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Biomedical subjects

T W Olsen

Publications and source records attributed to T W Olsen.

17 recordsLinked to original sources
PubMed1997

A model for light toxicity of cultured human retinal pigment epithelium.

BACKGROUND: The effect of visible light on human retinal pigment epithelial (HRPE) cells has not been characterized under conditions that provide strict thermal control. METHODS: HRPE cells were isolated and grown to confluence. Cells were exposed to light in an incubator in which the cell temperature was controlled in response to a temperature sensor maintained in the tissue culture medium. Cells were exposed: (A) for 24, 36, and 48 h; and using a 24-h exposure followed by 24 h darkness; (B) at varying intensities of light using neutral density filters; (C) under a yellow filter; and (D) with a 12-h on-off cyclic light. RESULTS: (A) Light exposure of 36 and 48 h resulted in significant cytotoxicity, while the initial 24-h exposure did not induce subsequent cytotoxicity. (B) Light irradiance levels from 43 to 54 mW/cm2 were required to demonstrate cytotoxicity. (C) Use of a yellow filter did not eliminate the observed cytotoxicity. (D) Cyclic exposure did not result in significant cytotoxicity. CONCLUSION: This study establishes a model and basic parameters of light toxicity to HRPE cells in vitro using strict temperature control that may be used to evaluate photochemical injury to HRPE cells.

Adolescent↗
PubMed1996

Postoperative hypopyon after intravitreal bovine thrombin for macular hole surgery.

PURPOSE: We used intravitreal autologous fibrinogen with bovine thrombin for the surgical closure of macular holes in 60 cases. METHODS: Pars plana vitrectomy with separation of the posterior cortical vitreous was performed after air/fluid exchange. One to two drops each of autologous fibrinogen and bovine thrombin (20 to 80 U) were instilled in each patient. RESULTS: Five (8%) of 60 patients developed a hypopyon without unusual pain on the first postoperative day. Inflammation responded to frequent topical corticosteroids within 48 to 72 hours. CONCLUSION: Postvitrectomy hypopyon after the use of bovine thrombin may represent an immune reaction that must be differentiated from endophthalmitis. We recommend careful observation and frequent topical corticosteroids.

Adult↗
PubMed1996

Subfoveal choroidal neovascularization in punctate inner choroidopathy. Surgical management and pathologic findings.

PURPOSES: To evaluate submacular surgery for the management of subfoveal choroidal neovascularization in punctate inner choroidopathy, to describe the histopathology and ultrastructure of the excised subretinal tissue, and to propose a staging system that characterizes the development of choroidal neovascularization with associated subretinal fibrosis. METHODS: The authors reviewed the records of five patients (6 eyes) with punctate inner choroidopathy who underwent submacular surgery for subfoveal choroidal neovascularization. Surgical specimens were examined using light and transmission electron microscopy. RESULTS: Visual improvement was noted postoperatively in all six eyes, with follow-up ranging from 8 to 36 months (median, 14 months). Recurrences (6 in 4 eyes) were common. Five of the six recurrences required additional procedures: three were managed surgically, two with laser photocoagulation, and one with observation. "Bridging" of separate foci of choroidal neovascularization resulted in stellate or "dumbbell-shaped" areas of subretinal fibrosis in four of six eyes. Histopathologic evaluation of the excised tissue showed endothelial-lined vascular channels, retinal pigment epithelium, lymphocytes, plasma cells, fibrocytes, collagen fragments, and rarely, outer retinal elements. CONCLUSIONS: Subfoveal choroidal neovascularization in punctate inner choroidopathy may be managed with submacular surgery. Recurrences are common and may result in substantial loss of vision. Choroidal neovascular membranes with an accompanying fibrotic reaction are responsible for the stellate or dumbbell-shaped areas of subretinal fibrosis. No beneficial effect was demonstrated using corticosteroid treatment of the choroidal neovascularization.

Adult↗
PubMed1996

Misoprostol with cyclosporin A prolongs corneal allograft survival in an animal model.

Cyclosporin A (CSA) has been shown to prolong corneal allograft survival in a variety of animal models. Misoprostol is a prostaglandin E1 analogue with oral bioavailability and immunosuppressive properties. Misoprostol and CSA are synergistic immunosuppressants in vitro. In the present study, we evaluated the effect of adding misoprostol to a subtherapeutic dose of CSA in the orthotopic allogeneic rat penetrating keratoplasty model. Seventy inbred Lewis rats were recipients of orthotopic corneal allografts from Brown-Norway donors. Ten Lewis rats received orthotopic syngeneic grafts (Lew to Lew). Two separate experiments with 40 animals per trial were performed. In each trial, the rats were divided equally into four groups. Trial A: allogeneic control (A1), syngeneic control (A2), CSA at 10 mg/kg/d (A3), and CSA at 15 mg/kg/d (A4). Trial B: allogeneic control (B1), CSA alone at 7.5 mg/kg/d (B2), misoprostol alone at 1 mg/kg/d (B3), and CSA with misoprostol at 7.5 and 1 mg/kg/d, respectively (B4). Syngeneic control A2 as well as group A4 remained clear through postoperative day 22. The allogeneic control groups A1 and B1, plus treatment groups B2 and B3, rejected their grafts by postoperative day 12. Groups A3 and B4 demonstrated a delay in allograft rejection that continued to be statistically significant through the 12th postoperative day (p < 0.001). We conclude that the addition of systemic misoprostol to CSA can effectively prolong corneal allograft survival in the orthotopic allogeneic rat penetrating keratoplasty model.

Animals↗
PubMed1995

Human scleral permeability. Effects of age, cryotherapy, transscleral diode laser, and surgical thinning.

PURPOSE: To determine the in vitro permeability of human sclera to compounds varying in molecular weight. To evaluate the effects of age, cryotherapy, transscleral diode laser, and surgical thinning on scleral permeability. METHODS: Scleral tissue from 97 human eye bank eyes was tested individually in a two-chamber Ussing apparatus with the following hydrophilic radiolabeled compounds on one side of the chamber: 5-fluorouracil, sucrose, dexamethasone, methotrexate, inulin, and three separate dextran polymers (MWt = 10,000, 40,000, and 70,000). Scleral hydration levels were obtained on 20 more scleral specimens. Additional groups of scleral specimens were treated with either a cryotherapy probe, a transscleral diode laser retinopexy probe, or partial thickness lamellar dissection, and specimens were mounted in the Ussing chambers for testing. Scleral tissue was digested to measure the amount of radioactivity present. Scleral sections were examined with electron microscopy. RESULTS: Scleral hydration was maintained during the perfusion. The mean scleral permeability (cm/second x 10(-6) +/- SD) was established for each of the above compounds. Age, cryotherapy, or diode laser treatment did not alter permeability or ultrastructure of the sclera. Surgical thinning significantly increased the scleral permeability to dexamethasone (P = 0.011) and methotrexate (P = 0.037). CONCLUSION: This study establishes baseline human scleral permeability to a series of hydrophilic compounds with various molecular weights. Age, cryotherapy, and diode laser treatment do not alter the permeability or ultrastructure of the sclera, whereas surgical thinning significantly increases permeability.

Adolescent↗
PubMed1994

Linear endotheliitis.

We treated six eyes of five patients with linear endotheliitis. This entity appears clinically as a line of keratic precipitates on the corneal endothelium that progresses centrally and is accompanied by peripheral stromal and epithelial edema. All five patients had ocular pain, redness, and photophobia. One eye had an episode of a dendritic lesion typical of herpes simplex. Two eyes had a history of cataract extraction before developing linear endotheliitis. We treated all patients aggressively with a combination of corticosteroids and antiviral agents. Complete resolution of inflammation and edema occurred in all cases. Four patients required the use of oral acyclovir to control the inflammation and prevent recurrence of the disease. Linear endothelitis is a distinct form of endotheliitis that may be associated with herpes simplex virus, and treatment included corticosteroid and antiviral therapy.

Acyclovir↗
PubMed1994

Rapamycin inhibits corneal allograft rejection and neovascularization.

OBJECTIVE: To investigate the immunosuppressive effect of rapamycin in prolonging allograft survival in the rat model of orthotopic allogeneic penetrating keratoplasty. DESIGN: Thirty inbred Lewis rats received corneal allografts from Brown Norway donors. Animals were divided into two rapamycin treatment groups and one allogeneic control group. RESULTS: By the second week after surgery, all of the control animals had experienced allograft failure due to allograft rejection. However, allografts in seven of 10 animals in the low-dose treatment group and allografts in seven of nine animals in the high-dose treatment group remained clear. In addition, corneal neovascularization was markedly reduced in the treated animals. CONCLUSIONS: The systemic administration of rapamycin prolongs corneal allograft survival and significantly inhibits the neovascular component of rejection in the rat model of orthotopic allogeneic penetrating keratoplasty.

Animals↗
PubMed1994

Suppression of graft rejection using 15-deoxyspergualin in the allogeneic rat penetrating keratoplasty model.

We tested the ability of 15-deoxyspergualin (DSG), a new immunosuppressant, to inhibit corneal allograft rejection in the rat penetrating keratoplasty model. Fifty-six inbred Lewis rats were recipients of orthotopic corneal allografts from Brown Norway rats. Allogeneic groups received daily intramuscular injections of DSG 2, 3, 4, or 10 mg/kg/day. The animals treated with 2 mg/kg/day had four out of 10 grafts rejected; in the 3 mg/kg/day group none of the six grafts rejected; whereas in the 4 mg/kg/day group one out of 15 grafts rejected. The animals treated with 10 mg/kg/day became emaciated and died during the second and third postoperative weeks with relatively clear grafts. All corneas rejected following discontinuation of the drug. We conclude that the systemic administration of DSG at 3 or 4 mg/kg/day results in effective suppression of corneal allograft rejection in the rat penetrating keratoplasty model.

Animals↗
PubMed1994

Kinetics of corneal transplant rejection in the rat penetrating keratoplasty model.

Kinetic changes of inflammatory cells and major histocompatibility (MHC) antigenic markers in syngeneic and allogeneic corneal grafts in rats were studied. Syngeneic grafts demonstrated mild inflammation in the first week with macrophages and T-helper/inducer cells found in a 2:1 ratio. By week 2 fewer macrophages were seen, and by week 4 no inflammatory cells were seen in the central graft. Central keratocytes and endothelium were negative for class II MHC expression. Significant inflammation persisted adjacent to the wound with macrophages and T-helper/inducer cells seen surrounding the sutures. Allogeneic grafts in the first week demonstrated mild inflammation with macrophages and T-helper/inducer cells in a 2:1 ratio. The central graft in week 2 had increased numbers of T-helper/inducer cells and T-suppressor/cytotoxic cells. By the third and fourth week, the T-suppressor/cytotoxic cells had become the major infiltrating cell. MHC class II antigens were seen on inflammatory cells, keratocytes, donor, and recipient endothelium.

Animals↗
PubMed1993

Topical cyclosporin A in the treatment of anterior segment inflammatory disease.

Topical cyclosporin A was used in the management of 43 patients with a variety of anterior segment inflammatory disorders that had failed corticosteroid treatment. Treatment with topical cyclosporin A ranged from 1 week to 43 months, with a mean treatment period of 13 months. Thirty-five patients (81%) with disorders including high-risk keratoplasty, atopic and vernal keratoconjunctivitis, ligneous conjunctivitis, ulcerative keratitis, and Mooren's ulcer had a beneficial result, with resolution, reduction, or prevention of inflammation. Six patients (14%) with scleritis, ocular cicatricial pemphigoid, or endothelitis showed no clinical improvement. Two patients (5%) had significant ocular discomfort, and the drug had to be discontinued in them. None of the other patients developed local side effects. Twenty-seven of these patients were followed with serial cyclosporin A blood levels and serum creatinine. None of these patients developed measurable drug blood levels or renal toxicity.

Administration, Topical↗
PubMed1976

A technique for open reduction of subcondylar fractures.

Described is a safe and efficient technique for open reduction of the subcondylar fracture. The technique utilizes a Risdon incision to expose the fracture site and a stab incision in the preauricular region. A University of Tennessee drill guide or bone screw is introduced through the stab incision to facilitate placement of drill holes in the fragments, threading of the transosseous wires, and repositioning of the condyle within the fossa.

Fracture Fixation↗
PubMedDate not supplied

Predicting visual acuity in children with colobomas involving the optic nerve.

BACKGROUND: This study evaluates the relationship to visual acuity of four ophthalmoscopic features of colobomas involving the optic nerve. The goal was to identify those features that could predict potential visual acuity of children with these colobomas. METHODS: Fundus photographs of 23 eyes with colobomas involving the optic nerve met the entry criteria and were evaluated by two masked observers. The following features were evaluated: coloboma size, optic nerve color, foveal development, and subfoveal retinal pigment epithelial changes. Simple linear regression was used to identify the feature that most closely correlated with visual acuity. Refractive status was assessed by cycloplegic refraction. RESULTS: The only component that correlated with the development of good visual acuity was the degree of foveal involvement by the optic nerve coloboma (P = .002, R = 0.8). Significant refractive error and anisometropia were common in patients with colobomas involving the optic nerve. CONCLUSION: Central visual acuity in children born with colobomas involving the optic nerve correlates with the development of normal foveal anatomy, regardless of the size of the coloboma, the color of the optic nerve, or the presence of subfoveal pigmentary changes. Because refractive error is common, these children should receive an accurate refraction and amblyopia treatment.

Child, Preschool↗