactions between lipid-lowering drugs and antiretroviral drugs require special attention.     

在193-nm准分子激光-引导下检测兔角膜中氟喹诺酮类药的荧光

目的：氟喹诺酮治疗后，在193-nm准分子激光引导下检测兔尸眼角膜中的荧光物质。方法：在使用经商业途径购买的眼科用准分子激光（Nidek EC-5000；Nidek Teehnoligies，Pasadena，Calif）切削角膜前，35只兔尸体眼角膜在局部消毒后分别用生理盐水、0．3％硫酸妥布霉素或氟喹诺酮类药-0．3％氧氟沙星，0．5％左旋氧氟沙星，0．3％环丙沙星和0．3％加替沙星处理。测量切削后角膜上产生的荧光并识别抗生素的存在。这种测量是通过对准一部分最小平方的模型，来区别接触抗生素和无抗生素（健康的）角膜的荧光素范围。     

Pathogenesis and management of lipoatrophy

Despite impressive decreases in mortality and morbidity, significant adverse events have surfaced as a result of combination antiretroviral therapy (ART). They include lipoatrophy, or subcutaneous fat wasting of the face, arms, buttocks, or legs, which can be associated with central fat accumulation. Although the underlying mechanism of ART-related body fat abnormalities has not been definitively established, mitochondrial toxicity is increasingly implicated in the lipoatrophy component of these fat abnormalities. Several studies evaluating switches off of nucleoside analogues have showed modest but statistically significant increases in limb fat. Because ART switches result in slow and small improvements and are not an option in many patients, other therapeutic interventions are needed. Although peroxisome proliferator-activated receptor chi agonist thiazolidinediones would be expected to have positive effects on lipoatrophy, initial clinical studies are conflicting. Other interventions of uridine, pravastatin, and facial fillers have been evaluated in small studies.     

Inhibition of corneal neovascularization by a peroxisome proliferator-activated receptor-gamma ligand

PURPOSE: To determine the efficacy of the peroxisome proliferator-activated receptor gamma agonist, pioglitazone, in inhibiting corneal neovascularization. METHODS: Twenty-six adult male Sprague-Dawley rats were randomly divided into three groups. Each group received intrastromal polymer micropellets containing one of the following: Group 1, no active ingredient (n=10); Group 2, vascular endothelial growth factor (VEGF) (n=7); Group 3, VEGF and pioglitazone (n=9). Neovascularization was evaluated 7 days after pellet implantation. After systemic India ink injection, digital photographs of the eyes were taken. The area and density of neovascularization were measured using imaging software. RESULTS: Mean area of neovascularization was 0.43+/-0.18 mm2 for Group 1, 2.87+/-0.48 mm2 for Group 2 and 2.10+/-0.22 mm2 for Group 3. Statistical analysis showed significant differences between Groups 1 and 2 and Groups 1 and 3. There was no significant difference between Groups 2 and 3. Mean density of neovascularization was 2.16+/-0.66 for Group 1, 27.14+/-2.93 for Group 2 and 12.02+/-2.24 for Group 3. All comparisons between groups were statistically significant (P<0.01). CONCLUSIONS: Pioglitazone is effective in decreasing the density of angiogenesis in a VEGF-induced neovascular rat cornea model. There is possibility of even greater effect with higher doses of the drug. Pioglitazone is a promising drug for the treatment of ocular neovascularization.     

Gaze stabilization test: a new clinical test of unilateral vestibular dysfunction.

OBJECTIVE: Evaluate the sensitivity, specificity, and reliability of the Gaze Stabilization Test (GST) for detection of unilateral vestibular dysfunction. STUDY DESIGN: Prospective controlled clinical trial. SETTING: Tertiary academic referral laboratory. PATIENTS: Fourteen patients (mean age, 63.8 yr; range, 43-77 yr) with history of vertigo and greater than 50% bithermal caloric asymmetry; 14 control subjects (mean age, 45.8 yr; range, 23-78 yr). INTERVENTION(S): Diagnostic test protocol with computerized system of target presentation and head velocity monitoring. MAIN OUTCOME MEASURE(S): Comparison of peak head velocity with ipsilesional and contralesional head movement-allowing gaze stability by randomly presenting transient (75 ms) targets of three optotypes above static acuity in patients and healthy subjects during self-generated headshake movements. RESULTS: GST demonstrated 93% specificity, 64% sensitivity, and a reliability index of 0.91 for the detection of unilateral dysfunction with ipsilesional movement. Peak head velocity in healthy subjects averaged 147 degrees per second, whereas ipsilesional velocities dropped significantly to an average of 84 degrees per second. Surprisingly, peak velocities were also significantly reduced to an average of 112 degrees per second with contralesional movements. CONCLUSION: GST is a reliable specific test of gaze stability which has diagnostic and rehabilitative applications in patients with vestibular dysfunction. Reduced contralesional velocities may help explain oscillopsia in patients with unilateral dysfunction.     

Fluoroquinolone therapy in multiple-drug resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model

PURPOSE: To assess the effectiveness of a fourth-generation fluoroquinolone for prophylaxis against multiple drug-resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model. DESIGN: Experimental study. METHODS: Twenty-eight New Zealand white rabbits underwent unilateral lamellar keratectomy using a manual microkeratome followed by the placement of 1000 colony-forming units (CFUs) of log-phase Staphylococcus aureus bacteria under each flap. Eyes (seven in each group) were randomized and treated with one of the following agents: sterile balanced salt solution, gatifloxacin (0.3%), ciprofloxacin (0.3%) or levofloxacin (0.5%) immediately and 6, 12, and 18 hours after surgery. Inflammation was graded by two masked observers at 24 and 48 hours, and the presence or absence of infectious infiltrates was determined. The means and standard deviations were calculated, and differences among the groups were statistically analyzed. RESULTS: There were no flap complications encountered during surgery. Eyes treated with ciprofloxacin, levofloxacin, and balanced salt solution developed infectious infiltrates in five of seven eyes per group. Gatifloxacin-treated eyes did not develop clinical infection and exhibited lower mean inflammation scores (P <.01 compared with the other groups). CONCLUSION: The fourth-generation fluoroquinolone, gatifloxacin, is an effective prophylaxis against the development of keratitis after lamellar keratectomy in rabbits with an organism resistant to methicillin, levofloxacin, and ciprofloxacin.