Linezolid-associated toxic optic neuropathy.

The oxazolidinone antimicrobial linezolid is effective against gram-positive bacteria. Although maximal recommended therapy is 28 days, treatment durations greater than this are common. Linezolid may cause reversible optic neuropathy and irreversible peripheral neuropathy after months of treatment. Three cases of linezolid-induced optic and peripheral neuropathy are described, and previously reported cases of linezolid-induced optic neuropathy are reviewed. The mechanism of neural toxicity may be impairment of mitochondrial protein synthesis.

Real-time optical coherence tomography of the anterior segment at 1310 nm.

BACKGROUND: Recent advances in high-speed scanning technology have enabled a new generation of optical coherence tomographic (OCT) systems to perform imaging at video rate. Here, a handheld OCT probe capable of imaging the anterior segment of the eye at high frame rates is demonstrated for the first time. OBJECTIVE: To demonstrate real-time OCT imaging of anterior segment structures. DESIGN: Survey of anterior segment structures in normal human subjects. SETTING: Laboratory. MAIN OUTCOME MEASURES: Achieving real-time imaging of the anterior segment, satisfactory image quality, and convenience of a handheld probe. RESULTS: Optical coherence tomographic imaging of the anterior segment of the eyes of human subjects was performed using 1310-nm wavelength light with an image rate of 8 frames per second. Imaging trials demonstrated clear resolution of corneal epithelium and stroma, sclerocorneal junction, sclera, iris pigment epithelium and stroma, and anterior lens capsule. The anterior chamber angle was clearly visualized. Limited imaging of the ciliary body was performed. Real-time imaging of pupillary constriction in response to light stimulus was also performed. CONCLUSION: High-speed OCT at 1310-nm wavelength is a potentially useful technique for noninvasive assessment of anterior segment structures. CLINICAL RELEVANCE: Our results suggest that real-time OCT has potential applications in glaucoma evaluation and refractive surgery.

Tears contain the complement regulator CD59 as well as decay-accelerating factor (DAF).

Previous studies have shown that DAF (or CD55), a cell surface inhibitor of autologous C3 activation, is present in tears and that > 90% of the C3 convertase regulatory activity in tear fluid resides in this protein (Lass JH et al., Invest Ophth Vis Sci 1990; 31:1136-48). This study investigated whether (i) the membrane cofactor protein (MCP or CD46), an additional factor that regulates C3 activation, and (ii) the membrane inhibitor of reactive lysis (MIRL or CD59), a cell surface regulator that acts to prevent formation of the membrane attack complex, are also present in tears, and if so, are functional. Two-site immunoradiometric assays showed that MCP is present in tears at low levels (42 + 8 ng/ml, n = 8) while CD59 is present at levels (222 + 78 ng/ml, n = 14) comparable to those of DAF (325 + 289 ng/ml, n = 12). The concentrations of CD59 (i) were increased two-fold or more in closed eye tears, and (ii) were decreased in reflex tears. Western blotting showed that CD59 protein in tears migrates with an apparent mol. wt similar to membrane CD59 protein. Phenyl-Sepharose adsorption and Triton X-114 partitioning of tear CD59 as well as of tear DAF however, showed that both proteins are devoid of GPI anchors. Assays using cobra venom factor-activated human serum and guinea pig erythrocytes showed that CD59 is functionally active in inhibiting autologous C5b-9-mediated lysis and, under constitutive conditions, accounts for > 85% of the C9 inhibitory activity in tear fluid.

Blockage of complement regulators in the conjunctiva and within the eye leads to massive inflammation and iritis.

The open environment of the eye is continuously subject to an influx of foreign agents that can activate complement. Decay-accelerating factor (DAF), membrane cofactor protein (MCP) and CD59 are regulators that protect self-cells from autologous complement activation on their surfaces. They are expressed in the eye at unusually high levels but their physiological importance in this site is unstudied. In the rat, a structural analogue termed 5I2 antigen (5I2 Ag) has actions overlapping DAF and MCP. In this investigation, we injected F(ab')2 fragments of 5I2 mAb into the conjunctiva and aqueous humor, in the latter case with and without concomitant blockage of CD59. Massive neutrophilic infiltration of the stroma and iris resulted upon blocking 5I2 Ag activity. Frank necrosis of the iris occurred upon concomitant intraocular blockage of CD59. C3b was identified immunohistochemically, and minimal effects were seen in complement-depleted animals and in those treated with non-relevant antibody. The finding that blockage of 5I2 Ag function in periocular tissues and within the eye causes intense conjunctival inflammation and iritis demonstrates the importance of intrinsic complement regulators in protecting ocular tissues from spontaneous or bystander attack by autologous complement.

Upregulation of DAF (CD55) on orbital fibroblasts by cytokines. Differential effects of TNF-beta and TNF-alpha.

PURPOSE: Decay accelerating factor (DAF) and membrane cofactor protein (MCP) are membrane complement regulators that protect self cells from deposition of autologous C3b on their surfaces. CD59, a third downstream regulator of the cascade, prevents the assembly on self cells of autologous membrane-attack complexes. All three proteins are highly expressed on corneal and conjunctival epithelia, and are present in lower levels on multiple intraocular and adnexal cell types. The purpose of this study was to determine whether, and if so, how DAF, MCP and CD59 expression by ocular and adnexyl cells is modulated by cytokines. METHODS: Primary cultures of orbital fibroblasts and corneal epithelial cells were incubated with TNF-alpha, TNF-beta, TGF-beta1, IFN-gamma, MIF or blocking anti-MIF mABs and extracts of the cells quantitated for DAF, MCP and CD59 by two-site immunoradiometric assays. Where inductions occurred, the kinetics of the increases, the effect of combining cytokines, and the effect of protein kinase-C inhibition were studied. RESULTS: DAF expression on orbital fibroblasts was upregulated 6.3-, 3.7- and 4.2-fold by TGF-beta1, TNF-beta and IFN-gamma, respectively, but that its expression on corneal epithelial cells was minimally affected. These same (or other) cytokines did not significantly upregulate MCP or CD59. The cytokine-induced upregulation of DAF expression on orbital fibroblasts requires 24 hr for IFN-gamma or 48 hr for TGF-beta1 or TNF-beta, is dependent on new protein synthesis, and does not involve protein kinase-C activation. CONCLUSIONS: TGF-beta1-, TNF-beta- and IFN-gamma-mediated upregulation of DAF should serve to prevent complement-mediated injury to orbital fibroblasts in the course of ocular inflammation. The induction by TNF-beta rather than TNF-alpha contrasts with that on all other cell types studied.

Long-term follow-up of giant nodular posterior scleritis simulating choroidal melanoma.

A 41-year-old asymptomatic woman was referred for enucleation of a 7. 5-mm-thick intraocular tumor suspected to be choroidal melanoma. The clinical findings combined with imaging studies suggested instead a diagnosis of giant nodular posterior scleritis. A scleral biopsy was performed to confirm the diagnosis. After 12 years of observation, the lesion has remained stable and visual acuity has been preserved. Nodular posterior scleritis can present with no symptoms of pain, redness, or visual disturbance and can remain quiet for many years. It must be clinically differentiated from choroidal melanoma. Arch Ophthalmol. 2000;118:1290-1292

Release of complement regulatory proteins from ocular surface cells in infections.

PURPOSE: The decay accelerating factor (DAF or CD55) and the membrane inhibitor of reactive lysis (MIRL or CD59), two complement regulatory proteins that protect self cells from autologous complement-mediated injury, are attached to corneal and cqonjunctival epithelial cells by glycosylphos-phatidylinositol (GPI) anchors. We sought to 1) determine the frequency with which bacteria recovered from patients with infections of the eye elaborate factors that can remove these surface proteins from ocular cells, 2) determine the spectrum of bacteria from other sites that have similar effects, and 3) establish the time interval required for reconstitution of the two regulators. METHODS: Culture supernatants of 18 ocular isolates [P. aeruginosa (n = 3), S. marcescens (n = 1), S. epidermidis (n = 9), and S. aureus (n = 5)], and > 100 other clinical specimens isolated in the hospital's microbiology laboratory [P. mirabilis (n = 1), S. aureus (n = 65), S. epidermidis (n = 24), B. cereus (n = 12), H. influenzae (n = 15), and Enterobacter sp. (n = 21)] were incubated at 37 degrees C for various times with conjunctival epithelial cells, conjunctival fibroblasts or HeLa cells and the release of DAF and CD59 proteins from the surfaces of the cells analyzed by 2-site immunoradiometric assays and by Western blotting. The kinetics of recovery of DAF and CD59 expression on the cells was measured by flow cytometry. RESULTS: DAF and/or CD59 release from the cell monolayers varied from < 5% to > 99% at as much as a 1:81 dilution of the supernatant from some bacteria. On conjunctival epithelial cells, more than 8 hr was required for 44% recovery of DAF expression and for 50% recovery of CD59 expression. CONCLUSIONS: Bacteria produce phospholipases and/or other enzymes which can efficiently remove DAF and CD59 from ocular cell surfaces. This phenomenon may correlate with their in vivo pathogenicity.

Cell surface regulators of complement, 5I2 antigen, and CD59, in the rat eye and adnexal tissues.

PURPOSE: Cell surface complement regulatory proteins have been identified in high levels in ocular tissues, but no experimental model is available for examining their physiological roles. To develop such a model, the distribution of 5I2 antigen, a protein possessing the functions of the human decay-accelerating factor (DAF [CD55]) and membrane cofactor protein (MCP [CD46]), and rat inhibitory protein (CD59), the homologue of the human membrane inhibitor of reactive lysis (MIRL[CD59]) were characterized in the rat eye and ocular adnexal structures. METHODS: After euthanasia of female Wistar rats, followed by orbital exenteration, eyelids and orbital tissue including the lacrimal gland were separated from the globes and immediately snap-frozen in liquid nitrogen at -70 degrees C. Tissues then were sectioned at -20 degrees C and examined immunohistochemically for 5I2 antigen and rat CD59. RESULTS: Both molecules were found to be present in high levels in multiple sites. Corneal and conjunctival epithelia showed moderate to intense labeling for both regulators. Fibroblasts in the corneal stroma, conjunctiva, and sclera labeled similarly. Corneal endothelial cells showed intense labeling for rat CD59 but not for 5I2 antigen. The iris and ciliary body showed intense labeling for both proteins. The retina showed labeling at multiple levels, with that of rat CD59 being more intense than that of 5I2 antigen. The lacrimal gland labeled for both regulators. Vessels, muscle, and nerves in the orbit labeled intensely for both antigens. In the eyelid, conjunctiva, sebaceous glands, and muscle and nerve tissues labeled moderately to intensely for both molecules, whereas skin epithelium labeled less intensely. CONCLUSIONS: 5I2 antigen and rat CD59 are expressed in high levels and distributed similarly in the rat eye and lacrimal gland to DAF, MCP, and MIRL in the human eye and lacrimal gland. These findings establish the rat ocular surface as a model for studying the role of cell surface complement regulators in this site. This first identification of copious expression of these proteins in eyelid structures, which also participate in protection of the ocular surface, further suggests an important role for surface complement regulatory proteins in this location.

The role of eosinophils and neutrophils in helminth-induced keratitis.

PURPOSE: Intrastromal injection of mice with antigens from the parasitic helminth that causes river blindness (Onchocerca volvulus) induces eosinophil recruitment to the corneal stroma at the time of maximum corneal opacification and neovascularization. The present study was conducted to examine the role of eosinophils and neutrophils in onchocercal keratitis in control C57Bl/6 mice and in interleukin-5 gene knockout (IL-5(-/-)) mice. METHODS: C57Bl/6 and IL-5(-/-) mice were immunized subcutaneously and injected intrastromally with soluble O. volvulus antigens. Mice were killed at various times thereafter. Development of keratitis was assessed by slit lamp examination, and inflammatory cells in the cornea were identified by immunohistochemistry. RESULTS: A biphasic recruitment of inflammatory cells was observed in C57Bl/6 mice; neutrophils predominated during the first 72 hours after intrastromal injection and subsequently declined, whereas eosinophil recruitment increased as time elapsed and comprised the majority (90%) of cells in the cornea by day 7. In contrast, neutrophils were the predominant inflammatory cells in IL-5(-/-) mice at early and late time points and were associated with extensive stromal damage and corneal opacification and neovascularization. Eosinophils were not detected in these mice at any time. CONCLUSIONS: In the absence of eosinophils, neutrophils can mediate keratitis induced by helminth antigens. Together with the early neutrophilic infiltrate in control animals, these observations indicate that neutrophils have an important role in onchocercal keratitis.

Pleomorphism of stromal eosinophils in murine experimental onchocercal keratitis.

Onchocercal keratitis (river blindness) is one of the leading worldwide causes of blindness. Light microscopic analysis of human specimens and corneal tissue from experimental models has implicated the eosinophil as an important cell in the inflammatory response. Our previous studies in experimental murine onchocercal keratitis have demonstrated that the inflammatory infiltrate is composed primarily of eosinophils displaying ring shaped or bilobed nuclei. However, a number of cells were not characterizable by light microscopy, presumably due to mechanical distortion. To more fully characterize the inflammatory cell infiltrate, we examined corneal specimens by transmission electron microscopy. In addition to typical eosinophils with bilobed and ring shaped nuclei, this approach revealed cells with variable nuclear morphology and cell shape which contained the dense cored granules characteristic of eosinophils. Hence, the degree of pleomorphism of eosinophils is broader than appreciated and underscores the importance of this cell in experimental murine onchocercal keratitis.

IL-12 exacerbates helminth-mediated corneal pathology by augmenting inflammatory cell recruitment and chemokine expression.

Corneal inflammation (keratitis) is a major cause of visual impairment in Onchocerca volvulus infection. Previous studies showed that onchocercal keratitis can be induced in mice following s.c. immunization and intracorneal injection with soluble O. volvulus Ags (OvAg), and that the inflammatory response is dependent on T cells and IL-4. Since recombinant IL-12 impairs IL-4-dependent, Th2-mediated responses in other parasitic infections and in models of allergic asthma, the present study was undertaken to determine the effect of IL-12 on onchocercal keratitis. Mice were injected i.p. with IL-12 or saline at the time of initial sensitization to OvAg. Surprisingly, IL-12 treatment caused significant exacerbation of corneal pathology, which was associated with increased eosinophil and mononuclear cell infiltration into the corneal stroma. Consistent with the well-documented effect of IL-12 on Th1 cell development, corneas of IL-12-treated animals had elevated expression of the Th1 cytokine IFN-gamma and diminished expression of the Th2 cytokines IL-4, IL-5, IL-10, and IL-13. However, corneas from these animals also had marked elevation of alpha- and beta-chemokines known to be active on eosinophils and mononuclear cells, including IFN-gamma-inducible protein (IP)-10, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, JE/monocyte chemotactic protein-1, RANTES (regulated upon activation, normal T expressed and secreted), and eotaxin. Together, these data indicate that IL-12 exacerbates OvAg-mediated corneal pathology by enhancing chemokine expression and recruitment of inflammatory cells.

Detection of complement regulatory proteins on soft contact lenses.

PURPOSE: To determine whether the regulators of complement activation, decay-accelerating factor (DAF) and CD59, which have been identified on the cornea and conjunctiva and in soluble forms in tears and lacrimal secretions, are transferred to soft contact lenses worn by normal subjects. METHODS: Following overnight wear of group 4 extended-wear hydrophilic contact lenses by five normal subjects, we examined the lenses immunohistochemically for decay-accelerating factor (DAF) and CD59, two regulators which interfere with the complement cascade at the C3 and C9 steps, respectively. RESULTS: Both proteins were detected on all worn lenses but not on controls. CONCLUSIONS: These findings raise the question of whether these proteins, as do other contact lens-bound proteins, have deleterious effects, or to the contrary, if they maintain their natural activity, might they have protective functions for contact lens wearers.

Onchocerca volvulus-mediated keratitis: cytokine production by IL-4-deficient mice.

Corneal inflammation similar to human onchocercal keratitis can be induced in mice by subcutaneous immunization of a soluble extract of Onchocerca volvulus (OvAg) followed by direct injection of OvAg into the corneal stroma. Previous studies have shown that corneal pathology is associated with increased systemic and corneal Th2 cytokine expression and that IL-4 gene knockout (IL-4-/-) mice develop less severe or no O. volvulus-mediated keratitis. The current study examined the contribution of Th2 cytokines to the diminished OvAg-induced corneal immunopathology observed in IL-4-/- mice. IL-4-/- mice (129Sv x C57B1/6), wild-type F2 littermates (IL-4+/+), and C57B1/6 mice were sensitized by repeated subcutaneous immunization with OvAg. Ten days after the final immunization, mice were sacrificed, spleens were removed, and cells were incubated with OvAg. Cells from immunocompetent C57B1/6 and IL-4+/+ mice produced IL-4 and IL-5, but no IFN-gamma, whereas cells from IL-4-/- mice had elevated IFN-gamma and no IL-4. Interestingly, cells from these animals produced levels of IL-5 protein equivalent to those of C57B1/6 and IL-4+/+ mice. To determine cytokine production in corneas during the onset of onchocercal keratitis, OvAg-immunized mice were injected intracorneally with OvAg, and cytokine gene expression in the cornea was determined by RT-PCR. Temporal analysis of cytokine gene expression in corneas of immunocompetent mice showed that the Th2-associated cytokines IL-4, IL-5, IL-10, and IL-13 were produced within 1 day of intrastromal injection, with sustained elevations for 10 days. Maximal IFN-gamma mRNA levels were not detected until Day 10. This was in contrast to IL-4-/- mice in which IFN-gamma appeared at Day 1 and remained elevated for at least 10 days. Moreover, in corneas from IL-4-/- mice, all Th2 cytokines with the exception of IL-4 were up-regulated and expressed with kinetics similar to that of IL-4+/+ littermates. Histologically, corneas from IL-4-/- mice were less edematous and contained fewer eosinophils and other inflammatory cells than those from immunocompetent controls. As there was no difference in peripheral eosinophil levels, these data indicate that the diminished severity of onchocercal keratitis in IL-4-/- mice is not due to failure to develop systemic or local Th2 cytokine responses or to produce eosinophils, but that IL-4 may be involved in recruitment of eosinophils and other inflammatory cells into the corneal stroma.

Severe acute graft-versus-host disease of conjunctivae after allogeneic blood progenitor cell infusion.

A 37-year-old woman with Philadelphia chromosome-positive acute lymphoblastic leukemia received allogeneic bone marrow transplants after first and second relapses from different HLA-identical brothers. After a third relapse, blood progenitor cells from one of the brothers were infused after six doses of cytarabine 1.5 g/m2 in an attempt to induce a graft-versus-leukemia effect. Seven weeks after the infusion, the patient developed delayed but severe acute graft-versus-host disease (GVHD) including the unusual manifestation of conjunctival involvement.

Interleukin 4 and T helper type 2 cells are required for development of experimental onchocercal keratitis (river blindness).

Inflammation of the corneal stroma (stromal keratitis) is a serious complication of infection with the nematode parasite Onchocerca volvulus. Because stromal keratitis is believed to be immunologically mediated in humans, we used a murine model to examine the role of T cells and T helper cell cytokines in the immunopathogenesis of these eye lesions. BALB/c mice immunized subcutaneously and injected intrastromally with soluble O. volvulus antigens (OvAg) developed pronounced corneal opacification and neovascularization. The corneal stroma was edematous and contained numerous eosinophils and mononuclear cells. Stromal keratitis in immunized mice was determined to be T cell dependent based on the following observations: (a) T cell-deficient nude mice immunized and injected intrastromally with OvAg fail to develop corneal pathology; and (b) adoptive transfer of spleen cells from OvAg-immunized BALB/c mice to naive nude mice before intrastromal injection of OvAg results in development of keratitis. OvAg-stimulated lymph node and spleen cell cytokine production was dependent on CD4 cells and included interleukin (IL)-4 and IL-5, but not interferon gamma, indicating a predominant T helper type 2 cell-like response. Inflamed corneas from immunized BALB/c mice and from reconstituted nude mice had greatly elevated CD4 and IL-4 gene expression compared with interferon gamma. Mice in which the IL-4 gene was disrupted failed to develop corneal disease, demonstrating that IL-4 is essential in the immunopathogenesis of O. volvulus-mediated stromal keratitis.

Hyperfocal cryotherapy of multiple Molluscum contagiosum lesions in patients with the acquired immune deficiency syndrome.

BACKGROUND: Patients with the acquired immune deficiency syndrome are at risk for the development of multiple lesions of Molluscum contagiosum on the eyelids. In this setting, traditional methods of treatment frequently are ineffective and pose risks to the patient as well as to the treating physician. METHODS: A technique was developed that combined lidocaine/prilocaine topical anesthesia with hyperfocal cryotherapy. Twelve patients with multiple M. contagiosum lesions of the eyelids were treated. Initially, two methods were used: one application for 30 seconds or two applications for 20 seconds. RESULTS: Lesions treated with two 20-second applications regressed. Most of those lesions treated for 30 seconds regressed. No scarring, lash complications, ptosis, or damage to the underlying cornea or deeper ocular structures was observed in any patient. CONCLUSIONS: Hyperfocal cryotherapy is an effective therapy for multiple M. contagiosum lesions of the periorbital region, posing minimal risk to the patient and physician. It is particularly useful in patients who are positive for the human immunodeficiency virus, who frequently have multiple lesions, are likely to have recurrent disease, and who pose risks of disease transmission to the medical personnel caring for them.

Trilateral retinoblastoma: two variations.

Two cases of trilateral retinoblastoma (a syndrome of midline, undifferentiated, intracranial tumor in a child with hereditary, bilateral ocular retinoblastoma) are described, one with a unique location of the intracranial tumor, and the other with an unusual temporal course of disease.

Localization of the complement membrane attack complex inhibitor (CD59) in human conjunctiva and lacrimal gland.

Recent studies have established that complement is present in the eye and participates in ocular defense. The mechanisms by which ocular tissues are protected from bystander injury arising from local activation of the cascade, however, have not been characterized. Decay accelerating factor (DAF or CD55) and the membrane inhibitor of reactive lysis (MIRL or CD59) are cell surface regulatory proteins that protect blood cells from uptake of autologous C3b and polymerization of autologous C9 on their surfaces. In previous studies, we found that DAF is expressed in high levels on corneal, conjunctival, and lacrimal gland acinar surfaces. In this study we assayed ocular and lacrimal gland tissues for CD59. Immunohistochemical analyses demonstrated large amounts of the protein the same locations. The presence of CD59 in these sites is consistent with the proposal that CD59 functions together with DAF in protecting ocular tissues from autologous complement-mediated injury.

Systematized epidermal nevi: case report and review of clinical manifestations.

A 19-year-old woman developed papillary and pigmentary changes of the skin over her entire body with extensive eyelid involvement causing trichiasis. A four-lid blepharoplasty with rotation of the anterior lid lamella led to resolution of the ocular symptoms and secondary cosmetic improvement. Histologic examination of the tissue demonstrated epidermal nevi which are congenital abnormalities of surface or adnexal epithelium. This patient was diagnosed with systematized epidermal nevus as described by Lever's classification. There is a high association of epidermal nevi with other systemic abnormalities; that association is known as "epidermal nevus syndrome" (ENS).

Neutrophilic eccrine hidradenitis simulating orbital cellulitis.

Orbital swelling in patients with cancer can reflect neoplastic or infectious processes. Accurate diagnosis can be especially difficult in the face of associated fever and neutropenia. We treated a 30-year-old man undergoing induction chemotherapy for acute myelogenous leukemia, who had fever of unknown origin and periorbital swelling suggestive of orbital cellulitis. However, the periorbital findings were more compatible with passive swelling and hemorrhage. A skin biopsy specimen demonstrated isolated neutrophilic inflammation and necrosis of the eccrine glands. Cultures of the tissue for bacteria and fungi were negative. Pertinent literature regarding eccrine-gland inflammatory disease was reviewed. This unusual entity, termed neutrophilic eccrine hidradenitis, is most common in patients undergoing induction chemotherapy. Cases with infectious causes and cases in neutropenic patients have also been reported. No other patients, to our knowledge, with periocular involvement by neutrophilic eccrine hidradenitis have been described. Neutrophilic eccrine hidradenitis should be added to the differential diagnosis of cases of periocular hemorrhage and swelling in patients with cancer who receive chemotherapy.