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Biomedical subjects

T Tervo

Publications and source records attributed to T Tervo.

At least 55 records · Page 3Linked to original sources
PubMed1995

Reassembly of the alpha 6 beta 4 integrin and laminin in rabbit corneal basement membrane after excimer laser surgery: a 12-month follow-up.

We investigated the reassembly of hemidesmosomes and epithelial basement membrane (BM) following experimental excimer laser photorefractive keratectomy (PRK) immunohistochemically using monoclonal antibodies against integrin subunits alpha 6 and beta 4 (hemidesmosome components) or laminin (a BM component). The rabbits were killed 3 days, 1, 3, 6, or 12 months after a -5.0 D PRK. For untreated corneas, integrin subunits alpha 6 and beta 4 and laminin showed normal distribution at the basal aspect of the basal epithelial cells, appearing as a distinct fluorescent line. The alpha 6 subunit was also found at the basolateral membranes of the basal epithelial cells. The average healing time for the PRK wound was 6 days, but secondary epithelial defects occurred in 17 of 22 corneas. The subepithelial labeling for all the antibodies investigated showed focal discontinuities at the level of the BM in the wound area up to 12 months after PRK. After 6 months, secondary epithelial defects were very rare. In addition to the patchy subepithelial labeling, lamellar anterior stromal immunoreaction for alpha 6 and beta 4 integrin subunits was also present 1-12 months after PRK. Laminin was also observed in the anterior stroma 1-6 months after PRK. Our results suggest that focal discontinuities of hemidesmosomes or BM observed immunohistochemically in the unexpectedly slow-healing PRK wound areas might correlate with the epithelial healing problems observed in most rabbits.

Animals↗
PubMed1994

A rapid fluorometric assay for tear fluid plasmin activity.

A rapid (5- to 10-min), sensitive (detection limit 0.6 IU/L), and moderately specific fluorometric plasmin assay for small volume tear fluid samples was developed. Addition of albumin (up to 0.1% final concentration) to the assay buffer improved the sensitivity of the test so that plasmin activity in healthy controls could be detected. pH in the reaction buffer was 8.0, Michaelis-Menten constant for the substrate, H-D-Val-Leu-Lys.7-amido-4-methyl-coumarin (AMC), was 0.28 mM, and final substrate concentration in the reaction buffer was 1 mM. Intra- and interassay imprecisions were 1.6 and 4.4%, respectively at a plasmin level of 10 IU/L. Tear fluid flow was significantly higher in the patients than in the healthy controls, and this dilatory effect must be considered when using plasmin determination for diagnostic purposes. This effect was counteracted by correcting the plasmin activity values by tear fluid flow. Plasmin flux is plasmin activity (microIU) secreted in units of time (min). This parameter showed highly significant differences between the patients and controls. All patients with microbial keratitis, corrosive trauma, ocular trauma, herpetic infection, and other diseases showed highly significant elevation of plasmin flux compared with controls. The highest plasmin flux values (several hundredfold that of controls) were recorded in patients with severe corneal ulcers. Few patient samples showed some involvement of other proteases, which were not inhibited by aprotinin.

Adult↗
PubMed1994

Elevation of tear fluid plasmin activity of contact lens wearers studied with a rapid fluorometric assay.

Tear fluid plasmin activities were measured by a fluorometric assay based on a lyophilized kit with the 7-amido-4-trifluoromethylcoumarin derivative of the tripeptidyl H-D-Val-Leu-Lys as substrate. The rapid, sensitive method can detect proteolytic activity in small volume tear fluid samples. Plasmin activity levels (IU/L) measured from the samples were corrected with tear fluid flows (microliters/min), yielding a parameter called plasmin flux (microIU/min). Correction is important when patients show tearing due to irritation. Tear fluid samples were collected from 32 asymptomatic contact lens (CL) wearers and 27 controls. Plasmin activity values (2.7 +/- 0.3 IU/L) of CL wearers were higher (p < 0.00006) than those of the controls (1.6-0.1). Mean plasmin flow was 12.6 +/- 1.5 microliters/min for CL wearers and higher for controls (6.8 +/- 0.5 microliters/min). The difference was not significant (p = 0.063). Plasmin flux values of CL wearers (30.0 +/- 4.1 microIU/min) were conspicuously higher than those of controls (10.2 +/- 0.7 microIU/min, p < 0.00006). We conclude that elevated tear fluid proteolytic activity may be related to pathological changes associated with CL wear.

Contact Lenses, Hydrophilic↗
PubMed1994

C-reactive protein serum levels in patients with ocular disease.

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 medicine 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.

C-Reactive Protein↗
PubMed1994

Tear fluid plasmin activity after excimer laser photorefractive keratectomy.

PURPOSE: Elevated tear fluid plasmin activity may correlate with delayed healing of corneal wounds. The present study was performed to establish the tear fluid plasmin activity after photorefractive keratoablation (PRK). METHODS: Tear fluid aspirated with microcapillaries was subjected to a fluorometric plasmin assay using the 7-amido-4-trifluoromethylcoumarin derivate of the tripeptide H-D-Val-Leu-Lys as substrate. RESULTS: Tear fluid flow, plasmin activity, and flow-corrected plasmin excretion rate in tears (plasmin flux) were determined preoperatively and 1, 2, and 7 days after PRK. The preoperative tear fluid flow was 6.55 microliters/min (median; range, 1.8 to 21.8 microliters/min), plasmin activity was 1.29 IU/l (median; range, 0.6 to 6.9 IU/l), and the excretion of plasmin in tears was 11.7 microIU/min (median; range, 1.6 to 41.5 microIU). A statistically significant decrease in tear fluid plasmin activity was found during the follow-up period on the first (0.6 IU/l; range, 0.6 to 1.7 IU/l, P < 0.01) and second (0.65 IU/l; range, 0.6 to 1.49 IU/l, P < 0.01) postoperative days. On the other hand, significant elevation of both tear fluid flow and plasmin flux values occurred during the first two postoperative days. The median plasmin flux values on days 1, 2, and 7 were 57.35 microIU/min (range, 16 to 540 microIU/min, P < 0.01), 40.0 microIU/min (range, 13.3 to 222.8 microIU/min, P < 0.01), and 10.2 microIU/min (range, 2.2 to 90.7 microIU/min, P > 0.05), respectively. CONCLUSION: The marked elevation of tear fluid flow coincided with the persistence of an epithelial defect. However, because of the acceleration of tear fluid flow, proteolytic activity due to plasmin (IU/l) actually decreases. Consequently, the increased excretion of plasmin in tears (plasmin flux) does not lead to highly elevated plasmin activity, which could inhibit wound healing. It seems to be a natural healing response because all corneas were epithelialized normally by or on day 3.

Cornea↗
PubMed1993

Cellular fibronectin and tenascin in an orbital nylon prosthesis removed because of infection caused by Staphylococcus aureus.

An orbital nylon prosthesis was removed because of an infection caused by Staphylococcus aureus that was resistant to antimicrobials. It was processed for histopathology and immunohistochemistry. Within 3 weeks the implant had an extensive ingrowth of fibrovascular tissue containing chronic inflammatory cells, foreign body giant cells, and myofibroblasts. By using the indirect immunofluorescent method, this tissue was found to react with monoclonal antibodies (Mabs) against extradomain A of cellular fibronectin (EDA-cFN) and tenascin (TN). The presence of EDA-cFN and TN within the implant are indicative of an active healing process, since both of these proteins, scarce in adult tissues, have been shown to be reexpressed during tissue regeneration. The findings suggest that fibronectin plays a definite role in bacterial adherence and foreign body infections.

Aged↗
PubMed1992

Expression of tenascin and fibronectin in the rabbit cornea after excimer laser surgery.

In order to investigate the effects of excimer laser surgery on corneal wound healing, 25 rabbits underwent anterior keratectomy at a depth of 100 or 300 microns with a Meditec MEL 50 excimer laser. After various intervals the animals were killed and the cornea excised and investigated immunohistochemically for the expression of extracellular matrix (ECM) proteins, fibronectin and tenascin. Fibronectin was shown to occur earlier than tenascin, and the two also had different distribution patterns. Wound depth showed no clear effect on the localization and time of ECM protein expression. This study indicates that corneal wounds caused by excimer laser radiation and those caused by mechanical surgery differ as to healing mechanisms.

Animals↗
PubMed1992

Distribution of integrins alpha 6 and beta 4 in the rabbit corneal epithelium after anterior keratectomy.

Integrins are heterodimeric cell-surface receptor glycoproteins involved in cell-matrix and also in cell-cell interactions. The alpha 6 beta 4 integrin heterodimer has been shown to be a component of the hemidesmosome. In response to wounding, hemidesmosomes are disassembled, the epithelium migrates to cover the denuded area, and eventually the hemidesmosomes reappear. In the present investigation the distribution of the integrin alpha 6 and beta 4 subunits after anterior keratectomy was studied by indirect immunohistochemistry. Labeling for the alpha 6 subunit was observed around the entire cell surface, right to the leading edge. The immunoreaction for the beta 4 subunit was confined to the basal cell membrane facing the basement membrane as in the normal cornea. Cells at the leading edge of the migrating epithelium did not show any labeling for beta 4. Patchy labeling for beta 4 was first observed in the region midway between the wound margin and the leading edge. Because integrins are only expressed as heterodimers, the alpha 6 subunit may be complexed with the beta 1 subunit, instead of with beta 4, at the leading edge of the migrating epithelium. We also suggest that this alpha 6 beta 1 heterodimer may play a role in the reformation of the adhesion complex.

Animals↗
PubMed1992

Pseudomembranous and membranous conjunctivitis. Immunohistochemical features.

A 63-year-old man, who had for one month been on sulfasalazine therapy, developed general malaise, high fever, severe stomatitis, and bilateral necrotizing pseudomembranous conjunctivitis with corneal erosion, identical to that seen in the Stevens-Johnson syndrome. Topical therapy with antibiotics and aprotinin rapidly healed the corneal surfaces, while densely adherent true membranes developed on the conjunctiva, and were removed surgically several times during the next week. After the acute stage, subtle subepithelial conjunctival scarring, superficial punctate keratitis, dry eye syndrome and fluctuating irregular corneal astigmatism became evident, but good visual acuity, lid function and ocular motility were retained. Histopathologic study of conjunctival membranes from two cases of membranous conjunctivitis revealed polymorphonuclear leukocytes within a matrix composed of fibrin, tenascin and fibronectin. In older membranes, histiocytes were additionally found. Surgical debridement of such membranes removes a substratum of inflammatory debris that is likely to promote secondary infection, fibrosis and symblepharon formation, and may decrease rather than increase subsequent scarring of the necrotized conjunctiva.

Adult↗
PubMed1992

Integrins as receptors for extracellular matrix proteins in human cornea.

Extracellular matrix (ECM) proteins form distinct protein families that play a role during tissue maturation, wound healing and maintenance of tissue architecture. Recent studies show that there are tissue type-specific variations in their expression. ECM proteins function by complexing with each other and also by interacting with their cellular receptors, called integrins. Integrins are heterodimeric membrane glycoproteins that are partly cell type-specifically expressed in human tissues. Like other stratified epithelia, corneal epithelium expresses alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 1, 4, and alpha v beta 1 integrins that mediate attachment to the basement membrane and cell-cell interactions.

Basement Membrane↗
PubMed1992

Integrins in the normal and healing corneal epithelium.

Integrins are heterodimeric plasma membrane glycoproteins involved in cell-matrix and cell-cell interactions. The present communication reviews the distribution of several of the currently known integrin subunits in the corneal epithelium. The corneal epithelium contains the following integrin heterodimers: alpha 2 beta 1, alpha 3 beta 1, and alpha 6 beta 4. The expression of alpha v with an unknown beta subunit is also recognized, whereas the expression of alpha 4 and alpha 5 subunits remains controversial. Some of the changes occurring in the distribution of integrins in response to wounding will also be discussed.

Basement Membrane↗
PubMed1992

Surface-associated activation of plasminogen on gram-positive bacteria. Effect of plasmin on the adherence of Staphylococcus aureus.

In this article we review a novel type of plasminogen activation on staphylococcal and streptococcal cells. The activation mechanism implies a specific binding of glu-plasminogen to bacterial surface via the lysine-binding sites of plasminogen. Association of plasminogen with bacterial surfaces greatly enhances the t-PA mediated activation which takes place only poorly in solution. The end product, surface-associated plasmin, is enzymatically active, protected against high molecular weight plasmin inhibitors and capable of converting itself from glu-plasmin to the lys-form. The modification is associated with an increased affinity of the bound lys-plasmin towards the binding molecules on bacterial surface. This novel way of retaining plasmin on the surface may be important for the bacteria to invade and penetrate surrounding tissues. Our data on the effect of plasmin on staphylococcal adherence indicate that plasmin is not very effective in cleaning bacteria from surfaces coated with extracellular matrix components, fibronectin and fibrinogen.

Bacterial Adhesion↗