[Feasibility of clinical examination scenarios under pandemic conditions]. / Möglichkeit von Prüfungsszenarien unter Pandemiebedingungen.

BACKGROUND: Due to the COVID-19 pandemic, contact restrictions occurred worldwide, which affected medical schools as well. It was not possible to hold classroom lectures. Teaching contents had to be converted to a digital curriculum within a very short time. Conditions for assessments posed an even greater challenge. For example, solutions had to be found for objective structured clinical examinations (OSCE), which were explicitly forbidden in some German states. The aim of this study was to evaluate the feasibility of an OSCE under pandemic conditions. MATERIALS AND METHODS: At the end of the 2020 summer semester, 170 students completed a combined otolaryngology and ophthalmology OSCE. Examinations were held in small groups over the course of 5 days and complied with strict hygiene regulations. The ophthalmology exam was conducted face to face, and the ENT OSCE virtually. Students were asked to rate the OSCE afterwards. RESULTS: Between 106 and 118 of the students answered the questions. Comparing the face-to-face OSCE with the virtual OSCE, about 49% preferred the face-to-face OSCE and 17% preferred the virtual OSCE; 34% found both variants equally good. Overall, the combination of an ENT and ophthalmology OSCE was rated as positive. CONCLUSION: It is possible to hold an OSCE even under pandemic conditions. For optimal preparation of the students, among other things, it is necessary to transform teaching contents to a digital curriculum. The combination of an ENT and ophthalmology OSCE was positively evaluated by the students, although the face-to-face OSCE was preferred. The overall high satisfaction of the students confirms the feasibility of a virtual examination with detailed and well-planned preparation.

Toric IOL positioning with a no-touch head-up display axis alignment.

PURPOSE: To compare a new no-touch alignment technique for toric intraocular lenses (IOL) with the conventional technique that uses a manual pendulum. METHODS: In this retrospective case-control study, patients who underwent toric IOL implantation using two different alignment techniques (digital Callisto® system vs. manual-pendulum-based marking) were compared in a vector analysis using the Alpins method and an analysis of variance regarding corrected and uncorrected visual acuity and the deviation of the achieved IOL axis from the targeted axis. RESULTS: Sixty-one eyes were included into analysis. Thirty-six of these surgeries were performed via the Callisto® system and 25 eyes via pendulum-based corneal markings. Median IOL axis misalignment was 3° in both groups. Median uncorrected distance visual acuity was 0.097 logMAR versus 0.200. Median best-corrected visual acuity was 0.000 logMAR versus 0.097. All these data were below the range of statistical significance (p > 0.05). Vector analysis showed no significant difference for TIA [median of 3.14 diopters (D) vs. 2.73 D], SIA (median of 3.82 D vs. 3.79 D), DV (1.18 D vs. 1.08 D), and CI (1.23 vs. 1.29). Median angle of error was 1.96° versus - 0.44° (p > 0.05). CONCLUSIONS: We found no significant difference in the refractive results, the IOL positioning, and the best-corrected and uncorrected distance visual acuity between the two compared methods. Nevertheless, the Callisto® IOL alignment system delivers a standardized and easy-to-use technology. In particular, less-experienced surgeons might benefit from this marking technique.

Early neuromodulation prevents the development of brain and behavioral abnormalities in a rodent model of schizophrenia.

The notion that schizophrenia is a neurodevelopmental disorder in which neuropathologies evolve gradually over the developmental course indicates a potential therapeutic window during which pathophysiological processes may be modified to halt disease progression or reduce its severity. Here we used a neurodevelopmental maternal immune stimulation (MIS) rat model of schizophrenia to test whether early targeted modulatory intervention would affect schizophrenia's neurodevelopmental course. We applied deep brain stimulation (DBS) or sham stimulation to the medial prefrontal cortex (mPFC) of adolescent MIS rats and respective controls, and investigated its behavioral, biochemical, brain-structural and -metabolic effects in adulthood. We found that mPFC-DBS successfully prevented the emergence of deficits in sensorimotor gating, attentional selectivity and executive function in adulthood, as well as the enlargement of lateral ventricle volumes and mal-development of dopaminergic and serotonergic transmission. These data suggest that the mPFC may be a valuable target for effective preventive treatments. This may have significant translational value, suggesting that targeting the mPFC before the onset of psychosis via less invasive neuromodulation approaches may be a viable preventive strategy.

Nanoscale Tipping Bucket Effect in a Quantum Dot Transistor-Based Counter.

Electronic circuits composed of one or more elements with inherent memory, that is, memristors, memcapacitors, and meminductors, offer lower circuit complexity and enhanced functionality for certain computational tasks. Networks of these elements are proposed for novel computational paradigms that rely on information processing and storage on the same physical platform. We show a nanoscaled memdevice able to act as an electronic analogue of tipping buckets that allows reducing the dimensionality and complexity of a sensing problem by transforming it into a counting problem. The device offers a well adjustable, tunable, and reliable periodic reset that is controlled by the amounts of transferred quantum dot charges per gate voltage sweep. When subjected to periodic voltage sweeps, the quantum dot (bucket) may require up to several sweeps before a rapid full discharge occurs thus displaying period doubling, period tripling, and so on between self-governing reset operations.

Outcomes of Descemet membrane endothelial keratoplasty, Descemet stripping automated endothelial keratoplasty and penetrating keratoplasty from a single centre study.

PURPOSE: According to some pioneer surgeons, lamellar endothelial keratoplasty techniques (EK), including Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK), yield excellent clinical results. However, there is a lack of studies with high levels of evidence and results of large national keratoplasty registers are contradictory. Therefore, two large cohorts of DMEK and DSAEK procedures are compared to a cohort of penetrating keratoplasty (PK). METHODS: The study reports 868 keratoplasty procedures at a single centre (694 eyes with Fuchs endothelial dystrophy (FED) and 174 with bullous keratopathy (BK)). Patients underwent DMEK (450 eyes), DSAEK (89 eyes), or PK (329 eyes). Postoperative visual acuity, endothelial cell density (ECD), rate of regrafting, and rejections were recorded. RESULTS: Visual acuity recovers faster and to a greater extent in EK compared to PK. DMEK performs better than DSAEK. ECD drops faster initially for EK compared to PK. In EK the rate of regrafting is higher than in PK (7 % in DMEK, 20 % in DSAEK and 2 % in PK in FED). The rejection rate is lowest following DMEK (7 % after DMEK, 21 % after DSAEK and 18 % after PK in FED). CONCLUSIONS: In contrast to recent reports from national keratoplasty registers, the overall clinical outcome of EK in FED and BK is superior to PK. Including ocular comorbidities and learning curves, these data reflect a realistic setting for comparing the different keratoplasty techniques. Corneal surgeons may be encouraged to preferentially use DMEK in FED and BK.

[Intraocular Lens Opacification Following Posterior Lamellar Keratoplasty]. / Kunstlinsentrübungen nach hinterer lamellärer Keratoplastik.

BACKGROUND: The opacification of an artificial intraocular lens is a rare but serious complication following cataract surgery as an exchange of the intraocular lens can become necessary. At our eye center we observed single cases of IOL opacifications following complicated posterior lamellar keratoplasty (Descemet stripping automated endothelial keratoplasty = DSAEK or Descemet membrane endothelial keratoplasty = DMEK). Therefore, we performed a retrospective analysis of all our digital charts regarding the incidence of this serious complication with respect to posterior lamellar keratoplasty, penetrating keratoplasty or sole cataract extraction. METHODS: We searched our digital patient database from 2003 to 2015 using the following headings: intraocular lens, artificial lens or IOL and opacification or calcification and selected only those patients who had undergone either DSAEK, DMEK, penetrating keratoplasty or sole cataract surgery (n = 19,565). RESULTS: In total we found five IOL opacifications out of 153 DSAEK and two out of 450 DMEK cases, respectively. Five of these seven cases had a complicated clinical course with repeated rebubbling or additional intraocular surgery (i.e., repeat DSAEK or DMEK or secondary penetrating keratoplasty). There were no documented IOL opacifications following penetrating keratoplasty or sole cataract extraction. In two cases intraocular lens exchange became necessary. All opacifications showed similar clinical appearance in form of small granular deposits on the surface of the intraocular lens. Almost all implanted lenses were made from hydrophilic acrylate. DISCUSSION: In total we found seven cases of intraocular lens opacification that have only been observed following DSAEK or DMEK. According to reports from the literature these opacifications are superficial calicifications of the hydrophilic lenses. As five of the seven cases had a complicated clinical course, the repeated air contact of the lens could be one major factor in inducing the calcification. Besides the air contact a breakdown of the blood-aqueous barrier could also play a role in the induction of calcium phosphate crystallisation on the intraocular lens. The risk of this serious complication in mainly hydrophilic intraocular lenses with respect to posterior lamellar keratoplasty should be kept in mind for the selection of the type of intraocular lens in patients with endothelial diseases or in patients undergoing combined cataract extraction and DSAEK/DMEK.

Efficacy and safety of telaprevir (TVR) triple therapy in a 'real-life' cohort of 102 patients with HCV genotype 1: interim analysis after 24 weeks of treatment.

Since 2011, telaprevir (TVR)-based triple therapy is the new treatment standard for hepatitis C genotype 1 virus infection. The aim of our retrospective interim analysis encompassing the first 24 weeks on TVR-based triple therapy was to assess 'real-life' antiviral efficacy and side effects in a large single-centre cohort, both in comparison with the data obtained in large prospective clinical trials. In total, we treated 102 patients: 24 treatment-naïve patients, 58 patients pretreated with PEG-IFN/RBV (thereof: 28 with nonresponse, 25 with relapse, five unknown) and 20 patients who previously had received nonpegylated interferon. 74 of 102 patients were assigned with HCV genotype 1b; 34 of 102 patients were treated in the context of liver cirrhosis. 72 of 102 patients have reached treatment week 24 (mean treatment duration 31 weeks). In the ITT analysis, overall response rates were at: week 4: 66%; week 12: 85%; and week 24: 78%. So far, 24 patients discontinued treatment prematurely, of those, 10 patients were due to virological failure. Haematological side effects were frequent (40% anaemia), as were 'flu-like' symptoms (94%), rash (65%) and pruritus (79%). According to our interim ITT analysis encompassing up to 24 weeks of TVR-based triple therapy, our 'real-life' antiviral effects are comparable to the results of large multicentric clinical trials. However, TVR-based triple therapy exhibited a high frequency of side effects requiring multiple therapeutic interventions. Notably, in our 'real-life' cohort, no lethal case was observed so far.

Visual outcome and histological findings following femtosecond laser-assisted versus microkeratome-assisted DSAEK.

BACKGROUND: The aim of this study was to compare the visual outcome of femtosecond laser-assisted Descemet stripping automated endothelial keratoplasty (DSAEK) to microkeratome-assisted DSAEK as well as to contrast precut versus surgeon-cut grafts. Histologic characterization of failed DSAEK grafts was performed in order to correlate ultrastructural changes with graft failures. METHODS: In this case control study, 47 cases of DSAEK were investigated in terms of visual acuity, keratometric astigmatism, spherical equivalent, endothelial cell count, and postoperative complications. We formed three groups: the femtosecondlaser-assisted DSAEK with precut grafts, the microkeratome-assisted DSAEK with precut and with surgeon-cut grafts. Mean follow-up was 6 months. In the case of graft failure, penetrating keratoplasty was performed, and the excised corneal buttons were investigated by light and electron microscopy. RESULTS: Microkeratome-assisted DSAEK lead to better visual outcome than femtosecond laser-assisted DSAEK. Keratometric astigmatism, spherical equivalent and endothelial cell count did not differ significantly between both methods. Precut and surgeon-cut grafts in microkeratome-assisted DSAEK did not show any significant difference regarding all upraised parameters. No definite histological correlate for graft failure following femtosecond laser-assisted DSAEK was found. CONCLUSIONS: Femtosecond laser-assisted DSAEK is not the method of choice, and needs further technical improvement. However, failed femtosecondlaser-assisted DSAEK grafts did not show significant histological changes related to the technique to explain reduced visual acuity. In microkeratome-assisted DSAEK, the preparation time point of the graft does not seem to influence the visual and optical outcome.

[HLA matching in keratoplasty: lessons learned from lamellar techniques]. / Immunologie der Keratoplastik: Macht HLA-Matching bei lamellären Verfahren Sinn?

BACKGROUND: The immunological mechanisms of graft rejections after penetrating keratoplasty are largely investigated in rodent models. Here, antigens are predominantly processed by host antigen presenting cells (APCs). For this reason, graft rejections are not primarily triggered by mismatches in the major histocompatibility complex (MHC). Consequently, MHC matching (equivalent of HLA matching) does not robustly prevent immunological graft rejections in mice. This, however, may not apply to humans because anatomy and the clinical picture of immune reactions differ vastly. METHODS: Immunological experiments are not feasible in humans for ethical reasons. However, the recent surgical modifications in keratoplasty inadvertently gave rise to several interesting immunological field experiments. We herein discuss the potential insight into human graft rejections from selected clinical observations. On this basis, we have evaluated HLA matching for keratoplasty techniques. RESULTS: Several clinical observations hint towards an active role of donor-derived APCs in graft rejections after human keratoplasty. Additionally, donor-specific anti-HLA antibodies may play a significant role. On this basis we suggest that HLA matching is potentially beneficial in human keratoplasty in contrast to the situation in mice. CONCLUSIONS: Graft rejections are rarely observed after Descemet membrane keratoplasty (DMEK). For this reason, we do not recommend HLA matching here. The same is true for deep anterior lamellar keratoplasty, where graft rejections can usually be treated well. However, HLA matching is a viable option in penetrating keratoplasty. This is especially true for high-risk eyes.

[Data quality of unsupervised endothelial cell counting vs. reading centre analysis in multicentric clinical trials]. / Endothelzellmessung in multizentrischen Studien: Verbesserung der Datenqualität durch zentralisierte Bildauswertung.

PURPOSE: The aim of this study was to assess data quality from unsupervised endothelial cell counting in the multicentric setting. PATIENTS AND METHODS: We performed an endothelial cell counting trial with two fictitious trial sites. The trial protocol simply demanded for marking 30 cells for analysis. Analyses were performed with the cell counting tool as built into the Topcon SP-3000P specular microscope. The first centre consequently dotted 30 cells. The other centre continuously dotted more cells until 30 cells were included in the cell counting analysis. Both sites analysed the same 89 eyes of corneal outpatients and heathy volunteers. Both sites used a dedicated Topcon SP-3000P microscope. The image pairs from both sites were eventually printed, scanned and re-evaluated with a programme that evaluated all visible cells ("reading centre"). The agreement between both sites was statistically assessed by means of Pearson's correlation and Bland-Altman analysis. The same statistical assessments were also performed for the image pairs as analysed in the reading centre. RESULTS: The determined cell densities as reported by both trial sites differed by -65 % to 42 %. Furthermore, we also observed a systematic deviation between both sites. Consequently, the coefficient of determination from Pearson's correlation was only 0.947. However, the agreement was as high as 0.997 when the image pairs were analysed in the reading centre. Here the difference between the cell densities of the image pairs ranged from merely -15 % to 9 % with no systematic deviation. CONCLUSIONS: Unsupervised endothelial cell counting does not result in sufficiently objective endothelial cell denstiy estimations. Furthermore, the built-in analysis tools can introduce systematic errors. Both drawbacks can be overcome by a reading centre that evaluates all visible cells on the images. For this reason, we recommend the involvement of a reading centre in multicentric clinical trials on the corneal endothelium.

[Early diagnosis of keratoconus]. / Frühdiagnose des Keratokonus.

Keratoconus is morphologically associated with increasing deformation, thinning and scarring of the cornea. This functionally leads to refractive changes and visual deterioration. In the early stages there are often no clear clinical signs in the slit-lamp examination; however, confirming the diagnosis as early as possible is important in order to provide patients with an appropriate treatment. For the early diagnosis of keratoconus, various diagnostic devices have been introduced in recent years and decades. These include keratometry with reflection-based or elevation-based systems and optical coherence tomography. High-frequency ultrasound microscopy and corneal biomechanics can also be used to establish the diagnosis of keratoconus by the measurement of other parameters. The necessity and the available possibilities for early diagnosis of keratoconus are presented in more detail in this article.

Chemoprotection of human hematopoietic stem cells by simultaneous lentiviral overexpression of multidrug resistance 1 and O(6)-methylguanine-DNA methyltransferase(P140K).

Myelotoxicity is a dose-limiting effect of many chemotherapeutic regimens. Thus, there is great interest in protecting human hematopoietic stem cells by the transfer of drug resistance genes. The main focus of this study was the simultaneous overexpression of multidrug resistance 1 (MDR1) and the O(6)-benzylguanine (O(6)-BG)-resistant mutant MGMT(P140K) (O(6)-methylguanine-DNA methyltransferase) with a bicistronic lentiviral vector (HR'SIN-MDR1-IRES-MGMT(P140K)), with regard to the capability to convey chemoprotection in the leukemia cell line, HL60, and human hematopoietic stem cells (CD34(+)). Combination therapy with O(6)-BG/1-(2-chloroethyl)-3-(4-amino-2-methylpyrimidine-5-yl)methyl-1-nitrosourea) (ACNU) plus paclitaxel showed a significant survival advantage of HL60 cells transduced with this combination vector. In CD34(+) cells, monotherapy with O(6)-BG/temozolomide (TMZ) resulted in an increased percentage of MGMT-positive cells (vs untreated cells) after transduction with HR'SIN-MDR1-IRES-MGMT(P140K) (28.3%). For combination therapy with O(6)-BG/temozolomide plus paclitaxel the increase was higher with the combination vector (52.8%) than with a vector expressing MGMT(P140K) solely (29.1%). With regard to MDR1-positive cells the protective effect of the combination vector (88.5%) was comparable to the single vector HR'SIN-MDR1 (90.0%) for monotherapy with paclitaxel and superior for combination therapy with O(6)-BG/temozolomide plus paclitaxel (84.6 vs 69.7%). In conclusion, the combination vector presents simultaneous protective effects of two drug-resistance genes, offering an opportunity to increase the cancer therapeutic index.

[Therapeutic applications of the femtosecond laser in corneal surgery]. / Therapeutischer Einsatz des Femtosekundenlasers in der Hornhautchirurgie.

Since 2001 the femtosecond laser has primarily been used in refractive surgery, e. g., for lasik, implantation of intracorneal ring segments or antiastigmatic corneal incisions. However, the femtosecond laser is more and more used for therapeutic reasons in corneal surgery. In this context it is used for profiled trephinations in penetrating keratoplasty where various profiles of the cutting edge can be designed (e. g., top-hat profile, mushroom profile, zig-zag profile). The potential advantages of these profiles include improved graft adaptation, better and more stable wound healing leading to earlier suture removal and eventually prolonged graft survival. However, none of these potential advantages has been demonstrated by reliable study results until now. First clinical experiences show that much earlier suture removal is possible without significant complications. However, with sutures in there seems to be no advantage of the femtosecond laser compared to mechanically guided trephination systems regarding visual acuity and postoperative astigmatism. Besides penetrating profiles, the femtosecond laser also allows for lamellar cuts. As deep anterior lamellar keratoplasty can only be supported by the femtosecond laser, it is mostly used for posterior lamellar grafts in this context. However, first clinical results using the femtosecond laser for DSAEK (descemet stripping automated endothelial keratoplasty) are poorer than those using microkeratome-prepared lamellar grafts for DSAEK.

Multiple displacement amplification enables large-scale clonal analysis following retroviral gene therapy.

Analysis of the fate of retrovirally transduced cells after transplantation is often hampered by the scarcity of available DNA. We evaluated a promising method for whole-genome amplification, called multiple displacement amplification (MDA), with respect to even and accurate representation of retrovirally transduced genomic DNA. We proved that MDA is a suitable method to subsequently quantify engraftment efficiencies by quantitative real-time PCR by analyzing retrovirally transduced DNA in a background of untransduced DNA and retroviral integrations found in primary material from a retroviral transplantation model. The portion of these retroviral integrations in the amplified samples was 1.02-fold (range 0.2, to 2.1-fold) the portion determined in the original genomic DNA. Integration site analysis by ligation-mediated PCR (LM-PCR) is essential for the detection of retroviral integrations. The combination of MDA and LM-PCR showed an increase in the sensitivity of integration site analysis, as a specific integration site could be detected in a background of untransduced DNA, while the transduced DNA made up only 0.001%. These results show for the first time that MDA enables large-scale sensitive detection and reliable quantification of retrovirally transduced human genomic DNA and therefore facilitates follow-up analysis in gene therapy studies even from the smallest amounts of starting material.

Specific locus mutations induced in somatic cells of rats by orally and parenterally administered procarbazine.

A new test, the granuloma pouch assay, was used in detecting specific locus mutations in somatic cells of rats in vivo after the animals were treated orally and parenterally with procarbazine hydrochloride, an agent used in cancer chemotherapy. The results indicate that stable intermediates are formed in the body and distributed as proximate mutagens.

Costs and financing. A cost calculation of an up-to-date eye bank in Germany.

PURPOSE: To estimate the averaged cost of processing a corneal graft for keratoplasty. METHODS: We estimated the total running costs of a German corneal bank for one year. All procurement-related expenses were calculated on the basis of 300 donors per year and a disavowal percentage of 50%. RESULTS: The running costs comprise of personnel (2 physicians, 2 technicians), amortization of equipment, laboratory costs, laboratory consumables, occupancy costs and quality management. Annual expenses total 584000 EUR. This aggregation divided by 300 corneal grafts released for transplantation results in a nominal charge of 1950 EUR per corneal graft. DISCUSSION: The DRG system in Germany (in-patients at a base rate of 1.0) refunds only 850 EUR, leaving a financial gap of 1100 EUR per keratoplasty. This financial burden is currently left over to the eye bank and/or the surgeon.