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Biomedical subjects

D A Lee

Publications and source records attributed to D A Lee.

At least 109 records · Page 6Linked to original sources
PubMed1995

A retrospective study of eye disease among first grade children in Los Angeles.

BACKGROUND: The prevalence of ocular disease among children in one school district in Los Angeles, California was studied to better understand the types of eye disorders among this population as well as to develop appropriate preventive programs. METHODS: A computer-assisted retrospective analysis of date was performed from charts of 2,204 first grade children examined in the UCLA Mobile Eye Clinic. RESULTS: One or more ocular disorders were observed in 22.3 percent of the subjects. Uncorrected best monocular visual acuity was 20/40 or worse in 3.4 percent of the children. Refractive errors were diagnosed in 15.7 percent of the subjects, astigmatism in 7.6 percent, hyperopia in 6.2 percent, and myopia in 6.0 percent. Color vision deficiencies (red-green) were found in 2.6 percent of boys. The prevalences of heterophorias and heterotropias were 1.2 percent and 1.3 percent, respectively. CONCLUSIONS: The variety of ocular disorders diagnosed in this demographic setting attests to the importance of performing early and effective screening eye examinations for children.

Child↗
PubMed1994

Eye disease among ambulatory Jewish senior citizens in California.

Knowledge of the epidemiology of eye disease among the elderly becomes increasingly important as our population ages. Leading causes of blindness in the elderly include age-related macular degeneration, open-angle glaucoma and cataract. Few studies have examined the prevalence of these blinding eye diseases among senior citizens. A retrospective review of vision screening examinations from 429 patients seen at the UCLA Mobile Eye Clinic in visits to a Jewish senior citizens' center was performed to examine the distribution of best recorded visual acuity and prevalence of eye disease in a group of ambulatory Jewish senior citizens. Best recorded visual acuity was > or = 20/40 in the better eye for 83.9% of the patients. The prevalence of age-related macular degeneration was 20.7%, and increased with increasing age (p < .00005). The prevalence of open-angle glaucoma was 6.3%. The prevalence of senile cataract was 59.0% and increased with increasing age (p < .00005). Despite the limitations imposed by a retrospective review of charts, our study provides an indication of the prevalence of blinding eye disease and distribution of visual acuity among ambulatory Jewish senior citizens in southern California. Except for the high prevalence of senile cataract, the prevalence data derived from this study are similar to other epidemiologic studies of eye disease in the elderly.

Aged↗
PubMed1994

Growth of rabbit pigmented and nonpigmented ciliary body epithelium.

Pigmented (PE) and nonpigmented epithelial (NPE) cells were carefully dissected from the ciliary processes of rabbit eyes and maintained in vitro. Both epithelial cultured cells showed hexagonal morphology by light microscopy; abundant granules containing pigment could be seen in PE cells while no pigment was seen in the NPE cells. S-100 protein exists in both cultured cells and was used as a marker for the in vitro confirmation of these cells. Collagen type III was used as a negative marker to rule out stromal cell contamination in tissue cultures. PE cells attached and proliferated well in 20% fetal bovine serum (FBS) in minimum essential media (MEM). Greater proliferation was attained when PE cells were exposed to 20% vitreous extract in addition to 20% FBS-MEM. Media conditioned by PE cells did not significantly stimulate PE cells. NPE cells showed greatest proliferation in 20% FBS-MEM with either 20% concentration of media conditioned by PE cells or when exposed to 20% concentration of vitreous extract. Rabbit vitreous may contain factor(s) which stimulate the proliferation of both cultured cells, and conditioned media from the PE cells may contain factor(s) which stimulate NPE cell proliferation.

Animals↗
PubMed1994

The isolation of a fibroblast growth inhibitor associated with perigraft seroma.

PURPOSE: Perigraft seroma is a rare complication of reconstructive vascular surgery characterized by a clear, sterile fluid collection confined within a fibrous pseudomembrane around a prosthetic graft. The exact cause of this disease is unknown but involves failure of surrounding connective tissue to incorporate the graft. To understand why this occurs, we studied sera from patients with perigraft seroma for their effect on human fibroblasts. Sera from control subjects, patients with uninfected prosthetic grafts, and patients with prosthetic grafts were tested for comparison. METHODS: Fibroblast growth was measured by radioactive thymidine uptake and hexosaminidase colorimetric cell proliferation assays. We fractionated sera with gel filtration columns and measured each fraction's effect on fibroblast growth. RESULTS: Serum samples from patients with perigraft seroma inhibited fibroblast growth in a dose-dependent manner. In contrast, a postseroma sample, normal human sera, and sera from patients with infected and uninfected grafts showed no significant fibroblast inhibition. An inhibitory factor with a molecular weight of 2000 d was isolated from serum of patients with perigraft seroma. CONCLUSIONS: Perigraft seroma is associated with a fibroblast inhibitor with a molecular weight of 2000 d. Further identification and characterization of this protein may lead to clinical applications in preventing and treating perigraft seroma.

Blood Vessel Prosthesis↗
PubMed1994

Intraocular complications associated with the Dubroff anterior chamber lens.

We examined a series of 53 consecutive eyes form which Dubroff-style anterior chamber lenses were explanted. The mean time from implantation to explantation was 46.21 months (range six to 99 months). Problems leading to explantation included bullous keratopathy (83%), glaucoma (51%), chronic cystoid macular edema (40%), and iritis (13%). Molteno valves were required in 9% of eyes. Progressive anterior synechias resulted in intraocular lens displacement against the cornea in 19%. The Dubroff lenses caused problems similar to those previously observed with closed-loop anterior chamber lenses but had a higher incidence of severe glaucoma and progressive peripheral anterior synechias.

Aged↗
PubMed1994

Proteoglycan depletion alone is not sufficient to stimulate proteoglycan synthesis in cultured bovine cartilage explants.

Articular cartilage comprises a small number of cells embedded within a matrix primarily composed of collagen and proteoglycan (PG). The functional integrity of the tissue is highly dependent on the maintenance of matrix structure, which, in turn, is controlled by the chondrocytes. In normal tissue there is a slow but steady turnover of matrix components such that their levels remain constant. In certain diseased states the equilibrium is upset, resulting in a net loss of matrix components. The object of the present study was to artificially upset the synthetic/loss equilibrium by enzymic depletion and assess the ability of chondrocytes to respond by increasing PG synthesis. Cultured bovine articular cartilage explants were depleted using enzymes as follows; 10 U/ml Streptomyces hyaluronidase (induced a 30% loss of PG), 2000 U/ml testicular hyaluronidase (70% loss of PG) and 100 U/ml collagenase (35% loss of PG) and control (6% loss of PG). Collagenase also induced a 50% loss of collagen. Collagenase treatment induced a 50% stimulation of PG synthesis above control levels. Elevated synthesis levels were maintained for 9 days. Testicular hyaluronidase induced a brief elevation in PG synthesis on day 3 of culture. Streptomyces hyaluronidase treatment did not cause an alteration in the rate of PG synthesis above control levels. Histological examination indicated that collagenase-treated explants formed outgrowths consisting of rounded chondrocytes within a fine fibrous matrix which stained intensely with safranin-O, indicating a high concentration of PG. The production of repair-like outgrowths may explain the elevated PG synthesis rates measured. It appears, therefore, that collagen and matrix organization is more important than PG levels in the control of PG synthesis in articular cartilage explant cultures.

Animals↗
PubMed1994

The role of iontophoresis in ocular drug delivery.

Iontophoresis has been utilized in the field of ophthalmology for many years. Present application of this technique has diminished considerably and few clinicians are currently familiar with its use. This review aims to educate the reader regarding the essential features of this procedure and to discuss the past and future role of iontophoresis in ocular drug delivery.

Animals↗
PubMed1994

A mouse chromosome 11 library generated from sorted chromosomes using linker-adapter polymerase chain reaction.

We describe the generation of a mouse whole chromosome library using sequence-independent polymerase chain reaction (PCR) to amplify sequences contained in DNA extracted from flow sorted chromosomes. DNA in sorted chromosomes from a human x mouse hybrid cell line was digested with a frequent four-cutter restriction enzyme, Sau3AI, and the ends were ligated to an adapter oligonucleotide. The ligated DNA fragments were amplified using PCR primers homologous to the linker-adapter oligonucleotide. PCR-generated products were characterized by gel electrophoresis. The size of the amplified DNA ranged from 100 to more than 1,000 bp with a relatively high proportion of products at approximately 400 bp. Biotinylated PCR products used for FISH showed specific hybridization to murine metaphases and no hybridization to human lymphocyte and hamster metaphase cells. Banding analysis indicated that the probes were specific for mouse Chromosome 11. We anticipate that availability of painting probes for specific murine chromosomes will facilitate cytogenetic studies in the mouse.

Animals↗
PubMed1994

Does the public understand the differences between ophthalmologists and optometrists?

Telephone interviews utilizing random digit dialing were conducted in Los Angeles County to assess the public's knowledge of differences between ophthalmologists and optometrists and to determine factors predictive of knowledge status. Knowledge status was determined by performance on a questionnaire specifically designed for this study. Using multiple logistic regression analysis for simultaneous evaluation of potentially predictive factors, higher education, history of prior eye examination as an adult, and history of prior or present contact lens or spectacle wear were associated with scoring as knowledgeable. Predicted probabilities of being knowledgeable and not knowledgeable were presented for all combinations of these predictive variables. Such information may be helpful in guiding public education campaigns regarding eye care.

Adult↗
PubMed1994

Transcriptional control of human Tenon's capsule fibroblast collagen synthesis in vitro by gamma-interferon.

PURPOSE: Gamma-interferon (gamma-IFN) has been shown to be a potent inhibitor of collagenous protein production independent of its effects on noncollagenous protein production and cell proliferation in vitro. To understand further the processes controlling tissue fibrosis and the potential use of gamma-IFN as an antifibrotic treatment after glaucoma filtering surgery, the in vitro effects of recombinant gamma-IFN on procollagen mRNA production were studied. METHODS: Subconfluent human Tenon's capsule fibroblast cultures were exposed to 10, 50, 500, and 1000 U/ml of human recombinant gamma-IFN for 48 hours and to 500 U/ml for 12, 24, and 72 hours. After the incubation period, polyA+ mRNAs were isolated by oligo (dT) cellulose columns, separated according to size by electrophoresis through a denaturing agarose gel, and transferred to an activated nylon membrane for Northern blot analysis. The levels of type III (alpha 1) procollagen, type I (alpha 1) procollagen, and fibronectin (noncollagenous protein) mRNA were determined by hybridization with radiolabeled cDNA probes specific for these components followed by autoradiography. RESULTS: Densitometric analysis showed gamma-IFN selectively inhibited type III and type I procollagen mRNA synthesis from 24% (10 U/ml) to 99% (1000 U/ml) while leaving fibronectin mRNA synthesis unaffected. The degree of inhibition was also time dependent; more inhibition occurred with increasing incubation time. CONCLUSIONS: These results indicate that gamma-IFN is able to regulate collagen synthesis at the transcriptional level and that its inhibition is relatively specific. Gamma-interferon's specific inhibitory effects may offer advantages over current therapies in modulating the fibrotic response after glaucoma filtering surgery.

Cell Line↗
PubMed1993

Collagen shields impregnated with gentamicin-dexamethasone as a potential drug delivery device.

We investigated the ability of collagen shields impregnated with gentamicin sulfate and dexamethasone to deliver medication into rabbit eyes. We compared the aqueous humor gentamicin and dexamethasone levels delivered by collagen shield and subconjunctival injection therapy at five time points over a ten-hour period, by using a fluorescence polarization immunoassay and high-pressure liquid chromatography. Our in vitro studies showed that impregnated collagen shields released most of the gentamicin within the first 30 minutes of elution, whereas dexamethasone was released gradually over a ten-hour period. The collagen shields impregnated with gentamicin and dexamethasone produced aqueous gentamicin levels that were significantly lower (P = .014) than those produced by subconjunctival injection therapy at 30 minutes and that were comparable to subconjunctival injection therapy at the other time points. Minimum inhibitory concentrations of gentamicin (approximately 4 micrograms) were observed in aqueous humor within 30 minutes in rabbits that received subconjunctival injections and at one hour in rabbits treated with impregnated collagen shields. The impregnated collagen shields produced aqueous dexamethasone levels that were significantly lower (P = .004) than those produced by subconjunctival injection therapy at one hour, significantly higher (P = .028) than subconjunctival injection therapy at six hours, and comparable to subconjunctival injection therapy at the other time points. Collagen shield delivery of gentamicin-dexamethasone may be comparable to subconjunctival injections and provide an alternative therapy after intraocular surgery.

Animals↗
PubMed1993

Reproducibility of postural changes in intraocular pressure with the Tono-Pen and Pulsair tonometers.

Reproducibility of measurements of postural changes in intraocular pressure was determined by using the Tono-Pen (Mentor O & O, Inc., Norwell, Massachusetts) and Pulsair (Keeler Instruments, Inc., Broomhall, Pennsylvania) tonometers. Thirty subjects had three repeated sitting and reclining measurements performed on three separate visit days. Reproducibility coefficients of 3.3% for the Tono-Pen and 6.3% for the Pulsair were obtained for the within-visit postural change measurements. Across-visit reproducibility coefficients were 7.9% and 26.2% for the Tono-Pen and Pulsair, respectively. The estimated standard deviations for both the within-visit and across-visit postural change measurements were high for both instruments. These results indicate poor reproducibility of measurements of postural changes in intraocular pressure.

Adult↗
PubMed1993

Transscleral iontophoresis of foscarnet.

Current local treatments of cytomegalovirus retinopathy may result in serious intraocular complications. Using an animal model, we investigated transscleral iontophoresis as a technique for delivery of foscarnet to the vitreous. Using a probe tip surface area of 0.19 mm2, a current of 1 mA, and a duration of ten minutes, transscleral iontophoresis of 0.5 ml of a 24-mg/ml foscarnet solution was administered to 72 normal rabbits. Vitreous aspiration was performed at 12 intervals (15 minutes, 30 minutes, and one, two, four, eight, 16, 24, 32, 40, 48, and 60 hours) after iontophoresis, and samples were analyzed by high-performance liquid chromatography to determine the vitreous pharmacokinetics of foscarnet. A peak foscarnet concentration of 200 +/- 31 microM (mean +/- standard deviation) was attained four hours after iontophoresis and was well below the concentration reported to cause retinal toxicity. Therapeutic levels were maintained until 60 hours after iontophoresis. The elimination half-life was approximately 24 hours. No toxic effects to anterior chamber structures were observed by biomicroscopy. Transscleral iontophoresis of foscarnet may provide an effective and safe technique for local treatment of cytomegalovirus retinopathy in patients with acquired immunodeficiency syndrome.

Animals↗
PubMed1993

In vitro evaluation of antiproliferative potential of topical cyclooxygenase inhibitors in human Tenon's fibroblasts.

Pharmacologic agents which inhibit fibroblast proliferation and scar formation may improve the success of glaucoma filtration surgery. To evaluate the potential use of nonsteroidal anti-inflammatory drugs as an antifibrotic treatment following glaucoma filtration surgery, the time and dose-related effects of four commonly used topical cyclo-oxygenase inhibitors--diclofenac, flurbiprofen, piroxicam, and suprofen--on human Tenon's fibroblast attachment and proliferation were studied. Fibroblasts were incubated with different concentrations of a drug and analysed for dose response 1, 3, and 8 days following drug addition. The cell density was quantified by Coulter counting, hexosaminidase assay, and [3H]thymidine uptake into the DNA. All four drugs inhibited fibroblast attachment at the highest concentrations. Diclofenac was the most effective agent in inhibiting fibroblast proliferation, with inhibition occurring at a range of concentrations above 10(-3)-10(-4) mmol l-1. Flurbiprofen, piroxicam, and suprofen were comparable to each other in their antiproliferative activities, with inhibition occurring at a range of concentrations above 10(-1)-10(-2) mmol l-1. These results suggest a potential role for the commonly used topical nonsteroidal anti-inflammatory drugs in preventing excessive fibroblast proliferation following GFS, but further clinical studies are indicated to assess their activity as anti-inflammatory and antiproliferative agents in preventing bleb failure.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Short tandem repeat loci: application to forensic and human remains identification.

The short tandem repeat (STR) locus ACTBP2 (common name SE33) was analyzed for its potential use in forensic and human remains identification. PCR amplification conditions were determined, and an allele-specific ladder was generated so that discrete alleles could be scored. The allele frequency distributions were determined for both Caucasian and Black populations. The frequency data meets Hardy-Weinberg expectations, and the allele distributions were similar from one racial group to another and between ethnic groups. SE33 analysis was subsequently used to confirm the identification of human remains for the Office of the Armed Forces Medical Examiners.

Alleles↗
PubMed1993

The development of chromosome-specific composite DNA probes for the mouse and their application to chromosome painting.

The speed and ease of human cytogenetic analysis has been greatly enhanced by the technique of fluorescence in situ hybridization (FISH). Non-radioactive fluorescently tagged complex DNA probes specific for individual chromosomes can be hybridized to conventionally obtained metaphase chromosome spreads. Several chromosomes may be "painted" concurrently by using combinations of different labeled probes. Surveys of chromosome breakage and rearrangement may be performed very quickly by avoiding the time consuming process of GTG-banding. The application of FISH to mouse cytogenetics would allow large scale molecular toxicology studies to be conducted on the effects of such environmental insults as potential carcinogens, mutagens and radiation. Progress has been hampered, however, as the Mus musculus karyotype consists of 40 acrocentric chromosomes of approximately the same size, making the recognition and separation of individual chromosomes very difficult. We now describe the successful production and application of chromosome-specific composite DNA probes for M. musculus chromosomes 2 and 8. Stable Robertsonian translocated chromosomes were isolated on a flow sorter and their DNA subsequently amplified by degenerate oligonucleotide primer (DOP) PCR. Small pools (300 copies) of each chromosome were denatured at 94 degrees C then annealed with the primer at 30 degrees C for 15 cycles. This was followed by 20 cycles at an annealing temperature of 62 degrees C. Additional amplification was performed at an annealing temperature of 62 degrees C. The chromosome-specific DNA was labeled with biotin 11-dUTP by nick translation and used for FISH. The usefulness of the technique for translocation detection is demonstrated by analyzing chromosome exchanges induced in mice irradiated with 137Cs gamma rays.

Animals↗
PubMed1993

The prevalence of ocular disorders among Hispanic and Caucasian children screened by the UCLA Mobile Eye Clinic.

A cross-sectional study was performed to describe the prevalence of ocular abnormalities among six and seven year old children of Hispanic and Caucasian ancestry in Los Angeles County. Data were obtained from vision screenings of lower to middle income Hispanic and Caucasian children completed by the UCLA Mobile Eye Clinic at public neighborhood elementary schools and community centers between January and August of 1989, and January and March of 1990. Out of a total sample of 854 children, 64% were Hispanic; 36% were Caucasian; 51% were female and 49% were male. Ocular abnormalities observed were similar for both ethnic groups. Caucasians, however, showed non-significant, but consistently higher prevalences of most ocular abnormalities. Stronger associations between ethnicity and visual abnormalities were observed within the female subgroup. For example, hyperopia was found more commonly among female Caucasian children than among female Hispanic children (p < 0.01). This information can be used in planning for the eye care needs of communities with Caucasian and Hispanic components.

Child↗