[Good practice procedures for acquisition and preparation of cryopreserved human amniotic membranes from donor placentas]. / Gute fachliche Praxis zur Gewinnung und Herstellung von kryokonservierter humaner Amnionmembran aus Spenderplazenta.

Within the framework of obtaining a valid authorization for tissue preparation of cryopreserved human amniotic membranes at the Paul Ehrlich Institute, pursuant to § 21a paragraph 1 of the German Medicines Act (AMG), parts of the existing good practice procedures for acquisition of cryopreserved human amniotic membranes from donor placentas were reviewed and supplemented by new knowledge. The present good practice procedures were formulated in cooperation with members of the section for tissue transplantation and biotechnology of the German Ophthalmological Society. The current revised version is presented in this article.

[Atypical genesis of anterior ischemic optic neuropathy]. / Atypische Genese einer anterioren ischämischen Optikusneuropathie.

BACKGROUND: This article presents a case of arteritic anterior ischemic optic neuropathy as a manifestation of granulomatosis with polyangiitis (GPA). CASE REPORT: A 52-year-old woman suffered acute unilateral vision loss. Besides a unilateral papillary edema, serological investigations revealed elevated inflammation parameters with a positive (cytoplasmic) anti-neutrophil cytoplasmic autoantibodies (c-ANCA) titer. In addition to the occurrence of pulmonary nodules and cavitary lesions this is indicative for the diagnosis of GPA. RESULTS: Treatment with cyclophosphamide and prednisolone led to a rapid regression of inflammation parameters but no visual improvement occurred.

[Microkeratome and excimer laser-assisted endothelial keratoplasty (MELEK)]. / Mikrokeratom- und Excimer-Laser-gestützte endotheliale Keratoplastik (MELEK).

INTRODUCTION: Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) have become well established procedures for the treatment of endothelial pathologies. In the last years the field of lamellar corneal surgery has further developed in terms of preparation of the lamellae as well as of implantation. PATIENTS AND METHODS: A modified form of the "ultrathin DSAEK" (UT-DSAEK) is the "microkeratome and excimer laser-assisted endothelial keratoplasty" (MELEK). In this new technique a corneal graft is prepared by a single cut of a microkeratome followed by a stromal excimer-laser thinning and smoothing. The purpose of the present report is to describe this new technique and present first clinical results. RESULTS: In this prospective clinical study 18 patients (76 ± 11 years) underwent a MELEK. The BCVA increased from 0.25 ± 0.1 preoperatively to one month postoperatively was 0.33 ± 0.21 (decimal, n = 12), after three months 0.51 ± 0.23 (n = 8) and after six months 0.80 ± 0.16 (n = 4). The average thickness of the residual stromal lamella before laser ablation was 173 ± 42 µm, after ablation 111 ± 15 µm. The central corneal thickness decreased from 704 µm to 639 µm, the thickness of the transplant decreased from 114 µm to 106 µm six months postoperatively. CONCLUSION: The ultrathin "microkeratome and excimer laser-assisted endothelial keratoplasty" (MELEK) is a new and safe technique in the field of lamellar keratoplasty. In the future it could have the potential to combine the advantages of DSAEK and DMEK for the treatment of endothelial pathologies.

[Ophthalmologic screening history and vision-targeted health status of patients suffering from chloroquine maculopathy]. / Screeninganamnese und sehkraftbezogene Lebensqualität von Patienten mit Chloroquin-Makulopathie.

BACKGROUND: Maculopathy or retinopathy can develop as a side effect of chloroquine intake. Despite recommendations for ophthalmologic screening by the American Academy of Ophthalmology (AAO) severe toxic retinal damage still occurs. This study aims to clarify how maculopathy affects patient quality of life and whether it arises only due to non-compliance with screening guidelines. METHODS: Patients suffering from chloroquine maculopathy were questioned about the ophthalmologic examinations that took place under therapy and completed a German version of the 25 item visual function questionnaire (VFQ-25). RESULTS: A total of ten female patients were included in the analysis. Weighted visual acuity ranged from 0.09 to 0.8. Median composite score of the VFQ-25 was 33.9. All patients were periodically screened for ocular toxicity with a median trimestrial screening frequency but five patients did not receive all recommended methods of examination. There was suspicion of retinal damage in only one patient even without the patient reporting complaints. Median time span between onset of visual complaints and the cessation of the drug was 12 months. All patients with complaints reported a continuing deterioration of vision even after cessation. CONCLUSIONS: Chloroquine maculopathy has a major impact on the vision-related health status of affected patients, emphasizing the need for its anticipation. Although patients were screened even more frequently than recommended by the AAO only half were examined properly and nine out of ten patients had a delay in diagnosis and in drug cessation. The continuing deterioration of vision even after termination of intake further contributes to the severity of the disease.

[Unusual presentation of a Langerhans cell histiocytosis]. / Ungewöhnliche Präsentation einer Langerhans-Zell-Histiozytose.

A 16-month-old male infant was presented with swelling of the left upper eye lid 4 weeks after a blunt orbital trauma. A prolonged hematoma was suspected and the child was discharged with an appointment 4 weeks later. However, the child was presented again with progressive swelling of the lid 10 days later. Magnetic resonance imaging (MRI) showed a tumor extending from the frontal bone to the anterior cranial fossa and into the orbit. An incisional biopsy led to the diagnosis of orbital Langerhans cell histiocytosis and systemic therapy led to complete remission of the tumor. Prolonged periorbital swelling must always prompt further diagnostics even when patients present with a history of trauma.

Comparative infectious serology testing of pre- and post-mortem blood samples from cornea donors.

Defined serological blood tests of deceased cornea donors are required to minimize the risk of viral infections of a transplant recipient as much as possible. Haemolysis, autolysis and bacterial contamination, may produce significant changes of post-mortem blood samples, which may lead to false serological test results. Pre- and post-mortem findings from the same cornea donors of the University Tissue Bank of the Charité in the years 2004-2009 (n = 487) were retrospectively analyzed and compared. The test results from pre-mortem blood samples were defined as the reference for the post-mortem blood test. Of 487 cornea donors, there were a total of 21 cases (4.3%) with discrepancies between serological test results from pre- and post-mortem blood samples. Of these, 7 values referred to the HBsAg-testing, 3 to the anti-HBs-, 1 to the anti-HBcIgG + IgM-, 1 to the anti-HCV-, 4 to the anti-HIV 1/2- and 5 to the TPLA-findings. False negative results within post-mortem serology occurred in 4 of 487 cases (0.8%). False positive results within the post-mortem blood samples occurred at a much more frequent rate, with 17 of 487 cases (3.5%). Discrepancies between serological pre- and post-mortem blood tests occur mainly due to the use of non-validated test systems. Therefore, it seems reasonable to test pre- and post-mortem blood samples serologically, whenever possible, at the same time, regardless of the sample age. Positive results, regardless of the sample type, should always be retested with validated confirmation tests (e.g. NAT), in order to differentiate between false and true positive results.

A lung dosimetry model of vapor uptake and tissue disposition.

Inhaled vapors may be absorbed at the alveolar-capillary membrane and enter arterial blood flow to be carried to other organs of the body. Thus, the biological effects of inhaled vapors depend on vapor uptake in the lung and distribution to the rest of the body. A mechanistic model of vapor uptake in the human lung and surrounding tissues was developed for soluble and reactive vapors during a single breath. Lung uptake and tissue disposition of inhaled formaldehyde, acrolein, and acetaldehyde were simulated for different solubilities and reactivities. Formaldehyde, a highly reactive and soluble vapor, was estimated to be taken up by the tissues in the upper tracheobronchial airways with shallow penetration into the lung. Vapors with moderate solubility such as acrolein and acetaldehyde were estimated to penetrate deeper into the lung, reaching the alveolar region where absorbed vapors had a much higher probability of passing through the thin alveolar-capillary membrane to reach the blood. For all vapors, tissue concentration reached its maximum at the end of inhalation at the air-tissue interface. The depth of peak concentration moved within the tissue layer due to vapor desorption during exhalation. The proposed vapor uptake model offers a mechanistic approach for calculations of lung vapor uptake, air:tissue flux, and tissue concentration profiles within the respiratory tract that can be correlated to local biological response in the lung. In addition, the uptake model provides the necessary input for pharmacokinetic models of inhaled chemicals in the body, thus reducing the need for estimating requisite parameters.

Intrathecal EBV antibodies are part of the polyspecific immune response in multiple sclerosis.

OBJECTIVE: One mechanism underlying the link between multiple sclerosis (MS) and Epstein-Barr virus (EBV) might be a direct CNS infection. Viral CNS infections cause elevated antibody indices (AIs). Elevated EBV AIs were found in MS; however, patients with MS frequently show a polyspecific intrathecal immune response with elevated antiviral AIs. To discriminate whether elevated EBV AIs indicate a virus-driven or a polyspecific intrathecal immune response, we determined the intrathecal fraction of anti-EBV antibodies. METHODS: The fraction of intrathecally synthesized EBV-specific immunoglobulin G (IgG) of the total intrathecally synthesized IgG (F(S) anti-EBV) was determined in 24 patients with a clinically isolated syndrome (CIS) or MS and 3 patients with cerebral posttransplantation lymphoproliferative disorder (PTLD), all of whom had elevated EBV AIs. F(S) anti-measles and AIs for measles, rubella, varicella zoster, and herpes simplex virus were measured as well. The prevalence of an elevated EBV AI was analyzed in another 36 patients with CIS. RESULTS: Median F(S) anti-EBV in patients with CIS/MS was low (0.65%) and did not differ from F(S) anti-measles (0.9%). Median F(S) anti-EBV was about 40-fold higher in patients with cerebral PTLD than in patients with CIS/MS. All 24 patients with CIS/MS with an elevated EBV AI had at least one further elevated antiviral AI. Only 2 of 36 (5.6%) patients with CIS showed an intrathecal synthesis of anti-EBV antibodies. CONCLUSIONS: Intrathecally produced anti-EBV antibodies are part of the polyspecific intrathecal immune response in CIS/MS and only rarely detectable in patients with CIS, both arguing against a direct CNS infection with EBV in patients with CIS/MS.

Derivation of mass transfer coefficients for transient uptake and tissue disposition of soluble and reactive vapors in lung airways.

Evaluation of vapor uptake by lung airways and subsequent dose to lung tissues provides the bridge connecting exposure episode to biological response. Respiratory vapor absorption depends on chemical properties of the inhaled material, including solubility, diffusivity, and metabolism/reactivity in lung tissues. Inter-dependent losses in the air and tissue phases require simultaneous calculation of vapor concentration in both phases. Previous models of lung vapor uptake assumed steady state, one-way transport into tissues with first-order clearance. A new approach to calculating lung dosimetry is proposed in which an overall mass transfer coefficient for vapor transport across the air-tissue interface is derived using air-phase mass transfer coefficients and analytical expressions for tissue-phase mass transfer coefficients describing unsteady transport by diffusion, first-order, and saturable pathways. Feasibility of the use of mass transfer coefficients was shown by calculating transient concentration levels of inhaled formaldehyde in the human tracheal airway and surrounding tissue. Formaldehyde tracheal air concentration and wall-flux declined throughout the breathing cycle. After the inhalation period, peak tissue concentration moved from the air-tissue interface into the tissue due to desorption into the air and continued diffusional transport across the tissue layer. While model predictions were performed for formaldehyde, which serves as a model of physiologically relevant, highly reactive vapors, the model is equally applicable to other soluble and reactive compounds.

Evaluation of risk factors for retinal damage due to chloroquine and hydroxychloroquine.

BACKGROUND/AIMS: To evaluate risk factors for retinal damage due to the intake of chloroquine and hydroxychloroquine. METHODS: In a retrospective chart review, patients receiving or having received one of the drugs were classified as affected by maculopathy or retinopathy, or as not affected on the basis of the documented findings. Uncertain cases were excluded. The risk factors as postulated by the American Academy of Ophthalmology (AAO) and additional factors like diagnosis of underlying disease, total dose, nicotine abuse and the sum of the AAO risk factors were compared between both groups. RESULTS: 51 patients with a history of or ongoing treatment with chloroquine (23 individuals) or hydroxychloroquine (28 individuals) were included. Most of the postulated risk factors were expectedly elevated in the affected group. Significant differences applied to age, duration of intake and the sum of AAO risk factors. Surprisingly, positive smoking history was more frequent in the not affected. The toxic threshold of the daily chloroquine dose was exceeded by most of the patients. CONCLUSIONS: Age and the duration of intake are major risk factors. Smoking seems to be negligible. The sum of AAO risk factors can give an estimation of the individual risk profile. Individual and weight-adapted dosing is especially essential for chloroquine.

[Insulation characteristics of transport containers for organ cultured donor corneas under different ambient temperatures]. / Isoliereigenschaft von Transportbehältern für organkultivierte Spenderhornhäute bei wechselnden Umgebungstemperaturen.

BACKGROUND: The aim of this study was to evaluate the ability of different transport containers to maintain an inside temperature between +10 and +40 degrees C, which is supposed to be safe for organ cultured donor corneas in dextran containing culture media, for a period of 24 hours at ambient temperatures of -10, 0, +10 and +50 degrees C. MATERIALS AND METHODS: 3 containers were tested: 1. Styrofoam box with 2.5 cm thick walls (Graft-tec, AL.CHI.MI.A., Padova, Italy). 2. Thermos jug 0.5 litre (Primus, Solna, Sweden), a double walled metal jug. 3. ThempShell-22 degrees (VWR International, Darmstadt, Germany), a box of gel filled plastic elements. The containers were exposed to -10, 0, +10 and +50 degrees C for 24 hours each. A continuous temperature recording of the ambient and internal environments was performed using electronic thermometers (Mini Intelligent Logger, Escort). RESULTS: The inside temperature of the styrofoam box reached the outside temperature level after 80 - 230 min for all tested settings. The Thermos jug reached the outside temperature approximately after 5 hours. In contrast, the inside temperature of the TempShell-22 degrees CC was at -10 degrees C outside temperature 21 degrees C after 6 hours, 19 degrees C after 12 hours and 12 degrees C after 24 hours. At an ambient temperature of 0 and +10 degrees C the inside temperature of the TempShell-22 degrees C was 19.2 and 17.8 degrees C respectively after 24 hours. An ambient temperature of + 50 degrees C led to an inside temperature of the TempShell-22 degrees C of 30.5 degrees C after 6, 38.3 degrees C after 12 hours and 47.0 degrees C after 24 hours. CONCLUSIONS: A standard Styrofoam box with 2.5 cm thick walls and the tested thermos jug are not suitable to assure a safe temperature range. The TempShell-22 degrees C assures a safe temperature range for low ambient temperatures (-10 to +10 degrees C) for at least 24 hours and for an ambient temperature of +50 degrees C for at least 10 hours.

[Procedural guidelines. Good tissue practice for cornea banks]. / Arbeitsrichtlinien. Gute Fachliche Praxis für Hornhautbanken.

A cornea bank must have an organizational structure in which responsibility and authority to issue directives are clearly defined. It must also use a documented quality management system on the basis of good practice procedures which is maintained to the current standards. The personnel of a cornea bank must be present in sufficient numbers and be suitably qualified. A cornea bank must be in possession of appropriate facilities which are suitable for the main purpose of conservation of donor corneas. All equipment must be designed and maintained corresponding to the intended purpose. Deviations from the stipulated quality and safety standards must give rise to documented investigations which include decisions on options for correctional and preventive measures. Acquisition of donors and tissue sampling must be strictly controlled and documented. This also applies to entry of donor tissue in the cornea bank. During conservation a microscopic examination of the endothelial cell layer must be carried out at least once. Measures must be taken to keep the risk of contamination as low as possible. Donor corneal tissue can only be released if defined criteria are fulfilled. Any suspicion of severe undesired reactions and events for the recipient of a corneal transplant must be registered with the authorities. The activities of a cornea bank must maintain and adapt the state-of-the-art with respect to scientific progress.

[Chloroquine/hydroxychloroquine: variability of retinotoxic cumulative doses]. / Variabilität der retinotoxischen Gesamtdosis Chloroquin/Hydroxychloroquin.

OBJECTIVE: The critical dose of chloroquine/hydroxychloroquine leading to a maculopathy or generalised retinopathy remains undetermined. In the literature, 100 g is considered the dose at which regular vision checks should be performed. Generally, chloroquine is said to be more toxic than hydroxychloroquine. A young patient presenting with toxic maculopathy after 57 g of hydroxychloroquine and a daily dosage of 2 mg/kg body weight prompted us to retrospectively look at our patients examined in this respect over about 1 year. METHODS: The data of patients who were examined because of chloroquine/hydroxychloroquine intake or a respective maculopathy/retinopathy were retrospectively analysed. The time period was January 2005 until March 2006. Retinal damage was defined by fundus changes and alteration of the multifocal electroretinogram (ERG). RESULTS: Twenty-one patients--18 women and three men--were examined. The mean age was 51 years (range 6-71). Five of the nine chloroquine-treated patients developed a maculopathy, and one of them developed an additional generalised retinopathy. Of the patients treated by hydroxychloroquine, three of 12 suffered from a maculopathy and one from an additional generalised retinopathy. The cumulative doses leading to retinal damage ranged from 170 g to 1650 g for chloroquine and from 57 g to 1190 g for hydroxychloroquine. The highest cumulative doses without leading to signs of retinopathy were 790 g for chloroquine and 1200 g for hydroxychloroquine. CONCLUSIONS: There is a high variability of cumulative doses of chloroquine/hydroxychloroquine that lead to a toxic retinopathy. Therefore, early and regular ophthalmologic examinations are recommended. Electrophysiological testing should be performed once a year, corresponding to about 60 g of base with one tablet a day. For electrophysiology, the multifocal ERG has turned out to be the most important test in this regard. However, visual acuity and funduscopy should be performed more frequently.

3D in silico modeling of the human respiratory system for inhaled drug delivery and imaging analysis.

The efficacies of inhaled pharmacologic drugs could be improved if drugs could be targeted to appropriate sites within the human respiratory system. The spatial deposition patterns of particles can now be detected with a high degree of resolution using advanced techniques of imaging (e.g., SPECT). However, the effectiveness of such laboratory regimens has been limited by the inability to clearly identify airway composition within images. Therefore, we have developed a theoretical protocol to map airways within human lungs that is designed to be used in a complementary manner with laboratory investigations. The in silico model has two components: a mathematical model based on concepts of topology; and, a computer algorithm which tracks the millions of constituent lung airways. The in silico model produces 3D lung structures that are anatomically correct and can be customized to each patient. We have applied the protocol to a SPECT study where the interiors of lungs were partitioned into a series of ten nested shells. Airway composition in the respective shells provides a heretofore unavailable quantification of scintigraphy images. The protocol can be employed in a practical manner in the medical arena to aid in the interpretation of SPECT images, and to provide a platform for the design of human subject tests.

Visual responses of crayfish ocular motoneurons: an information theoretical analysis.

Motoneuron responses were elicited by global visual motion and stepwise displacements of an illuminated stripe. Stimulus protocols were identical to those used in previous behavioral studies of compensatory eyestalk reflexes. The firing rates and directional selectivity of the motoneuron responses were measured with respect to four stimulus dimensions (spatial frequency, contrast, angular displacement and velocity). The directional selectivity of the motoneuron response was correlated to the previously measured gain of the reflex for each stimulus dimension. The information theoretical analysis is based upon Kullback-Leibler (K-L) distances which measure the dissimilarity of responses to different stimuli. K-L distances for single neurons are strongly influenced by the mean rate difference of the responses to any pair of stimuli. Because of redundancy, the joint K-L distances of pairs of neurons were less than the sum of the K-L distances of the individual neurons. Furthermore, the joint K-L distances were only weakly influenced by correlations among coactivated neurons. For most of the stimulus dimensions, the K-L distances of single motoneurons were not sufficient to account for the stimulus discriminations exhibited by the eyestalk reflex which typically required the summed output of 2 to 5 motoneurons. Thus the behaviorally relevant information is encoded in the motoneuron ensemble. The minimum time required to discriminate the direction of motion (the encoding window) for a single motoneuron is about 380 to 480 ms (including a 175 ms response latency) for stepwise displacements and up to 1.0 s for global motion. During this period a motoneuron fires 2 to 3 impulses.