摘要:

Peptide growth factors and other physiological growth modifiers were evaluated for their ability to stimulate DNA synthesis in early passage cultures of bovine corneal endothelial cells (BCEC). Increasing concentrations of newborn bovine serum (0.5–10%) causes a progressive increase in DNA synthesis, which approached a plateau at 10% serum. Supplementing medium with 10% serum from different lots of newborn bovine serum or fetal bovine serum stimulated significantly different levels of DNA synthesis by BCEC. Addition of epidermal growth factor (EGF) (2 nM) to medium containing 10% newborn or fetal bovine serum further increased DNA synthesis. Dose-response curves for EGF, transforming growth factor-α, basic fibroblast growth factor (bFGF), and insulin-like growth factor I showed that each significantly stimulated high levels of DNA synthesis (200–700% increase) compared with BCEC cultured in serum-free medium. Vaccinia growth factor, insulin, and transforming growth factor-β each significantly stimulated lower levels of DNA synthesis (30–200% increase), whereas nerve growth factor, multiplication stimulating activity, and platelet-derived growth factor all failed to significantly stimulate DNA synthesis above the level of serum-free medium. Other physiological growth modifiers were tested for their effects on DNA synthesis of BCEC. Transferrin and low levels of 3',5'-cyclic monophosphate (cAMP) stimulated very low levels of DNA synthesis (50% increase) whereas linoleic acid, high levels of selenium, or cAMP each inhibited DNA synthesis 25–75% below the level of BCEC cultured in serum-free medium. A series of eight formulations containing various combinations of EGF, FGF, insulin, transferrin, selenium, linoleic acid, retinoic acid, cAMP, heparin, and endothelial cell growth factor were tested for their mitogenic action on BCEC cultures. A formulation containing EGF, insulin, transferrin, selenium, and linoleic acid (EGF + ITSL) stimulated the highest level of DNA synthesis of BCEC, which was ~25% higher than the increase stimulated by addition of 10% newborn bovine serum. The formulation consisting of EGF + ITSL was also evaluated as a supplement to corneal storage media. Addition of EGF + ITSL to three corneal storage media (McCarey–Kaufman, K-Sol, CSM) significantly stimulated increases in cell numbers of ~50% above the unsupplemented corneal storage media. These results demonstrate that BCEC respond selectively to different defined peptide growth factors and physiological growth modifiers, and suggest that supplementation of corneal storage media with a defined formulation (EGF + ITSL) may enhance corneal endothelial cell density.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Epidermal growth factor (EGF) is a potent mitogen for corneal endothelial cells and may play a role in endothelial wound healing. To further characterize the interaction of EGF with endothelial cells, we measured biochemical parameters of125I-EGF binding to cultured bovine corneal endothelial cells (BCEC), determined the pattern of EGF-induced protein phosphorylation, and investigated the influence of retinoic acid (RA) and transforming growth factor β (TGF-β) on EGF-induced DNA synthesis and receptor levels. Binding of125I-EGF to BCEC was dependent on time, reaching a plateau after ~2 h at 37°C, was specific for EGF, and had high affinity (Kd= 100 pM) with approximately 21,000 receptors per cell. Cellular substrates for the EGF receptor kinase, which may function as initial second messengers for EGF, were detected by autoradiography of sodium dodecyl sulfate polyacrylamide gels of32P-labeled BCEC proteins. EGF stimulated phosphorylation of 170, 37, 21 and 20-kDa proteins. Addition of 1 nM100 nMand 10 µ,MRA to BCEC cultured in serum-free medium for 24 h progressively inhibited DNA synthesis by up to 80% compared with control cultures. However, when added in combination with 5 nMEGF, 1 nMand 100 nMRA synergistically stimulated DNA synthesis by up to 80% above the level of EGF stimulation without altering EGF receptor levels or binding affinity. Thus, short-term exposure of BCEC to RA potentiated EGF-stimulated DNA synthesis, most likely by acting at a postreceptor step. Addition of 10 nMTGF-β to BCEC cultured in serum-free medium for 24 h stimulated low levels of DNA synthesis and did not significantly alter EGF-induced DNA synthesis nor alter EGF-induced protein phosphorylation patterns. These results demonstrate that EGF receptor in BCEC has biochemical characteristics that are similar to EGF receptors in other mammalian cells including stimulation of phosphorylation of several cellular proteins that may mediate the biological action of EGF in BCEC, and that EGF may interact synergistically with other agents that influence corneal endothelial cell mitosis.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Human corneal endothelial cells (HCEC) do not mitose extensively in vivo after damage to the endothelial layer. However, HCEC will divide in vitro if cultured under appropriate conditions. We measured the ability of various sera, plasma, growth factors, and nutritional substances to stimulate mitosis of HCEC during 5 days of organ culture after a central freeze injury to the endothelium. Supplementation of a chemically defined medium (CDM) with 20% fetal human serum (FHS) induced significantly higher numbers of mitotic figures or labeled nuclei of human or cat corneas compared with paired corneas cultured in CDM alone. Furthermore, addition of 20% FHS produced more labeled nuclei than did addition of 20% fetal bovine serum or 20% adult human serum. Dialyzed fetal human serum failed to stimulate mitosis, indicating that one or more components of fetal human serum with molecular weight <12,000 are essential for mitosis. Human plasma also failed to stimulate mitosis, but an extract of human platelets significantly stimulated high levels of nuclear labeling, suggesting that growth factors contained in platelet granules were responsible for serum-stimulated mitosis of HCEC. Addition of 100 nM epidermal growth factor (EGF) or 10 µM insulin to CDM supplemented with low levels of adult human serum (0.5%) stimulated significantly higher numbers of labeled nuclei compared with paired corneas cultured with 0.5% adult human serum. Supplementation of corneal storage media (K-Sol and CSM) with a mixture of chemically defined agents consisting of EGF, insulin, transferrin, selenium, linoleic acid, and albumin stimulated significantly higher numbers of labeled nuclei compared with paired corneas cultured in the unsupplemented corneal storage media. These results demonstrate that HCEC can be stimulated to undergo extensive mitosis in vitro in response to a combination of chemically defined agents, and suggest that it may be possible to enhance healing of human endothelial cell injuries in vivo or during corneal storage by exposure to appropriate mitogenic factors.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Two computer-assisted topographic analysis systems were evaluated with calibrated spherical surfaces and normal human corneas. The Topographic Modeling System-1 (TMS-1) was found to be statistically more accurate in determing the power of calibrated spheres near the apex and at 1 mm from the apex than the Corneal Analysis System(CAS).The CAS, however, was statistically more accurate at 3 mm from the apex with each calibrated sphere. The small differences in accuracy between the two instruments, however, are unlikely to be of clinical significance. The topographic patterns on color-coded maps from 22 normal corneas of 11 subjects were similar with the two instruments. Simulated keratometry values with the CAS more accurately identified the keratometerdetermined major cylinder axis compared with the TMS- 1. Conversely, the TMS-1 was more accurate than the CAS at determining the level of corneal astigmatism.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

A computerized topographic analysis system was used to evaluate corneal changes after strabismus surgery in eight eyes of five patients with Graves' disease. All patients underwent inferior rectus muscle recession; three eyes also had medial rectus recession. Corneal topographic analysis revealed that, postoperatively, corneas steepened inferiorly and inferotemporally at 1.5 mm from corneal apex (p <0.05). The opposite effect was observed in the superior quadrant (average flattening of 1.20 ±0.32 D at 1.5 mm from corneal apex, and 1.08 ±0.39 Dat 3.0 mm from corneal apex; p<0.05).Superotemporally, the cornea flattened by an average of 0.65 ± 0.26 Dat 3.0 mm from corneal apex, and superonasally 0.72 ±0.19 Dat 3.0 mm from corneal apex (p <0.05).Central, nasal, and temporal cornea did not show statistically significant changes. Spherical equivalent did not change significantly after surgery. The amount of restriction and upgaze measured preoperatively was correlated weakly with inferior corneal steepening (r2=0.44;p=0.046). These results are indicative that corneal topography may be influenced by strabismus surgery for Graves' disease through alteration of extraocular muscle tension or intraocular pressure.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

We assessed the efficacy of the radioprotective effects of WR-2721 in radiation-induced goblet cell loss. Fourteen female New Zealand white rabbits were divided into radioprotected, radiounprotected, and control groups. Ten rabbits received 5,000 rad of p irradiation to the temporal conjunctiva of both eyes. The right eyes were pretreated with topical applications of WR-2721 30 minutes and 1 minute before irradiation. The left eyes received irradiation only. Four additional rabbits received neither irradiation nor pretreatment with WR-2721. After a 2-month waiting period, each animal was killed and goblet cell densities per high-power field (GCD/HPF) were determined over the areas in question and compared using paired sample t tests. The mean GCD/HPF for the radioprotected, unprotected, and control groups were 10.93, 4.68, 23.15 (right eye), and 26.25 (left eye).Paired sample t tests showed a significant radioprotective effect when comparing WR-2721-treated animals with those receiving radiation only (p <0.003). Independent sample / tests showed significant goblet cell loss in both the radioprotected (p <0.018) and radiounprotected eyes (p <0) when compared with control groups. These data suggest a radioprotective effect of WR-2721 in radiation-induced goblet cell loss.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Conjunctival flaps have been used in the treatment of corneal diseases since the 1800s, although in recent years their use has decreased. In selected cases, however, the placement of a conjunctival flap still may be the treatment of choice. We report our experience with the use of conjunctival flaps in patients with herpes keratouveitis who had persistent corneal epithelial defects. Preoperatively, all patients had chronic or recurrent epithelial defects and intraocular inflammation with or without recurrent live viral infection requiring frequent medicine application and office visits. Postoperatively, all patients had an intact, healthy ocular surface and a noninflamed eye requiring few to no medications and infrequent office visits. No patient has had recurrent live viral activity.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Jacksonville, FL, U.S.A.; etafilcon A) lenses were soaked in a Pseudomonas aeruginosa suspension (1.4 x 108 cfu/ ml). New Acuvue lenses served as controls. A single strain of P aeruginosa harvested from a human corneal ulcer was used throughout the experiment. Lenses were examined by culture and scanning electron microscopy (SEM). We found significantly greater (p c0.05) bacterial attachment to new Acuvue lenses [culture, 3.1 x 104 (±0.82 x 104cfu/mm2; SEM, 2.6 x 104 (±.0.47 x 104) bacteria/mm2] compared with those previously worn [culture, 1.0 x 104 (±.0.17 x 104) cfu/mm2; SEM, 0.73 x 104(±.0.21 x 104) bacteria/mm2]. No statistical difference was found among the individuals. Our findings demonstrate that the biological coating resulting from 1 week of continuous contact lens wear restricts P. aeruginosa attachment to the Acuvue lens when comparing new and used lenses.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The transport rates of radiolabeled ascorbic acid (AA), 3-O-methyl-D-glucose (mD-glu) and L-glucose (L-glu) from blood into the aqueous humor, corneal endothelium, and stroma compartments were studied in male Sprague-Dawley rats and English short-haired guinea pigs. In vivo pulse chase kinetic studies supplied transport entry rate constants, Ki(min−1), and used L-glu as a passive internal control. Results in the rat indicate that AA enters the aqueous humor at rates similar to L-glu and likely via simple passive diffusion. Rate constants for entry into endothelium for both L-glu and mD-glu were high, indicating a quick equilibrium with the aqueous humor. Endothelium AA levels continued to increase to levels higher than in the aqueous humor. Although all three test molecules quickly entered the endothelium, L-glu and mD-glu levels were soon found to decrease, whereas levels of AA or its metabolites remained high. AA entered the stroma of the rat cornea slower than either L-glu or mD-glu, suggesting that no special transport mechanism for AA is present. mD-glu moves into the stroma quickly, but high levels are not maintained. The guinea pig maintains AA levels in the cornea about 10 times higher than that of the rat by first accumulating AA in the aqueous humor and again by actively accumulating AA in the endothelium. Data at 24 h postbolus suggests that both the rat and guinea pig maintain high corneal AA levels for extended periods. Thus, whereas both glucose analogues enter and leave the cornea via the aqueous humor relatively quickly, A A appears to be actively taken up by the endothelium and thus maintained high in both species. Metabolic roles for ascorbate in the eye could conceivably be similar in both nocturnal rats and diurnal guinea pigs, even though the means of supply differ. Because the guinea pig does not produce AA, it conserves and stores a supply in the aqueous humor via active transport. The rat instead could rely on a steady supply of AA to meet intraocular needs

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

In nine rhesus monkeys, human corneal grafts were used for penetrating keratoplasty in one eye of each. The data were divided into three groups according to the size of grafts. Group 1 (n=3) received 5.5-mm human corneal grafts in 5.0-mm recipient beds; group 2 (n=3) received 6.2-mm human corneal grafts in 6.0-mm beds; and group 3 (n=3) received 7.5-mm grafts in 7.0-mm beds. Five of nine eyes in groups 1 and 2 (55%) maintained graft clarity for more than 1 year, but only two of the three in group 1 maintained clear human corneal grafts for 32 and 36 months, respectively. However, the three grafts in the third group maintained transparency for only 4-7 months. Our findings suggest that xenogeneic corneal grafts may have a greater success rate in humans than previously believed.

ISSN:0277-3740    

出版商:OVID    

年代:1992

数据来源: OVID