Sonja Heinzelmann

Multiple protective functions of catalase against intercellular apoptosis-inducing ROS signaling of human tumor cells

Abstract Tumor cells are protected against intercellular reactive oxygen species (ROS)-mediated apoptosis signaling mediated by the HOCl and/or the nitric oxide (NO)/peroxynitrite signaling pathway. We have recently shown that tumor cell resistance against HOCl signaling can be abrogated through inhibition of catalase. The protection of tumor cells against the NO/peroxynitrite signaling pathway has remained enigmatic so far. Here, we show that suboptimal inhibition of catalase by 3-aminotriazole or a monoclonal antibody against catalase, as well as partial knockdown of catalase by specific siRNA allows selective reactivation of the NO/peroxynitrite pathway in MKN 45 gastric carcinoma cells, followed by the HOCl pathway at higher inhibitor or siRNA concentrations. In SKN-MC Ewing sarcoma cells, catalase inhibition causes apoptosis induction solely based on the NO/peroxynitrite pathway. Protection against NO/peroxynitrite signaling is shown to be due to the potential of catalase to decompose peroxynitrite. The direct interaction of catalase with peroxynitrite is verified through the detection of compound I (CAT FeIV=O+·) after the interaction of peroxynitrite with catalase. In a complementary experiment, addition of catalase protects sensitive transformed cells against ROS-mediated apoptosis induction. Thus, the expression of membrane-associated catalase is sufficient to protect tumor cells against multiple intercellular ROS-mediated signaling pathways.

Giant Cell Arteritis: Diagnostic Accuracy of MR Imaging of Superficial Cranial Arteries in Initial Diagnosis—Results from a Multicenter Trial

PURPOSE To assess the diagnostic accuracy of contrast material-enhanced magnetic resonance (MR) imaging of superficial cranial arteries in the initial diagnosis of giant cell arteritis ( GCA giant cell arteritis ). MATERIALS AND METHODS Following institutional review board approval and informed consent, 185 patients suspected of having GCA giant cell arteritis were included in a prospective three-university medical center trial. GCA giant cell arteritis was diagnosed or excluded clinically in all patients (reference standard [final clinical diagnosis]). In 53.0% of patients (98 of 185), temporal artery biopsy ( TAB temporal artery biopsy ) was performed (diagnostic standard [ TAB temporal artery biopsy ]). Two observers independently evaluated contrast-enhanced T1-weighted MR images of superficial cranial arteries by using a four-point scale. Diagnostic accuracy, involvement pattern, and systemic corticosteroid ( sCS systemic corticosteroid ) therapy effects were assessed in comparison with the reference standard (total study cohort) and separately in comparison with the diagnostic standard TAB temporal artery biopsy ( TAB temporal artery biopsy subcohort). Statistical analysis included diagnostic accuracy parameters, interobserver agreement, and receiver operating characteristic analysis. RESULTS Sensitivity of MR imaging was 78.4% and specificity was 90.4% for the total study cohort, and sensitivity was 88.7% and specificity was 75.0% for the TAB temporal artery biopsy subcohort (first observer). Diagnostic accuracy was comparable for both observers, with good interobserver agreement ( TAB temporal artery biopsy subcohort, κ = 0.718; total study cohort, κ = 0.676). MR imaging scores were significantly higher in patients with GCA giant cell arteritis -positive results than in patients with GCA giant cell arteritis -negative results ( TAB temporal artery biopsy subcohort and total study cohort, P < .001). Diagnostic accuracy of MR imaging was high in patients without and with sCS systemic corticosteroid therapy for 5 days or fewer (area under the curve, ≥0.9) and was decreased in patients receiving sCS systemic corticosteroid therapy for 6-14 days. In 56.5% of patients with TAB temporal artery biopsy -positive results (35 of 62), MR imaging displayed symmetrical and simultaneous inflammation of arterial segments. CONCLUSION MR imaging of superficial cranial arteries is accurate in the initial diagnosis of GCA giant cell arteritis . Sensitivity probably decreases after more than 5 days of sCS systemic corticosteroid therapy; thus, imaging should not be delayed. Clinical trial registration no. DRKS00000594 .

Influence of donor characteristics on descemet membrane endothelial keratoplasty.

Purpose: Penetrating keratoplasty is being replaced by posterior lamellar techniques like Descemet stripping automated endothelial keratoplasty or Descemet membrane endothelial keratoplasty (DMEK) for the surgical treatment of patients with endothelial insufficiency. Although DMEK leads to the best visual results, Descemet stripping automated endothelial keratoplasty is still the standard procedure for many surgeons because it is technically more standardized. Here, we investigated how donor characteristics may influence DMEK surgery. Methods: After in vitro preparation of DMEK grafts (n = 28), we measured the width of the graft roll, which we correlated to various donor characteristics. In 31 DMEK cases, we measured the intraoperative time from implantation to attachment of the graft, which we correlated to the respective donor characteristics and endothelial cell loss. We used Pearsons method and a multifactorial linear model for the statistical assessments. Results: We found a statistically significant correlation between donor age (P < 0.001) and endothelial cell density (P < 0.05), and the width of the DMEK rolls. That is, older donors and grafts with higher endothelial cell densities formed broader graft rolls. Donor age also showed a trend to directly influence the unfolding time that took longer using younger grafts. Furthermore, the relative endothelial cell loss increased with longer unfolding times. Conclusions: We found that donor age and endothelial cell density influence the properties of DMEK grafts, and thereby the duration of the surgical procedure. Increased unfolding times result in higher endothelial cell loss. Therefore, it seems reasonable to accept preferably older donors with high endothelial cell densities for DMEK, which may be particularly true for inexperienced surgeons or complex clinical situations.

Cystoid macular oedema following Descemet membrane endothelial keratoplasty

Background To determine the incidence and potential risk factors of cystoid macular oedema (CMO) following Descemet membrane endothelial keratoplasty (DMEK) with or without simultaneous cataract surgery. Methods In this study, 155 eyes of 88 patients suffering from Fuchs endothelial dystrophy (81%), bullous keratopathy (17.6%) or other corneal diseases (1.4%) underwent DMEK. 52% were pseudophacic (DMEK) and 48% received simultaneous cataract surgery (DMEK combined with cataract surgery (Triple-DMEK)) at the Eye Center at Albert Ludwigs University of Freiburg between May 2011 and June 2013. Spectral-domain optical coherence tomography (SD-OCT) was performed 6 weeks, 3 months and 6 months following (Triple-)DMEK and in unscheduled visits due to limited or decreased visual acuity. The medical records were reviewed for pre-existing comorbidities limiting visual acuity. Patients with a history of macular oedema were excluded. We estimated the incidence of CMO using the Kaplan–Meier method. Potential risk factors for CMO were analysed with a Cox regression analysis and Pearsons correlation. The Cox model included the following variables: patient age and axial length, simultaneous cataract surgery, rate of rebubbling, donor age and donor endothelial cell density. Results 13% of all eyes developed a single episode of CMO at the end of the follow-up. After 6 months, 13.3% of eyes following Triple-DMEK and 12.5% of eyes following DMEK showed CMO. There was a statistically significant correlation between CMO development and best spectacle corrected visual acuity. Long axial length had a protective effect on CMO development (HR=0.3; p=0.03). Under medical therapy, central foveal thickness decreased in all patients. CMO did not have a relevant effect on long-term visual acuity. Conclusions CMO is a frequent complication following DMEK in phacic and pseudophacic eyes. The prognosis is excellent given medical treatment. We recommend regular SD-OCT monitoring during the first 6 months following DMEK.

Interleukin-2 Receptor and Angiotensin-Converting Enzyme as Markers for Ocular Sarcoidosis.

Purpose To study the impact of soluble IL2 receptor (sIL2R), chest x-ray (CxR), and angiotensin-converting enzyme (ACE) as markers for sarcoidosis in uveitis patients. Design Retrospective study. Methods Serum concentrations of sIL2R and ACE were measured in patients with active uveitis. Those with elevated sIL2R and /or ACE values were examined for suspected systemic sarcoidosis. Main Outcome Measure Our main outcome parameters were the specificity and sensitivity of sIL2R, CxR and ACE in screening for ocular sarcoidosis. Results We measured 261 patients with uveitis for sarcoidosis using sIL2R and ACE between January 2008 and November 2011; sarcoidosis was been diagnosed using other tests (e.g. computer tomography, brochoalveolar lavage, biopsy) in 41 of 53 patients with elevated sIL2R values (>639 U/ml) and in one patient with normal sIL2R (582 U/ml). Their mean sIL2R value was 1310 U/ml, extending from 582 to 8659 U/ml. Only 9 patients, however, presented elevated ACE (>82 U/l). Their mean ACE value was 116.4 U/l, ranging from 84.1 to 175.5 U/l. IL2R specificity was 94% with 98% sensitivity. In contrast, ACE had a specificity of 99.5%, but a sensitivity of only 22%; the chest x-ray had a specificity of 100% with 50% sensitivity in detecting sarcoidosis. We observed the entire spectrum of uveitis: sixteen patients suffered from anterior, 8 from intermediate, 16 from posterior, and 2 from panuveitis. Conclusions An elevated level of soluble IL2R suggests sarcoidosis with uveitis more convincingly than ACE, making sIL2R a more effective marker parameter for sarcoidosis than ACE or chest x-ray in uveitis patients.

Correlation between visual acuity and interface reflectivity measured by pentacam following DSAEK

Purpose:  Descemet‐stripping automated endothelial keratoplasty (DSAEK) is an advanced method of lamellar endothelial keratoplasty. In comparison with penetrating keratoplasty, visual rehabilitation seems to be faster. Final visual outcome of DSAEK, however, seems to be limited, especially in comparison with Descemet membrane endothelial keratoplasty (DMEK). DSAEK cases without graft failure often do not show any definite correlate for the reduced optical performance. In this study, we tried to correlate visual acuity following DSAEK with interface reflectivity as measured by a rotating Scheimpflug system.

Extracellular localization of catalase is associated with the transformed state of malignant cells

Abstract Oncogenic transformation is dependent on activated membrane-associated NADPH oxidase (NOX). However, the resultant extracellular superoxide anions are also driving the NO/peroxynitrite and the HOCl pathway, which eliminates NOX-expressing transformed cells through selective apoptosis induction. Tumor progression is dependent on dominant interference with intercellular apoptosis-inducing ROS signaling through membrane-associated catalase, which decomposes H2O2 and peroxynitrite and oxidizes NO. Particularly, the decomposition of extracellular peroxynitrite strictly requires membrane-associated catalase. We utilized small interfering RNA (siRNA)-mediated knockdown of catalase and neutralizing antibodies directed against the enzyme in combination with challenging H2O2 or peroxynitrite to determine activity and localization of catalase in cells from three distinct steps of multistage oncogenesis. Nontransformed cells did not generate extracellular superoxide anions and only showed intracellular catalase activity. Transformed cells showed superoxide anion-dependent intercellular apoptosis-inducing ROS signaling in the presence of suboptimal catalase activity in their membrane. Tumor cells exhibited tight control of intercellular apoptosis-inducing ROS signaling through a high local concentration of membrane-associated catalase. These data demonstrate that translocation of catalase to the outside of the cell membrane is already associated with the transformation step. A strong local increase in the concentration of membrane-associated catalase is achieved during tumor progression and is controlled by tumor cell-derived H2O2 and by transglutaminase.

Perspektiven der hinteren lamellären Keratoplastik

ZusammenfassungEndothelerkrankungen der Augenhornhaut wie die Fuchs-Endotheldystrophie und die bullöse Keratopathie gehören zu den häufigsten Indikationen für eine Keratoplastik. Der Ersatz der kompletten Hornhaut durch eine perforierende Keratoplastik (PKP) war bislang der Standardeingriff zur Behandlung der Endothelinsuffizienzen. In jüngster Vergangenheit wurden jedoch neue, progressive operative Techniken zum selektiven Endothelersatz entwickelt. Dies sind die „Descemet stripping (automated) endothelial keratoplasty“ [DS(A)EK], die „Descemet membrane endothelial keratoplasty“ (DMEK) und Hybridverfahren dieser beiden Operationstechniken. Vor- und Nachteile der lamellären und der perforierenden Verfahren machen deutlich, dass vergleichende Studien notwendig sind, um herauszufinden, welche Technik für welchen Patienten im Hinblick auf eine lang anhaltende visuelle Rehabilitation sinnvoll ist.AbstractCorneal endothelial diseases, such as Fuchs’ endothelial dystrophy and bullous keratopathy represent the most common indications for keratoplasty. Replacement of the entire cornea by penetrating keratoplasty has been the gold standard in treating corneal endothelial diseases for many decades. However, recently new and innovative surgical techniques for selective endothelial replacement have been developed. These are Descemet stripping (automated) endothelial keratoplasty (DS(A)EK), Descemet membrane endothelial keratoplasty (DMEK) and hybrid techniques of both. The distinct advantages and drawbacks of lamellar and penetrating techniques reveal the need of comparative studies to find out which method is suitable for which patient, particularly with regard to long-term visual rehabilitation.

Perspectives of posterior lamellar keratoplasty. In search of the perfect lamella

ZusammenfassungEndothelerkrankungen der Augenhornhaut wie die Fuchs-Endotheldystrophie und die bullöse Keratopathie gehören zu den häufigsten Indikationen für eine Keratoplastik. Der Ersatz der kompletten Hornhaut durch eine perforierende Keratoplastik (PKP) war bislang der Standardeingriff zur Behandlung der Endothelinsuffizienzen. In jüngster Vergangenheit wurden jedoch neue, progressive operative Techniken zum selektiven Endothelersatz entwickelt. Dies sind die „Descemet stripping (automated) endothelial keratoplasty“ [DS(A)EK], die „Descemet membrane endothelial keratoplasty“ (DMEK) und Hybridverfahren dieser beiden Operationstechniken. Vor- und Nachteile der lamellären und der perforierenden Verfahren machen deutlich, dass vergleichende Studien notwendig sind, um herauszufinden, welche Technik für welchen Patienten im Hinblick auf eine lang anhaltende visuelle Rehabilitation sinnvoll ist.AbstractCorneal endothelial diseases, such as Fuchs’ endothelial dystrophy and bullous keratopathy represent the most common indications for keratoplasty. Replacement of the entire cornea by penetrating keratoplasty has been the gold standard in treating corneal endothelial diseases for many decades. However, recently new and innovative surgical techniques for selective endothelial replacement have been developed. These are Descemet stripping (automated) endothelial keratoplasty (DS(A)EK), Descemet membrane endothelial keratoplasty (DMEK) and hybrid techniques of both. The distinct advantages and drawbacks of lamellar and penetrating techniques reveal the need of comparative studies to find out which method is suitable for which patient, particularly with regard to long-term visual rehabilitation.

Instrumented indentation for determination of mechanical properties of human cornea after ultraviolet-A crosslinking: MECHANICAL PROPERTIES OF HUMAN CORNEA

UVA crosslinking is used for treatment of corneal diseases such as keratoconus in order to stabilize the corneal tissue by crosslinking of the collagen fibers. It has been shown that the crosslinking treatment leads to a stiffening of the central corneal tissue. However, knowledge of lateral extent of the corneal stiffening as well as a systematic study of the mechanical response of human cornea is still missing. In our study we measured the stiffness (elastic modulus) of the anterior surface of healthy and crosslinked human corneas by instrumented indentation using a spherical indenter. The results show that the stiffness of the central and paracentral cornea increased almost two times after the crosslinking but the stiffening effect rapidly decreased towards the periphery of the radiation field. These new insights into the understanding of the biomechanical response of corneal crosslinking shall contribute to a better understanding and an optimization of this perspective medical treatment.