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Mit modernen nicht invasiven bildgebenden Verfahren lassen sich anhand der Fundusfotografie bzw. der optischen Verfilmung Aspekte der funktionellen und strukturellen retinalen Gefäßveränderungen objektiv untersuchen. Der Zustand und das Verhalten retinaler Gefäße beeinflussen im prä-, post- und kapillaren Bereich den Blutfluss und strömungsbedingte Stoffwechselverhältnisse passiv und aktiv über den Gefäßdurchmesser. Retinale Gefäße gleichen von Aufbau und Funktion den zerebralen Gefäßen und spiegeln den Zustand der Mikrozirkulation wider. Mithilfe von aus den Gefäßweiten berechneten Biomarkern soll eine Aussage über die Prognose von systemischen vaskulär bedingten Erkrankungen getroffen werden. Die statische retinale Gefäßanalyse befasst sich mit der Untersuchung des Zustandes der prä- und postkapillaren Gefäßdurchmesser der retinalen Mikrozirkulation anhand einer optischen Fundusaufnahme. Bei der dynamischen retinalen Gefäßanalyse wird der Längsschnitt eines retinalen Gefäßes nicht invasiv funktionell und strukturell über einen Zeitraum vor, während und nach einer spezifischen vaskulären Stimulation untersucht. Die genaue Methodologie der Auswertung und die Bezeichnung der Parameter variieren bei unterschiedlichen Ansätzen. Mittels retinaler Gefäßanalyse wurden bislang mehrere klinische Querschnitts- und Interventionsstudien in der Augenheilkunde und anderen Fachgebieten, inkl. Kardiologie, Neurologie, Neurochirurgie, Nephrologie, Gynäkologie, Sportmedizin, Diabetologie, Hypertensiologie usw. durchgeführt. Mit der statischen retinalen Gefäßanalyse steht eine kostengünstige, reproduzierbare, nicht invasive Screeningtechnik zur Verfügung, um eine prognostische Aussage über die Gefäßgesundheit eines individuellen Patienten zu treffen. Die dynamische retinale Gefäßanalyse besitzt ein weiteres diagnostisches Anwendungsspektrum als die statische, da sie das Verhalten retinaler Gefäße zeitkontinuierlich untersucht. Die Evaluation vaskulärer Erkrankungen sowie zerebro- bzw. kardiovaskulärer Morbidität und Mortalität mittels mehrerer methodologischer Modalitäten retinaler Gefäßanalyse mit ihren jeweiligen quantitativen Biomarkern bietet eine zukunftsträchtige diagnostische Perspektive. Die interdisziplinäre klinische Anwendung dieser vaskulären Biomarker gewinnt zunehmend an Bedeutung, sowohl in der Augenheilkunde als auch in anderen Fachgebieten.
False spectra formation in the differential two-channel scheme of the laser Doppler flowmeter
(2018)
Noise in the differential two-channel scheme of a classic laser Doppler flowmetry (LDF) instrument was studied. Formation of false spectral components in the output signal due to beating of electrical signals in the differential amplifier was found out. The improved block-diagram of the flowmeter was developed allowing to reduce the noise.
Background
Impairment of neurovascular coupling (NVC) was recently reported in the context of subarachnoid hemorrhage and may correlate with disease severity and outcome. However, previous techniques to evaluate NVC required invasive procedures. Retinal vessels may represent an alternative option for non-invasive assessment of NVC.
Methods
A prototype of an adapted retinal vessel analyzer was used to assess retinal vessel diameter in mice. Dynamic vessel analysis (DVA) included an application of monochromatic flicker light impulses in predefined frequencies for evaluating NVC. All retinae were harvested after DVA and electroretinograms were performed.
Results
A total of 104 retinal scans were conducted in 21 male mice (90 scans). Quantitative arterial recordings were feasible only in a minority of animals, showing an emphasized reaction to flicker light impulses (8 mice; 14 scans). A characteristic venous response to flicker light, however, could observed in the majority of animals. Repeated measurements resulted in a significant decrease of baseline venous diameter (7 mice; 7 scans, p < 0.05). Ex-vivo electroretinograms, performed after in-vivo DVA, demonstrated a significant reduction of transretinal signaling in animals with repeated DVA (n = 6, p < 0.001).
Conclusions
To the best of our knowledge, this is the first non-invasive study assessing murine retinal vessel response to flicker light with characteristic changes in NVC. The imaging system can be used for basic research and enables the investigation of retinal vessel dimension and function in control mice and genetically modified animals.
BACKGROUND
Immunosuppression is often considered as an indication for antibiotic prophylaxis to prevent surgical site infections (SSI) while performing skin surgery. However, the data on the risk of developing SSI after dermatologic surgery in immunosuppressed patients are limited.
PATIENTS AND METHODS
All patients of the Department of Dermatology and Allergology at the University Hospital of RWTH Aachen in Aachen, Germany, who underwent hospitalization for a dermatologic surgery between June 2016 and January 2017 (6 months), were followed up after surgery until completion of the wound healing process. The follow-up addressed the occurrence of SSI and the need for systemic antibiotics after the operative procedure. Immunocompromised patients were compared with immunocompetent patients. The investigation was conducted as a retrospective analysis of patient records.
RESULTS
The authors performed 284 dermatologic surgeries in 177 patients. Nineteen percent (54/284) of the skin surgery was performed on immunocompromised patients. The most common indications for surgical treatment were nonmelanoma skin cancer and malignant melanomas. Surgical site infections occurred in 6.7% (19/284) of the cases. In 95% (18/19), systemic antibiotic treatment was needed. Twenty-one percent of all SSI (4/19) were seen in immunosuppressed patients.
CONCLUSION
According to the authors' data, immunosuppression does not represent a significant risk factor for SSI after dermatologic surgery. However, larger prospective studies are needed to make specific recommendations on the use of antibiotic prophylaxis while performing skin surgery in these patients.
The available data on complications after dermatologic surgery have improved over the past years. Particularly, additional risk factors have been identified for surgical site infections (SSI). Purulent surgical sites, older age, involvement of head, neck, and acral regions, and also the involvement of less experienced surgeons have been reported to increase the risk of the SSI after dermatologic surgeries.1 In general, the incidence of SSI after skin surgery is considered to be low.1,2 However, antibiotics in dermatologic surgeries, especially in the perioperative setting, seem to be overused,3,4 particularly regarding developing antibiotic resistances and side effects.
Immunosuppression has been recommended to be taken into consideration as an additional indication for antibiotic prophylaxis to prevent SSI after skin surgery in special cases.5,6 However, these recommendations do not specify the exact dermatologic surgeries, and were not specifically developed for dermatologic surgery patients and treatments, but adopted from other surgical fields.6 According to the survey conducted on American College of Mohs Surgery members in 2012, 13% to 29% of the surgeons administered antibiotic prophylaxis to immunocompromised patients to prevent SSI while performing dermatologic surgery on noninfected skin,3 although this was not recommended by Journal of the American Academy of Dermatology Advisory Statement. Indeed, the data on the risk of developing SSI after dermatologic surgery in immunosuppressed patients are limited. However, it is possible that due to the insufficient evidence on the risk of SSI occurrence in this patient group, dermatologic surgeons tend to overuse perioperative antibiotic prophylaxis.
To make specific recommendations on the use of antibiotic prophylaxis in immunosuppressed patients in the field of skin surgery, more information about the incidence of SSI after dermatologic surgery in these patients is needed. The aim of this study was to fill this data gap by investigating whether there is an increased risk of SSI after skin surgery in immunocompromised patients compared with immunocompetent patients.
Purpose — to compare the chemical elemental composition of vitreous cavity content taken from cadaveric eyes compared to samples taken from the eyes with terminal stage refractory glaucoma with decompensated intraocular pressure (IOP). Material and methods. The vitreous contents of the eyes from 2 groups were studied. The 1st group included 15 cadaveric eyes; the 2nd group included 15 eyes with refractory glaucoma in the terminal stage of the disease with decompensated IOP in patients with hypertension pain. The vitreal content samples were taken in the course of antiglaucoma surgery aimed at preserving the eye as an organ and involving employment of drainage in the vitreous cavity. The study of virtual contents was carried out on energy dispersive spectrometer Oxford X-Max 50 integrated into scanning electron microscope Zeiss EVO LS10. Results. Increased concentrations of Kalium and Phosphorus were detected in the vitreous content of cadaveric eyes compared with the vitreal content from the eyes with terminal glaucoma with decompensated IOP taken in vivo (K — 0.172/0.093; P — 0.045/0.025 mmol/L). In the vitreous cavity in the eyes with end-stage glaucoma with decompensated IOP, the concentration of Nitrogen was higher in comparison with human cadaver eyes (2.030/1.424 mmol/L). Conclusion. The increased concentrations of Kalium and Phosphorus in the vitreous content of cadaveric eyes is associated with postmortem autolytic processes and with the release of intracellular content in the destruction of cell membranes. The increased Nitrogen concentration in the vitreal contents of the eyes with terminal stage glaucoma with decompensated IOP may be associated with the presence of osmotically active nitrogen-containing compounds in the eyes with increased IOP.
Sampling of dry surfaces for microorganisms is a main component of microbiological safety and is of critical importance in many fields including epidemiology, astrobiology as well as numerous branches of medical and food manufacturing. Aspects of biofilm formation, analysis and removal in aqueous solutions have been thoroughly discussed in literature. In contrast, microbial communities on air-exposed (dry) surfaces have received significantly less attention. Diverse surface sampling methods have been developed in order to address various surfaces and microbial groups, but they notoriously show poor repeatability, low recovery rates and suffer from lack of mutual consistency. Quantitative sampling for viable microorganisms represents a particular challenge, especially on porous and irregular surfaces. Therefore, it is essential to examine in depth the factors involved in microorganisms’ recovery efficiency and accuracy depending on the sampling technique used. Microbial colonization, retention and community composition on different dry surfaces are very complex and rely on numerous physicochemical and biological factors. This study is devoted to analyze and review the (a) physical phenomena and intermolecular forces relevant for microbiological surface sampling; (b) challenges and problems faced by existing sampling methods for viable microorganisms and (c) current directions of engineering and research aimed at improvement of quality and efficiency of microbiological surface sampling.
Suspension depletion approach for exemption of infected Solanum jasminoides cells from pospiviroids
(2018)
Despite numerous studies, viroid elimination from infected plants remains a very challenging task. This study introduces for the first time a novel ‘suspension depletion’ approach for exemption of Solanum jasminoides plants from viroids. The proposed method implies initial establishment of suspension cultures of the infected plant cells. The suspended cells were then physically treated (mild thermotherapy, 33 °C), which presumably delayed the replication of the viroid. The viroid concentration in the treated biomass was monitored weekly using pospiviroid-specific PCR. After 10–12 weeks of continuous treatment, a sufficient decrease in viroid concentration was observed such that the infection became undetectable by PCR. The treated single cells then gave rise to microcolonies on a solid culture medium and the obtained viroid-negative clones were further promoted to regenerate into viroid-free plants. Three years of accumulated experimental data suggests feasibility, broad applicability, and good efficacy of the proposed approach.
Recent analysis of scientific data from Cassini and earth-based observations gave evidence for a global ocean under a surrounding solid ice shell on Saturn's moon Enceladus. Images of Enceladus' South Pole showed several fissures in the ice shell with plumes constantly exhausting frozen water particles, building up the E-Ring, one of the outer rings of Saturn. In this southern region of Enceladus, the ice shell is considered to be as thin as 2 km, about an order of magnitude thinner than on the rest of the moon. Under the ice shell, there is a global ocean consisting of liquid water. Scientists are discussing different approaches the possibilities of taking samples of water, i.e. by melting through the ice using a melting probe. FH Aachen UAS developed a prototype of maneuverable melting probe which can navigate through the ice that has already been tested successfully in a terrestrial environment. This means no atmosphere and or ambient pressure, low ice temperatures of around 100 to 150K (near the South Pole) and a very low gravity of 0,114 m/s^2 or 1100 μg. Two of these influencing measures are about to be investigated at FH Aachen UAS in 2017, low ice temperature and low ambient pressure below the triple point of water. Low gravity cannot be easily simulated inside a large experiment chamber, though. Numerical simulations of the melting process at RWTH Aachen however are showing a gravity dependence of melting behavior. Considering this aspect, VIPER provides a link between large-scale experimental simulations at FH Aachen UAS and numerical simulations at RWTH Aachen. To analyze the melting process, about 90 seconds of experiment time in reduced gravity and low ambient pressure is provided by the REXUS rocket. In this time frame, the melting speed and contact force between ice and probes are measured, as well as heating power and a two-dimensional array of ice temperatures. Additionally, visual and infrared cameras are used to observe the melting process.
The search for life on Mars and in the Solar System - strategies, logistics and infrastructures
(2018)
The question "Are we alone in the Universe?" is perhaps the most fundamental one that affects mankind. How can we address the search for life in our Solar System? Mars, Enceladus and Europa are the focus of the search for life outside the terrestrial biosphere. While it is more likely to find remnants of life (fossils of extinct life) on Mars because of its past short time window of the surface habitability, it is probably more likely to find traces of extant life on the icy moons and ocean worlds of Jupiter and Saturn. Nevertheless, even on Mars there could still be a chance to find extant life in niches near to the surface or in just discovered subglacial lakes beneath the South Pole ice cap. Here, the different approaches for the detection of traces of life in the form of biosignatures including pre-biotic molecules will be presented. We will outline the required infrastructure for this enterprise and give examples of future mission concepts to investigate the presence of life on other planets and moons. Finally, we will provide suggestions on methods, techniques, operations and strategies for preparation and realization of future life detection missions.