Expression of two molecular forms of the complement decay-accelerating factor in the eye and lacrimal gland

Complement is present in ocular fluids, but the molecular mechanism(s) restricting its activation to exogenous targets and not to autologous ocular cells are currently unknown. To clarify how this control is achieved, monoclonal antibody (mAb)-based techniques were used to examine the eye, the lacrimal gland, and ocular fluids for the decay-accelerating factor (DAF), a membrane regulatory protein which protects blood cells from autologous complement activation on their surfaces. Immunohistochemical staining of tissue sections revealed DAF antigen on corneal and conjunctival epithelia, corneal endothelium, trabecular meshwork, and retina, as well as on lacrimal gland acinar cells and in adjacent lumens. By flow cytometry, cultures of conjunctival epithelium exhibited the highest DAF levels and levels on corneal epithelium greater than corneal endothelium greater than conjunctival fibroblasts. Biosynthetic labeling of corneal endothelium yielded de novo DAF protein with an apparent molecular weight (Mr) of 75 kD, approximating that of blood cell DAF protein, and digestions of conjunctival epithelium with phosphatidylinositol-specific phospholipase C (PI-PLC), an enzyme which cleaves glycoinositolphospholipid membrane anchors, released approximately 70% of the ocular surface DAF protein similar to leukocyte surface DAF protein. Quantitations of DAF by radioimmunometric assay employing mAbs against two DAF epitopes revealed 325 ng/ml (n = 12), 4.8 ng/ml (n = 10), and 22.0 ng/ml (n = 8) of soluble DAF antigen in tears, aqueous humor, and vitreous humor, respectively. Western blot analyses of the tear DAF antigen revealed two DAF forms, one with an apparent Mr of 72 kD resembling membrane DAF forms in other sites, and a second with an apparent Mr of 100 kD, which is previously undescribed. Since DAF activity is essential physiologically in protecting blood cells from autologous complement attack, the identification of DAF on the ocular surface, intraocularly, in the lacrimal gland, and in tears suggests that DAF-mediated control of complement activation is also required in these locations.

Beta adrenergic binding sites in the human eye: an autoradiographic study

Beta adrenergic binding sites were localized and characterized in the human eye by means of "in vitro" autoradiography, using [125I] (-) iodocyanopindolol (125ICYP) as radioligand. Binding sites were visualized by apposition of isotope sensitive film to slide mounted eye sections. Receptor sites were present in the extraocular muscles, in the conjunctiva, in the epithelium and endothelium of the cornea, in the trabeculum and in the ciliary muscle. They were also present in the lens epithelium and in the retina. The pigmented ocular structures were heavily labelled but the binding was nonspecific. Characterization of these binding sites was achieved by testing the ability of selective adrenergic compounds to displace 125ICYP binding. These studies suggested that the majority of adrenergic binding sites in nonpigmented structures of human eye were of a beta2 type.

[Morphological and histochemical studies on the development of human conjunctival goblet cells]

This report deals with the development of human conjunctival goblet cells. Fifty-six eyes of human embryos and fetus ranging from 5 to 41 weeks of gestational age were used in this study. Glycosaminoglycans in the goblet cells were investigated histochemically using 1% alcian blue staining (pH = 2.5) and PAS reagent staining and sialidase (neuraminidase) digestion. At 8 weeks, goblet cells appeared in the forniceal area, and they extended to the palpebral and bulbar conjunctiva. These cells were already similar to adult goblet cells. Alcian blue staining and the enzyme digestion method revealed the existence of sialic acid in the goblet cells from 9 weeks. These results suggest that at the early developmental stage the goblet cells develop from the forniceal area. It is also indicated that the goblet cells in the early developmental stage are already similar to cells in the adult stage because they contain mainly sialic acid as glycosaminoglycans.

Experimental mucopolysaccharidosis: preservation and ultrastructural visualization of intralysosomal glycosaminoglycans by use of the cationic dyes cuprolinic blue and toluidine blue

The cationic dyes Cuprolinic Blue (CB) and Toluidine Blue (TB) were used to preserve the intralysosomal storage material accumulating in tilorone-induced mucopolysaccharidosis. As shown in previous studies, the stored glycosaminoglycans (GAGs) are leached during the conventional fixation procedure, with the result that the lysosomes appear empty. In the present study, the liver, spleen, and cornea-conjunctiva of tilorone-treated rats were examined. The application of CB in the presence of 0.1 M or 0.3 M MgCl2 simultaneously with, or subsequently to the primary fixative yielded electron-dense precipitates within the storage lysosomes. When TB (0.1%) was added to the primary fixative, the storage lysosomes contained filamentous structures arranged in reticular patterns. With increasing TB concentrations (up to 1%) the lysosomes increasingly often showed apparently amorphous storage material which was continuous with the reticular filamentous structures. Similar ultrastructural patterns were obtained with GAG-TB complexes prepared in vitro. The intralysosomal storage material preserved by TB is interpreted as GAG-TB precipitates. In conclusion, the use of CB provides a method which allows direct cytochemical demonstration of the subcellular sites of GAG-storage. The use of TB represents an easy method to obtain electron micrographs pathognomonic of the mucopolysaccharidosis induced by tilorone and congeners. Either method may be helpful to detect this adverse drug effect at the subcellular level.

Neoglycoprotein binding distinguishes distinct zones in the epithelia of the porcine eye

The presence and location of specific endogenous lectins in the anterior epithelia of the porcine eye were determined by histochemical staining using biotinylated glycosylated carrier molecules. Endogenous lectins with specificities for galactosides, alpha-mannosides and beta-xylosides were present in the conjunctival epithelium, but the corneal anterior epithelium appeared essentially free of histochemically demonstrable endogenous lectins. The corneal posterior epithelium contained a rich and complex set of endogenous lectins. The transitional area between conjunctival and corneal anterior epithelia at the limbus cornea contained, in striking contrast to either of the epithelia bordering it, cells expressing endogenous lectins in considerable wealth and variety.

Conjunctival cell glycoprotein pattern of healthy persons and of patients with primary Sjögren's syndrome--light microscopical investigation using lectin probes

Formalin-fixed biopsies of conjunctival tissue from the lower fornix of 10 healthy persons and of 10 patients with primary Sjögren's syndrome (primary SS) were examined by light microscopy. Deparaffinized, rehydrated sections of 5 microns were incubated overnight, each with one of 15 different biotinylated lectins. Bound lectins were visualized using avidin-HRP-substrate complexes. Five lectins did not bind to conjunctival cells, and further six lectins bound in an unspecific manner to conjunctival cells of both healthy persons and of primary SS patients. Jacalin lectin bound selectively to goblet cells of all specimens. Peanut agglutinin (PNA) and wheat germ agglutinin (WGA) bound significantly stronger to basal conjunctival epithelial cells of patients with primary SS. This binding pattern may be of diagnostic value.

Attempts of tissue typing from human donor eyes

A method for HLA-ABC typing using pigmented retinal epithelial and uveal cells of the donor eye is described and the possible implications for corneal grafting are mentioned.

Association of elastin with pseudoexfoliative material: an immunoelectron microscopic study

Using immunoelectron microscopy, the presence of elastin and tropoelastin was demonstrated in pseudoexfoliative (PSX) material in all its classical sites on the lens capsule, ciliary non-pigment epithelium, iris epithelium and stroma, and conjunctiva. Some variability in binding affinity was seen in different sites, and labelling was more often on the periphery than the center of the PSX fibers. The elastin epitope on PSX material was more sensitive to processing than the remarkably stable epitope on mature elastic fibers. Since neither elastin nor a related component of PSX fibers, elastic microfibrillar protein, is a circulating protein, both are likely to be secreted by local ocular cells. Most of these local cells are not involved in elastogenesis normally, suggesting that an abnormal stimulus or defective regulation of matrix synthesis exists in this disease.

Conjunctival oxygen tension monitoring in emergency department patients

Conjunctival oxygen tension (PcjO2) was sequentially monitored in 96 medical and surgical patients admitted to the emergency department resuscitation suite during a 6-month period. There were 28 patients with cardiac arrest, 44 with major trauma, and 24 with severe medical problems. A total of 2,392 PcjO2 data points were collected in these patients. In patients with cardiac arrest, PcjO2 showed changes in physiological condition as early as or earlier than measurement of vital signs. Measurement of PcjO2 and the finding of a PcjO2 index (PcjO2/PaO2) less than .5 in normotensive multiple trauma patients allowed rapid detection of hemorrhagic hypovolemia. In critically ill medical patients, low values for PcjO2 were found with hypoxemia as well as in conditions associated with decreased cardiac output and tissue oxygen delivery. These two conditions could be distinguished by measuring PaO2 and calculating the PcjO2 index; a PcjO2 index less than .5 was associated with diminished peripheral perfusion and cardiac output, and a PcjO2 index greater than .5 indicated hypoxemia without any compromise in cardiac output. In the group of critically ill surgical and medical patients included in this study, conjunctival oxygen monitoring provided clinically useful information not available from vital signs and permitted identification of physiological instability associated with abnormalities in peripheral tissue perfusion and oxygenation as early as or earlier than conventional monitoring methods.

Non-invasive conjunctival PCO2 and PO2 monitoring during hyper- and hypoventilation

In order to evaluate potential applications of non-invasive fiberoptic conjunctival carbon dioxide (Pcj,CO2) and polarographic oxygen (Pcj,O2) sensors, we studied the effects of graded hyper- and hypoventilation on Pcj,CO2 and Pcj,O2 values in dogs. Pcj,CO2 values correlated well with Pa,CO2 (r = 0.95, n = 114); the mean Pcj,CO2--Pa,CO2 gradient was 4 +/- 3 (S.D.) Torr. Both hyper- and hypoventilation resulted in decreased Pcj,O2 values, whereas decreased Pa,O2 was observed only during hypoventilation; thus, the Pcj,O2/Pa,O2 index decreased during hyperventilation but was maintained during hypoventilation. Because both cerebral and conjunctival capillary beds vasoconstrict during hyperventilation, this methodology may assist in the non-invasive monitoring of cerebral oxygenation during cerebral resuscitation and surgery. Non-invasive Pcj,CO2 monitoring, which reflects Pa,CO2 during changes in ventilation, may be used to simplify ventilator management and weaning, as well as guide appropriate timing of arterial blood gas analysis in hemodynamically stable patients.

Noninvasive measurement of tissue carbon dioxide tension using a fiberoptic conjunctival sensor: effects of respiratory and metabolic alkalosis and acidosis

To evaluate potential clinical applications of a newly developed, noninvasive fiberoptic conjunctival carbon dioxide (PcjCO2) sensor designed to measure continuously tissue PCO2 in a vascular bed supplied by the internal carotid artery, we studied the effects of graded respiratory and metabolic alkalosis and acidosis on PcjCO2 in a hemodynamically stable canine model. Respiratory changes were induced by varying the frequency of ventilation and metabolic changes were induced by incremental infusions of sodium bicarbonate and hydrochloric acid. Continuous measurement of end-tidal carbon dioxide tension (PETCO2) was also performed. During respiratory alkalosis and acidosis, PcjCO2 values correlated well with PaCO2 (r = 0.96, n = 106); linear regression analysis of PcjCO2 vs. PaCO2 produced a slope of 1.01 and a y-intercept of 3.94 over a PaCO2 range of 12 to 76 torr. The mean PcjCO2-PaCO2 gradient was 4 +/- 3 (SD) torr. PETCO2 values also correlated well with PaCO2 (r = 0.91), as well as with PcjCO2 values (r = 0.91). Both PcjCO2 and PETCO2 showed a much weaker correlation with PaCO2 during metabolic alkalosis and acidosis, partly because the variation in PaCO2 was less. Moreover, the PcjCO2-PaCO2 gradient increased during the metabolic portion of the study up to a mean of 10 +/- 8 (SD) torr during metabolic acidosis, implying a build-up and/or lack of washout of CO2 from the conjunctival tissues, despite the normal physiologic range of PaCO2 values. We conclude that in a hemodynamically stable canine model, PcjCO2 and PETCO2 values correlate well with PaCO2 during pure respiratory alkalosis and acidosis; the correlation weakens significantly, however, with metabolic alterations in tissue CO2 levels.

Detection of mucus glycoconjugates in human conjunctiva by using the lectin-colloidal gold technique in TEM. III. A quantitative study in asymptomatic contact lens wearers

We characterized the mucus glycoconjugates produced by goblet and non-goblet epithelial cells in asymptomatic contact lens (CL) wearers. We employed four lectins (proteins of vegetal origin which specifically recognize glycosidic residues: WGA, PNA, SBA and ConA) conjugated with colloidal gold as ultrastructural marker, at Transmission Electron Microscopy. A computerized quantitative analysis was carried out in order to compare the results from the CL wearers to those from the control patients. Goblet cells produce different amount of glycosidic residues, in particular, a significant decrease in the distribution of sialic acid, N-acetylglucosamine, N-acetylgalactosamine, galactose-N-acetylgalactosamine and mannose was observed. The content of glycosidic residues in the mucus vesicles of the non-goblet epithelial cells appeared unchanged as to the normal situation. We speculate that the CL could possibly contribute to the failure of the tear film stability by altering the production of mucus.

Conjunctival oxygen tension at high altitude

Transconjunctival oxygen tension (PcjO2) was studied using a hypobaric chamber and during mountaineering excursions. Measurements obtained during acute chamber exposures (15-20 min) at sea level, 1829 m (6,000 ft), 3048 m (10,000 ft), 4267 m (14,000 ft) and return to sea level were (means +/- SEM): 60.1 +/- 2.7, 49.1 +/- 1.8, 38.3 +/- 2.4, 27.4 +/- 1.5, and 61.1 +/- 2.8 mm Hg, respectively (n = 13). The ratio of PcjO2 to arterial blood oxygen tension (PaO2) did not change in a consistent manner between sea level and 4267 m; PcjO2 was 74 +/- 6.9% of PaO2. The 16 subjects participating in the mountaineering phase of the study revealed similar means at sea level and 1829 m (57.4 +/- 2.4 and 46.3 +/- 1.9 mm Hg respectively), but a smaller decrement was observed at 3048 m (43.0 +/- 1.6 mm Hg). The difference between mountain and chamber values may be accounted for by a partial acclimatization to altitude brought about by longer exposure on the mountain excursions. A comparison between PcjO2 and transcutaneous oxygen tension during the chamber study suggests that a greater precision and sensitivity is obtained with measurement of oxygen tension at the conjunctival site. PcjO2 measurement is a non-invasive reflection of PaO2 which is suitable for continuous monitoring during hypoxia studies.

Noninvasive conjunctival oxygen monitoring during carotid endarterectomy

Conjunctival oxygen tension (PcjO2) was measured continuously during carotid endarterectomy in 15 patients to evaluate its sensitivity in patients receiving shunts. These studies suggest that PcjO2 tracks brain perfusion during periods of carotid artery occlusion. Reduced PcjO2 was clearly demonstrated with systemic hypotension, carotid artery clamping, and carotid shunt obstruction and clamping. Monitoring of PcjO2 is noninvasive, easy to perform, offers no danger to the patient, and allows real-time assessment of the local tissue perfusion. It provides valuable information on the effectiveness of carotid oxygen transport and, in conjunction with arterial blood gas values, expresses carotid artery perfusion relative to systemic oxygen transport. Further investigations using the PcjO2 sensor may define criteria for intraoperative carotid arterial shunting in patients with tenuous cerebral perfusion, and for prompt intervention in patients with deteriorating perfusion prior to the onset of life-threatening cerebral ischemia.

Ocular distribution of keratan sulfates during pre- and postnatal development in rabbits

Twenty-six monoclonal antibodies (MAbs) developed against rabbit corneal proteokeratan sulfate (PKS), were used to evaluate immunohistochemically the ocular distribution of PKS during prenatal and early postnatal development in rabbits. These MAbs were directed against epitopes located in the keratan sulfate (KS) chains of the proteoglycan (SundarRaj et al., 1985). Staining of cryostat sections of the eyes was carried out using an indirect peroxidase-conjugated technique. Only one of the MAbs reacted with the presumptive corneal region at day 13 or 16 of fetal development. By day 20, more MAbs reacted with the corneal stroma. There were distinct differences, however, in the distribution of the epitopes recognized by the various MAbs. A few of them stained only the posterior region of the cornea, whereas others showed a decreasing staining gradient from the posterior to the anterior region. By day 24, all of the MAbs reacted with the corneal stroma, but some reacted also with the limbal region and with the conjunctival stromal matrix. One MAb also reacted with the conjunctival epithelial layer, but only at this stage of development. Conjunctival staining was more intense at day 28 of fetal development and at day 2 postnatally. KS was not detectable in the conjunctiva of adult rabbits with any of the MABs. These results suggest that although KS synthesis starts at very early stages of fetal development, there are progressive changes in its antigenic structure in specific regions of the cornea and conjunctiva during corneal development.

Clinical, electron microscopic, and monoclonal antibody studies of intraocular epithelial downgrowth

Epithelial downgrowth developed in three patients following cataract extraction and keratoplasty. Light and electron microscopy of the downgrowth tissue disclosed stratified squamous epithelium, but could not determine whether they were derived from conjunctival or corneal epithelium. The epithelial downgrowth contained cells that were connected laterally by desmosomal junctions and displayed well-defined basement membranes. Surface epithelial cells exhibited myriad microvillous processes scant to moderate mitochondria. In one case, prominent hemidesmosomal junctions were present. Immunohistochemical staining with monoclonal antikeratin antibodies revealed immunoreactivity with AE1, AE3, and AE11 in all cases, but with a cornea-specific antibody, AE5, in only one case. We concluded that in this last case, the epithelial downgrowth appears to have originated from the corneal epithelium.

Human T-cell leukemia/lymphotropic virus type III in the conjunctival epithelium of a patient with AIDS

The human T-cell leukemia/lymphotropic virus type III (HTLV-III), the causative agent of the acquired immunodeficiency syndrome (AIDS), has been isolated from the conjunctival epithelium of a 33-year-old woman with AIDS, suggesting that an important reservoir of the virus may be the ocular surface epithelial cells. The tears and conjunctival epithelium from normal controls were negative for HTLV-III. The finding of HTLV-III in the tears and conjunctival epithelium indicated that HTLV-III may be ubiquitous in bodily cells and fluids. Repeated contact with the tears and ocular surface epithelium of patients with AIDS may possibly facilitate transmission of HTLV-III, and precautions are advisable during routine ophthalmologic procedures such as glaucoma testing and contact-lens fitting.

Application of lectins for detection of goblet cell carbohydrates of the human conjunctiva

Paraffin-embedded and frozen biopsies from the human conjunctival epithelium were examined by fluorescence microscopy after labeling with eight fluorescein-conjugated lectins: wheat germ agglutinin; soybean agglutinin; peanut agglutinin; Ricinus communis agglutinin-1; Limulus polyphemus agglutinin; Ulex europaeus agglutinin-1; Dolichos biflorus agglutinin; concanavalin A. The lectins were used as specific molecular probes to detect carbohydrate composition of glycoproteins secreted from the conjunctival goblet cells. The labeling pattern of goblet cells and conjunctival epithelial surfaces with various lectins suggested that N-acetyl-glucosamine, galactose, N-acetyl-galactosamine and sialic acid are contained in goblet cells and contribute to the formation of tear mucus glycoprotein. Fucose and mannose, which are present in the tear mucus, were not detectable in goblet cells.

Synthesis of slow reacting substance-like activity in rabbit conjunctiva and anterior uvea

The ability of rabbit conjunctiva and anterior uvea to synthesize lipoxygenase products was assessed. Using autoradiographic techniques, we demonstrate that rabbit anterior uvea synthesizes 5 and 12 lipoxygenase products such as 12-HETE, 5-HETE and 5,12-DiHETE and cyclooxygenase product HHT from 14C-arachidonic acid. Indomethacin pretreated conjunctiva and anterior uvea generated slow reacting substance (SRS)-like activity from arachidonic acid in the presence of reduced glutathione and A23187. This SRS-like activity contracted guinea pig ileum. Specific SRS-like activity antagonist FPL-55712 inhibited the contractions of guinea pig ileum induced by SRS-like substance generated by either conjunctiva or anterior uvea. The activity was still present in the sample following extraction with organic solvents. SRS-like activity was destroyed by arylsulfatase and its generation was prevented by either boiling or pretreatment with cyclooxygenase/lipoxygenase inhibitors, BW755 and nordihydroguaiacetic acid. These results indicate that following cyclooxygenase inhibition by indomethacin rabbit conjunctiva and anterior uvea generate SRS-like activity from arachidonic acid via lipoxygenase pathways.

Prevalence of episcleral and subconjunctival lipid deposits in Eskimos

Slit lamp examinations of 340 Eskimos in Greenland revealed lipid deposits in 12%. The prevalence was significantly lower than in a Copenhagen series of Caucasians (45% out of 689 subjects) recorded for 10-year age groups. The numbers of lipid deposits seemed to be equal in lipid-positive subjects of the 2 ethnic groups, but the globules were more often localized temporally and more rarely superiorly in Eskimos than in Caucasians. The relatively rare occurrence of lipid deposits in Eskimos may possibly be due to the special composition of lipids on the blood and the rare occurrence of arteriosclerosis in Eskimos.

The transconjunctival oxygen monitor

The transconjunctival oxygen monitor, mounted on a polymethylmethacrylate conformer, continuously measures the tissue oxygen tension of the palpebral conjunctiva. It is preferable to transcutaneous monitors because it requires no heat and correlates arterial oxygen in cerebral blood flow by monitoring a tissue bed vascularized by the internal carotid artery. We used it on 19 adult patients. The monitor was valuable in correlating arterial oxygen in hemodynamically compromised and uncompromised patients. However, the measurements decreased abruptly when the conjunctival temperature fell below 33 C in the compromised patients. The only ocular complications were conjunctival chemosis and mild punctate keratopathy in some patients; these resolved within 48 hours. This device may be useful in monitoring tissue oxygen tensions in critically ill patients and neonates at risk for retinopathy.

Adolescent cystinosis, presenting with proteinuria

Isolated proteinuria preceding tubular dysfunction for years was the presenting laboratory sign in a patient with adolescent cystinosis, followed up to end-stage renal failure in the second decade of life. The renal biopsy showed the early characteristic features, multinucleated giant podocytes. The diagnosis was documented by slit lamp examination of the eyes and cystine determination in fibroblasts.

Episcleral and subconjunctival lipid deposits. One year follow-up

A series of 39 subjects, aged under 70, had the numbers of lipid globules counted in the slit lamp within 4 regions of the right eye and 4 regions of the left. The counting was repeated after an averaged period of 12 months (range 7-20 months). The investigation disclosed that the number of lipid globules rises. No instances were detected of a fall in their number, allowance being made for errors of measurement, assessed on the basis of blind double counting. The degeneration is not positively correlated to xanthelasma, diabetes mellitus, or presenile arcus.

Keratin-like proteins in corneal and conjunctival epithelium are different

Using SDS polyacrylamide slab-gel electrophoresis, water-insoluble (keratin-like) proteins in normal and regenerated ocular surface epithelium from rabbits were studied. The results indicated that keratin-like proteins from corneal and conjunctival epithelia in vivo distinctly different. Regenerated epithelia from either source retained their original keratin characteristics for at least 10 days after healing over the cornea, but at very early stages of healing migrating and regenerated epithelia showed either an extra band or a prominent band in addition to the original keratin-like proteins. Three months after healing, however, regenerated conjunctival epithelium on the cornea had changed its keratin characteristics, and resembled, but was not identical to, corneal epithelium.

Zinc, cobalt and selenium concentrations in the premature and full-term newborn eye

Zinc, cobalt and selenium concentrations were determined in tunics, vitreous and lens of the eyes of 17 infants who died during the neonatal period. Significantly higher concentrations of the measured elements were found in the vitreous. The tunics contained more zinc and cobalt than the lens, while the latter contained more selenium.

Limbal epithelium in ocular surface wound healing

The regenerated epithelium derived from limbal epithelium was histologically and biochemically compared with epithelia regenerated from corneal and bulbar conjunctival epithelia. The histologic results indicated that regenerated epithelium of limbal origin increased in thickness with time after healing and showed no goblet cell appearance on the cornea. This suggests that regenerated epithelium from the limbus is more like regenerated epithelium of corneal origin than that of bulbar conjunctival origin. However, the glycogen content and protein pattern profile showed that regenerated epithelium of limbal origin had characteristics intermediate between those of corneal and bulbar conjunctival origin. Thus it is proposed that there are three distinct types of ocular surface epithelia--corneal, bulbar conjunctival, and limbal--and that limbal epithelium behaves differently from corneal and conjunctival epithelia in ocular surface wound healing.

H2-receptors in the human ocular surface

Ten normal human volunteers participated in a two-part study of H2-receptor activity in the ocular surface. Dimethylaminopropylisothiourea (trivial name, dimaprit dihydrochloride), a highly selective H2-receptor agonist, produced vasodilation without itch. Pretreatment with the H2-receptor antagonist, cimetidine, significantly blocked the vasodilatory effect of dimethylaminopropylisothiourea, whereas pretreatment with the H1-receptor antagonist, antazoline phosphate, did not. We conclude that H2-receptors are present in the human ocular surface.

Human conjunctival surface mucins: a quantitative study of normal and diseased (KCS) tissue

The architecture and distribution of surface mucins were studied qualitatively and quantitatively by transmission electron microscopy in ruthenium red stained biopsies of the human conjunctiva. Six control specimens were compared with three from early keratoconjunctivitis sicca (KCS) and with three specimens from severe KCS cases. The area of the ruthenium red/OsO4/mucin reaction product on the conjunctival epithelial surface was measured by image analysis and the values were expressed in micron2 per micron length of epithelium. The total area of surface mucins was differentiated from the narrow zone of mucins in close contact with the microplicae. The value for total mucins in two cases of early KCS was higher (0.4 micron2/micron) than the control range (0.1-0.3 micron2/micron) due to the presence of large clumps of mucins on the surface. The values for microplical mucins in early and severe KCS were within the control range, but were an overestimate owing to the presence of abnormal structures, e.g. vesicles, and abnormal clumps on the surface. This morphometric technique has limitations, but with appropriate material it might be a useful tool for the identification of conjunctival surface mucins.

Corneal-conjunctival uptake of topical 3H-dexamethasone in the rabbit eye

Topically administered 3H-dexamethasone was localized radioautographically to the nuclei of several cell types in the cornea and conjunctiva. In the cornea, label was found in the epithelium and keratocytes. In the conjunctiva, label was found in the epithelium and in the connective tissue cells and blood vessel endothelial cells of the stroma. Prior administration of a 350-fold excess of nonlabeled hormone completely suppressed this localization, indicating that these cells are specific glucocorticoid target cells. There was no localization found in the corneal endothelium. Accumulation of silver grains between corneal stroma and Descemet's membrane suggests that this membrane acts as a partial barrier to diffusion of the steroid.

Glucocorticoid localization by radioautography in the rabbit eye following systemic administration of 3H-dexamethasone

Dexamethasone was localized radioautographically in the nuclei of target cells of the rabbit eye following intravenous administration of the labeled steroid. Specifically bound steroid was found in the nuclei of stromal and endothelial cells of the outflow pathway region. This suggests that the glucocorticoid-induced alteration in outflow facility may be mediated by specific effects in these target cells. Nuclear localization was also found in conjunctiva, iridial smooth muscle, choroidal stroma, retina, and sclera, suggesting a physiologic role for glucocorticoids in these tissues as well.

Lactoferrin in human ocular tissues

The main lacrimal gland and accessory lacrimal tissue from seven autopsy cases, lacrimal biopsy specimens from three patients, and conjunctival biopsy specimens from ten patients were examined for lactoferrin by an immunohistologic technique. Lactoferrin was identified and localized to acinar epithelial cells of both main and accessory lacrimal tissue. Lactoferrin was not found in conjunctival tissue except within conjunctival neutrophils. Other possible sources of human tear lactoferrin were considered, but we concluded from our data that the primary source of lactoferrin in normal human tears is the acinar epithelium of the main and accessory lacrimal glands.

Natural fat in external eye. Vital-stained by Sudan III powder

Examination of 113 eyes vital-stained by Sudan powder revealed that fat on the skin of outer canthus may pass onto the precorneal film (in 68%), and that the most reliable staining is obtained by application on the bulbar conjunctiva below the limbus corneae at 6 o'clock. In 41%, the precorneal film had stained drops or foam, with a tendency towards an increase among pathological cases (infectious conjunctivitis and blepharitis). An increased amount of fat was found in the mucous thread of eyes affected with infectious conjunctivitis and lagophthalmos. In a small number of pathological cases fat was also detected on cornea, bulbar conjunctiva, and inferior fornix. The fatty layer on the lower lid margin was stained more frequently and more intensely than that on the superior. The secretion of the meibomian glands was stained in no more than a scant one half of the glands (on an average 44%), independently of age, sex, site, and diagnosis.

Ultrastructural and histochemical studies of conjunctival concretions

Ultrastructural and histochemical studies were performed on conjunctival concretions (yellow spots in the tarsal conjunctiva) from two patients who had associated atopic keratoconjunctivitis and posttrachomatous degeneration. By electron microscopy, these concretions were composed of finely granular material and membranous debris accumulating in the conjunctival subepithelium. Histochemically, concretions stained strongly positive for phospholipid and elastin, weakly positive for neutral polysaccharides and lipid, and were negative for amyloid, collagen, glycogen, iron, mucopolysaccharides, RNA, and DNA. In view of the absence of both calcium and phosphate in the accumulated material, the use of the term "lithiasis" is misleading and should be avoided. These findings support a hypothesis that concretions that follow chronic conjunctivitis represent products of cellular degeneration.

Prelminary examination of rabbit conjunctival mucins

Conjunctival mucins from albino rabbits were fractionated using gel filtration and anion-exchange chromatography. Charge homogeneity of the various conjunctival mucin fractions was confirmed by polyacrylamide gel electrophoresis. The molecular weight characteristics of the isolated fractions varied with the analytical scheme employed. Two schemes yielded mucins with molecular weights of 10(4), 10(5), and 10(6). However, when anion-exchange chromatography was the first step in the fractionation scheme, the dominant mucin had a molecular weight of 1.7 x 10(5). In contrast, when gel filtration chromatography was the first step, the dominant mucin had a molecular weight of 5.7 x 10(4). It was postulated that during migration through the anion-exchange matrix, the low molecular weight conjunctival mucin underwent trimer formation. Comparison with the mucin fractions isolated from tear mucoid threads revealed that the scheme beginning with anion-exchange chromatography preserved the fractionation pattern seen in tear mucoid threads. This result implies that conjunctival mucins undergo an association prior to or after their entry into the tear film. The molecular event of interest in this process is self-association of the species with a molecular weight of 5.7 x 10(4), resulting in a trimer with a molecular weight of 1.7 x 10(5). This trimer appears to resist deaggregation on exposure to a medium of lesser ionic strength. Several explanations are offered for its formation as well as for its stability. The implication of multiple conjunctival (tear) mucins for tear film stability also is discussed.

Secretory component in human ocular tissues

Lacrimal tissue and accessory lacrimal tissue from seven autopsy cases, lacrimal tissue from three patients undergoing orbital exploration, and biopsy specimens from conjunctiva of 14 subjects were examined for the presence and distribution of secretory component by three anti-secretory-component antisera. Secretory component was present in all lacrimal and accessory lacrimal tissues but in no other ocular tissues. Over 60% of acinar cells stained for secretory component; about 5% of acinar cells stained brightly; about 30% of tubular cells stained brightly. Main and accessory lacrimal tissues appeared identical in their staining patterns. We concluded that the main sites of synthesis of secretory IgA in human ocular tissues are the lacrimal and accessory lacrimal tissues.

Keratopathy after oral administration of tilorone hydrochloride

Two patients given tilorone HCl orally for varying periods of time had clinical and histopathologic ocular changes. Retrospective study of 14 cancer patients who were taking tilorone HCl orally revealed that three patients had similar ophthalmic findings accompanied by the appearance of blue halos around pinpoint light sources. Examination revealed a diffuse clouding of the epithelium sometimes associated with subepithelial infiltrates. Abnormalities seen histologically included cloudy swelling of the epithelium and cytoplasmic inclusions. By electron microscopy these were found to be myelinoid bodies. Gas chromatography and mass spectrophotometry showed that tilorone HCl was present in the cornea and conjuctiva. Visual acuity was not affected and these changes were slowly reversible with the cessation of therapy. Biomicroscopic and conjunctival cytologic examination may serve to indicate the drug's storage and potential damage in the body.

Adult cystinosis. A case report

A 41-year-old man, referred because of the suspicion of retinal detachment, was found to have retinoschisis, moderately severe renal disease, and adult cystinosis with crystals in the cornea and conjunctiva. Conjunctival crystals were demonstrated by light and electron microscopy, and chemical analysis confirmed the presence of excessive amounts of cystine. Studies of renal tissue showed changes that were interpreted as being due to hypertensive vascular disease. Light and electron microscopic examination of kidney tissue showed no cystine crystals, and chemical analysis indicated only trace amounts of cystine.

Unusual intracytoplasmic inclusions in a case of idiopathic scleritis

Large cells containing prominent, refractile PAS-positive inclusions were found in cytological smears prepared from scrapings of the conjunctiva of an elderly diabetic patient with idiopathic scleritis progressing to scleromalacia perforans. Electron-microscopic study of these inclusions revealed them to be intracellular accumulations of dense, flocculent mucoid material within vacuoles whose interior surface was frequently decorated with microvilli. Similar inclusions have been reported in a number of neoplasms in nonocular tissue. The significance of these findings with regard to the patient's condition is not understood.

Congenital alacrima

A sixteen-year-old black male with congenital alacrima and deficient salivary secretion demonstrated evidence of keratoconjunctivitis sicca. The workup revealed elevated immunoglobulins and histologically normal lacrimal and salivary glands, but there was deposition of amyloid in the conjunctival stroma. The differential diagnosis of the dry eye is discussed.

IgE in limbal conjunctiva in Mooren's ulcer

A patient with a severe, progressive Mooren's ulcer was unsuccessfully treated by limbal conjunctival resection and cryotherapy. The excised conjunctiva demonstrated a band of IgE along the basement membrane.

Biochemical transformation of regenerating ocular surface epithelium

Several biochemical parameters, including glycogen levels, and the activities of hexokinase, phosphorylase, and lactate dehydrogenase have been compared in regenerating epithelium of conjunctival and corneal origin in rabbits. The study was designed to determine the extent of biochemical transformation of conjunctival into corneal epithelium completed within 6 weeks. Although histological transformation, especially in the case of the chemically damaged eyes, is not. Glycogen and lactate dehydrogenase levels remained well below normal corneal epithelial levels for the period of observation.

[Early alterations of the conjunctiva after alkali-burning (author's transl)]

Early alterations of the conjunctiva after alkaliburning (with 0.25 N NaOH) are described. After chemical damage, there is a nearly total loss of conjunctival epithelium, with simultaneous marked edema in the lower conjunctival parts. Alterations of the surface are examined by scanning electronic microscopy (SEM). Within 24 h marked infiltration of round cells into the conjunctival stroma takes place. After burning, we find a rapid decrease in the ATP level in the conjunctiva to about one-tenth of the normal value, whereas glucose and lactate showed only small alterations before and after chemical injury.