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Biomedical subjects

G B van Setten

Publications and source records attributed to G B van Setten.

At least 37 records · Page 2Linked to original sources
PubMed1991

Epidermal growth factor in human tear fluid: a minireview.

This minireview deals with the presence of epidermal growth factor (EGF) in human tear fluid. It explains the occurrence of EGF in tear fluid, the origin of EGF and its dependency on tear fluid dynamics. The alterations in tear fluid EGF concentrations that occur during diseases of the ocular surface are described and discussed in the context of the current knowledge about the interaction between EGF and EGF receptors. The possible clinical implications of topical treatment with EGF are considered.

Epidermal Growth Factor↗
PubMed1991

Integrins in human corneal epithelium.

Monoclonal antibodies (Mabs) were used for immunohistochemical location of integrin beta- (beta 1,3, and 4) and alpha subunits (alpha 1-6 and alpha v) in the epithelium of both normal and tissue-cultured human cornea. Immunoreaction for the beta 1 integrin subunit was the most intense at the membranes of the basal epithelial cells and weaker at the superficial cell membranes. Anti-beta 4 immunofluorescence appeared in the basal part of the epithelium only, apposing the basement membrane. Both anti-alpha 2 and anti-beta 3 Mabs showed an immunoreaction with distribution similar to the beta 1 integrin subunit. Immunoreaction for the alpha 6 integrin subunit resembled the distribution of the beta 4 subunit. Anti-alpha v showed a faint immunoreaction at the basal and lateral aspects of the basal cell layer. Antisera against beta 3, alpha 1, alpha 4, and alpha 5 integrin subunits showed no specific reactions. The present results suggest that both the normal and tissue-cultured human corneal epithelium contain alpha 2 beta 1, alpha 3 beta 1, and probably also alpha v beta 1 and alpha 6 beta 4 integrin dimers or complexes. We discuss their role as possible receptors for some known ligands.

Adult↗
PubMed1991

Ocular irritation leads to the appearance of proteolytic activity in the aqueous humor.

Aqueous humor (AH) collected from healthy eyes of man and rabbit was analysed for proteolytic activity using a casein-agar assay. Normal AH collected during surgery or rabbit AH aspirated before ocular irritation contained no caseinolytic activity. In rabbits, mechanical irritation of the iris and subconjunctival as well as intracameral injection of capsaicin led to ocular irritative response. AH samples collected after such manipulation contained a considerable caseinolytic activity. On the other hand, anterior chamber puncture alone did not seem to induce elevation of caseinolytic activity in AH. The clinical significance of this phenomenon and the mechanisms behind it are discussed.

Animals↗
PubMed1991

Ocular disease leads to decreased concentrations of epidermal growth factor in the tear fluid.

The concentration of epidermal growth factor (EGF) in tear fluid (TF) was recently shown to decrease with increasing tear fluid flow (TFF). The purpose of the present study was to clarify the effects of ocular surface disease on the TF EGF concentrations. Tear fluid samples (n = 243) were collected from diseased eyes by means of blunted glass capillaries. The time of collection was measured for each sample, and the tear fluid flow in the capillaries (TFFc) was calculated. The concentration of human EGF (hEGF) was determined using a time-resolved immunofluorometric assay (TR-IFMA). For statistical analysis diagnosis-dependent multigrouping was performed and the data of the patient groups were compared to the data for a control group. The control material consisted of 271 TF samples collected from healthy eyes before (n = 59) and after stimulation of reflex tearing (n = 212). It was shown that TF specimens of patients (n = 243) contained significantly (p less than 0.001) less EGF (mean 952 pg/ml) than the TF of healthy control individuals before (n = 59 samples; mean 6589 pg/ml) or after stimulation of reflex tearing (n = 212 samples; mean 2762 pg/ml). The EGF concentration of every patient group was significantly lower than that found in the TF of control individuals both before and during reflex tearing (p less than 0.001). The rate of EGF released with TF during collection did not differ significantly between the various groups of patients or from that released with the TF of normal individuals before induction of reflex tearing.(ABSTRACT TRUNCATED AT 250 WORDS)

Corneal Diseases↗
PubMed1991

Expression of tenascin and cellular fibronectin in the rabbit cornea after anterior keratectomy. Immunohistochemical study of wound healing dynamics.

Anterior keratectomy (AKE) was done on rabbits, and the appearance of immunohistochemically demonstrable tenascin (TN) or cellular fibronectin (cFN) was studied at different times (5 min to 14 months) after the operation. The substance TN was first observed 12 hr after wounding in the posterior stroma; cFN appeared with the same localization 12 hr later. During postoperative week 1, both TN and cFN immunoreactions shifted to more anterior parts of the cornea, and 9 days after wounding, they were localized in the most anterior part of the stroma only. Thereafter the reactions gradually decreased in intensity but still were visible 3 months after AKE. No reaction for TN or cFN was present 14 months postoperatively.

Animals↗
PubMed1990

Effects of the Schirmer test on the fibrinolytic system in the tear fluid.

Human tear fluid was collected with blunted glass capillaries before and after performing the Schirmer test (ST). The test caused an increase in the tear fluid (TF) plasmin concentration (from 0.40 +/- 0.29 microgram ml-1 (mean +/- S.E.M.) to 1.14 +/- 0.26 microgram ml-1; Mann-Whitney test P less than 0.001) and a decrease in plasminogen activator activity (from 2.04 +/- 0.24 IU ml-1 to 1.04 +/- 0.17 IU ml-1; Mann-Whitney test P less than 0.002). In the filter paper used for ST, that segment that had been in contact with the conjunctiva (5 mm) usually contained higher amounts of plasmin than the following 5 mm of the paper overhanging the lidmargin. The present results indicate that the TF collection may affect the plasminogen activator-plasmin system in TF, depending on the collection method used.

Fibrinolysin↗
PubMed1990

On the proteolytic activity of contact lenses and bacteria.

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 during CL wear.

Adolescent↗
PubMed1990

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

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 intraorbital) 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.

Animals↗
PubMed1990

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.

Anterior Eye Segment↗
PubMed1990

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.

Conjunctiva↗
PubMed1990

Epidermal growth factor in human tear fluid: increased release but decreased concentrations during reflex tearing.

To further clarify the role of epidermal growth factor (EGF) in the physiology and pathophysiology of the ocular surface the effects of reflex tearing on concentrations of EGF in tear fluid were studied. Tear fluid samples were collected with glass capillaries before (basal samples, 59 eyes, 30 individuals) and during reflex tearing (stimulated samples, n = 212, 40 eyes, 20 individuals). The rate of tear fluid flow in the capillaries (TFFc) was measured. The concentrations of human EGF (hEGF) was determined by time-resolved immunofluorometric assay (TR-IFMA). The first basal samples contained higher concentrations of hEGF than the samples from the contralateral eyes (n = 28) collected thereafter (p less than 0.05). The basal samples from 40 eyes contained a significantly higher mean concentration of hEGF (8466 pg/ml) than did the stimulated samples (n = 212, 2763 pg/ml); p less than 0.001). The mean TFFc increased from 63 nl/s to 506 nl/s during reflex tearing (p less than 0.001) and the amount of hEGF released from 567 fg/s (n = 40) to 1400 fg/s (n = 212; p less than 0.001). Basal samples from females contained higher concentrations of hEGF than did those from males. The maintenance of the hEGF concentration at a certain level and the increased amount of hEGF released into the tear fluid during reflex tearing suggests continuous release of hEGF into tear fluid from the lacrimal gland.

Epidermal Growth Factor↗
PubMed1989

Epidermal growth factor is a constant component of normal human tear fluid.

Epidermal growth factor (EGF) is a mitogenic polypeptide, which was first isolated from mouse submaxillary gland. Since EGF also stimulates the growth of corneal epithelial cells and only preliminary data exist on its presence in tear fluid, we studied the occurrence of human EGF (hEGF) in the tear fluid of 36 healthy persons (31 women and 5 men from 20 to 59 years of age; 60 eyes). hEGF, as measured by an immunofluorometric assay, was present in all tear fluid samples investigated. Its concentration varied from 200 to 2860 pg/ml (median, 705 pg/ml). The tear fluid hEGF concentrations differed less between the eyes of one individual than between individuals. The total amount of hEGF released to the tear fluid increased with fluid flow, but the higher the flow was, the lower the concentration of hEGF. We could not find any evidence of sex dependency in the hEGF concentrations. In demonstrating that hEGF is a normal component of human tear fluid, the results of this study suggest that hEGF may be important for conjunctival and corneal epithelial integrity.

Adult↗
PubMed1989

Contact lens wear is associated with the appearance of plasmin in the tear fluid--preliminary results.

We determined biochemically the plasmin concentration in tear fluid from 50 externally healthy eyes and from 49 eyes during contact lens (CL) wear. After cessation of CL wear, samples were collected again from 41 of the 49 eyes. Plasmin was detected more frequently (P less than 0.0001) in the CL-wearing group (75.5%) than in the control group (20%). After the cessation of CL wear (3-21 days), the frequency of plasmin detection in tear fluid decreased significantly (P less than 0.0006) but was still higher (39%) than in the control group. We conclude that the occurrence of plasmin in tear fluid is correlated with CL wear. The proteolytic activity of plasmin may contribute to the development of corneal epithelial pathology associated with CL wear.

Contact Lenses↗
PubMed1989

Plasminogen activator and its inhibitor in the experimental corneal wound.

Anterior keratectomy was performed to 10 eyes of 8 adult rabbits. The animals were killed 3-24 hr after wound closure. The corneas were excised and subjected to histochemical demonstration of urokinase-type plasminogen activator (u-PA), tissue-type PA (t-PA) and plasminogen activator inhibitor [PAI-1) using commercial antibodies. A strong immunoreaction for u-PA, a weaker reaction for PAI-1 and a very weak t-PA-like immunoreaction appeared in the anterior stroma of the wounded area. None of the antisera used showed any immunostaining in the cornea outside the wound. The role of the plasminogen activator-plasmin system in the healing of the corneal wound is discussed.

Animals↗
PubMed1989

Demonstration of tenascin-like immunoreactivity in rabbit corneal wounds.

Tenascin, a novel extracellular matrix protein, was demonstrated immunohistochemically in rabbit corneas that had healed after anterior keratectomy. Tenascin-like immunofluorescence (T-LI) appeared in the corneal stroma at the wound area only. The wound edge showed the most intense specific fluorescence. The corneal epithelium, in general, displayed a moderate T-LI. Wounding did not induce any change in epithelial T-LI or T-LI located in the stroma outside the wound.

Animals↗
PubMed1989

Plasmin and plasminogen activator activities in tear fluid during corneal wound healing after anterior keratectomy.

Plasmin can degrade fibronectin and laminin, two important components of the extracellular matrix facilitating cell sliding and healing following a wound. In this study we investigated the relationship between the tear fluid level of plasmin and plasminogen activator and the healing of a corneal wound. Anterior keratectomy (AKE) was performed for seven rabbits (11 eyes). Eight eyes were rewounded after re-epithelialization. Tear fluid samples were collected with capillaries before wounding and during wound healing. Plasmin and plasminogen activator (PA) activities were determined using radial caseinolysis procedures. After AKE the plasmin concentrations increased rapidly, from a mean (+/- SEM) of 3.9 +/- 0.9 micrograms/ml to a mean of 37.9 +/- 7.8 micrograms/ml (p less than 0.01), and decreased during wound healing. Rewounding also resulted in an increase in plasmin concentration in the tear fluid (from a mean of 2.9 +/- 0.6 micrograms/ml to a mean of 5.0 +/- 1.1 micrograms/ml; p greater than 0.05). The PA activity showed an inverse trend as it decreased after AKE from a mean of 2.0 +/- 0.6 IU/ml to a mean of 0.3 +/- 0.1 IU/ml (p less than 0.001). During wound healing and re-epithelialization, the PA activity increased again, to 2.1 +/- 0.3 IU/ml (p less than 0.001). Abrasion of the newly grown epithelium in eight eyes caused a second elevation of PA activity which was not significant. This study demonstrates a close association between the healing of corneal wounds and changes in the plasmin and PA activities in tear fluid. Determination of the activity of these enzymes may therefore be useful for monitoring corneal wound healing.

Animals↗
PubMed1989

[Acute keratitis and contamination of contact lens care systems with Bacillus cereus].

Two patients, both contact lens wearers, were treated for acute keratitis in both eyes. Routine microbiologic tests done for all four eyes confirmed merely the presence of Staphylococcus epidermidis in the conjunctival flora; neither fungi nor any viruses were detected on the patients' corneas. However, the contact lens soaking solutions were contaminated with a large number of microorganisms, including above all--or solely--Bacillus cereus. Two of the contact lenses used were also colonized by fungi of the genus Rhodotorula, Cryptococcus albicans and Wangiella dermatidis. The acute inflammation was treated quickly and effectively in all cases by specific antimicrobial therapy. Bacterial contamination of lens care systems is well known as a potential cause of keratitis in contact lens wearers. Although the clinical importance of Bacillus cereus in ocular surface pathology is still unknown, the cases reported here indicate that this microorganism may be of pathological significance in lens care systems. The authors therefore recommend including the lens care systems in routine bacteriologic tests in all cases of corneal infection where the patient wears contact lenses.

Acute Disease↗