[A new technique to facilitate donor preparation for DMEK surgery]. / Eine neue Technik zur Optimierung der Spenderpräparation bei der DMEK.

BACKGROUND: Descemet membrane endothelial keratoplasty (DMEK) is becoming more and more the method of choice to treat corneal endothelial diseases in specialized centers. The reasons that prevent this technique from becoming widespread are the delicate donor tissue preparation. By inverting the curvature of the cornea from convex to concave after mounting onto an artificial anterior chamber, we developed a combined manual delamination and hydrodissection technique, which allows a rapid and endothelium-preserving method of separating donor Descemet membranes from the underlying stroma. MATERIAL AND METHODS: Experiments were perfomed with 60 donor corneas that were not suitable for transplantation. Donor age ranged between 42 and 94 years. Two experimental groups were formed: 1 inverse manual delamination (n = 16) and 2 combined manual delamination and hydrodissection (n = 44). All experiments were undertaken by an experienced surgeon who was, however, not experienced with these techniques. We examined the frequency of Descemet membrane rupture as well as the amount of induced endothelial damage (trypan blue staining with quantitative image analysis). RESULTS: Significant lesions of Descemet's membrane that would have led to a loss of the graft occurred in 25% of the manual delamination cases and in 4.5% using the combined technique. Endothelial damage induced by both techniques was low (6 and 5.2%, respectively). CONCLUSION: For DMEK donor preparation, a combination of manual delamination and hydrodissection was shown to be a safe and endothelium-protective technique to separate Descemet membranes from the underlying stroma. A very rapid learning curve for the combination technique is of specific additional interest for beginners in DMEK surgery.

Bumblebee Flight in Heavy Turbulence.

High-resolution numerical simulations of a tethered model bumblebee in forward flight are performed superimposing homogeneous isotropic turbulent fluctuations to the uniform inflow. Despite tremendous variation in turbulence intensity, between 17% and 99% with respect to the mean flow, we do not find significant changes in cycle-averaged aerodynamic forces, moments, or flight power when averaged over realizations, compared to laminar inflow conditions. The variance of aerodynamic measures, however, significantly increases with increasing turbulence intensity, which may explain flight instabilities observed in freely flying bees.

PP051. Prediction of preeclampsia with the sFlt-1/PLGF ratio: impact of the slope of repeated measurements.

INTRODUCTION: Patients with preeclampsia (PE) exhibit different serum concentrations of sFlt-1 and PlGF. The sFlt-1/PlGF ratio can be used as an aid in the diagnosis of preeclampsia. OBJECTIVES: The objective of this study was to explore the use of the sFlt-1/PlGF ratio as an aid in the prediction of preeclampsia in women with a high risk of the condition. METHODS: 150 patients with high risk of preeclampsia were included in this prospective study. Groups were compared according to the outcome of pregnancy: healthy pregnant women (controls, n=114), pregnancies complicated by intrauterine growth restriction without PE (IUGR, n=14), early PE<34 weeks of gestation (early PE, n=6) and late PE⩾34 weeks of gestation (late PE, n=16). Measurements of sFlt-1 and PlGF were performed on the automated Elecsys system. Statistical comparison of the sFlt-1/PlGF ratio in different outcome groups and multilevel analysis for logistic data using the random slope model was performed. RESULTS: We found significant differences in the sFlt-1/PlGF ratio between the outcome groups in weeks 24-36 of gestation (p=0,05). A significant difference in the sFlt-1/PlGF ratio between controls, IUGR and PE (early and late PE) could be measured up to six weeks before diagnosis (PE) or birth (IUGR, controls) (p=0,05). The random slope model showed significant different slopes (p=0,05) for individual outcome groups (controls 0,657; IUGR 1,786; early PE 1,951; late PE 0,881). CONCLUSION: The sFlt-1/PlGF ratio is able to identify pathologic pregnancy outcomes in gestational weeks 24-36. Prediction is feasible up to six weeks before clinical diagnosis (PE) or 6 weeks before birth (IUGR, controls). Repeated measurements are necessary beginning in 24 weeks of gestation with a maximum distance of six weeks. The slope between two measurements of the sFlt-1/PlGF ratio is predictive of further pregnancy outcome and the risk of developing preeclampsia.

Time-dependent failure in load-bearing polymers: a potential hazard in structural applications of polylactides.

With their excellent biocompatibility and relatively high mechanical strength, polylactides are attractive candidates for application in load-bearing, resorbable implants. Pre-clinical studies provided a proof of principle for polylactide cages as temporary constructs to facilitate spinal fusion, and several cages already made it to the market. However, also failures have been reported: clinical studies reported considerable amounts of subsidence with lumbar spinal fusion cages, and in an in vivo goat study, polylactide spinal cages failed after only three months of implantation, although mechanical testing had predicted sufficient strength for at least eight months. The failures appear to be related to the long-term performance of polylactides under static loading conditions, a phenomenon which is common to all glassy polymers and finds its origin in stress-activated molecular mobility leading to plastic flow. This paper reviews the mechanical properties and deformation kinetics of amorphous polylactides. Compression tests were performed with various strain rates, and static stress experiments were done to determine time-to failure. Pure PLLA appeared to have a higher yield strength than its co-polymers with D: -lactide, but the kinetic behaviour of the polymers was the same: an excellent short-term strength at higher loading rates, but lifetime under static stress is rather poor. As spinal implants need to maintain mechanical integrity for a period of at least six months, this has serious implications for the clinical application of amorphous polylactides in load bearing situations. It is recommended that standards for mechanical testing of implants made of polymers be revised in order to consider this typical time-dependent behaviour.

Contrast-enhanced adenosine-stress magnetic resonance imaging--feasibility and practicability of a protocol for detection or exclusion of ischemic heart disease in an outpatient setting.

BACKGROUND: Evaluating myocardial function, assessing ischemic myocardial areas and detecting myocardial viability are necessary diagnostic information for guiding further therapy in patients with angina. The aim of this study was to show feasibility and safety of a compiled contrast- enhanced magnetic resonance imaging (ceMRI) protocol providing the above mentioned diagnostic possibilities and to demonstrate its applicability in daily routine. METHODS: Consecutive patients with angina were screened on a 1.5 Tesla system. Functional images in short and long axis orientation were acquired for each patient. First-pass kinetics of a gadolinium-based contrast agent (0.1 mmol/kg) were measured after three minutes of stress with adenosine infusion (140 microg/kg/min). 10 min after a second bolus injection of contrast agent "late enhancement" (MLE) sequences were acquired for the detection of myocardial necrosis. RESULTS: We enrolled 3174 patients referred for ceMRI for detection or exclusion of ischemic heart disease. One patient experienced a major complication due to hyperventilation followed by grand mal seizure. In 1121 (35.3%) patients minor complications, such as mild chest pain or dyspnea (30%), temporarily and asymptomatic AV block (3%) or nausea (2%) could be observed under adenosine infusion. Hypoperfusion in more than one myocardial segment and affecting more than 1/3 of the myocardial wall diameter could be detected in 1972 (62%) patients. Subendocardial hypoperfusion with limited duration could be shown in 897 (28%) patients. In 305 (10%) patients hypoperfusion could be excluded. MLE could be seen in 532 (17%) patients. CONCLUSION: This compiled ceMRI protocol is suitable for detection or exclusion of ischemic heart disease in an outpatient routine. We showed feasibility, applicability and safety of our protocol. CeMRI may serve as a useful surrogate for non-invasive diagnostics prior to invasive coronary angiography in many outpatients.

Molecular dynamics simulations of stratum corneum lipid models: fatty acids and cholesterol.

We report the results of an investigation on stratum corneum lipids, which present the main barrier of the skin. Molecular dynamics simulations, thermal analysis and FTIR measurements were applied. The primary objective of this work was to study the effect of cholesterol on skin structure and dynamics. Two molecular models were constructed, a free fatty acid bilayer (stearic acid, palmitic acid) and a fatty acid/cholesterol mixture at a 1:1 molar ratio. Our simulations were performed at constant pressure and temperature on a nanosecond time scale. The resulting model structures were characterized by calculating surface areas per headgroup, conformational properties, atom densities and order parameters of the fatty acids. Analysis of the simulations indicates that the free fatty acid fraction of stratum corneum lipids stays in a highly ordered crystalline state at skin temperatures. The phase behavior is strongly influenced when cholesterol is added. Cholesterol smoothes the rigid phases of the fatty acids: the order of the hydrocarbon tails (mainly of the last eight bonds) is reduced, the area per molecule becomes larger, the fraction of trans dihedrals is lower and the hydrophobic thickness is reduced. The simulation results are in good agreement with our experimental data from FTIR analysis and NIR-FT Raman spectroscopy.

[Cavernous hemangioma of the maxillary sinus]. / Kavernöses Hämangiom des Sinus maxillaris.

Cavernous haemangioma of the paranasal sinuses is very rare. We describe the X-ray and CT findings in a case of cavernous haemangioma which originated from the mucous membrane of the maxillary sinus and eroded the bony boundary of the sinus.

[Sonographic detection of embolic masses in the ventricular passage]. / Sonographischer Nachweis von embolischen Massen während der Ventrikelpassage.

Using echocardiography, we succeeded in identifying thromboembolic masses in the heart of 5 patients suffering from massive pulmonary or arterial embolism. In another case we found a thrombus in the right ventricular outflow tract. Premonitorial pulmonary embolism preceded in all cases. One thrombus in arterial embolism was found by tm-echocardiography, five thrombi by sector-echocardiography. The examinations were performed after acute worsening of the clinical condition. In four patients, death resulted from the embolism, whereas two survived, one old patient without thrombolytic or operative therapy.

The influence of angiotensin II antagonist postischemic acute renal failure.

In 34 dogs the effect of a 90-min period of warm ischemia on renal perfusion and function was studied with and without (Sar1, Ile8) angiotensin II treatment. In the first 3 h after the release of renal arterial occlusion, a significant influence of the angiotensin II antagonist on changes in postischemic vascular resistance, intrarenal hemodynamics and renal function could be demonstrated, all being well preserved in the treated group.

[Avulsio bulbi (author's transl)]. / Avulsio bulbi.

It is reported about a 14 year old girl, sustaining an avulsion of the left eye-ball by a coat-rack. The optic nerve was cutted 18 mm retrobulbarly. In perimetry of the fellow-eye a temporo-superior defect was found as proof of traumatisation of the anterior-loop-fibers in the chiasm.

[The influence of dopamine of kidney function during continuous positive-pressure ventilation (PEEP) (author's transl)]. / Der Einfluss von Dopamin auf die Nierenfunktion während kontinuierlicher Uberdruckbeatmung (PEEP).

In a group of 20 patients the influence of continuous positive-pressure Ventilation (PEEP) on cardiac output, kidney function and renal and intrarenal hemodynamics was investigated. During ventilation with PEEP 10 ccm H2O a reduction of cardiac output, glomerular filtrationrate, sodium excretion and urinary output was observed. Renal blood flow, especially the cortical fraction, also decreased. Dopamine infusion, in a dose of 4 ng.kg-1.min-1, during continuous PEEP-ventilation, induced an increase of cardiac output, glomerular filtrationrate, renal sodium excretion and diuresis. The decreased renal cortical perfusion particularly was improved by Dopamine application.

[Aqueous-and serum levels of cephalexin and penicillin V after oral application in man (author's transl)]. / Kammerwasser- und Serumkonzentration nach oraler Applikation von Cephalexin und Penicillin V beim Menschen.

This clinical study implies orally administered cephalexin and penicillin V as agents with effective aqueous homor penetration in noninfected human eyes. Aqueous humor concentration of cephalexin increases up to 15% of the serum level 2 h after application. Administration of 1 g or 2 g cephalexin revealed no significant difference in aqueous humor concentration. So penetration of blood-aqueous-humor barrier can be regarded as a saturation process. Individual results of 92 cephalexin determinations are variant and not related to body weight or age of the patients.

[Treatment of retinal detachment with macular hole: scleral buckling with an absorbable fibrin sponge (author's transl)]. / Operation der Netzhautablösung bei Makulaforamen mit resorbierbarer Plombe.

In 21 patients with macular hole and retinal detachment a macular buckling procedure was performed including diathermic or cryogenic coagulation. An absorbable fibrin sponge (Fibrospum) was used as a new buckling material, which needs not to be sutured to the sclera at the posterior pole. In comparison to other procedures the use of fibrin sponge seems to be more simple and at least of the same results.

[Aphakic retinal detachment as a function of the technic and course of cataract extraction]. / Aphakieamotio in Abhängigkeit von Technik und Verlauf der Kataraktoperation.

Myopic patients, in particular, should be carefully observed by contactglass examination prior to and after cataract surgery, in order to be able to perform prophylactic photocoagulation. In cases of vitreous loss, the risk of having an aphakic retinal detachment will be 20 times as high; that is to say, in one of every five cases cataract extraction with vitreous loss can be expected to produce a retinal detachment. It can be said, therefore, that the best cataract procedure- as far as aphakic retinal detachment is concerned-will be that in which we can expect the lowest rate of vitreous loss. Whether an extensive anterior vitrectomy will reduce the number of aphakic detachments, we cannot yet say defintely, because in these cases we have only routinely performed vitrectomy during the past 2 years.