[Visual ergonomy and flying safety. The importance of recognizing the instruments]. / Visuelle Ergonomie im Cockpit. Die Bedeutung der Instrumenteerkennbarkeit für die Flugsicherheit.

While flying, more than 90% of all relevant information reaches the pilots visually, the so-called primary flight display providing the most important information. The size, brightness, contrast, and color perception of these instruments are important for precise recognition. We discuss the results from a study of new flying instruments.

Mathematical modelling of epidemics under specific regard of adenoviral keratoconjunctivitis.

At first ADV is presented as a typical pandemic. The contagiosity of adenovirus is high because of the viability of the virus on inorganic surfaces in medical offices up to 35 days. Outbreaks and epidemics occur 3-30 days after infection, which is mainly contracted from medical facilities. EKC is considered a notifiable condition in most countries, and outbreaks, suspects and infections must be reported. Symptoms like "pink eye", foreign body sensations, photophobia, pain, signs such as follicles, hemorrhages and corneal infiltrates, and vision decrease associated with malaise are frequently observed first in one eye, later involving the fellow eye. Unilateral disease has a high rate of misdiagnosis. Currently no vaccine or virustatic is available, which is effective, cost-efficient and tolerable. Treatment is symptomatic and antiinflammatory. Late scarring may be amenable to phototherapeutic keratectomy. Infection control measures focus on the disinfection of equipment and hands of staff, the handling of infected patients with gloves, spatial separation of infected individuals resp. cohorting of infected patients, use of unit-dose eye solutions, and the chlorination of pools by approved and registered disinfectants and germicides. In connection with this it is shown how to handle the dynamics of infections by mathematical models like cellular automation, systems of differential equations and to visualize periodic effects by Fourier Analysis and to calculate costs by mathematical programming. Using mathematical analysis the percentage of a population needing vaccination to prevent spreading of pandemic can be calculated. It is shown here that especially the method of cellular automation is a simple way to simulate complex epidemiological situations without completely knowing the mathematical details.

[The history of optical signals for traffic regulation]. / Zur Geschichte der optischen Signalgebung im Verkehrswesen.

For signal transmission in traffic today, different optical, acoustic, or other physical or technical means are used for information. The different kinds of traffic (water navigation, road and rail, and, later air transport) made traffic regulation necessary early on. This regulation, from its very beginning in ancient times, began by means of optical signals; nowadays, this remains the most important method. From the very start, minimum requirements for the navigator's vision, color discrimination, dark adaptation, and even visual field were needed. For historical reasons, it was in seafaring medicine that these first developed. Besides the development of the different signals, methods for checking the requirements were soon developed. National and international requirements have been very different. Only within the last 50 years has international cooperation led to the acceptance of general standards for the different traffic modes. This article discusses the technical development of optical signals for the different kinds of traffic, from ancient times to the present, and explains the development of minimum requirements for the different visual functions.

[New trends in tonometry]. / Neue Trends in der Tonometrie.

BACKGROUND: Though the knowledge about the risk of elevated intraocular pressure for pathogenesis for development and progress of glaucoma is more than 400 years old. It took another 300 years before by means of tonometry this elevation could be quantified. After discussion of the key words it is our aim to demonstrate the latest trends in tonometry, specifically by use of modern electronics for instrument design. MATERIALS: Goldmann was the founder of the "applanation tonometry", measuring the corelation of applanated area and applied force. Here, the next step was the development of instruments, measuring independent of position or gravity to allow application also at the lying patient. Electronic area detection was the next step to avoid examinor's error. Also important was the introduction of automatic UV-desinfection to avoid contamination of the other eye or other patients. Other tonometers control the force applied by an inductive method, which also allows application independent of position. Airpuff-tonometry uses completely different measuring principles - the resulting change of corneal curvature indicates the intraocular pressure. The impedance principle is applied even through the closed eye lid. The shock waves resulting shall be measured. Direct application of a surface sensor incorporated into a concave surface contact body shall allow direct measurement of intraocular pressure independent of corneal thickness, curvature, astigmatism. This method has been tried for more than 20 years. Also exposition of the eye to count waves of different frequency was an early attempt. Here also change of reflectivity is used to calculate intraocular pressure. CONCLUSIONS: Even after use of modern electronic technology the precision of many of these new devices does not lead to better results. This specifically is shown by modern calibration methods.

[Clinical evaluation of a new tonometer on the basis of international standard ISO 8612]. / Klinische Evaluierung eines neuen Tonometers auf der Basis des internationalen Standards für Augentonometer ISO 8612.

BACKGROUND: There is a continuous process of development of new tonometer types following different measurement principles on the tonometer market. A new tonometer working on the dynamic contour measurement principle is currently available for ophthalmologists. This device has special properties, since it determines the intraocular pressure as well as the ocular pulse amplitude. So far, clinical comparison measurements exist between the new tonometer Pascal and the applanation tonometer by Goldmann albeit without any reference to a standard. Besides, these measurements cover only a small pressure range between 7 mmHg and 23 mmHg which is not sufficient for medical diagnosis. PATIENTS AND METHODS: This new tonometer was investigated by clinical comparison measurements according to the currently valid international standard for human eye tonometers (ISO 8612). The tested tonometer determines the intraocular pressure without fluorescein. In an ophthalmogical hospital in Berlin the clinical comparison measurements were carried out by ophthalmologists on 127 patients according to the methods and criteria of the above-mentioned standard. A calibrated AT 870 from the Haag-Streit company served as reference tonometer. RESULTS: The different cornea surface geometries of individual eyes, the variation of tear liquid volume, and also the different elastic properties of the human eye due to a large variation in rigidity led to measurements of intraocular pressure by this tonometer with an excessively high number of outliers p (i) (i = 1, ..., 3) per group (p (1) = 16.28 %, p (2) = 8.85 %, p (3) = 15.69 %, 5.0 % outliers per group only are permitted for the differences method), which do not correspond to the requirements of the international standard for tonometers ISO 8612. This is also shown by application of total method of least squares of regression line (slope a = 0.964, interception b = 2.868 mmHg, standard deviation s (y) = 2.628 mmHg). CONCLUSIONS: The test of conformity of results of clinical comparison measurements to the international standard for tonometers ISO 8612 is the target of this work. The measurement results of the investigated tonometer are analysed and discussed according to this standard. Statements about the medical application of this medical measurement device for ophthalmologists are presented. According to the presented investigations the requirements of this international standard are not fulfilled by the tonometer Pascal.

[Clinical Testing of New Tonometers on the Basis of the International Standard for Human eye Tonometers ISO 8612]. / Klinische Erprobung neuer Augentonometer auf der Basis des internationalen Standards für Augentonometer ISO 8612.

There is a continuous process of development of new tonometer types following different measurement principles. The impedance measurement method, using the elasticity of the eyeball, allows tonometry even through the eyelid. Two new tonometers based on the impedance principle were investigated by clinical comparison measurements according to the international standard for human eye tonometers ( ISO 8612). The tested tonometers determine the intraocular pressure without topical anaesthesia. The different elastic properties of an individual eyelid and also the different elastic properties of the human eye due to a large variation in rigidity cause serious problems for these measurements. Statistical properties of the two investigated tonometers are presented and discussed. Statements and conclusions about the medical application of these measurement devices for ophthalmologists are made.

Anaesthesiological experiences with whole body hyperthermia.

OBJECTIVE: In order to investigate the safety of whole body hyperthermia (WBH) within the context of systemic Cancer Multistep Therapy (sCMT) in patients with disseminated malignancies, cardiopulmonary changes and various organ functions were examined. METHODS AND PROCEDURES: Fifty-seven sCMT treatments were performed in 22 patients. WBH with a plateau phase of 1 h at 41.8 degrees C was induced by an IRATHERM 2000 device. Cardiopulmonary parameters were measured at 37, 40, 41.8 and 39 degrees C by use of a pulmonary artery catheter, femoral oxymetry and a radial artery catheter. Organ functions of the liver, kidney, cardiovascular and central nervous system were evaluated before and after treatment. RESULTS: Compared with the initial values, significant alterations were found of most cardiopulmonary parameters in the sense of hypercirculation at 41.8 degrees C. With the exception of extra vascular lung water index, all parameters showed a clear tendency towards the pre-treatment levels at 39 degrees C. In eight out of 57 sCMT treatments, reversible organ dysfunctions were observed. Comparison of radial and femoral arterial blood pressure showed significantly different values at 40 and 41.8 degrees C. CONCLUSIONS: WBH induces cardiovascular stress, but by careful selection of patients and appropriate anaesthesiological monitoring it can be performed safely using general anaesthesia. This enables further evaluation of WBH in multimodal treatment concepts.

[Technical construction, calibration and results with a new intraocular pressure sensor with telemetric transmission]. / Technischer Aufbau, Kalibrierung und Ergebnisse mit einem neuen intraokularen Drucksensor mit telemetrischer Ubertragung.

BACKGROUND: Presently intraocular pressure is measured indirectly by applanation or impression of the cornea. Only isolated values are available with this method. We present a new implantable system for direct and continuos measurement of the intraocular pressure. METHODS: An implantable system consisting of a miniaturized sensor and a telemetric unit was integrated in an intraocular lens. The eye pressure is determined by the sensor, modulated and transduced by the telemetric system. By an extracorporal receiver the signal is demodulated. The electric supply of the intraocular system is achieved by external electromagnetic induction. RESULTS: The telemetric transmission of the intraocular pressure can be achieved with an accuracy of +/- 1 mm Hg and a frequency of registration of 3 values per second. CONCLUSION: Clinical application necessitates further animal trials in vivo.

[New diagnostic possibilities by a fully automatic applanation tonometer for the ophthalmologist. From the Goldmann principle to automated tonometry]. / Neue diagnostische Möglichkeiten durch ein vollautomatisches Applanationstonometer für den Augenarzt. Vom Goldmann-Prinzip zur automatischen Tonometrie.

Applanation tonometry, following Goldmann's hypothesis serves as the gold Standard in tonometry. However, even this approach principle does not always eliminate examiner's error, especially in defining the applanation surface. An automatic surface and force control system is used to increase measurement precision, thus increasing precision and speed of measurement. The instrument, already in use for the patient's self-tonometry, is now also available for the ophthalmologist. An additional coaxial observation system allows precise centering of the applanation surface onto the cornea. This allows new applications of applanation tonometry in daily routine.

[Revisions in the assessment of fitness for aircraft flying]. / Neuerungen in der Beurteilung der Luftfahrttauglichkeit.

So far medical requirements for aviators have been defined by national licensing authorities. For a long while ophthalmological problems, insufficiencies in vision, refraction or color vision, have been responsible for approximately 50% of rejection of applicants for medical reasons. New international regulations proposed as well by ICAO as JAA try to lead to a new balance in these requirements. In general, ophthalmological requirements now allow for lower standards, specifically in refraction, but also in color vision. Also new examination methods are admitted. German and French authorities have announced their opposition being concerned about flight safety for the future.

Extracellular glutamate and other metabolites in and around RG2 rat glioma: an intracerebral microdialysis study.

The current study determined the extracellular content of glutamate, 10 additional amino acids, lactate, glucose and some antioxidants in a rodent model of malignant glioma, its peritumoral space and the adjacent cortex. RG2 tumors were induced in the right frontal cortex of Fischer-344 rats (n = 10) by a standardized procedure to obtain a maximum sagittal tumor width of 3-4 mm diameter. After confirmation of tumor growth and localization by contrast enhanced MRI three microdialysis probes were implanted simultaneously in the cortex: at the tumor implantation site (tumor), 2 mm caudally, brain around tumor (BAT) and 4 mm caudally (cortex) to the site of implantation. Dialysate concentrations of glutamate were increased 3.9-fold in tumor and 2-fold in BAT compared with cortex. Glycine was elevated 11.4-fold in tumor and 2.6-fold in BAT. Lactate was increased 1.7-fold in tumor, 1.2-fold in BAT. Levels of glucose, ascorbic acid and uric acid were not significantly different in tumor, BAT and cortex. The increased dialysate levels of glutamate and glycine in the peritumoral space may contribute to impaired neuronal function and epileptiform activity associated with this tumor type in humans.

Continuous assessment of intraocular pressure - telematic transmission, even under flight- or space mission conditions.

Fluid shift after entering into microgravity, but also under equivalent flight conditions leads to enormous increase of intraocular pressure. To assess this precisely position - and gravity independent, handsome, automatic tonometers have been developed (German-Spacelab D1-Mission, German-Spacelab D2-Mission, German-Russian-MIR-Mission) telemetric transmission of measuring results of course would find scientific but also functional interest. The same is true for recently designed automatic intraocular pressure sensors, registering intraocular pressure continuously, day and night. Also recently designed new automatic ophthalmodynamometer, allowing directly to assess the intracranial pressure, but also perfusion pressure within the eye also could benefit from a direct telemetric transmission. New technical solutions allowing for the first time even telematic data transmission, are reported.

Intracranial pressure in microgravity conditions: non-invasive assessment by ophthalmodynamometry.

BACKGROUND: As well known from former manned spaceflight experiments (German D2-Mission/German D1-Mission 1985/German-Russian MIR-Mission 1 992/German-D2-Mission 1993), fluid shift after entry into microgravity leads to a rapid increase in pressure and volume within the upper compartments of the human body. This has been proven by precise measurements with automatic selftonometers for intraocular pressure. HYPOTHESIS: There is little doubt, that a very similar--even more, marked--increase of intracranial pressure happens soon after entry into microgravity. This may be the cause for some of the reported hormonal and even neurological changes in metabolism. There is no non-invasive method to assess these important increases in pressure. METHODS: Ophthalmodynamometry in general allows for rather precise estimation of intracranial BP, but so far the method was too complicated for routine application, specifically in spaceflight conditions. Therefore, using the microprocessor controlled technology of our automatic selftonometer we have designed a very precise automatic instrument which can be applied by the astronaut/kosmonaut. The measurement takes only a few seconds. CONCLUSIONS: This easily applied, non-invasive method would allow for completely new insights into these important changes and explain some of the clinical consequences noted so far.

Differentiation between Spitz nevi and malignant melanomas by interphase fluorescence in situ hybridization.

Spitz nevi are benign melanocytic neoplasias which have distinct pathological features that make the pathological differential diagnosis from malignant melanomas extremely difficult. The Spitz nevi may be misdiagnosed as malignant melanoma and vice versa. Therefore, interphase fluorescence in situ hybridization (I-FISH) was used for a possible discrimination between Spitz nevi and malignant melanomas on the basis of numerical aberrations of the chromosome complement in interphase nuclei of thin sections. Previous studies had shown changes in malignant melanomas which were not found at the same level in normal tissue or benign tumors. Thin sections of archival paraffin material from 42 Spitz nevi with different histological type and grade of anomaly were subjected to FISH-analyses using commercially available biotinylated and/or digoxigenated alphoid DNA probes of chromosomes 1, 6, 7, 9, 17 and 18, which were applied in combinations in a two- or three-color-FISH. Unaffected epithelial areas from the same sections served as. The obtained data were compared with those collected previously from thin sections of malignant melanomas prepared in the same way. Due to the sometimes limited nevus area investigated, the number of evaluable nuclei was lower than expected from previous experiences with malignant melanomas. Therefore, only 20 nevi could be reliably evaluated. The comparison of the group of Spitz nevi with the group of controls did not show any significant difference regarding chromosomes 1, 6, 7, 9 and 17 (Wilcoxon test). The method used to detect chromosomal loss or gain in the individual Spitz nevi demonstrated only two nevi (one of the spindle cell type with a low to middle grade of anomaly, the other of the epitheloid cell type with a middle grade of anomaly) with a gain of chromosome 7 and chromosome 17, respectively. So, with respect to the histological type and grade of anomaly, no numerical aberrations could be detected in Spitz nevi. The comparison of the group of Spitz nevi with subgroups of malignant melanomas (metastatic, non-metastatic, melanomas with a thickness <1.5 mm and melanomas with a thickness >2. 0 mm) and with the whole group of malignant melanomas showed significant differences concerning chromosome 9 (Mann-Whitney U test), signal indices, which were higher in the melanomas than in the Spitz nevi. Regarding chromosomes 6, 7 and 17 no significant differences could be shown, although a trend of gain in melanomas and of loss in Spitz nevi was observed of these chromosomes.