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Biomedical subjects

W Sekundo

Publications and source records attributed to W Sekundo.

At least 19 recordsLinked to original sources
PubMed2003

[Wavefront analysis and adaptive optics].

In this paper we attempt to provide an overview of the principles of wavefront measurement. We also discuss the operational principles of different systems currently present on the market including their advantages and disadvantages. Moreover, we speculate on current and possible future implications of this new technology in the laser refractive surgery. Adaptive optics are explained in the context of "customized ablation" and preoperative verification of the desired results. Finally, the first international clinical results of wavefront guided excimer laser surgery are reviewed and critically commented.

Equipment Design↗
PubMed2003

[Laser-assisted subepithelial keratectomy (LasEk). Review of the current state of knowledge].

This article offers an overview of the current state of knowledge on the results and techniques of the evolving refractive procedure called laser-assisted subepithelial keratectomy (LasEk). A few peer-reviewed published clinical and experimental studies on this new technique are critically debated. Furthermore we discuss the indications for this procedure in comparison to photorefractive keratectomy (PRK) and laser in situ keratomileusis (Lasik) based on the current body of literature and the first author's clinical and scientific personal experience.

Epithelium, Corneal↗
PubMed2001

[Histopathology of 8 corneal buttons after penetrating keratoplasty in silicone oil-associated keratopathy].

BACKGROUND: In the literature there is only a limited number of morphological reports on clinically diagnosed silicone oil associated keratopathy describing different histological changes. The purpose of the present study was to evaluate the most common histopathological features of this disorder. MATERIAL AND METHODS: We reviewed the registry of the ophthalmopathological laboratory at the University of Marburg with respect to the following histopathological diagnoses: "bullous keratopathy", "endothelial-epithelial corneal decompensation", "band keratopathy" and "endothelial degeneration". These specimens were cross-checked with appropriate medical records. Eight specimens with a clinical diagnosis of silicone oil induced keratopathy were identified. All specimens were examined by light microscopy. RESULTS: Histologically, a long-standing bullous keratopathy was seen in 5 out of 8 specimens. A descemetocele was present in two other corneas. One case displayed band keratopathy. A posterior collagenous layer (PCL) between Descemet's membrane and the endothelium was identified in 7 out of 8 specimens examined. This layer was of a fibrillar type in 2 corneal buttons and of a fibrocellular type in all remaining specimens with PCL. PCL was associated with endothelial cell loss and degeneration. The endothelial cell density varied between 0 and 5 cells per high power field. CONCLUSION: Posterior collagenous layer associated with degenerating endothelium appears to be the most frequent histopathological feature in silicone oil induced keratopathy. The variety of PCL in this condition makes a firm histopathological diagnosis of "Silicone oil induced keratopathy" rather difficult.

Adolescent↗
PubMed2000

Induced corneal astigmatism using an asymmetric corneoscleral tunnel and a large-optic intraocular lens.

PURPOSE: To prospectively evaluate the induction of corneal astigmatism using an asymmetric corneoscleral tunnel incision (J-incision) to implant large-optic (7.0 mm) intraocular lenses (IOLs). SETTING: Department of Ophthalmology, University of Bonn, Germany. METHODS: Thirty-five patients had sutureless phacoemulsification with implantation of a 7.0 mm poly(methyl methacrylate) posterior chamber IOL using an inverse J-shaped asymmetric tunnel incision. The corneal astigmatism was measured by corneal keratometry and topography preoperatively and 1 day and 1 and 3 months postoperatively. Induced astigmatism was calculated by vector analysis. RESULTS: Mean induced changes in the corneal radii measured by keratometry were 0.17 mm +/- 0.14 (SD) on the first postoperative day, 0.18 +/- 0.14 mm after 1 month, and 0.17 +/- 0.14 mm after 3 months. Mean postoperative induced astigmatism measured by corneal topography was 1.08 +/- 0.66 diopters (D), 0.89 +/- 0.78 D, and 0.85 +/- 0.70 D, respectively. No signs of wound instability were detected. CONCLUSION: An asymmetric corneoscleral incision was suitable for implantation of large-optic IOLs, resulting in immediate stability of the induced cylindrical power in the central 3.0 mm zone as measured by keratometry. A reduction in induced corneal astigmatism can be achieved using this technique versus using symmetrical wound constructions and large-optic IOLs.

Aged↗
PubMed2000

[Immunological effect of systemically administered allopurinol in experimental autoimmune uveitis].

PURPOSE: Allopurinol shows beneficial effects in the systemic treatment of lens-induced uveitis. This is believed to be due to the reduction of oxidative tissue damage via a dose-dependent free radical scavenging ability and an immunomodulating effect. The purpose of this study was to investigate the immunological effects in experimental autoimmune uveitis after systemic treatment with allopurinol (AL) and steroids (STER). METHODS: 31 male Lewis rats were immunized with crude retinal extract, Freund's Adjuvans and pertussis toxin. The rats were divided into four groups: healthy rats (BASIS, n = 3), experimental autoimmune-uveitis without therapy (EAU, n = 9), 50 mg/kg bw. allopurinol i.v. (ALSYS, n = 9), and 7.5 mg/kg bw. methylprednisolone i.v. (STSYS, n = 10). ALSYS and STSYS received five intravenous injections during the 2 weeks immunization period. The rats' sera were tested against Western Blots (WB) of electrophoretic separations of retinal proteins. Based on digital image analysis, an analysis of discriminance was performed. RESULTS: The multivariate analysis of discriminance revealed a significance difference between the WBs of ALSYS and STSYS (p < 0.01) compared to EAU without therapy. The number and intensity of peaks in WBs were strongly reduced in the ALSYS group compared to EAU. CONCLUSION: AL revealed a strong immunomodulating effect in the treatment of experimental autoimmune uveitis that is markedly stronger than that of steroids. Together with the antioxidative effect of allopurinol known from previous studies, this drug could be a new promising therapeutic approach in the treatment of uveitis.

Allopurinol↗
PubMed1999

Effects of systemically applied allopurinol and prednisolone on experimental autoimmune uveitis.

PURPOSE: To compare the effects of allopurinol to those of prednisolone on the oxidative tissue damage and inflammatory response in experimental autoimmune uveitis (EAU). METHODS: Experiments were performed using 27 male Lewis rats. EAU was induced by means of crude retina extract, Freund's adjuvant and pertussis toxin. One group of animals served as controls and two groups were treated systemically, one with allopurinol and one with prednisolone. At the end of the experiments lipid peroxides (LPO), myeloperoxidase activity (MPO), and histological changes were determined in the retinal tissue. LPO were measured by two different methods [thiobarbituric acid reactive substances (TBARS) and malondialdehyde-like substances]. RESULTS: Allopurinol led to a significant reduction in LPO and MPO levels. The steroid treatment also resulted in a significant reduction in MPO activity but LPO were significantly reduced only when measured as TBARS. Histological changes were significantly reduced by allopurinol only. DISCUSSION: Allopurinol is more effective than prednisolone in treating EAU. Its efficacy can be explained by the antioxidative/antiinflammatory and probably immunological action. The antiinflammatory effects of prednisolone are not sufficient to reduce the tissue damage. Allopurinol promises to be a useful alternative to steroids in the treatment of uveitis.

Allopurinol↗
PubMed1999

Long-term ultrastructural changes in human corneas after tattooing with non-metallic substances.

AIM: To investigate the ultrastructural appearance and the deposition pattern of dye particles in long term non-metallic corneal tattooing. METHODS: Two tattooed human corneas were obtained by keratoplasty. One corneal button was fixed in Karnovsky's solution and the other in Trumps' solution. Both corneas were divided and processed for conventional light (LM) and transmission electron microscopy (TEM). Five additional formalin fixed corneas with tattoos were retrieved from paraffin for TEM. The time between tattoo and removal of the corneal button/enucleation ranged from 7 to 61 years. All seven corneas were examined using a Jeol JCXA733 microprobe for wave length dispersive analysis in order to exclude any presence of metallic salts in the tattooed area. RESULTS: Histologically, clumps of brown-blackish granules were present mainly in the mid stroma, but also in anterior and partially in the posterior half of the stroma. On TEM, numerous round and oval electron dense particles were seen in the cytoplasm of keratocytes arranged as clusters or large islands. The larger particles appeared black, while the smaller particles were grey. In well fixed tissue a unit membrane was observed around these clusters. No granules were detected in the extracellular matrix. CONCLUSIONS: Keratocytes can actively ingest and retain tattooing particles of non-metallic dyes within their cell membrane for very long periods of time.

Adolescent↗
PubMed1998

Primary conjunctival rhabdomyosarcoma: 2.5 years' follow-up after combined chemotherapy and brachytherapy.

BACKGROUND: The 2.5-year outcome of a 3-year-old girl with a primary intraconjunctival rhabdomyosarcoma treated by biopsy-controlled combined chemo- and brachytherapy is reported. METHODS: The patient presented with a conjunctival dermoid-like lesion which showed modest growth on 1-month follow-up. The first biopsy appointment was missed because of a viral illness. When she showed up 3 months later a further increase in size was obvious and several incisional biopsies were taken immediately. RESULTS: Light microscopy revealed an undifferentiated subepithelial small cell tumour. On immunohistochemistry the tumour reacted with vimentin and desmin antibodies. Thus, the diagnosis of an embryonal rhabdomyosarcoma was made. The patient underwent 9 cycles of polychemotherapy and the tumour mass disappeared macroscopically. However, immunohistochemistry of incisional biopsies showed residual tumour cells. The latter were eradicated by an individually shaped strontium-90 applicator. CONCLUSION: At 2.5 years after biopsy-controlled combined chemotherapy and brachytherapy the patient is free of tumour at a manageable level of complications. This new approach appears to be a good alternative in the treatment of primary conjunctival rhabdomyosarcomas since it takes advantage of the unique location of this rare tumour and avoids hemifacial retardation, known to be induced by external beam radiation.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Hydroxyapatite orbital implant. A light- and electron-microscopic and immunohistochemical study.

OBJECTIVE: This study aimed to characterize the constituents of the ingrown host tissue in explanted orbital coral spheres by means of light electron microscopy and immunohistochemistry and to compare findings at different intervals after implantation. DESIGN AND METHODS: A microscopic retrospective laboratory study of three explanted coral spheres from three different patients was undertaken. The first specimen was an infected hydroxyapatite orbital implant, which was removed after 18.5 months and processed for standard light microscopy and transmission electron microscopy. Immunohistochemistry was performed using vimentin, actin, CD-68, and CD-34 marker. Two other explanted spheres (after 3 weeks and 2.5 months) were examined by light microscopy only, because no fibrovascular ingrowth could be detected. RESULTS: On light microscopy, the pores of the first coral were filled entirely with the fibrovascular tissue. A basophilic line reminiscent of calcium deposition was seen along hydroxyapatite spicules, where it often was associated with newly formed bony lamellae. Similar lines were seen partially in the 2.5-month specimen but not in the 3-week specimen. Immunohistochemistry of the first specimen enhanced visualization of the capillary network when the CD-34 marker was used. The fibrovascular tissue was uniformly vimentin-positive and partially actin-positive. On transmission electron microscopy, typical fibroblasts and myofibroblasts were observed. The latter were separated by thin sheets of banded collagen and formed pseudoepithelial structures. Proliferating vessels often showed high endothelial cells. CONCLUSIONS: The fibrovascular ingrowth contains not only vimentin-positive regular fibroblasts but also actin-positive myofibroblasts. Interaction between the invading tissue and hydroxyapatite structures leads to long-term ossification.

Actins↗
PubMed1998

Capillaries in the epithelium of pterygium.

AIM: To present new morphological observations of intraepithelial capillaries in pterygium and to provide some explanations for this phenomenon. METHODS: The ultrastructural features of pterygia from 26 patients were examined. Surgically excised tissue was processed for conventional light and transmission electron microscopy. RESULTS: Individual capillaries within the epithelium of the anterior half towards the head of pterygia were identified in 11 specimens out of 26 pterygia examined (42.3%). The perivascular connective tissue of the intraepithelial capillaries contained fibroblasts, collagen fibrils, and elastin-like material. Epithelial cells surrounding these capillaries showed defects in the basal lamina in contrast with the continuous basal lamina of the endothelium. In the intercellular space of the epithelium an amorphous substance, occasional fibroblast processes, and collagen fibrils were frequently observed. CONCLUSION: Capillaries in the epithelium of pterygia are rare, but not exceptional. The ingrowth of these vessels from the stroma into the epithelium can be interpreted as a reaction to hypoxia or deficiency of any other substance transported via the bloodstream. Apparently, the perivascular connective tissue can be used by ingrowing fibroblasts as a migration pathway. The migrating fibroblasts appear to use the defects of the epithelial basal lamina (whether partially or complete) in order to reach the intercellular space. It is possible that collagen fibrils in the epithelial intercellular space have been laid down by fibroblasts which contribute to the pathological dedifferentiation of the conjunctival epithelium.

Adult↗
PubMed1997

Immunomodulating activity of allopurinol in experimental lens-induced uveitis.

PURPOSE: The aim of this study was to evaluate the immunomodulating activity of allopurinol using a model of lens-induced uveitis (LIU) and to compare these effects to those of steroids. METHODS: We tested the sera of both LIU and control rats against western blots (WB) of SDS-PAGE separations of protein fractions from normal and LIU rat lenses. These blots were scanned using digital image analysis. A newly developed technique was used to compare the complex autoantibody (AAB) repertoires. Five groups of LIU rats were investigated: no treatment; single doses of methylprednisolone (MPR; 7.5 mg/kg body wt.i.v.); allopurinol (AL; 50 mg/kg body wt. i.v.); a combination of both drugs (AL and MPR); repeated application of AL (ALFR; 50 mg/kg body wt.i.v. every 2 weeks during the immunization period and a daily dose of approx. 25 mg/kg body wt. orally). RESULTS: Immunization induced complex antibody repertoires against lens proteins. Antibody repertoires of LIU rats were identical, regardless of whether the proteins were obtained from control, uveitis eyes, or corresponding healthy eyes of the same individual. AL showed a dose-dependent immunological effect in LIU treatment. Given as a single dose, AL revealed no significant change in the AAB repertoire; however, ALFR showed very clear modification of the AAB repertoires compared to both controls and rats receiving steroids. CONCLUSIONS: These results suggest dose-dependent effects of allopurinol in LIU treatment. Repeated application during the immunization period induced a strong immunomodulating effect of AL that was not observed after single doses.

Adjuvants, Immunologic↗
PubMed1997

Orbital tumour as a presenting symptom of breast carcinoma: value of detecting hormone receptors.

A 54-year-old woman was referred for evaluation of an orbital tumour after 5 months of non-specific ophthalmic symptoms. Tissue obtained by an open orbital biopsy was highly suspicious for asymptomatic metastatic breast carcinoma, which was discovered a few weeks later. Unlike the primary tumour, which was an invasive lobular breast carcinoma, the metastatic tissue was repeatedly negative for oestrogen and progesterone receptor markers. A possible reason is a change in cellular cytoplasmic and nuclear protein composition during the metastatic process. Since the primary tumour was positive for the hormone receptors, the patient was treated by chemotherapy and tamoxifen. The follow-up supports a favourable effect of adjuvant endocrinological therapy even in cases with receptor-negative metastatic tissue. This report is in partial contradiction to some previously published cases and emphasises the role of receptor status in the primary tumour.

Biomarkers, Tumor↗
PubMed1996

Hemangiopericytoma of the inner canthus.

PURPOSE: A 31-year-old woman with a mass at the left inner canthus was referred to our hospital. METHODS: Clinical examination failed to establish a diagnosis and the patient underwent an incisional biopsy. RESULTS: Histopathologic examination disclosed a hemangiopericytoma. CONCLUSIONS: Because the behavior of a hemangiopericytoma is unpredictable, this tumor should be included when making a differential diagnosis in lesions of the inner canthus.

Adult↗
PubMed1996

Effects of allopurinol and steroids on inflammation and oxidative tissue damage in experimental lens induced uveitis: a biochemical and morphological study.

AIMS: To evaluate the effects of allopurinol in lens induced uveitis (LIU) by morphological methods and to compare these effects with those of steroids and a combination of both drugs biochemically and morphologically. METHODS: Lipid peroxides (LPO) of the retinal tissue were determined by two different methods (thiobarbituric acid assay (TBA) and high performance liquid chromatography expressed as malondialdehyde-like substances). Myeloperoxidase (MPO) activity in the iris/ciliary body complex was analysed spectrophotometrically. Histological changes on three morphological levels of LIU eyes were evaluated. RESULTS: Both allopurinol and the combination of allopurinol/prednisolone led to a significant reduction in the increaed retinal LPO values. Prednisolone only revealed significant effects on retinal LPO when being measured with the TBA method. MPO activity in iris and ciliary body was significantly reduced in all therapy groups. The morphological evaluation of the sections by two masked investigators revealed a significant reduction (p < 0.05) in the inflammation score in all therapy groups. Morphometric studies using the QUANTIMED system (Leica, Cambridge) showed significantly reduced values (p < 0.05) in the allopurinol group and in the group receiving prednisolone and allopurinol. Prednisolone alone did not lead to a significant reduction in the values. CONCLUSIONS: The findings show that both allopurinol and steroids exert positive effects on the variables determined in LIU. The effects of steroids are believed to be mostly due to their direct action on inflammatory cells. The recently reported scavenging effects of methylprednisolone should play a minor role in this disease model. Allopurinol and oxypurinol act as direct scavengers of free radicals and hypochlorous acid, which is produced via MPO catalysis, thus leading to a reduction in tissue inflammation and tissue damage.

Allopurinol↗
PubMed1996

Monoclonal corneal gammopathy: topographic considerations.

Desposition of immunoglobulins in the cornea occasionally occurs in benign and malignant lymphoproliferative conditions. A 52-year-old woman with recently discovered monoclonal gammopathy of undetermined significance (MGUS) was referred to our hospital. Slit-lamp and ultrasound biomicroscopy revealed bilateral deposits within all corneal layers. The precipitates were organized in a circle, leaving a perilimbal zone and the axial cornea clear. Light microscopy of a biopsy disclosed confluent subepithelial deposits and defects in Bowman's layer. Immunoperoxidase reaction was positive only for IgG and IgG-kappa. Transmission electron microscopy confirmed the presence of extracellular rectangular and arcuate immunoglobulin crystalloids with a 10-nm periodicity but a non-crystalline defraction pattern. A review of the literature showed that the circumferential pattern of immunoglobulin deposition is associated with short-term visual symptoms and good visual acuity. The present report supports a hypothesis of immunoglobulin deposition via the limbal arcade and contradicts the "tear theory."

Biopsy↗
PubMed1995

[Traumatic wound dehiscence and corneal rupture 3 1/2 years after radial keratotomy].

BACKGROUND: Severe complications such as a traumatic wound dehiscence have been described very rarely after radial keratotomy. The following case demonstrates for the first time that wound healing is not completed even 31/2 years postoperatively and that therefore an ocular blunt trauma may still cause a dehiscence of the radial incisions. CASE REPORT: A 22-year-old patient presented in July 1993 to our emergency unit because of a corneal perforation in his right eye after a blunt trauma. His past medical history was significant for radial keratotomy surgery performed in January 1990 to correct a bilateral low-degree myopia (OD = -3.25 D; OS = -3.75 D). At surgery a horizontal rupture running through the entire cornea and including the two radial keratotomies at the 3 and 9 o'clock position was evident. The whole iris and lens were missing. The retina was completely detached. The corneal laceration was sutured. Twelve days later the retina was reattached with an encircling band, vitrectomy, endolaser and cryocoagulation, as well as silicone oil fill. Finally, a penetrating keratoplasty was performed 6 months after the accident. Thereafter, visual acuity improved to 0.1. The histologic examination of the corneal button showed that the wound healing of the incisions that had remained intact was not completed yet. Epithelial plugs of various size were still filling the somewhat dehiscent wound margins. Fibroblastic activity was detected in the surrounding stroma. CONCLUSION: Even several years after surgery, blunt traumas represent a definite risk for eyes undergoing radial keratotomy.

Adult↗