The corneal epithelium: clinical relevance of cytokine-mediated responses to maintenance of corneal health: [review] / O epitélio da córnea: relevância clínica das respostas mediadas por citocinas para manter a saúde da córnea: [revisão]

We review the growth factor receptor-mediated cell signaling events that induce the responses required for the maintenance of corneal epithelial health. Our focus is to show how such responses contribute to sustaining corneal transparency and deturgescence, so basic to the pathogenesis of corneal diseases. Furthermore, we point out how alterations of receptor-mediated control of these responses account for losses in corneal transparency. In particular, the roles of growth factors in the mediation of normal corneal function, including epithelial cell proliferation, prevention of compromise of the barrier function of the cornea, and maintenance of normal renewal processes are discussed in relation to clinical entities involving the cornea.

Revimos os eventos de sinalização celular mediados por receptores de fatores de crescimento, usados para manter a saúde do epitélio da córnea. O objetivo é mostrar como essas respostas contribuem para manter a transparência e a deturgescência da córnea, críticos na patogênese das doenças da córnea. Mais ainda, enfatizamos como alterações no controle mediado por receptor dessas respostas contribuem na transparência da córnea. Especificamente, o papel dos fatores de crescimento na mediação do controle funcional normal da córnea, incluindo proliferação epitelial, prevenção da quebra da função de barreira, manutenção do processo de renovação são discutidos em relação às entidades clínicas envolvidas na córnea.

The corneal epithelium: clinical relevance of cytokine-mediated responses to maintenance of corneal health.

We review the growth factor receptor-mediated cell signaling events that induce the responses required for the maintenance of corneal epithelial health. Our focus is to show how such responses contribute to sustaining corneal transparency and deturgescence, so basic to the pathogenesis of corneal diseases. Furthermore, we point out how alterations of receptor-mediated control of these responses account for losses in corneal transparency. In particular, the roles of growth factors in the mediation of normal corneal function, including epithelial cell proliferation, prevention of compromise of the barrier function of the cornea, and maintenance of normal renewal processes are discussed in relation to clinical entities involving the cornea.

The role of proliferating cell nuclear antigen (PCNA) in differentiating idiopathic orbital inflammatory disease and lymphoid proliferations.

The purpose of the present study was to determine whether proliferating cell nuclear antigen (PCNA), an immunohistochemical marker for a nuclear protein abundant in actively proliferating (dividing) cells, is useful as an aid in differentiating idiopathic orbital inflammatory syndrome (IOIS) from lymphoproliferative lesions (LLs). Records of all patients with IOIS and LLs were studied retrospectively. Tissue biopsy specimens from four patients with IOIS and nine patients with LLs were examined. The diagnosis in each case was based on presenting signs and symptoms, orbital computed tomography (CT) and/or magnetic resonance (MR) scans, histopathologic criteria, and follow-up data consistent with the entity. These findings were correlated with the percentage of B- and T-cells in the lesions as well as with the number of cells that demonstrated staining for PCNA in formalin-fixed tissue. PCNA activity was markedly increased in the higher grade (HG) lymphoma group as compared to that in the low grade (LG) lymphoma and idiopathic inflammatory group. Lymphoma cases showed a significantly increased B-/T-cell ratio compared to IOIS lesions. PCNA activity in conjunction with the ratio of B-/T-cells may be a helpful immunohistologic adjunct for differentiating purely inflammatory lesions of the orbit from lymphoid tumors. Further studies are necessary to compare PCNA activity in fresh frozen tissue with that in formalin-fixed tissue.

Conjunctival scarring after eyelid surgery as first sign of ocular cicatricial pemphigoid.

Diagnosis of ocular cicatricial pemphigoid (OCP), a chronic cicatrizing autoimmune disease of the conjunctiva, may be difficult in the early stages of the disease. We noted abnormal conjunctival scarring in three patients who had undergone eyelid and strabismus surgery, which caused us to suspect OCP. In all three patients who subsequently underwent conjunctival biopsy, immunoglobulin or complement in the basement membrane zone detected by direct immunofluorescence helped establish the diagnosis. Although OCP typically is a disease of the elderly, the three patients in this study were aged < 50 years; one patient was 19 years old. The present study demonstrates that a diagnosis of OCP should be considered for patients who develop abnormal conjunctival scarring after eyelid or strabismus surgery.

Histopathology of human keratorefractive lenticules.

Eight human corneal lenticules (three from keratophakia, two from hypermetropic keratomileusis, and three from myopic keratomileusis) were examined by light and electron microscopy. The keratophakic lenticules were removed for optical reasons 3, 3.5, and 6 months after surgery. Microscopically, all displayed hypocellularity, mature collagen fibrils and microfibrils, keratocyte ghosts, and keratocytic debris. The hypermetropic keratomileusis specimens were removed at 13 and 14 months postoperatively, the first because of opacities from enzymatic digestion of the cornea, and the second due to contact lens-induced erosion of Bowman's layer and decreased lacrimal secretion. Ultrastructurally, both lenticules exhibited fractures in Bowman's layer, and the 14-month specimen showed multilayered squamous epithelia. The myopic keratomileusis specimens were removed at 4, 8, and 48 months postoperatively due to opacification of the interface caused by delayed epithelial healing, detergent trauma, and previous epithelization, respectively. Electron microscopy revealed fractures in Bowman's layer, subepithelial fibrocellular growth, sparse keratocyte populations of the anterior stroma, porous collagen bundles, keratocytic debris, and regions of epithelial ingrowth.

The ecology of Colorado tick fever in Rocky Mountain National Park in 1974. III. Habitats supporting the virus.

Ecologic studies of small mammals in Rocky Mountain National Park (RMNP) were conducted in 1974 in order to identify the specific habitats within the Lower Montane Forest that support Colorado tick fever (CTF) virus. Data was collected on the abundance and distribution of 4 primary rodent species, tick infestation, CTF virus, and neutralizing antibody prevalence. Rodents were captured along transects crossing different habitats. Open stands of ponderosa pine and shrubs on dry, rocky surfaces were found to be important for maintaining CTF virus.

Use of split-thickness dermal graft in the surgical treatment of corneal and scleral defects.

We used split-thickness dermal grafts for the surgical treatment of corneal and scleral perforations in two patients and obtained excellent results. Patient 1 had severe lye burns and bilateral corneal perforations and Patient 2 had scleromalacia perforans. The dermal graft self-epithelializes and, thus, does not need to be covered by conjunctiva; is supple, without the bulkiness of other materials, particularly cartilage and periosteum; is hearty and flourishes on avascular surfaces such as cornea and sclera; has good tensile strength; and is autogenous.

Epibulbar choristomas containing lacrimal tissue. Clinical distinction from dermoids and histologic evidence of an origin from the palpebral lobe.

Three new cases of epibulbar choristomas, all containing lacrimal tissue, are presented and compared with those reported previously in the literature. The first and second cases were unilateral, complex choristomas, consisting of ectopic lacrimal tissue, smooth muscle, and cartilage; the first case was also remarkable for the presence of lesional tissue in the peripheral cornea and evidence of progressive growth during puberty. The third case was a bilateral, complex choristoma, manifesting epibulbar lacrimal tissue, cartilage, and smooth muscle; also associated were bilateral optic nervehead colobomas and a uniocular focus of posterior scleral cartilage demonstrated by computed tomography (CT) scanning. On clinical examination, all three lesions displayed highly vascularized thickenings of the conjunctiva with diagnostically useful gelatinous elevations, which corresponded microscopically to lobules of lacrimal tissue. In addition, all three cases had the interesting diagnostic feature of superficial corneal scarring or sclerosis, with a fine vascularity adjacent to the conjunctival lesional tissue. Electron microscopy of the third case demonstrated completely normal cytoarchitecture of the lacrimal tissue. Because of the frequent presence of Müller's smooth muscle in epibulbar lacrimal choristomas, the authors propose that these lesions represent embryologic ectopias or overly extensive field effects of the palpebral lobe of the lacrimal gland.

Ocular pathology of Fabry's disease in a hemizygous male following renal transplantation.

The ocular pathology of a hemizygous male with Fabry's disease after renal transplantation is reported. The ocular pathology in this patient was essentially identical to that which has previously been reported for both hemizygotes and heterozygotes afflicted with Fabry's disease. Glycolipid deposits and/or osmophilic inclusion bodies were found universally throughout the ocular vasculature. Endothelial, perithelial and smooth muscle cells of the vessel walls were preferentially involved. Iris pigment epithelium was affected as were the corneal epithelium cells. Reduplication of the basement membrane was seen on electron microscopy. Retinal ganglion cells were unaffected. Involvement of the retinal pigment epithelium and the corneal endothelium was documented for the first time.

Ultrastructure of the eye in fetal type II glycogenosis (Pompe's disease).

Type II glycogenosis is an autosomal recessive storage disease characterized by absence of the enzyme acid alpha-1,4-glucosidase. The eye of a 16 week fetus, aborted after diagnosis by amniocentesis, was studied by light and electron microscopy. Extensive deposits of lysosomal and cytoplasmic glycogen were present in virtually all ocular tissues examined, with the notable exception of pigment epithelia (iris and retina). The massive glycogen deposits present in this, the youngest case thus far examined histologically, emphasize the involvement of the fetus from its earliest stages and the importance of prenatal diagnosis.

The ecology of Colorado tick fever in Rocky Mountain National Park in 1974. II. Infection in small mammals.

Field studies of Colorado tick fever (CTF) in small mammals in Rocky Mountain National Park (RMNP) in 1974 established that Eutamias minimus and Spermophilus lateralis were the most important hosts for CTF virus and were the source of virus for immature stages of the tick vector, Dermacentor andersoni. Other species (Peromyscus maniculatus, Spermophilus richardsonii, Eutamias umbrinus) are secondary hosts. The intensity of viral activity in rodents varied greatly from locality to locality. Highest rodent infection rates were found to occur in the Moraine Park area of RMNP. Lowest infection rates occurred above 3,290 meters in altitude at Rainbow Curve and on the tundra. The prevalence of infection in rodents was constant from April--July (5--6% of animals captured were viremic) and then declined to 1.7--2.5% in August and September coincident with a decline in nymphal tick ectoparasitism. Many animals were captured which were simultaneously viremic and antibody-positive. Under field conditions, neutralizing antibody seroconversion does not always occur.

Experimental Colorado tick fever virus infection in Colorado mammals.

One hundred and twenty-four small mammals of six species were inoculated with three strains of Colorado tick fever (CTF) virus to define viremia and neutralizing (N) antibody responses. Adult Eutamias minimus and Eutamias embrinus, and juvenile Peromyscus maniculatus and Spermophilus lateralis, were highly susceptible to development of viremic infection. Adult S. lateralis and P. maniculatus were moderately susceptible (greater than or equal to 50% viremic). Five Sylvilagus nuttalli did not become viremic following experimental inoculation. Spermophilus richardsoni was also relatively resistant (less than or equal to 50% viremic). The longest duration of viremia (mean 15.8 days) and highest peak viremia levels (mean peak titer 10(3.9 plaque-forming units per ml) occurred in E. minimus. Adult E. umbrinus, juvenile S. lateralis, and juvenile P. maniculatus had moderate viremias. Adult S. lateralis and S. richardsoni often had short viremias during which virus was only intermittently detectable. N antibody production was most rapid in E. minimus in comparison with other species. In addition, N antibody persisted for 1 year in this species. In other species, many animals lost detectable antibody 5-11 months after infection. No significant differences were found in patterns of infection between three CTF virus strains. We conclude that of the six species inoculated, E. minimus is the best experimental host for CTF virus.

Electron microscopic observations of intravitreal Cysticercus cellulosae (Taenia solium).

Cysticercus cellulosae, the larval stage of Taenia solium, was studied by light and electron microscopy after its removal from the vitreous. The ultrastructure of the larva is highly organized and displays a superficial tegument and deeper parenchyma. The tegument contains a microvillous surface overlying a syncytial cytoplasm. A deeper muscular layer overlies the parenchyma, within which are highly specialized structures important in water balance, flame cells, and acid-neutralizing calcareous corpuscles.