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Biomedical subjects

Per Fagerholm

Publications and source records attributed to Per Fagerholm.

12 recordsLinked to original sources
PubMed2006

A simple, cross-linked collagen tissue substitute for corneal implantation.

PURPOSE: To develop a simple corneal substitute from cross-linked collagen. METHODS: Porcine type I collagen (10%; pH 5), was mixed with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The final homogenous solution was molded to corneal dimensions, cured, and then implanted into rabbits and minipigs by lamellar keratoplasty. The implants were followed for up to 6 months after surgery. Clinical examinations of the cornea included detailed slit lamp biomicroscopy, in vivo confocal microscopy, topography and esthesiometry for nerve function. Histopathologic examinations were also performed on rabbit corneas harvested after 6 months. RESULTS: Cross-linked collagen (refractive index, 1.35) had optical clarity superior to human corneas. Implanted into rabbit and porcine corneas, only 1 of 24 of the surgical corneas showed a slight haze at 6 months after surgery. All other implants showed no adverse reactions and remained optically clear. Topography showed a smooth surface and a profile similar to that of the contralateral nonsurgical eye. The implanted matrices promoted regeneration of corneal cells, tear film, and nerves. Touch sensitivity was restored, indicating some restoration of function. The corneas with implants showed no significant loss of thickness and demonstrated stable host-graft integration. CONCLUSIONS: Collagen can be adequately stabilized, using water soluble carbodiimides as protein cross-linking reagents, in the fabrication of corneal matrix substitutes for implantation. The simple cross-linking methodology would allow for easy fabrication of matrices for transplantation in centers where there is a shortage of corneas, or where there is need for temporary patches to repair perforations in emergency situations.

Animals↗
PubMed2005

Proteome profiling of corneal epithelium and identification of marker proteins for keratoconus, a pilot study.

The purpose of this study is to identify corneal proteins differentially expressed between keratoconus and normal epithelial samples. Proteins from the corneal epithelium were isolated from 6 keratoconus and 6 myopia patients (controls) and separated by 2D-gel electrophoresis. Six % and 12% SDS-PAGE gels were used to separate low and high molecular weight proteins. Gels were silver stained and protein spots were defined by Melanie II software. The proteins that were most altered in expression comparing keratoconus and controls were extracted, trypsin-digested, and identified by mass spectroscopy. Approximately 200-500 protein spots were detected on each gel. Nineteen spots were identified as differentially expressed between keratoconus and reference epithelium including cytokeratin 3 (< 7.8 fold), gelsolin (1.6 fold), S100A4 (1.9 fold), and enolase 1 (0.72 fold). Another identified protein found at very high levels was cytokeratin 12. Gelsolin, cytokeratin 3, and cytokeratin 12 have previously been described to be involved in other corneal diseases. Three proteins, gelsolin, alpha enolase, and S100A4 were identified to be differentially expressed in keratoconus compared to reference epithelium and thus may be involved in the pathogenesis.

Biomarkers↗
PubMed2005

Expression of basic fibroblast growth factor in rabbit corneal alkali wounds in the presence and absence of granulocytes.

PURPOSE: To study the expression of basic fibroblast growth factor (bFGF) in the early phases of corneal wound healing in the presence or absence of granulocytes. METHODS: A central penetrating corneal alkali wound was inflicted to one eye in each of 14 rabbits under general anaesthesia. Subsequently, seven of the rabbits were given fucoidin i.v. for 36 hours in order to block the selectins on the vascular endothelium, thus preventing blood granulocytes from entering the tissues. Then, corneas were prepared, stained for bFGF and evaluated by light microscopy. RESULTS: Whereas normal corneal epithelium expressed bFGF weakly, conjunctival epithelium did so strongly, particularly the goblet cells. The corneal endothelium showed medium staining, while keratocytes and vascular endothelial cells did not consistently express bFGF. After 36 hours of wound healing, a marked up-regulation of bFGF expression was observed in the corneal epithelial and endothelial cells, as well as in the keratocytes, that were migrating into the wound. No other changes were noted. None of these features were modulated when granulocyte emigration was prevented by fucoidin administration. CONCLUSIONS: The difference in bFGF expression between the corneal and conjunctival epithelium suggests a role for this growth factor in the barrier function at the limbus. Moreover, the specific presence of bFGF in cells migrating into the wound indicates the participation of bFGF in corneal wound healing. Expression of bFGF was independent of granulocytes.

Animals↗
PubMed2005

The expression pattern of the subunit of chaperonin containing T-complex polypeptide 1 and its substrate, alpha-smooth muscle actin, during corneal wound healing.

PURPOSE: This study was designed to demonstrate the expression of the chaperonin containing T-complex polypeptide 1 (CCT) and alpha-smooth muscle actin (alpha-SMA), in normal corneas and corneas treated with ultraviolet radiation (UVR). The wound model chosen is previously characterized, the injury is mild and the cornea heals to transparency. METHODS: Rabbit corneas were exposed to UVR at the dose producing keratitis. The corneas were allowed to heal for up to 5 days and the paraffin-embedded tissue specimens were double stained and examined morphologically and immunohistochemically. Expression of CCT and alpha-SMA genes was investigated by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: There was a front of repopulating keratocytes that showed positive staining for alpha-SMA after 3 days. The alpha-SMA mRNA was already strongly expressed after 1 day, whereas the expression level of CCT was increased after 2 days. After 5 days the levels were decreased. By this time the stroma was partly repopulated by keratocytes. CONCLUSION: In a mild wound, the expression of alpha-SMA mRNA is followed by expression of mRNA of at least one subunit of the complex folding alpha-SMA. At protein level, alpha-SMA is detected in the front line of repopulating keratocytes. Expression levels for both mRNAs decline as the stroma repopulation process progresses.

Actins↗
PubMed2004

Phototherapeutic keratectomy in Salzmann's nodular degeneration.

PURPOSE: To describe the outcome in vision and refraction of phototherapeutic keratectomy (PTK) in Salzmann's nodular degeneration (SND). METHODS: Five eyes of four patients underwent PTK with the objective of restoring an acceptable refractive status and improving visual acuity. This surgical technique aims to make the nodules level with the corneal surface using an excimer laser. RESULTS: Best corrected visual acuity (BCVA) improved in all five eyes. Astigmatism was reduced in four eyes and increased somewhat in one. During the observation period one eye suffered a late recurrence that required a penetrating graft. CONCLUSION: Salzmann's nodular degeneration is a rare disease that is sometimes difficult to diagnose as it has some resemblance to other diseases. The aetiology of the disease is unknown. Phototherapeutic keratectomy is a safe and effective mode of treatment. Recurrences occur with time.

Adult↗
PubMed2004

Biglycan gene expression in UVR-exposed rabbit corneas.

PURPOSE: It is known that stromal proteoglycans play an important role in the hydration and transparency of the mammalian cornea. Proteoglycans have been described as a pathological deposit in climatic proteoglycan stromal keratopathy, which is associated with chronic ultraviolet radiation (UVR) exposure. The expression of dermatan sulfate proteoglycan biglycan in the cornea was thus studied after exposure of rabbit eyes to UVR. METHODS: New Zealand albino rabbit corneas were exposed to UVR at 310 nm at the dose producing biomicroscopically significant keratitis (0.47 J/cm2). Animals were killed 3, 7 and 28 days after exposure (five rabbits in each group). Five rabbits were used as controls and did not receive any UVR treatment. Expression of biglycan mRNA in the corneas was investigated by competitive reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: There was no expression of biglycan mRNA in the control group. In the UVR-exposed groups, biglycan mRNA had still not been expressed 3 days after exposure. The expression of biglycan mRNA was observed in all UVR-treated corneas 7 days after exposure (p < 0.05). By 28 days after UVR exposure the expression of biglycan mRNA had decreased (not statistically significant). CONCLUSIONS: There is no detectable biglycan gene expression in the normal rabbit cornea. Ultraviolet radiation exposure leads to a distinct expression of biglycan mRNA in the rabbit cornea that decreases 4 weeks after exposure, indicating the involvement of biglycan in the corneal repair process. Biglycan appears to be a novel marker of corneal wound healing.

Animals↗
PubMed2004

Vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 in the regulation of corneal neovascularization and wound healing.

PURPOSE: To study the change in expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 in the rabbit cornea and limbus following a penetrating, central corneal alkali burn. The influence of different cells on VEGF and VEGFR-2 expression was studied by excluding granulocytes from the wound area. METHODS: Fourteen New Zealand white rabbits were subjected to a penetrating, 5-mm diameter, central corneal alkali burn in one eye under general anaesthesia. Seven of the rabbits were given injections of fucoidin for 36 hours. The rabbits were killed after 36 hours and the corneas were excised with a sclera rim and prepared for immunohistochemistry. RESULTS: Both VEGF and VEGFR-2 are strongly expressed in the frontline of repopulating epithelial, stromal and endothelial cells during wound healing, irrespective of granulocyte presence. Vascular endothelial cells express VEGF strongly after injury, but only in the presence of granulocytes. CONCLUSION: Corneal neovascularization requires the presence of granulocytes to stimulate vascular endothelial cells. During wound healing in this area, VEGF is a factor that stimulates proliferation and migration and that is not influenced by granulocytes.

Animals↗
PubMed2004

Epithelial ingrowth after LASIK treatment with scraping and phototherapeutic keratectomy.

PURPOSE: To evaluate the effect of phototherapeutic keratectomy (PTK) in combination with manual scraping when removing epithelial ingrowth under a LASIK flap. MATERIAL AND METHODS: Three patients, who had undergone several surgeries following LASIK in order to remove epithelial ingrowth that was threatening vision, were treated with a flap lift, manual abrasion and PTK. The PTK was performed on both the stromal and the flap side with the aim of eliminating the threat and improving vision. Two patients underwent primary surgery to remove epithelial ingrowth with manual abrasion and PTK. The influence on vision, topography and cell recurrences was evaluated. RESULTS: Uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA) improved in four cases and remained good in the fifth case. The refraction did not change significantly. Topography disclosed changes in the irregular astigmatism, explaining the improved BSCVA. Central epithelial ingrowth did not recur, whereas peripheral ingrowth did. The peripheral ingrowth did not progress, except in case 1, where a cyst formed that required surgery. CONCLUSIONS: It is our belief that adding PTK to manual scraping improves the prognosis for eyes with epithelial ingrowth. It is mainly the central ingrowth that is positively affected. Improved adhesion between the stroma and the flap is one possible explanation.

Adult↗
PubMed2003

Phototherapeutic keratectomy: 12 years of experience.

BACKGROUND: Phototherapeutic keratectomy (PTK) has been employed as a surgical tool to treat corneal disease for more than 10 years. The laser has made it possible to remove superficial corneal opacities and thereby restore vision. The 193 nm ultraviolet light separates molecules and splits molecules in biological tissue, thereby ablating it. About 0.25 microm of tissue is ablated by each pulse. The development of the excimer laser technique has been fast. It has principally focused on refractive surgery but has also benefited PTK. CORNEAL DYSTROPHIES: The ability to delay or postpone corneal grafting in superficial corneal dystrophies represents a very important achievement. Map-dot-fingerprint dystrophy or basal membrane dystrophy is a common indication for PTK. Other dystrophies such as Meesman's, Reis-Bückler's, Thiel-Benke's, granular, macular, lattice and Schnyder's can be treated, although with differing degrees of success and varying rates of recurrence. Subepithelial scarring in Fuchs' dystrophy has been ablated. Other trials have involved the removal of substantial parts of the stroma in order to reduce the load on the endothelium. Recurrent dystrophic changes can likewise be removed from corneal grafts and thus prevent the need for regrafting. RECURRENT EROSIONS: Laser treatment has made it possible to manage wound-healing problems better after recurrent erosions. Recurrent erosions are the most common indications for PTK: several studies show good and persistent effects with this type of treatment. Persistent epithelial defects of various origins, among them corneal ulcers resulting from allergic disease, can likewise be treated. SCAR TISSUE: Scars after surgery such as pterygeum excision can be removed. Smooth muscle actin containing fibroblasts in old scars should be given special consideration in PTK. Excimer laser surgery can be successfully combined with conventional surgery to remove excessive scar tissue, Salzmann's nodules and very flaky and coarse band keratopathy. Irregular corneal surfaces following ulcers and injuries pose problems that have so far proved difficult to overcome. Thinning is often seen after bacterial corneal ulcers or after herpes simplex keratitis. A rough or uneven surface can be made smoother by using modulators during treatment by casting a new surface under a hard contact lens (PALM technique), a surface that is then projected into the stroma by laser ablation. Modern techniques linking the excimer laser with computerized corneal topography and wavefront analysis promise to further improve the smoothing capacities of lasers and to increase the quality of optical results. COMPLICATIONS: The most feared complication of PTK is the postoperative infection. These are rare. Haze is usually not prominent but scar tissue formation of a more persistent type has been noted after laser surgery in eyes with pre-existing surgical scars. Keratectasia has been described after PTK. Failure due to deep opacities or a surface that is too uneven is a more common frustration. This paper reviews advances in excimer laser treatment of corneal disease.

Cornea↗
PubMed2002

[Growing waiting list for corneal transplantation].

New corneal storage techniques and legislative changes have transformed conditions for corneal grafting in Sweden. Since 1995, the Swedish Corneal Surgery Society has registered the number of grafts, the size of waiting lists for surgery as well as changes in the capacity of the banks. Since 1995 the number of procedures per year has declined while the waiting list has grown. The required number of procedures is 650 rather than the 448 performed in 1999. The decline is due to a lack of donor corneas, priority accorded to other surgery, efforts to adapt contact lenses to keratoconus, and further indications for excimer laser surgery. The four established corneal banks as well as two opening in 2001 will increase the number of grafts available for surgery.

Corneal Transplantation↗
PubMed2002

The expression of Fas ligand protein in ultraviolet-exposed rabbit corneas.

PURPOSE: Keratocytes undergo apoptosis during various pathologic conditions and after exposure to ultraviolet radiation (UVR). It was reported that the Fas/Fas ligand system is involved in modulating keratocyte apoptosis. The expression of Fas ligand (FasL) protein was studied in rabbit corneas after photokeratitis induced by different UV wavelengths. METHODS: Six New Zealand albino rabbit corneas were exposed to 280- and 310-nm UVR in 10-nm full wavebands at doses producing biomicroscopically significant keratitis (0.12 J/cm2 for 280 nm and 0.47 J/cm2 for 310 nm). Animals were killed 24 hours after exposure. Immunohistochemistry was performed to localize FasL protein in paraffin sections of rabbit corneas. Primary antibody was polyclonal goat anti-FasL IgG. RESULTS: FasL protein was uniformly detected in epithelial and endothelial layers of all UVR-exposed and control, nonexposed corneas. The positive staining of keratocytes was confined to the anterior stroma of corneas that were exposed to 280-nm UVR. Corneas exposed to 310-nm UVR showed positively stained keratocytes throughout the entire thickness of the stroma. CONCLUSIONS: These data strongly suggest that the Fas/FasL system may play an important role in apoptosis of corneal cells after UVR. The FasL expression in the corneal stroma was more extensive after exposures at 310-nm UVR than at 280-nm UVR.

Animals↗