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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 125 (1987), S. 613-628 
    ISSN: 1420-9136
    Keywords: Aegean area ; seismicity rate ; Poisson process ; seismic energy release ; thermal stresses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The most complete and reliable data of strong (M s≥6.5), shallow (h〈70 km) earthquakes which occurred in the inner Aegean seismic zone have been utilized to describe its seismicity time variation during 1800–1986 by two independent statistical models. The first is a sequentially stationary model of seismicity rates which shows that intervals of low seismicity rate, lasting for some 37 years, alternate with high rate intervals of 8–12 years duration. The second model is a statistical model according which seismic energy released within 5-year time windows approximates a harmonic curve within a period of about 50 years. This model is in agreement with the notion that the time series of strong earthquake occurrences in the inner Aegean seismic zone consists of a random (shocks withM s=6.5–6.8) and a nonrandom component (M s≥6.9). Maxima and minima of the harmonic curve coincide with the high and low rate intervals, respectively. A model of regional stationary accumulation of thermal stresses along certain seismic belts and their cyclic relaxation may explain this periodicity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Antigen presentation ; autoimmune diseases ; diabetes mellitus ; juvenile diabetes ; histocompatibility antigens ; HLA-DQ molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The structural features of HLA-DQ alleles which are susceptible and resistant to insulin-dependent diabetes mellitus (IDDM) have been examined using a model of their three-dimensional structure obtained by energy minimisation, based on the published structure of HLA-DR1. The model shows DQ molecules to have an overall shape nearly identical to that of DR molecules, but with significant differences in the fine structure: 1) the antigen-binding groove of DQ molecules has a polymorphic first pocket; this pocket can be either amphiphilic or hydrophilic, 2) The Β49–56 dimerisation domain of DQ is polymorphic: hydrophobic, or amphiphilic, or hydrophilic and positively charged, leading to spontaneous or T-cell receptor-induced homodimer formation, or difficulty of the formation of such dimers, respectively; 3) a prominent Arg-Gly-Asp loop is formed by some DQ alleles (Β167–169) and probably functions in cell adhesion. There are also small differences in the residues and sequences implicated in CD4 binding (mostly in DQΒ134–148) but the significance of these differences cannot be evaluated at present. All seven DQ alleles which confer susceptibility to IDDM posses a hydrophilic first pocket in the antigen-binding groove, a hydrophobic or amphiphilic Β49–56 dimerisation patch that allows for spontaneous or T-cell receptor-induced dimerisation, and the Arg-Gly-Asp loop. By contrast, in the protective alleles at least one of these three features is absent. This segregation of phenotypes according to susceptibility or resistance can well explain the model of tighter autoantigen binding by the protective alleles compared to the susceptible alleles, previously proposed for the pathogenesis of IDDM.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Key words Antigen presentation ; autoimmune diseases ; diabetes mellitus ; juvenile diabetes ; histocompatibility antigens ; HLA-DQ molecules.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The structural features of HLA-DQ alleles which are susceptible and resistant to insulin-dependent diabetes mellitus (IDDM) have been examined using a model of their three-dimensional structure obtained by energy minimisation, based on the published structure of HLA-DR1. The model shows DQ molecules to have an overall shape nearly identical to that of DR molecules, but with significant differences in the fine structure: 1) the antigen-binding groove of DQ molecules has a polymorphic first pocket; this pocket can be either amphiphilic or hydrophilic, 2) The β49–56 dimerisation domain of DQ is polymorphic: hydrophobic, or amphiphilic, or hydrophilic and positively charged, leading to spontaneous or T-cell receptor-induced homodimer formation, or difficulty of the formation of such dimers, respectively; 3) a prominent Arg-Gly-Asp loop is formed by some DQ alleles (β167–169) and probably functions in cell adhesion. There are also small differences in the residues and sequences implicated in CD4 binding (mostly in DQβ134–148) but the significance of these differences cannot be evaluated at present. All seven DQ alleles which confer susceptibility to IDDM posses a hydrophilic first pocket in the antigen-binding groove, a hydrophobic or amphiphilic β49–56 dimerisation patch that allows for spontaneous or T-cell receptor-induced dimerisation, and the Arg-Gly-Asp loop. By contrast, in the protective alleles at least one of these three features is absent. This segregation of phenotypes according to susceptibility or resistance can well explain the model of tighter autoantigen binding by the protective alleles compared to the susceptible alleles, previously proposed for the pathogenesis of IDDM. [Diabetologia (1995) 38: 1251–1261]
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Keywords Autoimmunity ; I-Ag7 molecule ; MHC class II structure ; protein modelling ; NOD mice ; Type I diabetes mellitus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. We modelled the three-dimensional structure of I-Ag7, the chief genetic component of diabetes in non-obese diabetic mice, to understand the unusual properties of this molecule. Methods. Modelling was done, in complex with established antigenic peptides, based on the structure of I-Ak. Results. The selectivity of the I-Ag7 molecule changes greatly at pockets 9 and 6 but hardly at all at pockets 1, 4 and 7, between endosomal pH (5.0) and extracellular pH (7.0), in agreement with previous results. This selectivity is attributed to the unique combination of β9His, β56His and β57Ser. The positive charges in and around pocket 9 at pH 5, favour binding by negatively charged residues. At pH 7 however, the uncharged α68, β9 and β56 histidines favour the accommodation of the bulky residues lysine, arginine, phenylalanine and tyrosine at pocket 9. The combination of β9His and α66Glu is responsible for the pH-dependent selectivity at pocket 6. Furthermore, the lack of repulsion between β56His and α76Arg at pH 7 leads to a more stable ternary complex. Conclusion/interpretation. These results reconcile previous conflicts over the peptide binding ability of I-Ag7 and its motif. They furthermore provide possible explanations for the short lifetime of cell-surface I-Ag7 complexes in vivo, the higher threshold of thymic negative selection and inherent self-reactivity shown by immunocytes in these mice and the protection from diabetes afforded to them by several transgenically expressed mouse class II alleles. This contributes to an understanding of the pathogenesis of Type I (insulin-dependent) diabetes mellitus in this animal. [Diabetologia (2000) 43: 609–624]
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  • 6
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Nichtinvasive Blutdruckmessung ; Oszillometrie ; Geräteprüfung ; Dinamap 1846 ; HP M-1008B ; Intensivemedizin ; Simulator ; Key words Blood pressure measurement ; Oscillometric method ; Intensive care patients ; Performance test ; Simulator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Using the PTB simulator, which emits real signals from patients, we examined the precision of the oscillometric blood pressure measurement with the Dinamap 1846 (Critikon) and the HP M-1008B (Hewlett Packard). For this purpose we simultaneously registered invasive arterial pulsewave, cuff pressure and cuff pressure oscillations of 20 patients from our intensive care unit and stored them in the database of the simulator. The invasive reference blood pressure values were determined following the recommendations given by the Association for the Advancement of Medical Instrumentation. The invasive system showed a cut-off frequency of 35 Hz; the damping constant was 0.21. With 49 record signals from patients we carried out 15 simulated measurements each. From a total of 49 bio-signals from patients the Dinamap 1846 was able to process 41 signals and the HP M-1008B 47 signals. The mean error of the oscillometric blood pressure measurement of the systolic, diastolic and mean arterial pressure amounted to −2.50 mmHg, 3.35 mmHg (P〈0.05) and 1.51 mmHg with the Dinamap 1846 and to −8.5 mmHg (P〈0.001), −5.15 mmHg (P〈0.001) and −5.58 mmHg (P〈0.001) for the HP M-1008B. The 95% confidence limit for the systolic, diastolic and the mean arterial pressure amounts to 56 mmHg, 30 mmHg and 35 mmHg for the Dinamap 1846 and 50 mmHg, 38 mmHg and 35 mmHg for the HP M-1008B. The differences between that two instruments could be caused by the different algorithms for the calculation of blood pressure values and different artefact detection and elimination techniques. The results of the performance tests we achieved with the PTB simulator correspond to the results of other clinical examinations. The American Association for the Advanecement of Medical Instrumentation recommends a maximum mean error of 5±8 mmHg. None of the examined instruments lay within these limits. Due to the systematic and stochastic errors, we think that the Dinamap 1846 (Critikon) and the HP M-1008B (Hewlett Packard) do not achieve performance levels that are adequate for measuring critically ill patients.
    Notes: Zusammenfassung Mit Hilfe eines Simulators, der reale Biosignale von Patienten verwendet, wurde die Meßgenauigkeit der Geräte Dinamap 1846 (Critikon) und HP M-1008B (Hewlett Packard) untersucht. Es wurden 49 artefaktfreie oszillometrische Signale von 20 Intensiv-Patienten für die Simulationsmessungen benutzt. Das Dinamap 1846 konnte nur 41 Signale von Patienten auswerten, das HP M-1008B 47 Signale. Bei dem Vergleich mit der invasiven Blutdruckmessung betrug der mittlere Meßfehler für den systolischen, diastolischen und mittleren arteriellen Blutdruck für das Dinamap 1846 2,50 mm Hg, 3,35 mm Hg (p〈0,05) und 1,51 mm Hg, sowie für das HP M-1008B −8,51 mm Hg (p〈0,001), 5,15 mm Hg (p〈0,001) und −5,58 mm Hg (p〈0,001). Das 95%-Toleranzintervall für den systolischen, diastolischen und mittleren arteriellen Blutdruck betrug 56 mm Hg, 30 mm Hg und 35 mm Hg für das Dinamap sowie 50 mm Hg, 38 mm Hg und 35 mm Hg für das HP M-1008B. Die unterschiedlichen Meßergebnisse sind vermutlich auf verschiedene Algorithmen zur Bestimmung der Blutdruckwerte und verschiedene Artefakterkennungsprogramme der Geräte zurückzuführen. Wegen der systematischen und stochastischen Abweichungen sind wir der Auffassung, daß das Dinamap 1846 und das HP M-1008B noch nicht den technischen Stand erreicht haben, um auch bei kritisch Kranken eingesetzt zur werden.
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  • 7
    ISSN: 1432-0568
    Keywords: Auditory cortex ; Thalamus ; Thalamocortical connections ; Horseradish peroxidase ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The auditory area of the sheep cerebral cortex was studied on the basis of its afferents from the medial geniculate nucleus, traced with the horseradish peroxidase retrograde transport method. The results show that the medial geniculate nucleus projects only to the anterior parts of the posterior ectosylvian gyrus and the posterior sylvian gyrus. A small area of the posterior ectosylvian gyrus receives afferents exclusively from the ventral part of the medial geniculate nucleus, while the anterior part of the posterior sylvian gyrus receives also afferents from the posterior nucleus of the thalamus and the pulvinar. In addition, it was found that the medial part of the medial geniculate nucleus projects in a sparse way to the auditory cortex. The middle part of the posterior ectosylvian gyrus receives afferents from the posterior nucleus of the thalamus, the suprageniculate nucleus and the pulvinar, while the posterior part of the posterior ectosylvian gyrus together with the posteriormost part of the posterior sylvian gyrus receive afferents from the pulvinar. Finally, the area located between the anterior and the posteriormost part of the posterior sylvian gyrus receives afferents from both the posterior nucleus of the thalamus and the pulvinar.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0568
    Keywords: Cortex ; Brain stem ; Spinal afferents ; Horseradish peroxidase ; Hedgehog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cortical and brain stem neurons projecting to the spinal cord in the hedgehog were studied by means of the horseradish peroxidase (HRP) tracing method. HRP injections were placed in the first cervical segments, in the cervical enlargement (C5-T3) and in the lumbar enlargement. Following injections in the first cervical segments and in the cervical enlargement labelled neurons were observed in the somatic motor and somatic sensory cortices, the paraventricular and the dorsomedial hypothalamic nucleus, the lateral hypothalamic area, the nuclei of field H of Forel, the red nucleus, the mesencephalic reticular formation, the deep layers of the superior colliculus, the Edinger-Westphal nucleus, the periaqueductal grey, the mesencephalic trigeminal nucleus, the loci coeruleus and subcoeruleus, the nuclei raphe dorsalis, centralis superior, raphe magnus, raphe pallidus, and raphe obscurus, the rhombencephalic reticular formation, the lateral, medial and caudal vestibular nuclei, the nucleus ambiguus, the nucleus of the solitary tract and the gracile nucleus. After HRP injections in the lumbar enlargement, labelled neurons were not found in the cortex, the dorsomedial hypothalamic nucleus, the nuclei of field H of Forel, the superior colliculus and the mesencephalic trigeminal nucleus. These results show that cortical and brain stem projection to the spinal cord are comparable to those described in other species.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Der Anaesthesist 43 (1994), S. 441-446 
    ISSN: 1432-055X
    Keywords: Schlüsselwörter: Nichtinvasive Blutdruckmessung – Oszillometrie – Neonaten – Simulator – Geräteprüfung ; Key words: Blood pressure measurement – Oscillometric method – Neonates – Simulator – Performance test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Non-invasive blood pressure measurements by the auscultatory method do not provide reliable, reproducible blood pressure values in many neonates because the Korottkoff sounds are often very difficult to detect. This resulted in the development of many alternative indirect methods. Devices utilizing the Doppler ultrasound technique have not found wide acceptance. Since the introduction of automated oscillometric blood pressure monitors, arterial blood pressure has been increasingly brought into discussion as an indicator of the circulatory state. This is the first study to investigate the similarity and reproducibility of the data obtained with five oscillometric devices for measurement of blood pressure in neonates. Materials and methods. Since investigations on the technical performance are not practical in the clinical setting of a neonatal or pediatric ward, we used two simulators, the CuffLink (Dynatech, Nevada, USA) and a device developed by the PTB (Physikalisch-Technische Bundesanstalt). While the latter uses oscillations originally obtained from neonates, the CuffLink uses artificial and therefore ideal signals for the blood pressure monitors. The signals used for the PTB simulator were obtained from three neonates with an average age of 2 months and a weight of 3.5 kg, 4.4 kg, and 7.8 kg. The following blood pressure monitors were studied: Hoyer/Colin, BP-1001; Datex, Cardiocap II; SpaceLabs, model no. 90426; Hewlett-Packard, NBP M1008A; Critikon, Dinamap 1846. Before the measurements were started, the cuff pressure display of each monitor was checked according to a verification procedure. Although the 4 mm Hg margin of error was not exceeded, the results were corrected. Results. The results of the measurements show significant differences between the blood pressure monitors from the various manufacturers, with the differences for the ideal signals of the CuffLink-Simulator being less pronounced than those for the PTB simulator. Direct comparison of results is therefore often impossible. The standard deviation, taken from 20 measurements per monitor and simulation, is below 4 mm Hg for both simulators. We can therefore conclude that the reproducibility of data is satisfactory and the emerging trend is reliable. Discussion. The difference between the results of the PTB simulator and the CuffLink are probably due to the method of evaluation and the identification of artifacts of each blood pressure monitor. This is also confirmed by the studies of Mieke et al. The manufacturers should provide devices that display comparative results and improve the algorithms for detection of artefacts, increasing the accuracy of their blood pressure monitors. This could be done with the help of simulators. Considering the pathophysiological characteristics of neonates and infants, the systematic differences between the five monitors have to be regarded as serious.
    Notes: Zusammenfassung. Mit Hilfe zweier Simulatoren wurde das Meßverhalten von fünf automatischen Blutdruckmeßgeräten für Neugeborene (Hoyer/Colin, BP-1001; Datex, Cardiocap II; SpaceLabs, Modul 90426; Hewlett-Packard, NBP M1008A; Critikon, Dinamap 1846) auf Vergleichbarkeit und Reproduzierbarkeit der Ergebnisse untersucht. Die an den Simulatoren durchgeführten Messungen zeigen deutliche Unterschiede zwischen den Geräten verschiedener Hersteller. Da die Standardabweichung, ermittelt aus jeweils 20 Wiederholungsmessungen meist unter 4 mm Hg liegt, kann bei diesen Geräten von einer guten bis befriedigenden Reproduzierbarkeit der Messungen gesprochen und der Trend somit relativ sicher ermittelt werden. Angesichts der pathophysiologischen Besonderheiten beim Neugeborenen sind die systematischen Unterschiede zwischen den einzelnen Geräten als gravierend einzustufen. Die Industrie wird aufgefordert, die Vergleichbarkeit der Geräte verschiedener Hersteller zu erreichen.
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  • 10
    ISSN: 1432-055X
    Keywords: Schlüsselwörter: Offenes Foramen ovale – Transösophageale Echokardiographie – Transthorakale Echokardiographie ; Key words: Patent foramen ovale – Transoesophageal echocardiography – Transthoracic echocardiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Preoperative detection of a patent foramen ovale (PFO) may be achieved employing either transthoracic echocardiography (TTE) with the Valsalva manoeuvre in the awake patient or trans-oesophageal echocardiography (TEE) in the anaesthesised patient. Our study was undertaken to validate these methods with regard to their efficacy in identifying patients at risk for paradoxical air embolism (PAE). Methods. In 67 patients ranging from 28 to 70 years of age, TEE was performed utilising the Valsalva manoeuvre prior to surgery. The patients were informed about all procedures and agreed to take part in the study. After induction of anaesthesia the patients were evaluated with TEE in the supine and sitting positions. At end-inspiration 10 ml agitated gelatine solution (Gelafundin) was injected through a central venous catheter into the right atrium after airway pressure of 20 cm H2O had been maintained for 5 s. The injected bolus was observed throughout the ventilatory cycle, with special attention being given to early expiration and systole. A right-to-left shunt was assumed if five echo targets were observed in the left atrium. Results. The prevalence of PFO detected by TTE/Valsalva was 9%. The diagnosis was confirmed by TEE in 2 patients in the supine and 1 in the sitting position. An echocardiogram in these patients showed bulging of the septum to the left, which was not seen in those patients in whom PFO was detected only by TTE. Discussion. The reason for the lower incidence of PFO detected by TEE during airway pressure 20 cm H2O may have been an insufficient increase of pressure in the right atrium with a negative right-to-left atrial pressure gradient. A standardised ventilation manoeuvre with supra-atmospheric airway pressure of 20 cm H2O is not sufficient. Bulging of the intra-atrial septum from right to left during airway pressure is a possible indication of the efficacy of the manoeuvre, regardless of the influence of the breathing pattern.
    Notes: Zusammenfassung. In einer offenen prospektiven Untersuchung wurde die Wertigkeit der transösophagealen Echokardiographie (TEE) zum intraoperativen Nachweis eines funktionell offenen Foramen ovale (PFO) untersucht. Die Untersuchungen auf das Vorliegen eines PFO erfolgten präoperativ durch die transthorakale Echokardiographie (TTE) mit Hilfe des Valsalvamanövers, intraoperativ mittels TEE unter Durchführung eines Ventilationsmanövers (Atemwegsdruck von 20 cm H2O). Dabei wurde als Kontrastmittel Gelatinelösung (Gelafundin®) injiziert. Bei sechs von 67 Patienten konnte durch die TTE ein PFO mit Rechts-links-Shunt nachgewiesen werden. Nur drei dieser sechs Patienten zeigten mit der TEE (Ventilationsmanöver) einen positiven Befund. Echokardiographisch zeigte sich eine linkskonvexe Verlagerung des interatrialen Septums. Dies war nicht der Fall bei den Patienten mit nur durch TTE nachgewiesenen PFO. Als Ursache für die geringere Sensitivität der TEE unter Provokationsmanöver mit Atemdruck von 20 cm H2O kommt eine nicht ausreichende Druckerhöhung im rechten Vorhof mit negativem rechts/linksatrialen Druckgradienten in Frage. Aufgrund unserer Ergebnisse und Literaturangaben erscheint uns ein standardisiertes Ventilationsmanöver mit Atemwegsdruck von 20 cm H2O zum Nachweis eines PFO mit Rechts-links-Shunt nicht ausreichend. Die transiente linksgerichtete Verlagerung des interatrialen Septums während eines Manövers bei beatmeten Patienten kann möglicherweise als Hinweis auf eine effektive Provokation angesehen werden.
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