Biomedical subjects
Publications and source records attributed to D A Lee.
This case report describes an unusual complication of Descemet membrane detachment after anterior chamber reformation to treat a flat anterior chamber and hypotony from a trabeculectomy. This large Descemet membrane detachment was unexpectedly associated with a clear cornea. Treatment was conservative, and the Descemet membrane detachment spontaneously resolved in 6 months.
PURPOSE: A double-blind, randomized, placebo-controlled clinical trial to examine the safety, tolerability, and antiepileptic activity of ganaxolone in patients after withdrawal from other antiepileptic drugs during presurgical evaluations was performed. METHODS: Fifty-two eligible patients were withdrawn from antiepileptic drugs and randomized to receive ganaxolone (24 patients) or placebo (28 patients) for up to 8 days. Ganaxolone was administered at a dose of 1500 mg/d on day 1 and 1875 mg/d on days 2 to 8. Dosing occurred three times per day: immediately after breakfast, lunch, and dinner. RESULTS: The primary measure of antiepileptic activity was duration of treatment before withdrawal from the trial. Kaplan-Meier curves depicted a clear separation between treatment groups, with 50% of the ganaxolone-treated patients completing the entire study, compared with 25% of patients treated with placebo. Intent-to-treat survival analyses revealed a trend toward efficacy with ganaxolone (p = 0.0795, log rank test). Covariate analyses revealed a significant treatment effect on survival time in men (p = 0.03). Post-hoc chi2 probe analyses focusing on patients who completed the entire study revealed a significant difference (p = 0.04) between treatment groups. The tolerability of ganaxolone was similar to that of placebo, with adverse events being reported by 79% of patients in the ganaxolone group and 68% of patients in the placebo group. CONCLUSIONS: Ganaxolone monotherapy was well tolerated for the duration of this clinical trial, and the results provide preliminary evidence that ganaxolone does have antiepileptic activity.
Articular cartilage is subjected to dynamic compressive loading during normal activity which influences chondrocyte metabolism through various mechanotransduction pathways. A well characterised and reproducible model system, involving chondrocytes embedded in agarose gel, has been used to investigate the effects of mechanical compression on chondrocytes, isolated from full depth cartilage or separately from the superficial and deep zone tissue. The role of nitric oxide as a mediator of mechanical-induced effects has also been studied. Chondrocytes were isolated, separately, from full depth, superficial and deep zone cartilage and seeded in 3% agarose constructs. Dynamic compressive strain was applied to the constructs using a range of frequencies (0.3, 1 and 3 Hz). Glycosaminoglycan synthesis, cell proliferation and nitrite production were assessed. In further experiments, constructs were compressed in the presence of 1 mM L-NAME or 10 microM dexamethasone. Glycosaminoglycan synthesis by full depth chondrocytes was affected by compressive strain in a frequency dependent manner. Dynamic strain at all frequencies induced an increase in [3H]-thymidine incorporation. Glycosaminoglycan synthesis by deep zone cells was affected by the strain regimes in a similar fashion to full depth cells, while superficial cells exhibited a similar proliferative response to full depth cells. Dynamic compression inhibited nitrite production, the effect being reversed by L-NAME. Compression induced stimulation of [3H]-TdR incorporation was reversed by L-NAME. These studies demonstrate that glycosaminoglycan synthesis and proliferation are influenced by the dynamic strain regimes in a distinct manner. Indeed the data suggest that these processes occur in different chondrocyte sub-populations. It may be speculated that nitric oxide acts as a mediator of mechanotransduction processes affecting proliferation primarily in the superficial cell sub-population.
The transforming growth factor-beta (TGF-beta) signaling pathway subserves an essential tumor suppressor function in various cell types. A heteromeric complex composed of TGF-beta type I (RI) and type II (RII) receptors is required for TGF-beta signaling. We have identified a subset of human gastric cancer cell lines which are insensitive to TGF-beta and which express a low level of TGF-beta type I receptor mRNA relative to a gastric cancer cell line which is highly responsive to TGF-beta. Using these cells, we show that hypermethylation of a CpG island in the 5' region of the TGF-beta RI gene provides another potentially important mechanism of escape from negative growth control by TGF-beta. This hypermethylation was found in four of five human gastric cancer cell lines and five out of 40 (12.5%) primary tumors examined. In human gastric cancer cell lines, treatment with the demethylating agent, 5-aza-2'-deoxycytidine, resulted in increased expression of the TGF-beta RI gene, but not the RII gene. Transient transfection of an RI expression vector into the TGF-beta resistant SNU-601 cell line restores TGF-beta responsiveness. These findings suggest that one of the mechanisms of escape from autocrine or paracrine growth control by TGF-beta during carcinogenesis could involve aberrant methylation of CpG islands in the 5' region of the TGF-beta RI gene.
Occupational injury is a major source of ocular trauma and is often preventable. A statewide population-based survey of severe work-related ocular injury was generated by using the California Hospital discharge database to identify hospitalized ocular injury and workers compensation as principal payor to identify work-relatedness. Information concerning diagnoses, procedures, causes of injury, length of hospital stay, total hospital charges and disposition at hospital discharge were obtained for injuries occurring during the calendar year 1988. A total of 455 admissions for work-related ocular trauma were identified. The most common work-related ocular trauma diagnoses associated with hospitalizations were open globe injury (46%), adnexal wounds (20%), orbital fractures (11%), and traumatic hyphema (11%). The most common causes of work-related ocular trauma were foreign-body or projectile objects (19%), transport vehicles (18%), cutting or piercing objects (17%), and assaults (9%). Approximately 8% reported other than routine disposition at time of hospital discharge, including long-term nursing or rehabilitation services and death. Mean hospital stay when ocular trauma was the principal admitting diagnosis was 3.7 days. Results differed significantly for admissions reporting ocular trauma as the principal admitting diagnosis compared to admissions that did not. Hospitalized work-related ocular trauma is represented by a wide spectrum of injuries with substantial morbidity and economic costs. Projected to the United States population, these data indicate annual hospital charges excluding professional fees of $14.6 million when work-related ocular trauma is the principal admitting diagnosis and $40 million for admissions where ocular trauma is either a principal or secondary diagnosis.
Dorzolamide is the first commercial topical carbonic anhydrase inhibitor approved by the Food and Drug Administration (FDA) for the treatment of glaucoma. In a prospective, open label, uncontrolled study on 245 glaucoma patients, dorzolamide significantly lowered the intraocular pressure at least 14% when used alone or in combination with one, two, or three other antiglaucoma medications over ten weeks. There were very few adverse reactions to dorzolamide. Dorzolamide is effective and safe when used alone or in combination with other topical antiglaucoma medications for the treatment of glaucoma.
PURPOSE: This study was conducted to evaluate the ocular hypotensive efficacy, safety, and side effects of latanoprost 0.005% administered as adjunctive therapy in patients with Sturge-Weber syndrome (SWS) and glaucoma. METHODS: Commercially available latanoprost 0.005% was added as a single drop once daily to other antiglaucoma medications. Intraocular pressure (IOP) was measured at 1, 3, and 6 months of treatment. A successful response was defined as a reduction of at least 20% in IOP at the final follow-up evaluation without additional medical or surgical therapy and no adverse events related to latanoprost. RESULTS: 18 eyes of 18 patients with SWS and glaucoma were enrolled from 9 clinical centers. Mean baseline IOP was 28.4 +/- 7.1 mmHg (range, 17-42 mmHg). Using Kaplan-Meier analysis, a successful response to latanoprost was observed in 3 of 18 (16.7%) patients at the 6-month interval. Seven (38.9%) patients required surgery; three (16.7%) patients required additional medical therapy, seven (38.9%) patients had no change in therapy. One (5.6%) patient discontinued latanoprost treatment because of intolerable conjunctival hyperemia. Two successfully treated patients had significantly greater episcleral vessel engorgement after initiation of latanoprost therapy. CONCLUSION: Patients with SWS and glaucoma respond poorly to adjunctive latanoprost therapy and often require additional medical or surgical intervention. Increased episcleral vascular engorgement might result in greater operative risks should filtration surgery become necessary in these patients.
BACKGROUND: The purpose of our study was to present descriptive findings of ocular abnormalities in vision screening examinations of abused and neglected children. We compared the prevalence and the nature of eye diseases and refractive error between abused and neglected boys staying at the Hathaway Home, a residential facility for abused children, and boys from neighboring Boys and Girls clubs. METHODS: The children in the study received vision screening examinations through the UCLA Mobile Eye Clinic following a standard format. Clinical data were analyzed by chi-square test. RESULTS: The children with a history of abuse demonstrated significantly higher prevalence of myopia, astigmatism, and external eye disorders. CONCLUSIONS: Our study suggests that children with a history of abuse may be at higher risk for visual impairment. These visual impairments may be the long-term sequelae of child abuse.
A validation study was conducted to demonstrate that deoxyribonucleic acid (DNA) could be successfully extracted from human nail material and analyzed using short tandem repeat (STR) profiling and/or mitochondrial DNA (mtDNA) sequencing. This study involved the development of a DNA extraction protocol that includes a cleaning procedure designed to remove external contaminants (e.g., biological, chemical). This protocol was used to test human nail material that had been soaked in whole blood from a second donor and coated with gold-palladium to simulate scanning electron microscopic analysis. The results showed no indication of a mixture and were consistent with that of the nail donor. Fresh human nail material usually yielded both STR profiles and mtDNA sequence information; however, aged human nail material (approximately eight years old) yielded only mtDNA sequence information. Upon completion of the validation study, the extraction protocol was used for the analysis of a torn fingernail fragment recovered from the scene of a violent homicide in 1983. A partial STR profile and mtDNA sequence information indicated that the fingernail fragment was excluded as originating from the suspect and was, in fact, consistent with originating from one of the victims.
BACKGROUND: Occurrence of refractive errors and uncorrected visual acuity impairment among self-selected, indigent, medically underserved Hispanic, white, and black adults examined by the staff of the UCLA Mobile Eye Clinic (MEC) are described in this study and compared to population-based studies. METHODS: The study sample consisted of all 2,970 Hispanic, 1,228 white, and 1,028 black participants, for a total of 5,226 self-selected adults, ages 25 to 74 years, who received vision screenings and eye examinations by the staff of the UCLA MEC from 1987 to 1997. Tests consisted of visual acuity, refractive error, intraocular pressure, retinoscopy, slit-lamp biomicroscopy, direct ophthalmoscopic examination, and indirect ophthalmoloscopy with pupillary dilation. Levels of visual acuity impairment were defined as mild (20/50-20/80), moderate (20/100), or severe (20/200 or worse) in either eye. RESULTS: Self-selected whites in this study had higher rates of astigmatism, anisometropia, and hyperopia, while myopia was higher among self-selected blacks. Myopia and hyperopia occurred more frequently among younger age groups for all ethnic groups. Whites had a higher occurrence of mild, moderate, and severe visual acuity impairment, as compared with Hispanics and blacks. CONCLUSIONS: Both refractive errors and impaired visual acuity of this self-selected sample are similar to those of adults from the National Health and Nutrition Examination Survey, Hispanic Health and Nutrition Examination Survey, and the Baltimore Eye Survey. The data presented in this study provide a crude estimate of the occurrence of refractive errors and impaired visual acuity among self-selected, medically underserved, indigent Hispanic, white, and black adults in the Los Angeles area.
This study investigates the mechanical influence of pericellular matrix on the deformation of isolated articular chondrocytes compressed within 3% agarose specimens. After 1 day in culture, the cells were associated with minimal amounts of sulphated glycosaminoglycan (GAG) and hydroxyproline and exhibited substantial deformation from a spherical to an oblate ellipsoid morphology when subjected to 20% gross compressive strain. However, over the 6 day culture period, there was a reduction in cell deformation associated with an increase in matrix content. Treatment with testicular hyaluronidase at days 3 and 6 reduced sulphated GAG content to levels observed in untreated specimens at day 1. At day 3, the resulting cell deformation during 20% compression was equivalent to that in specimens compressed at day 1. However, at day 6 cell deformation was only partially restored, suggesting the presence of additional structural matrix components, other than sulphated GAG, which were not present at day 3. Dual scanning confocal microscopy indicated that the elaborated matrix formed a pericellular shell which did not deform during compression and was therefore stiffer than the 3% agarose substrate. Therefore, the elaboration of a mechanically functional pericellular matrix within 6 days, effectively limits the potential involvement of cell deformation in mechanotransduction within cell seeded systems such as those employed for cartilage repair.
Nitric oxide (NO) has been implicated in the inhibition of cell proliferation in cytokine and lipopolysaccharide (LPS)-stimulated chondrocytes and is known to be influenced by physical forces in several tissues. In this study, a well-characterized model system utilizing bovine chondrocytes embedded in 3% agarose constructs has been used to investigate the effect of dynamic strain at 0.3, 1, or 3 Hz on NO production. LPS induced a significant increase in nitrite levels, which was reversed by both L-NAME and dexamethasone. Dynamic compressive strain produced a significant reduction in nitrite production. The effect was partially blocked by L-NAME but unaffected by dexamethasone. L-NAME also reversed dynamic compression-induced stimulation of [3H]-thymidine incorporation. NO appears to be a constituent of mechanotransduction pathways which influence proliferation of bovine chondrocytes seeded within agarose constructs. The inhibitor experiments also infer that alterations in cNOS activity primarily determine the response.
Although it is well known that the metabolism of chondrocytes can be altered by the application of mechanical strain, it is unclear whether chondrocytes from the superficial and deep zones of cartilage respond in a similar manner. In this study, chondrocytes from the uppermost 15-20% (superficial cells) and the remaining tissue (deep cells) from bovine articular cartilage were isolated separately and cultured in agarose constructs. Cell deformation on application of a 15% static compressive strain was identical for both subpopulations after 24 and 72 hours in culture. The constructs were incubated under static and dynamic (0.3, 1, and 3 Hz) strains of 15% amplitude. Glycosaminoglycan synthesis by deep cells was unaffected by static strain or 3 Hz dynamic strain, whereas 0.3 Hz produced a significant reduction and 1 Hz induced a highly significant 50% stimulation of glycosaminoglycan synthesis (p < 0.001). Superficial cells exhibited a general inhibition of glycosaminoglycan synthesis. By contrast, proliferation of superficial cells was stimulated by dynamic strain whereas deep cells were not influenced. It has been suggested previously that mechanotransduction-induced controls of glycosaminoglycan synthesis and proliferation in chondrocytes embedded in agarose are uncoupled. Data presented in this study demonstrate that the two processes do, in fact, occur in different subpopulations of chondrocytes within the full-depth cell isolate.
A reduction in pH induces the release of iron from transferrin in a process that involves a conformational change in the protein from a closed to an open form. Experimental evidence suggests that there must be changes in the protonation states of certain, as yet not clearly identified, residues in the protein accompanying this conformational change. Such changes in protonation states of residues and the consequent changes in electrostatic interactions are assumed to play a large part in the mechanism of release of iron from transferrin. Using the x-ray crystal structures of human ferri- and apo-lactoferrin, we calculated the pKa values of the titratable residues in both the closed (iron-loaded) and open (iron-free) conformations with a continuum electrostatic model. With the knowledge of a residue's pKa value, its most probable protonation state at any specified pH may be determined. The preliminary results presented here are in good agreement with the experimental observation that the binding of ferric iron and the synergistic anion bicarbonate/carbonate results in the release of approximately three H+ ions. It is suggested that the release of these three H+ ions may be accounted for, in most part, by the deprotonation of the bicarbonate and residues Tyr-92, Lys-243, Lys-282, and Lys-285 together with the protonation of residues Asp-217 and Lys-277.
The measurement of collagen synthesis by seeded cells in vitro is a prerequisite for the assessment of biocompatibility of many biomaterials. Existing methods are either complicated or not applicable to systems utilizing collagen-based materials, and the development of a rapid and simple technique would be an advantage. In the current paper, a method is described which relies on the radiolabelling of newly synthesized protein with [3H]-proline followed by specific precipitation of collagen using 1% sirius red dissolved in water. The results indicate that collagen binding to sirius red is unaffected by using water rather than picric acid as a solvent and the dye binds in a similar fashion to collagen type I, II and III. Cycloheximide treatment of the gels indicated that precipitated [3H]-proline was restricted to macromolecular protein. Collagenase treatment eradicated labelled precipitation formation when using 1% sirius red in water, indicating a high degree of specificity for collagen whilst specificity was poor when using 1% sirius red in picric acid. The method described is both simple and rapid and shows a high degree of specificity and sensitivity. For these reasons it is highly suited for the assessment of collagen synthesis by cells in collagen-based materials.
Previous studies indicate that there may be differences in the protein composition of the aqueous humor in normal and glaucomatous human eyes. These differences in protein composition and concentration may be due to the topical antiglaucoma medications used to treat glaucoma. These differences should be distinguished from any possible protein composition changes due to glaucoma. In order to study the effects of topical antiglaucoma medications on aqueous humor protein composition, we analyzed the aqueous humor of rabbit eyes topically treated with various antiglaucoma medications (timolol, pilocarpine, and dipivefrin). One eye of each rabbit was treated with the experimental drug, and the fellow eye was treated with saline solution (control). Thirty-six aqueous humor samples from 18 rabbits were obtained after 24 hours and 36 samples were obtained from 18 additional rabbits after 7 days of topical drug treatment. The protein composition of the aqueous humor samples was analyzed by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Significant protein differences in aqueous humor samples were found between the eyes treated with timolol and the control eyes, whereas no significant differences were found between the eyes treated with pilocarpine or dipivefrin and the controls. These protein differences ranged from 14,000 to 18,000 daltons in molecular weight.
The purpose of this study was to compare means, variability, and reproducibility in intraocular pressure and in outflow facility measured repeatedly over several days by Bio-Rad pneumatonography and Schiotz tonography in normal human volunteers. For each instrument a measurement of intraocular pressure and one of outflow facility were obtained at each of three repeated examinations of eight healthy subjects in the supine position. For pressure, the Bio-Rad mean was significantly higher by 5.31 mmHg than the Schiotz mean (p < 0.00005). Reproducibility was 71.1% and 59.0% for the Bio-Rad and Schiotz, respectively. For outflow, the Bio-Rad and Schiotz means were not significantly different. Reproducibility was 17.3% and 58.7% for the Bio-Rad and Schiotz, respectively. For measuring pressure, both the Bio-Rad and Schiotz instruments had good reproducibility; for measuring outflow, the Bio-Rad and Schiotz instruments had low and good reproducibility, respectively.
Success of glaucoma filtration surgery is influenced by the wound healing response. Attention has been focused on pharmacological agents to control a process that leads to excessive scarring and eventual failure of glaucoma filtration surgery. Several agents, including 5-fluorouracil and mitomycin C, as well as other antiproliferative drugs will be discussed. Newer antifibrotic agents and novel drug delivery systems are under development in tissue culture and animal models in an effort to improve efficacy and safety. This article summarizes current treatment modalities and future prospects to prevent excessive wound healing and improve the success of glaucoma filtration surgery.