Faculty Bibliography

Electronic energy transfer plays an important role in many types of organic electronic devices. Forster-type theories of exciton diffusion provide a way to calculate diffusion constants and lengths, but their applicability to amorphous polymer systems must be evaluated. In this paper, the perylenediimide dye Lumogen Red in a poly(methyl methacrylate) host matrix is used to test theories of exciton motion over Lumogen Red concentrations (C(LR)'s) ranging from 1 x 10(-4) to 5 x 10(-2) M. Two experimental quantities are measured. First, time-resolved anisotropy decays in films containing only Lumogen Red provide an estimate of the initial energy transfer rate from the photoexcited molecule. Second, the Lumogen Red lifetime decays in mixed systems where the dyes Malachite Green and Rhodamine 700 act as energy acceptors are measured to estimate the diffusive quenching of the exciton. From the anisotropy measurements, it is found that theory accurately predicts both the C(LR)(-2) concentration dependence of the polarization decay time tau(pol), as well as its magnitude to within 30%. The theory also predicts that the diffusive quenching rate is proportional to C(LR)(alpha), where alpha ranges between 1.00 and 1.33. Experimentally, it is found that alpha = 1.1 +/- 0.2 when Malachite Green is used as an acceptor, and alpha = 1.2 +/- 0.2 when Rhodamine 700 is the acceptor. On the basis of the theory that correctly describes the anisotropy data, the exciton diffusion constant is projected to be 4-9 nm(2)/ns. By use of several different analysis methods for the quenching data, the experimental diffusion constant is found to be in the range of 0.32-1.20 nm(2)/ns. Thus the theory successfully describes the early time anisotropy data but fails to quantitatively describe the quenching experiments which are sensitive to motion on longer time scales. The data are consistent with the idea that orientational and energetic disorder leads to a time-dependent exciton migration rate, suggesting that simple diffusion models cannot accurately describe exciton motion within this system.

OBJECTIVE:To evaluate the role of immunohistochemical methods in the diagnosis of benign and malignant conjunctival melanocytic proliferations. DESIGN/METHODS:Retrospective immunohistopathologic study. METHODS:Paraffin-embedded tissue sections from 20 conjunctival nevi and 15 invasive melanomas were immunoreacted with antibodies against cellular antigens S-100 protein, MART-1, HMB-45, CD-45, and Ki-67 nuclear proliferation protein. RESULTS:All nevi immunostained moderately to strongly for S-100 protein and MART-1. Results for HMB-45 were negative in the middle and lower subepithelial portions of 18 of 20 lesions; it was usually only weakly positive within the superficial junctional zone. Only 1 melanoma did not stain positively for S-100; MART-1 and HMB-45 were positive in all lesions at some level of intensity. Ki-67 positivity was restricted to the junctional zone of nevi and was diffuse in melanomas. The mean Ki-67 proliferation indices were 1.89% for the nevi and 17.3% for the melanomas. CD-45 can help to highlight lymphocytes that immunostain with Ki-67. Melanomas in situ and atypical primary acquired melanoses had more than twice the Ki-67 proliferation counts of intraepithelial junctional nevocytes (P < .001) and more intense HMB-45 cytoplasmic staining than junctional zone nevocytes. CONCLUSIONS:S-100 and MART-1 were not useful in separating benign from malignant lesions. Results for nevus cells beneath the junctional zone were overwhelmingly negative for HMB-45 and Ki-67. Two nevi and all melanomatous nodules were positive for HMB-45 (P < .001). A higher Ki-67 proliferation index convincingly separated melanomas from nevi (P < .001). Immunostaining for HMB-45 and Ki-67 are valuable adjuncts to careful histopathologic evaluation in assessing benign and malignant conjunctival melanocytic tumors.

PURPOSE/OBJECTIVE:To describe a case of conjunctival malignant melanoma (MM) arising from primary acquired melanosis in a patient with neurofibromatosis type 1 (NF-1). METHODS:Case report and literature review. RESULTS:A 66-year-old woman with a history of NF-1 presented with extensive pigmentation of the left bulbar conjunctiva. Conjunctival biopsies demonstrated MM arising from primary acquired melanosis with atypia. Two excision and cryotherapy procedures did not completely eradicate the conjunctival pigment, which was then treated with topical mitomycin C. Subsequent biopsies and clinical examinations have revealed no remaining tumor. CONCLUSION/CONCLUSIONS:Conjunctival MM is uncommon in patients with NF-1 and can be successfully treated with excision, cryotherapy, and topical mitomycin C.

PURPOSE/OBJECTIVE:The purpose of this study was to report a case of Phomopsis fungal keratitis that was diagnosed 2 months after a rose thorn injury that occurred while gardening. METHODS:The authors conducted a retrospective case report with literature review. RESULTS:Deep stromal keratitis with extension of hyphae through Descemet's membrane was treated by therapeutic keratoplasty combined with oral and topical antifungal medications. The causative organism, a Phomopsis species, was identified by culture of the surgical specimens. Phomopsis, a plant fungus, has not been previously reported as a cause of human fungal keratitis. One year after the initial surgery, visual rehabilitation was accomplished with a repeat cornea transplant and cataract extraction with return of vision to 20/25. CONCLUSIONS:Advanced fungal keratitis can be successfully treated by a combination of surgery to debulk the infectious organisms and pre- and postoperative medical therapy. Prompt recognition of fungal keratitis will increase the likelihood of cure. Phomopsis species, ubiquitous plant fungi, can cause infectious keratitis in humans.

OBJECTIVE:To evaluate with immunohistochemical methods 5 atypical melanocytic conjunctival lesions. METHODS:This was a retrospective clinicoimmunopathologic study. Routine histochemical staining was performed with multiparametric immunohistochemical analysis with monoclonal antibodies immunoreacted on paraffin sections to identify the following cell antigens: S-100, MART-1, HMB-45, CD45, CD68, CD1a, lysozyme, and Ki-67 (nuclear proliferation protein). RESULTS:A unique granular cell nevus contained periodic acid-Schiff-positive, diastase-resistant granules and immunoreacted with monoclonal antibodies against S-100 protein and melanocytic-associated antigens MART-1 and HMB-45. Results for CD45, CD1a, CD68, and lysozyme immunostaining of the granular cells were negative. Two epithelioid cell (clonal or inverted) nevi exhibited an identical immunohistochemical profile. Only the balloon cell nevus was MART-1-positive and HMB-45-negative. The granular cell and blue nevi immunoreacted negligibly with Ki-67 (approximately 1% of cells). CONCLUSIONS:S100 and MART-1 reliably immunostained all nevocytic morphologic variants. HMB-45 immunoreactivity of the granular, epithelioid/clonal, and blue nevi did not indicate a more active or proliferative lesion but instead suggested abnormal melanogenesis. Ki-67 was the most valuable immunohistochemical adjunct to morphology for the diagnosis of these benign variant conjunctival nevi, because melanomas display a much higher proliferation index (>10% nuclear positivity among all cells counted) than the current nevi (approximately 1%).

PURPOSE/OBJECTIVE:To describe changes in demographics and pathogens for fungal keratitis cases diagnosed at the Massachusetts Eye and Ear Infirmary. METHODS:Patient demographics, clinical and laboratory findings, treatment and outcomes of 46 cases of culture-proven fungal keratitis diagnosed from January 2004 through November 2007 were compared with 23 cases of fungal keratitis previously collected over a similar period from January 1999 through November 2002. RESULTS:During 2004-2007, the rate of fungal keratitis was 1.0 cases per month, an increase from the baseline rate of 0.5 cases per month during 1999-2002. The proportion of cases caused by filamentous fungi increased from 30% (1999-2002) to 65% (2004-2007) (P = 0.01). Soft contact lens wear accounted for 41% of fungal keratitis cases in 2004-2007, as compared with 17% in 1999-2002. The majority of patients (70%) received oral antifungal treatment in addition to topical amphotericin B and natamycin. Seventeen patients (40%) required therapeutic keratoplasty. Patients with a history of corneal transplant had the highest rate of therapeutic keratoplasties (67%) and had the poorest visual outcome (40% counting fingers or less). In the contact lens group, 94% of patients maintained vision of at least 20/40 and only 12% required surgery to control the infection. CONCLUSIONS:There has been an increase in fungal keratitis in the Boston area and a change in the causative pathogens and risk factors for infection. Filamentous fungi now account for the majority of fungal keratitis cases, whereas yeasts were the predominant pathogen in the past. Soft contact lens wear is currently the most common risk factor for development of fungal keratitis.