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Biomedical subjects

T Reinhard

Publications and source records attributed to T Reinhard.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Endothelial evaluation of corneal transplants by digital imaging].

BACKGROUND: Evaluation of corneal graft endothelium in organ culture comprises judgement of cell area, cell form and cell density by phase contrast microscopy after cell border swelling in hypotonic solution. Up to now, cell density has been determined via counting cells by hand within a fixed frame on polaroid images regarding the magnification factor. It was the purpose of this paper to establish a facilitated and reliable method for endothelial cell count by digital imaging and to compare it with our standard procedure of endothelial cell count by hand. MATERIAL AND METHODS: After cell border swelling in hypotonic solution endothelial images are recorded by a digital camera that is connected to a computer system where the grey scale images are processed into binary images using specialized enhancement and thresholding techniques. A fuzzy logic based computer program was developed in order to differentiate between single and multiple objects, i.e. living and necrotic cells. This digital imaging system determines endothelial cell density automatically and offers the possibility to correct the data in any case of misinterpretation. Twenty corneal grafts were evaluated with this system by two experienced investigators and the results were compared with endothelial cell count by hand. RESULTS: Using the new system, intra- and interindividual variability of endothelial cell count was statistically significantly lower compared with evaluation by hand. Furthermore, less time for evaluation and documentation was necessary. CONCLUSIONS: In a reduced period of time endothelial cell density of corneal grafts in organ culture can be determined reliably and reproducibly with the new digital imaging system if the possibility of data correction is used in case of misinterpretation. In the future, the necessity of corrections should be reduced and the use of multiple fixed frames should further improve quality control of corneal grafts.

Cell Count↗
PubMed1999

Penetrating keratoplasty in patients with atopic dermatitis with and without systemic cyclosporin A.

PURPOSE: Clinical experience suggests that atopic dermatitis is a considerable risk factor in penetrating keratoplasty. The scientific evidence, however, has been equivocal. Systemic cyclosporin A reduces the threat of immune reactions and simultaneously improves atopic dermatitis. The purpose of this study was to evaluate to what extent and for how long systemic cyclosporin A improves graft prognosis in patients with atopic dermatitis. PATIENTS AND METHODS: Between November 1986 and July 1994, 173 penetrating keratoplasties were performed on keratoconus patients without skin disease (I). Fifteen penetrating keratoplasties were performed on patients with keratoconus associated with slight atopic dermatitis (II), 24 on patients with keratoconus associated with severe atopic dermatitis (III), and 13 on patients with keratitis in atopic dermatitis but without keratoconus (IV). Systemic cyclosporin A was administered for at least 6 months in groups III and IV. Clear graft survival was estimated according to Kaplan and Meier, and statistical significance was evaluated via log-rank test. RESULTS: Six months/6 years postoperatively 99.5 and 96.5% (I), 80 and 80% (II), 96 and 83.2% (III), and 100 and 65.8% (IV) of the grafts were clear. Only the differences between the survival curve of group I and the curves of each of groups II-IV were statistically significant (p < 0.001). CONCLUSIONS: To our knowledge, this is the first study proving that atopic dermatitis with and without keratoconus deteriorates graft prognosis statistically significantly. The application of systemic cyclosporin A improves graft prognosis in atopic dermatitis as long as the drug is applied, and this effect slowly fades thereafter.

Adolescent↗
PubMed1999

Homologous penetrating central limbokeratoplasty in granular and lattice corneal dystrophy.

PURPOSE: Subepithelial recurrences in the graft are well known after conventional penetrating keratoplasties in granular and lattice dystrophies. In contrast to what is still written in most textbooks, both dystrophies have their origin in the epithelium, which originates from the limbal stem cells. The aim of this study, therefore, is to investigate whether recurrences can be avoided or minimized by simultaneous transplantation of healthy donor limbus by means of a homologous central limbokeratoplasty. METHODS: Since October 1995, five patients with granular and four patients with lattice dystrophies were treated with homologous penetrating central limbokeratoplasties. Approximately 40% of the graft's circumference contained limbal donor stem cells. After surgery, cyclosporin A was administered for at least 6 months to protect the limbal stem cells from immunologic destruction. RESULTS: During a follow-up period of 12-35 months, one recurrence was observed, probably because of an immune reaction against the transplanted limbal stem cells after tapering off the immune prophylaxis. CONCLUSION: These first results are in agreement with our expectations. More patients, however, must be operated on in this way. Follow-up must occur for many years before we will definitely know under which conditions long-term survival of donor stem cells occurs to such an extent that subepithelial recurrences in granular and lattice dystrophies stop being a major problem after keratoplasty in these patients.

Adolescent↗
PubMed1999

Mycophenolate mofetil versus cyclosporin A in high risk keratoplasty patients: a prospectively randomised clinical trial.

BACKGROUND/AIMS: The requirement for an effective, minimally toxic immunosuppressive agent remains a major obstacle to performing high risk corneal transplantation. Although therapy with cyclosporin A (CSA) allows superior graft survival, its use is limited because of a wide range of side effects. Mycophenolate mofetil (MMF) has been shown to be a safe and effective immunosuppressive agent following renal transplantation. This prospective, randomised clinical trial was carried out to investigate the efficacy and safety of MMF in preventing corneal allograft rejection. METHODS: Recipients of corneal transplants who were at high risk for graft failure were randomly assigned to either CSA or MMF immunosuppressive therapy. CSA was given in doses to achieve whole blood trough levels of 120-150 ng/ml. MMF was given in a daily dose of 2 g. Both therapy groups additionally received oral corticosteroids (fluocortolone 1 mg/kg) which were tapered and discontinued within the first 3 postoperative weeks. Patients were monitored closely for evidence of corneal graft rejection and adverse side effects. Drug efficacy was measured, primarily, by the number of patients who experienced at least one episode of clinical graft rejection. Safety analysis focused on reported adverse side effects and laboratory measurements. RESULTS: 41 patients were enrolled in the study. There was no statistically significant difference between the two groups. 20 patients received CSA and 21 patients received MMF. Two patients in each group showed evidence of acute graft rejection which could be treated effectively by corticosteroids. All corneal grafts remained clear throughout the follow up. CONCLUSIONS: In this study it was shown that MMF is just as effective as CSA in preventing acute rejection following high risk corneal transplantation. Mycophenolate mofetil represents a promising alternative therapeutic option in patients who are at high risk for corneal graft failure.

Adult↗
PubMed1998

Rapid method for successful HLA class I and II typing from cadaveric blood for direct matching in cornea transplantation.

BACKGROUND: The aim of the study was to establish fast methods for postmortem HLA class I and II typing of cornea donors using cadaveric blood. METHODS: The commercially available reagents Lymphokwik MN and Dynabeads were evaluated here to provide an enriched living mononuclear cell (MNC) population and B-cell population for HLA class I and II typing of cadaveric blood by serology. Cadaveric blood was obtained 1-80 h post mortem. After isolation of living B-cells and B-cell-depleted living MNC's, cells were serologically typed by double-fluorescence cytotoxicity assay for HLA class I and II antigens. RESULTS: In 373 (81%) of 461 cadaveric blood samples HLA class I typing, and in 36 (62%) of 56 cadaveric blood samples HLA-class II typing, by serology was successful and accomplished within 5 h. Results from the serological HLA class I typing were confirmed by the results of HLA class I typing by RNA-based sequencing in seven cases. To improve the HLA class II typing, DNA typing using PCR with sequence-specific primers was performed in 148 samples and reverse hybridization of PCR-amplified DNA to immobilized HLA class II specific primers in 270 samples. These data were confirmed by DNA-based sequencing in five cases and by sequence-specific oligonucleotide hybridization in all cases. CONCLUSIONS: These results lead to the following typing strategy: HLA class I typing should be performed by serology. HLA class II typing should be performed by DNA technology because of its relative independence of the quality of the blood sample. The strategy we have developed is very successful and fast for tissue typing post mortem, thus expanding the time available for ideal HLA matching, increasing the number of available HLA-matched corneas and therefore reducing the number of graft rejections.

Blood Grouping and Crossmatching↗
PubMed1998

A comparative investigation of FK506 and cyclosporin A in murine corneal transplantation.

BACKGROUND: Acute rejection is the cause of over 50% of transplant opacifications in some immunological high-risk groups. More potent immunomodulating substances must be found in order to allow extended or individualised therapeutic options for combating rejection. METHODS: Rats of the inbred strains Brown Norway and Lewis were used as donors and recipients, respectively. FK506 (Prograf) was administered intraperitoneally for 14 days in a dosage of 0.3 mg/kg bw, and cyclosporin A (CSA; Sandimmun) was administered, likewise for 14 days, in an intramuscular dosage of 10 mg/kg bw. The transplants were examined every 3rd day by slit-lamp microscopy. Every transplant was subjected to histological or immunohistological evaluation. RESULTS: The average transplant survival period in the allogeneic strain combination was 7.9 days (SEM = 1.1). Therapy with FK506 led to a statistically significant prolongation of transplant survival to 17.1 days (SEM = 1.5, P < 0.05). Therapy with CSA delayed transplant rejection to 21 days (SEM = 0.0, P < 0.05). No statistically significant difference was found between the two therapeutic regimens. There were no significant histomorphologic differences in rejected grafts in the FK506- and CSA-treated animals. CONCLUSIONS: In this study we have shown that FK506 is able to delay corneal allograft rejection at a much lower dosage than CSA without a higher incidence of side effects related to toxicity or overimmunosuppression.

Animals↗
PubMed1998

[Homologous lamellar central limbokeratoplasty in severe limbal stem cell deficiency].

PURPOSE: It is the purpose of this case report to present a new surgical technique for treatment of severe limbal stem cell deficiency. CASE REPORT: In a 42-year-old female patient with conjunctivalization of the cornea in congenital aniridia a homologous lamellar central limbokeratoplasty was performed. Postoperatively systemic Ciclosporin A was administered in order to prevent the transplanted limbal stem cells from immunological destruction. During the follow-up period of 16 months no immune reaction against the transplanted limbal stem cells could be observed. Visual acuity was ameliorated considerably. CONCLUSIONS: Homologous lamellar central limbokeratoplasty is a promising surgical procedure in selected patients with severe limbal stem cell deficiency having less complications compared with penetrating central limbokeratoplasty.

Adult↗
PubMed1998

[Mycophenolatemofetil in ocular immunological disorders. A survey of the literature with 3 case reports].

BACKGROUND: Up to now ophthalmologists have only a small number of substances in their therapeutic armamentarium for the treatment of ocular immunological disorders. These are very potent agents, and any rapidly proliferating cells are extremely sensitive to such agents, thus the possibility of severe side effects is great. Mycophenolatemofetil (MMF) has been shown to be effective in preventing acute graft rejection following clinical renal and cardiac transplantation with a low risk of adverse events. Likewise MMF was effective in the treatment of experimental immunological disorders. A review of literature was performed in Medline. CASE REPORTS: We report on the effective use of MMF in a patient with ocular cicatricial pemphigoid, the switch from Cyclosporin A (CSA) therapy to MMF therapy following high-risk keratoplasty due to CSA allergy and about the combination therapy (CSA/MMF) in a patient following high risk keratoplasty, in whom CSA monotherapy was not sufficient to prevent allograft rejection. CONCLUSIONS: In these three cases MMF has been shown to be a safe and effective agent for the treatment of ocular immunological disorders. Whether these beneficial casuistic experiences will hold true will be depended on the outcome of longterm studies underway.

Corneal Transplantation↗
PubMed1998

Effect of mycophenolate mofetil, cyclosporin A, and both in combination in a murine corneal graft rejection model.

AIMS: To compare the effectiveness of mycophenolate mofetil (MMF), cyclosporin A (CSA), and both in combination, in preventing rejection following corneal transplantations. METHODS: Rats of the inbred strains Brown Norway and Lewis were used as donors and recipients respectively. MMF was administered orally in both monotherapy and combination therapy for 14 days in a dosage of 40 mg/kg body weight, and CSA was administered, likewise for 14 days, in an intramuscular dosage of 10 mg/kg body weight. The transplants were examined every third day by slit lamp microscopy. Every transplant was subjected to histological or immunohistological evaluation. RESULTS: The average transplant survival rate in the allogenic strain combination was 7.9 days (SEM 1.1). Monotherapy with MMF led to a statistically significant prolongation of transplant survival to 11.6 days (SEM 0.9, p < 0.05). Monotherapy with CSA delayed transplant rejection statistically significantly longer than MMF (21 days, 0.0, p < 0.05). The combination therapy with CSA and MMF was statistically significantly superior to the monotherapy with MMF (22.3 days, 0.5, p < 0.05). The combination therapy prolonged transplant survival compared with the CSA monotherapy, albeit not to a statistically significant extent. CONCLUSIONS: In this study we were able to prove the immunosuppressive effect of oral MMF on acute rejection following corneal transplantation. Double drug therapy with CSA and MMF conferred a marginal benefit without a higher incidence of complications related to drug toxicity or overimmunosuppression.

Animals↗
PubMed1997

The influence of glaucoma history on graft survival after penetrating keratoplasty.

BACKGROUND: It was the purpose of this retrospective study to evaluate the effect of a preoperative history of glaucoma on graft survival after penetrating keratoplasty. PATIENTS AND METHODS: Six hundred and forty-six penetrating keratoplasties with generally good prognosis were analyzed retrospectively. Indications for surgery were corneal dystrophy, degeneration and scarring. Only first keratoplasties in corneas without severe vascularization or acute inflammation were included. Surface disorders, a history of herpes or Acanthamoeba keratitis were further exclusion criteria. Keratoplasties were performed only if glaucoma seemed to be controlled preoperatively. Graft survival ratios were calculated according to Kaplan and Meier, and statistical significance was evaluated by means of the log-rank test. RESULTS: With a glaucoma history the estimated 3-year graft survival rate was 71%, in contrast to 89% without such a history. This difference was statistically significant (P < 0.001). There was no difference between the groups with respect to immune reactions. With a glaucoma history, postoperative episodes of glaucoma decompensation were responsible for half of the graft failures. CONCLUSIONS: A preoperative history of glaucoma affects graft prognosis negatively, presumably through a negative influence of postoperatively elevated intraocular pressure on a vulnerable graft endothelium, and not by an increase in immune reactions. Therefore, keratoplasties in eyes with glaucoma are high-risk procedures and glaucoma has to be monitored more efficiently pre- and postoperatively.

Adolescent↗
PubMed1997

[Therapy of advanced amoeba keratitis with keratoplasty à chaud and adjuvant cryotherapy].

BACKGROUND: Since the mid-1980s acanthamoeba keratitis has been diagnosed with increasing frequency, especially in contact lens wearers. The assignment to specialized centers is often delayed many months and there is hardly any chance of controlling the disease by conservative treatment alone. In these cases, penetrating keratoplasty offers the only chance for rehabilitation. The therapeutic role of penetrating keratoplasty and supportive intraoperative cryotherapy is demonstrated by the courses of six patients with unilateral acanthamoeba keratitis. PATIENTS AND METHODS: The data of six patients aged 41.2 (22-63) years with medically uncontrollable acanthamoeba keratitis were evaluated retrospectively. The diagnosis was confirmed histologically in all cases. All patients were contact lens wearers. They underwent a total of ten keratoplasties between November 1986 and January 1995. The donors were 44.8 (23-58) years of age. The transplant diameters varied between 7.7 and 9.5 mm. The margins of the host cornea were intraoperatively frozen by a cryoprobe in three patients with a far advanced stage of corneolimbal parasitic infiltration. RESULTS: During a follow-up period of +/-10.2 (1-22) months, five of six eyes were rehabilitated with visual acuities between 0.4 and 1.0. One eye went blind after the fourth keratoplasty because of uncontrollable secondary glaucoma. After three keratoplasties with simultaneous application of cryocoagulation because of an especially high risk of persisting acanthamoeba infection, all corneae remained clear and free of recurrences. CONCLUSIONS: In advanced acanthamoeba keratitis which has not responded to conservative treatment, penetrating keratoplasty not only provides elimination of the pathogen, but also good functional results. In far advanced stages, the intraoperative application of cryocoagulation for parasite elimination in the host cornea seems to be a very effective measure against local recurrences of the infection.

Acanthamoeba Keratitis↗
PubMed1997

[Preventive systemic cyclosporin A after keratoplasty at increased risk for immune reactions as the only elevated risk factor].

BACKGROUND: In this retrospective study our aim was to evaluate the effectiveness of systemic cyclosporin A (CsA) after keratoplasties with an elevated risk for immune reactions as the only elevated risk factor. PATIENTS AND METHODS: Between November 1986 and June 1994, 1121 penetrating keratoplasties, 646 normal-risk and 475 high-risk keratoplasties were performed. In 130 out of the 475 high-risk keratoplasties an elevated risk for immune reactions was the only elevated risk factor. Twenty-six of these 130 high-risk keratoplasties were treated with systemic CsA. RESULTS: In the high-risk group keratoplasties with an elevated risk for immune reactions as the only elevated risk factor no permanent graft failure occurred with CsA (100% clear grafts). Without CsA the percentage of clear grafts in this high risk group was only 71.7% according to Kaplan Meier 3 years postoperatively in contrast to 86.0% in normal-risk keratoplasties. The differences between these three groups were statistically significant. In the high-risk group keratoplasties with on elevated risk for immune reactions as the only elevated risk factor more immune reactions occurred than without CsA or than in normal-risk keratoplasties. However, these immune reactions were mostly of the benign chronic types. CONCLUSIONS: Systemic CsA considerably improves graft prognosis after high-risk keratoplasties with an elevated risk for immune reactions as the only elevated risk factor. With CsA application we observed a significant shift from acute to chronic immune reactions, which respond much better to topical steroids.

Cyclosporine↗
PubMed1997

[Corneoscleral transplant excision in the cadaver. Experiences of the North Rhine Westphalia Lions Cornea Bank 1995 and 1996].

BACKGROUND: Donor corneas are normally obtained by whole globe enucleation-a procedure often refused by the bereaved. To increase the acceptance of cornea donation, we have exclusively obtained donor corneas by in situ excision since the end of 1994. There have been reports of increased endothelial damage and higher contamination rates. We report our experience in 1995 and 1996. METHODS: The in situ excision was performed by staff trained in microsurgical techniques. Only donor corneas with negative end-storage cultures after at least 10 days and an endothelial cell count of more than 2500 cells/mm2 were used for transplantation. RESULTS: In all, 705 corneoscleral buttons were excised from 1/95 to 12/96. The bereaved consented in 34% in 1996. A total of 30.5% of the corneas were ineligible for transplantation which corresponds to the discard figures from all cornea banks with culture methods. We did not observe any primary transplant failure nor endophthalmitis after 444 perforating keratoplasties. CONCLUSION: In situ corneal excision is safe, and helps to reduce the shortage in donor corneas.

Cadaver↗
PubMed1997

[Postoperative complications of penetrating keratoplasty in herpes infected eyes. Differential diagnosis, therapy and prognostic significance].

BACKGROUND: We evaluated in this retrospective study the impact of our diagnostic and therapeutic regimens--as illustrated by typical clinical pictures--on the frequency and prognostic values of postkeratoplasty complications in herpes eyes. PATIENTS AND METHODS: Between November 1986 and June 1994, 112 penetrating keratoplasties (KPS) in herpes eyes were performed, 76 as planned and 36 as emergency procedures. The results were compared with 646 KPS with normal risk. For statistical analysis we used the Kaplan-Meier estimation, and statistical significance was tested by the log rank test. RESULTS: After 6 years, 75% of the grafts in the planned herpes group, 86% of the à chaud KPS and 76% of the grafts of the normal-risk group were still clear without significant differences between these three groups. Fifty-four percent of the planned KPS in herpes eyes, 73% of the à chaud KPS in herpes eyes and 80% of the normal-risk KPS experienced no immune reaction, with both herpes groups showing significantly more reactions than the normal-risk KPS. There was, however, no significant difference in immune reactions between the two herpes groups. The percentage of grafts with recurrence of herpes simplex virus infection after 6 years was significantly higher in the à chaud group. CONCLUSIONS: With proper postoperative care and optimal management of immunologic and virologic complications--but only with this!--the prognosis of penetrating keratoplasties in herpes eyes equals that of normal risk eyes. An particular, the prognosis is not dependent on whether surgery was performed as a planned or as an emergency procedure.

Diagnosis, Differential↗
PubMed1997

[Homologous central limbo-keratoplasty in limbus stem cell damage. Retrospective study of 3 years' experience].

BACKGROUND: Problems with epithelial healing are the main cause of corneal graft failure in patients with limbal stem cell deficiency. This post-operative complication cannot be eliminated by conventional penetrating keratoplasty alone, but only by additional limbal grafting, which is, however, highly immunogenic. We report here our 3 years' experience with a new surgical procedure which we developed called homologous central limbokeratoplasty. PATIENTS AND METHODS: We have performed 52 homologous central limbo-keratoplasties in patients with limbal stem cell deficiency since February 1993. We report here the results of the first 18 transplantations with the longest follow-up periods (mean 22 months). The unmatched donor cornea was trephined in a way such that 40% of its circumference contained limbus. These grafts were then sutured centrally into the host cornea. Systemic cyclosporin A (CSA) was administered for at least 1 year after all transplantations. RESULTS: Fourteen of the 18 grafts failed during the follow-up period. The reasons for graft failure were severe surface disorders (7), severe surface disorders in combination with endothelial immune reactions (5) and endothelial immune reactions alone (2). The four patients with centrally clear grafts no longer receive systemic CSA with follow-up periods between 20 and 30 months. CONCLUSIONS: Central limbo-keratoplasty is a very promising procedure. However, the average results are not yet satisfying, because the majority of limbal stem cells undergo rejection within 2 years. Improved results will be achievable in the future by using well-matched instead of non-matched transplants and by further improving immune modulation beyond the effectiveness of current CSA treatment.

Adolescent↗