PubMed Health⌕ Search

Biomedical subjects

D A Lee

Publications and source records attributed to D A Lee.

At least 19 recordsLinked to original sources
PubMed1992

Reliability coefficients of three corneal pachymeters.

We compared the accuracy and reproducibility of a hand-held portable ultrasound pachymeter, the Pach-Pen (Bio-Rad, Ophthalmic Division, Santa Ana, California); another ultrasound pachymeter, the DGH 1000 (DGH Technology, Inc., Frazer, Pennsylvania); and the Pro-Cem 4 endothelial specular microscope (Alcon-Surgical, Inc., Irvine, California). Each eye of 18 healthy human subjects was examined to determine corneal thickness using the three different instruments. For each instrument, five repeated measurements were obtained at each of five corneal locations (one central, four peripheral), for a total of 25 measurements per eye. The accuracy of the two ultrasound pachymeters was tested by comparing measurements obtained on specially designed test blocks of known thickness. The Pach-Pen was the more accurate of the two ultrasound pachymeters, with measurements within the range of 0.003 to 0.065 mm from the true thickness. The three instruments were most consistent in mean thickness in the center of the cornea. All three instruments showed excellent intraobserver reproducibility, as measured by reliability coefficients over 90%. Overall, the Pach-Pen pachymeter had high reproducibility, and produced more accurate measurements than the DGH 1000 pachymeter.

Adult↗
PubMed1992

Use of collagen shields containing amphotericin B in the treatment of experimental Candida albicans-induced keratomycosis in rabbits.

We evaluated the effect of collagen shields presoaked with amphotericin B on the treatment of experimental Candida albicans-induced keratitis. Treatment results were compared to those of amphotericin B eyedrops instilled hourly. Forty-eight albino rabbits received intrastromal injections of 10(8) C. albicans organisms. Twenty-four hours later, eyes were treated for eight hours each day with hourly instillation of 0.15% amphotericin B drops, hourly instillation of saline drops, or application of a collagen shield presoaked in 0.5% amphotericin B for one hour. The rabbits were killed after one, three, or five days of treatment. Quantitation of fungi in the cornea was achieved by culturing homogenates and counting colony-forming units. Treatment with amphotericin B applied either as hourly instilled drops or absorbed in collagen shields significantly (P less than .05) reduced corneal fungal counts at all time points when compared to saline-treated control eyes. Rabbit eyes treated with amphotericin B-soaked collagen shields had significantly lower fungal counts compared with hourly instilled amphotericin B drops at Days 1 (P = .02) and 3 (P = .04), but not at Day 5. The collagen shields were as effective in reducing the number of colony-forming units as were amphotericin B drops at Day 5. These data suggest that collagen shields soaked in amphotericin B could be a useful and convenient treatment device in keratomycosis such as that caused by C. albicans.

Administration, Topical↗
PubMed1992

The effects of transferrin receptor antibody, transferrin receptor antibody bound to Pseudomonas exotoxin and transforming growth factor-alpha bound to Pseudomonas exotoxin on human tenon's capsule fibroblast proliferation.

Pharmacological agents which modulate the wound healing process by the inhibition of proliferation of fibroblasts may improve the success of glaucoma filtration surgery. Since cell proliferation is essential to the wound healing process, we targeted the surface receptors that are associated with proliferating cells. We present the effects of three such agents-purified mouse anti-human transferrin receptor monoclonal antibody 42/6 (anti-TfR-42/6), anti-transferrin monoclonal antibody bound to a Pseudomonas exotoxin (anti-TfR-PE40) and transforming growth factor-alpha Pseudomonas exotoxin (TGF-alpha-PE40)--on human fibroblasts from Tenon's capsule. The inhibition of human subconjunctival fibroblast proliferation by anti-TfR-42/6 (with a concentration up to 25 micrograms/ml) and by anti-TfR-PE40 and TGF-alpha-PE40 (both with a concentration range of 5000-0.00001 micrograms/ml) was determined by colorimetric (OD), and cell counting (CC) assays over a 9-day period. Neither anti-TfR-42/6 nor anti-TfR-PE40 had an antiproliferative effect on the fibroblasts. TGF-alpha-PE40 demonstrated an antiproliferative effect in a dose response manner. The mean 50% inhibitory dose (ID50) by OD was 32.91 micrograms/ml, while the ID50 by CC was 27.88 micrograms/ml. EGF was used as a negative control for TGF-alpha-PE40 toxin. The inhibitory effect of the toxin conjugate was completely blocked by the addition of 1000 micrograms/ml of EGF. These in vitro studies show that TGF-alpha-PE40 may be useful in modulating the proliferation of human ocular fibroblasts; they also give some indication of drug dosages for future in vivo testing.

ADP Ribose Transferases↗
PubMed1992

Effect of steroids and nonsteroidal antiinflammatory agents on human ocular fibroblast.

5-fluorouracil and steroids have been used to suppress excessive scar formation after glaucoma filtering surgery (GFS). Steroidal and nonsteroidal antiinflammatory drugs (NSAIDs), which are inhibitors of arachidonic acid (AA) pathway, both limit fibroblast activity and reduce inflammation. In this experiment, the ability of corticosteroid (dexamethasone sodium phosphate), cyclooxygenase inhibitor (piroxicam), lipoxygenase inhibitor (ferulic acid), and dual cyclo/lipoxygenase inhibitor (phenidone) to inhibit human Tenon's fibroblast proliferation was evaluated in culture. After human Tenon's fibroblast cell lines were established, a complete dose-response curve was done for the representative compounds for 8 days. Fibroblast attachment and proliferation were quantified by Coulter counter, hexosaminidase, and tritiated thymidine uptake assays. All four drugs inhibited attachment and proliferation at high concentrations. Phenidone was the most effective, with inhibition occurring within the 0.001-0.1 mmol/l range. It also was the only drug that showed inhibition at the antiinflammatory range in vivo. Dexamethasone, piroxicam, and ferulic acid did not inhibit fibroblast attachment and proliferation until doses well above those required to inhibit AA biosynthesis were attained. Only dexamethasone showed increased potency with incubation time. Overall, the NSAIDs showed antiproliferative activity comparable to or better than that of the steroids. Because the potency of steroids increases over time, these drugs may be more beneficial if given prior to initiation of inflammation. These results suggest that NSAIDs may be useful as both antiinflammatory and antiproliferative agents in preventing bleb failure after GFS.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1992

Effects of timolol, betaxolol, and levobunolol on human tenon's fibroblasts in tissue culture.

Evidence has been found suggesting that long-term therapy with topical antiglaucoma medications may decrease the success of glaucoma filtering surgery. To investigate this question further, the antiproliferative effects of the preservative benzalkonium chloride and three pure and commercially available beta-adrenergic antagonist preparations (timolol, betaxolol, and levobunolol) were studied on tissue cultures of human Tenon's capsule fibroblasts. Each drug preparation was tested on three different cell lines. Fibroblast growth was measured with tritiated thymidine uptake and hexosaminidase assays. Trypan blue uptake was used to assess cell viability microscopically. The commercially available preparations containing benzalkonium chloride and those of betaxolol and levobunolol without the preservative had similar inhibitory doses for 50% of cells. The timolol preparation without preservative was significantly less toxic than its commercially available one. The three tested beta-adrenergic blockers did not stimulate fibroblast proliferation directly in this in vitro model. Even when the cultures were washed free of the drugs, growth continued to be suppressed, suggesting that the inhibition was not reversible. An increase in fibroblasts and inflammatory cells after long-term antiglaucoma medical therapy thus may be caused not by a direct stimulation of cell proliferation but by chronic inflammation from the irritating effects of antiglaucoma medications and/or their preservatives.

Benzalkonium Compounds↗
PubMed1991

The effects of Nd:YAG laser iridotomy on the corneal endothelium.

We studied 18 eyes of 18 patients undergoing Nd:YAG laser peripheral iridotomy for occludable anterior chamber angles. A Q-switched laser was used for all treatments. Preoperative and postoperative pachymetry and corneal endothelial cell counts were obtained centrally, in the nontreated superonasal quadrant, and in the treated superotemporal quadrant. No significant differences were found between preoperative and postoperative corneal thickness at any site. A small decrease in endothelial cell count (95 cells/mm2) at the treated site was statistically significant (P = .04).

Cell Count↗
PubMed1991

The ocular effects of gases when injected into the anterior chamber of rabbit eyes.

We studied the toxic effects of sulfur hexafluoride and perfluoropropane in comparison with air, balanced salt solution, hyaluronate sodium, and aqueous humor in a rabbit model. Sixty normal pigmented rabbits were studied during a period of 4 weeks. The variables studied were slit-lamp biomicroscopic examination of the anterior segment, intraocular pressure as measured by pneumotonometry, corneal thickness and endothelial cell count as measured by specular microscopy, lens opacity by Scheimpflug photography, and light and transmission electron microscopy. All three gases were more toxic to the cornea and lens than were balanced salt solution, hyaluronate, and aqueous humor. However, 15% perfluoropropane and 50% sulfur hexafluoride were no more toxic to the eye than air was. Therefore, this study suggests that nonexpansile mixtures of perfluoropropane and sulfur hexafluoride may be beneficial and relatively safe in re-forming persistently flat anterior chambers in situations where the use of air is being considered.

Air↗
PubMed1991

Use of bioerodible polymers impregnated with mitomycin in glaucoma filtration surgery in rabbits.

A prospective, randomized, double-masked, and placebo-controlled study was performed to evaluate the effects of a localized and sustained release of mitomycin on the success of glaucoma filtration surgery in rabbits. A bioerodible polymer was used as the drug carrier. Full-thickness filtration surgeries were performed and data from 22 rabbits were collected. One eye received a polymer impregnated with mitomycin (0.02 mg or 0.06 mg), while the fellow eye received a drug-free polymer. Intraocular pressure, bleb survival, and postoperative complications were investigated. Intraocular pressures remained lower for a longer period of time (P less than 0.004) and filtration blebs lasted longer (P less than 0.05) in experimental eyes than in control eyes. Conjunctivitis and sectorial corneal haze occurred more frequently in eyes treated with the higher dosage mitomycin compared with control eyes. The use of mitomycin-C in a polymer delivery system appeared to promote the success of glaucoma filtration surgery in rabbits. With the lower dosage of mitomycin, clinically significant ocular toxicity was not noted.

Animals↗
PubMed1991

The effects of topical mitomycin on glaucoma filtration surgery in rabbits.

A prospective, randomized, double-masked, and placebo controlled study was performed to examine the effects of topically applied mitomycin on the success of full thickness filtration surgery in 23 rabbits. Both eyes of each rabbit had surgery by the same surgeon. After surgery, the experimental eye received a single subconjunctival injection of mitomycin (0.2 mg), and 50 microliters of a 0.2 mg/cc solution of mitomycin topically four time daily. The fellow control eyes were treated with sterile water. The mean intraocular pressure reduction from baseline exhibited by the experimental eyes was greater than that observed for the control eyes. The difference in intraocular pressure reduction between the two groups was statistically significant from post-operative day three through day 21 (p less than .05). With survival analysis, fewer failures were noted in the experimental eyes compared to control eyes for each time period throughout the study (p less than .005). The experimental eyes also demonstrated a longer time to bleb failure although this difference did not achieve statistical significance (p less than .10). An additional five rabbits were treated with the experimental drop in one eye and sterile water in the fellow eye but underwent no surgery. No differences between eyes were noted with regard to intraocular pressure change or anterior segment pathology. These data demonstrated the efficacy of mitomycin in promoting filtration surgical success in rabbits.

Administration, Topical↗
PubMed1991

The effect of a glaucoma medication reminder cap on patient compliance and intraocular pressure.

A multi-site, open-labeled clinical trial was conducted to evaluate the ease of use and acceptance of a newly developed medication cap with a memory aid (C Cap Compliance Cap, Allergan, Inc.) and its effect on patient compliance and intraocular pressure. One-hundred-twenty-two patients with glaucoma or ocular hypertension received their prescribed eye drops in bottles with the compliance cap. Overall, 83% of the patients found the compliance cap very easy to use. By the end of the study, significantly more patients (67%) claimed 100% compliance than prior to using the compliance cap (41%). An overall drop in intraocular pressure of 0.8 mm Hg was seen. However, in a subset of patients who reported an increase in compliance, mean intraocular pressure decreased from baseline by 1.7 mm Hg. The results of this study suggest that the compliance cap helps patients with glaucoma or ocular hypertension remember to take their medication as prescribed.

Adolescent↗
PubMed1991

Experimental transscleral iontophoresis of ciprofloxacin.

Ciprofloxacin was administered into the aqueous humor and vitreous body of the rabbit eye by transscleral iontophoresis. Positively and negatively charged forms of the drug molecule were tested. Therapeutic concentrations of ciprofloxacin were achieved in the aqueous body only when the negatively charged drug molecule was used. Ciprofloxacin did not reach the vitreous body in therapeutic concentrations in either the positively or negatively charged form, but higher concentrations were achieved when the drug was negatively charged. Peak levels were obtained in the aqueous and vitreous bodies (0.62 micrograms/ml and 0.19 micrograms/ml, respectively) one hour after transscleral iontophoresis of negatively charged ciprofloxacin at 5 mA for 15 minutes.

Animals↗
PubMed1991

Inhibition of rabbit ocular fibroblast proliferation by 5-fluorouracil and cytosine arabinoside.

Inhibition of rabbit subconjunctival fibroblast attachment and proliferation by the antimetabolites 5-fluorouracil (5-FU) and cytosine arabinoside (ara-C) was determined by radionucleotide uptake, cell counting, and colorimetric assays for the concentration range of 1000 to 0.0001 micrograms/ml over an 11-day period. The mean 50% inhibitory doses (ID50s) against proliferation were calculated for each assay. Rabbit fibroblast attachment was not inhibited at any drug concentration by either 5-FU or ara-C. Ara-C was a 10 to 100 times more potent inhibitor of rabbit fibroblast proliferation than 5-FU. The mean ID50s for rabbit subconjunctival fibroblasts were compared with the mean ID50s from a similar series of experiments conducted in our laboratory on human subconjunctival fibroblasts. Unpaired t-test analysis showed a significant difference between the inhibitory effects of 5-FU on rabbit and human fibroblast proliferation. An ID50 against rabbit fibroblasts was detectable after 24 hours of incubation with 5-FU by the 3H-thymidine uptake assay, whereas the ID50 against human fibroblasts was detectable after 48 hours of incubation. Once inhibition of proliferation occurred, however, human fibroblasts were up to six times more sensitive to the antiproliferative effects of 5-FU than rabbit fibroblasts as measured by the 3H-thymidine uptake assay (p = 0.0005). Unpaired t-test analysis showed no statistical difference between the ID50s of ara-C on rabbit and human fibroblasts. Starting on day 3, however, doses greater than 1 micrograms/ml of ara-C were cytotoxic to rabbit fibroblasts but only cytostatic to human fibroblasts as determined by trypan blue uptake assay microscopically. Rabbit ocular fibroblasts may be useful in modelling the proliferation of human ocular fibroblasts in vitro to a limited degree. This tissue culture system may be useful for predicting optimal drug dosages for in vivo rabbit and human glaucoma filtering surgery.

Animals↗
PubMed1991

The effects of 5-fluorouridine, 5-fluorodeoxyuridine, and 5-fluorodeoxyuridine monophosphate on rabbit tenon's capsule fibroblasts in vitro.

Inhibition of rabbit subconjunctival fibroblast attachment and proliferation by 5-fluorouridine (FUR), 5-fluoro-2 deoxyuridine (FUdR), and 5-fluoro-2-deoxyuridine-5-monophosphate (FdUMP), was determined by 3H-adenosine uptake, cell counting, and colorimetric assays for the concentration range of 1000 to 0.0001 micrograms/ml over an 9 day period. The mean 50% inhibitory doses against proliferation were calculated for each assay. Rabbit fibroblast attachment was not inhibited at any drug concentration by either FUR, FUdR, or FdUMP. For rabbit fibroblast proliferation, FUR was found to be 10-100 fold more potent than FUdR and FdUMP. When comparing the human and rabbit cells, the unpaired t-test analysis showed no consistent statistical difference of the ID50s for FUR, FUdR or FdUMP. Rabbit ocular fibroblasts may be useful in modeling the proliferation of human ocular fibroblasts. These in vitro results may be useful for predicting optimal drug dosages for future in vivo testing of these drugs.

Adenosine↗
PubMed1991

Characterization of human and rabbit pigmented and nonpigmented ciliary body epithelium.

Nonpigmented epithelial (NPE) and pigmented epithelial (PE) cells were carefully dissected from both human and rabbit ciliary processes and have been maintained in vitro and partially characterized by morphology and immunocytochemical techniques using polyclonal and monoclonal antibodies against S-100 proteins, collagen type I and type III. The tissue distribution of these proteins was studied in formalin fixed deparaffinized tissue sections of human and rabbit eyes by immunoperoxidase staining techniques. Both NPE and PE cell lines from human and rabbit showed hexagonal morphology by light microscopy; distinct granules containing pigment could be visualized in the PE cell lines, but not in the NPE cells. Antibodies against S-100 proteins stained NPE layer intensely and PE layer slightly in the human tissue sections. The staining was less intense in rabbit tissues than human tissues. The ciliary body stroma was positive for collagen type III and negative for collagen type I or S-100.

Animals↗
PubMed1991

Ophthalmic beta-blockers: determination of plasma and aqueous humor levels by a radioreceptor assay following multiple doses.

We determined the binding affinities of multiple doses of four ophthalmic beta-blockers, timolol, betaxolol, levobunolol and carteolol, to the beta-1 and beta-2 receptors. With a Ki value of 0.39 nM and 0.36 nM for the beta-1 and beta-2 receptors, respectively, levobunolol shows the highest binding affinity to both beta receptors. The Ki values of timolol (1.97 nM for the beta-1 receptor and 2.0 nM for the beta-2 receptor) and of carteolol (0.83 nM and 0.85 nM for the beta-1 and beta-2 receptors, respectively) are characteristic of a nonspecific beta-blocker. On the contrary, betaxolol is a beta-1 specific antagonist (Ki of 23.33 nM) and has a very low binding affinity to the beta-2 receptor (Ki of 200.00 nM). With a radioreceptor assay, levels of beta-antagonist were measured in the plasma and aqueous humor 1 hour and 12 hours after instillation of 50 microliters of 0.5% or 2% each of the four beta-blockers into the rabbit eye. At 1 hour after administration, the plasma levels of timolol, levobunolol, and carteolol are 9.89 ng/ml, 1.60 ng/ml and 8.00 ng/ml, respectively; such levels of 11.82 to 29.22 times the respective Ki values cause a virtually total blockade of both beta-1 and beta-2 receptors and suggest significant systemic absorption. Betaxolol has a peak 1 hour plasma level of 22.28 ng/ml, which is equivalent to only 3.08 times its Ki for the beta-1 receptor and 0.36 times its Ki for the beta-2 receptor; it has less systemic beta-1 blocking activity than the other three drugs and very minimal systemic beta-2 blocking activity. Peak aqueous humor concentrations of all 4 beta-blockers are extremely elevated at 1 hour after administration (timolol 1613.58 ng/ml; betaxolol 866.06 ng/ml; levobunolol 750.89 ng/ml; and carteolol 859.18 ng/ml). Such levels of 14 to 7192 times the respective Ki values should cause a virtually complete blockade of both beta-1 and beta-2 receptors in the iris-ciliary body complex. At 12 hours after administration, plasma levels of all four beta blockers remain moderately elevated (timolol 0.94 ng/ml; betaxolol 9.43 ng/ml; levobunolol 0.66 ng/ml; and carteolol 1.61 ng/ml). Trough aqueous humor levels of levobunolol (43.38 ng/ml) and carteolol (92.81 ng/ml) remain elevated at least 300 times their Ki value. On the contrary, 12-hour trough aqueous humor levels of timolol (33.67 ng/ml) and betaxolol (94.86 ng/ml) have decreased to 2 to 40 times their Ki value, which may explain their requirement for twice daily administration clinically.

Absorption↗
PubMed1991

The effects of the fluorinated pyrimidines FUR, FUdR, FUMP, and FdUMP on human Tenon's fibroblasts.

5-Fluorouracil (5-FU) has effectively inhibited fibroblast proliferation to prevent scar formation and bleb failure after glaucoma filtering surgery. To identify more potent but less toxic antiproliferative drugs, the authors studied cell attachment and proliferation of 5-FU metabolites: 5-fluorouridine (FUR), 5-fluorodeoxyuridine (FUdR), 5-fluorouridine-5'-monophosphate (FUMP), and 5-fluorodeoxyuridine-5'-monophosphate (FdUMP) on human Tenon's fibroblasts in vitro.

Adenosine↗
PubMed1991

Burnout, job stress, anxiety, and perceived social support in neonatal nurses.

Forty-nine nurses working in neonatal intensive care were surveyed by using measures of job stress, burnout, anxiety, and perceived social support. On the Maslach Burnout Inventory, they scored in a moderate range of burnout for emotional exhaustion and depersonalization and in a high range of burnout for sense of personal accomplishment. Stepwise regression analyses revealed that higher job stress scores, higher anxiety scores, perception of less supervisor (head nurse) support, and less experience were associated with higher burnout subscale scores.

Adult↗