T. Tervo

Immunohistochemical demonstration of epidermal growth factor in the lacrimal and submandibular glands of rats.

Abstract. The extraorbital and intraorbital lacrimal glands, the Harderian glands, and the submandibular glands of five rats were excised after ethanol perfusion under general anesthesia. Indirect immunohistochemistry with antibodies specific to epidermal growth factor (EGF) was performed. EGF‐like immunofluorescence (EGF‐LI) was shown to be present both in the lacrimal glands (extra‐ and intraoribtal) and in the submaxillary gland. In the lacrimal glands the specific immunoreaction appeared within the lumen of the acini and the cells of the tubular ducts close to the acini. Only faint EGF‐LI was observed within the acinar cells. The submandibular glands showed intense EGF‐LI only in the cells of the granular convoluted tubules. The Harderian gland did not show any EGF‐LI. The results strongly support the idea that the lacrimal gland is a source of EGF in tear fluid (TF). Diseases of the lacrimal gland therefore may lead to decreased concentrations of EGF in tears. This may account in part for the pathophysiology of tear deficiency syndromes and may serve as the basis of a new rationale for the external application of EGF.

Elevation of tear fluid plasmin in corneal disease

Abstract. Plasmin concentration was determined in tear fluid from 76 eyes showing corneal epithelial disorders, such as corneal ulcers and erosions due to trauma or contact lens wear. Nearly 70% of the eyes with corneal disease had plasmin in their tear fluid, whereas plasmin was present in only 20% of the eyes in a control group of 50 eyes. Re‐examination of the plasmin positive control eyes revealed conjunctival bacterial growth or mild subclinical viral infection in most cases. We conclude that plasmin is released into the tear fluid in the presence of corneal or conjunctival lesions or infections, suggesting a pathogenic role of plasmin in these disorders. The significance of the occurrence of plasmin in tear fluid during corneal wound healing is discussed.

Selective Changes in Human Corneal Sensation Associated with Herpes Simplex Virus Keratitis

PURPOSE To determine corneal sensitivity to selective mechanical, chemical, and thermal (heat and cold) stimulation in patients with a history of herpes simplex virus (HSV) keratitis. METHODS Corneal sensitivity to different modalities of stimulus was determined in both eyes of 16 patients with unilateral HSV keratitis diagnosed 1 to 12 months before the study. On slit lamp examination, 13 HSV-affected eyes showed corneal scarring or opacities, and three had no signs of previous keratitis. Corneal sensitivity was determined with the Belmonte gas esthesiometer. Mechanical, chemical, heat, and cold stimuli were applied on the central cornea. Eyes from 10 healthy subjects served as controls. RESULTS In all control and contralateral eyes, selective mechanical, chemical, heat, and cold stimulation evoked sensations of subjective intensity proportional to the magnitude of the applied stimulus. In one HSV patient, the affected cornea was unresponsive to all types of stimuli, four lost only corneal sensitivity to mechanical stimulation, and three lost only sensitivity to heat. Mechanical (P<0.005) and heat (P<0.05) thresholds were raised in HSV eyes, whereas thresholds for CO2 were not modified. Also, HSV subjects identified poorly the intensity of mechanical, chemical, and heat stimuli, whereas sensitivity to cold stimulation was unaffected. CONCLUSIONS In eyes that had had HSV keratitis, corneal sensitivity to mechanical forces and heat was significantly impaired, suggesting that axonal damage and/or altered expression of membrane ion channels involved in transduction and membrane excitability affects primarily the mechano- and polymodal nociceptor terminals. Corneal cold-sensitive terminals remain largely unaffected.

Integrins in human anterior chamber angle.

Abstract•Background: Integrins, which are composed of an α and β subunit, are capable of binding to a number of extracellular matrix proteins and, hence, affect cell adhesion and proliferation.•Methods: The distribution of the integrin β (β1, β3-β5) and α (α1–6 and αv) subunits in human anterior chamber angle was studied in eyes from subjects aged 9 months to 81 years using the indirect immunofluorescence technique.•Results: Immunoreaction for the β1 subunit was found throughout the trabecular meshwork (TM), in the cribriform layer, and in the endothelial lining of Schlemms canal (SC). Labelling for the α3 subunit was found in the TM and the cribriform layer only. In infant eyes the α5 subunit was present in all three areas with the highest concentration in the cribriform layer, whereas no reaction was observed in adult eyes. The α6 subunit was localized to the endothelium of SC only. Immunoreaction for the αv subunit was present in the TM and the cribriform layer of infants and young adults.•Conclusion: The present results suggest the presence of several integrin heterodimers, acting as potential receptors for laminin, collagen, fibronectin, and vitronectin, in the anterior chamber angle.

Immunohistochemical Demonstration of Tenascin in the Normal Human Limbus with Special Reference to Trabeculectomy

Sections from the anterior segment of the fetal and adult human eye and from limbal tissue excised during standard trabeculectomies were studied immunohistochemically with monoclonal antibodies against human tenascin or monoclonal antibodies against cellular fibronectin (cFN). In the fetal eye, tenascin-like immunoreactivity (TEN-LI) was observed in the area of the developing limbus. In the adult eye TEN-LI was most intense at the corneoscleral margin in the stromal tissue and decreased towards the posterior sclera. No reaction was observed in the corneal stroma, but the epithelium showed moderate immunofluorescence. All tissues obtained during trabeculectomy showed similarly strong TEN-LI. The sections from trabecular specimens incubated with antibodies against cFN were negative.

Plasmin and epidermal growth factor in the tear fluid of contact-lens wearers: effect of wearing different types of contact lenses and association with clinical findings.

The concentrations of plasmin and epidermal growth factor were determined in tear fluid (TF) samples from wearers of different types of contact lenses (CLs) during and after cessation of CL wear (CLW). TF samples of 50 healthy eyes served as controls. The plasmin concentrations in the control group (0.4 +/- 0.1 microgram/ml; mean +/- SEM) were significantly lower (p less than 0.001) than in the group of soft CL (SCL) wearers during CLW (1.2 +/- 0.2 microgram/ml). Cessation of CLW led to a decrease in TF plasmin concentrations from 1.2 +/- 0.2 to 0.6 +/- 0.1 micrograms/ml in the group of SCL wearers (p less than 0.001), from 1.5 +/- 1.1 to 0.3 +/- 0.2 micrograms/ml in the group of extended-wear SCL wearers (p greater than 0.05) and from 0.4 +/- 0.3 to 0.0 +/- 0.0 microgram/ml in the group of gas-permeable CL wearers (p greater than 0.05). After CLW cessation, TF plasmin levels of CL wearers did not differ from those of controls. The occurrence of plasmin in TF was associated with a higher degree of corneal neovascularization and with the presence of limbal injection. The concentrations of epidermal growth factor in TF were not significantly altered by the discontinuation of CLW.

C-reactive protein serum levels in patients with ocular disease

Abstract. Hepatocyte derived C‐reactive protein (CRP) is a sensitive indicator for inflammatory or infectious processes in a variety of tissues. As several other plasma proteins it is regarded as part of the acute phase response to a variety of tissue damage. CRP is commonly used in general medicin as a tool for the follow‐up of especially bacterial infections. However, it has not been widely used in ophthalmology. In the present study CRP values in serum samples from 51 patients with various acute ocular diseases were determined semiquantitatively. High CRP levels were found most frequently in patients with either preseptal cellulitis (83.3%) or endophthalmitis (25.8%) whereas in the serum of patients with keratitis and uveitis, CRP exceeded 20 mg/l in only 18.7% of the cases. In a control group of 10 patients with retinal detachment the mean CRP level was 2.3 mg/l (sd±0.98 mg/ml). The clinical significance and the prognostic value of CRP determinations during ocular diseases are discussed.

Updating of methods for prevention of HIV transmission during ophthalmological procedures

Abstract. The presence of HIV (human immunodeficiency virus) particles in the tear fluid, on the conjunctival surface or in the contact lenses of patients with chronic HIV infection has made it necessary to establish better for guide‐lines for decontamination of instruments during ophthalmological procedures. The methods are now at the stage of evolution. The present paper describes the disinfection procedures used in the Helsinki University Eye Hospital and updates the present decontamination protocols.

On the proteolytic activity of contact lenses and bacteria

Abstract. Contact lens wear (CLW) has been shown to cause an elevation in tear fluid (TF) plasmin levels. This study investigated whether the proteolytic activity assayed by a caseinolytic technique was also bound by CLs and whether certain bacterial species contribute to the production of plasmin. CLs worn by patients with corneal disease showed proteolytic activity in five out of nine cases when examined on casein agar. Histological and electron microscopic examination of the lenses revealed bacterial adherence and growth on both surfaces of the CLs. Strains of Staph. epidermidis, Staph. aureus, Pseudomonas aeruginosa and Branhamella catarrhalis, isolated from eyes with external infections, were cultured on a modified milk casein agar and examined for their proteolytic activity. Neither cultures of Branhamella catarrhalis nor Staph. aureus showed proteolytic activity when examined by direct caseinolytic assay. The proteolytic activity shown by Staph. epidermidis or Pseudomonas aeruginosa was not affected by a proteinase inhibitor aprotinin. However, when exogenous plasminogen was added into the casein agar, Staph. aureus was shown to produce caseinolytic activity. This activity was interpreted to be due to plasminogen activator (PA) activity. It was inhibited by aprotinin. Examination of culture fluids of the bacterial species mentioned above did not show caseinolytic activity. Culture fluid of Staph. aureus contained PA activity. The present study confirms the ability of certain bacterial species to adhere to CLs. Moreover, proteases such as plasmin and bacterial enzymes are present in TF during CL wear and may even adhere to the surface of CLs. Hence, bacterial growth probably contributes to the production of proteases on the ocular surface du ring CL wear.

Epidermal growth factor is resistant to plasmin.

Epidermal growth factor is resistant to plasmin in vitro Tear fluid (TF) of eyes with corneal disease often contains proteolytic activity, e.g. plasmin (Tervo et al. 1988). This enzyme cleaves the glycoproteins laminin and fibronectin both of which are important for corneal wound healing. Destruction of these molecules is suggested to interfere with cellular attachment, thus delaying wound healing (Berman et al. 1988; Tervo 8c van Setten 1989). This idea is supported by the observation that topical application of fibronectin (Nishida et al. 1988) or the proteinase inhibitor aprotinin@ (Salonen et al. 1987; Tervo & van Setten 1989) accelerates corneal wound healing. Epidermal growth factor (EGF), a constant component of the TF in humans (van Setten et al. 1989), has also been shown to enhance corneal wound healing (Burstein 1987). In the TF of eyes with corneal disease both EGF and plasmin are present simultaneously. Therefore we tried with the present study to clarify whether plasmin might cleave the EGF in vitro. Plasmin (Sigma, St. Louis, MO, USA) was added to a 10 ng/ml low molecular weight EGF (6 kD) solution at final concentrations of 0.85, 0.17, 0.034, 0.0043 and 0.0 IU/1. Tris-HC1 buffer (pH 8.0) containing 0.1% I@ free BSA (Sigma, St. Louis, MO, USA) was used as the medium for incubation of the dilutions at 37°C. EGF concentrations were determined in duplicate after 3,24 and 48 h of incubation using the time-resolved immunofluorometric assay (TR-IFMA) described previously (Pesonen et al. 1986). It was shown that EGF concentration was not affected by the concentration of plasmin in the medium (Table 1). The present results imply that plasmin does not hydrolyse low molecular weight EGF in vitro. Investigations on the correlations between EGF concentration and plasmin activity in the TF of patients are under way. Prelinlinary results suggest that high plasmin activity does not lead to decreased EGF concentrations in TF (van Setten et al. in preparation). We conclude that, in contrast to the glycopro-