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  • 1
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Human apolipoproteins (apo) E and apo A-IV are polymorphic with significantly different allele frequencies among different ethnic groups. Whereas the variation at the apo E gene locus affects plasma cholesterol levels in all populations studied so far and is associated with longevity in Caucasians, the influence of the common apo A-IV polymorphism on plasma lipoproteins has not been unanimously accepted. We have therefore determined the common apo E and apo A-IV polymorphisms by isoelectric focusing, calculated the respective allele frequencies and studied their effects on plasma lipoproteins in a random sample of 240 nonrelated Turkish subjects (141 males, 99 females) living in Germany and originating from central and eastern Anatolia. When compared with the German population and other Caucasians in Europe a prominence of the apo ɛ3 allele frequency (0.885) was accompanied by a decrease in the frequencies of both the apo ɛ2 allele (0.048) and the apo ɛ4 allele (0.067). Thus, the Turkish population studied here clustered with populations mainly from southern Europe and Japan, which have low ɛ2 and ɛ4 allele frequencies. Also, the frequency of the A-IV-1 allele was higher (0.967) and that of the A-IV-2 allele lower (0.033) in the Turkish subjects studied than in other populations. At an average level of total cholesterol of 194.5 ± 45 mg/dl, no significant influence of the A-IV alleles on plasma lipoproteins was seen. However, apo E and apo B differed significantly between apo E phenotypes, with high levels of apo E and low levels of cholesterol and apo B in carriers of the ɛ2 allele, and vice versa for the ɛ4 allele. The average cholesterol excess for the ɛ2 allele was –7.95 mg/dl, for the ɛ3 allele, –1.34, and for the ɛ4 allele, +14.15 mg/dl. Thus, despite the unusual frequency distribution of the apo E alleles, their effects on plasma lipoproteins are within the range reported for other populations in Europe.
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  • 2
    ISSN: 1432-1076
    Keywords: Respiration ; Sleep apnea ; Sudden infant death syndrome ; Aminophylline ; QT interval ; Postnatal period
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined the application of statistical parameters related to respiratory control in order to assess possible risk for the sudden infant death syndrome (SIDS). The suitability of these parameters was tested in 287 infants between 1 day and 6 months of age. Respiration of the infants was recorded during sleep, and duration and frequency of apneic spells was evaluated. All infants were patients of the department of pediatric surgery, and were free of pulmonary, cardiac or cerebral diseases. Of the investigated infants, 54 were assigned as an at risk group, for they had already had demonstrable serious or life threatening apneas or respiratory problems during anesthesia. We computed the frequency distribution of sleep apnea durations, and calculated the respective probabilities for the occurrence of apnea of a certain duration according to age. By analogy with Shannon's well known definition of average information content we defined an entropy term, which formally agrees with the definition of entropy in thermodynamics. This statistical procedure seems to be well suited for the identification of disorders in respiration control possibly related to a risk for SIDS. All at risk infants were treated with aminophylline, and the respiratory state improved significantly in nearly all cases. In some infants QT intervals were evaluated from the ECG recordings during sleep, but no significant differences between risk and control infants could be demonstrated.
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  • 3
    ISSN: 1615-6714
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Levelling arches made of stainless-steel wires were compared with nickel-titanium wires of the new generation which are distinguished by their shape memory, superelasticity and their excellent spring-back. The data received from a bending test have been analysed statistically and revealed a linear unloading curve of the twisted stainless-steel wires. The nickel-titanium wires, however, showed a clear deviation form the linearity with a curviform course. Besides the unusual unloading curve with a constant force mechanism in the middle range of deactivation the wires give off the same amount of force irrespective of the degree of activation (that is to say, regardless whether the level difference between the brackets amounts to 1 or to 4 mm). The diagram shows that the greater the activity between the brackets, the longer the period of superelasticity. Therefore the nickel-titanium wires are suited for large level differences or deflections. At a low activation rate the characteristic line takes a very steep and almost linear deactivation curve. In these cases twisted stainless steal wires should be preferred because of their lower load deflection rate and flexibility.
    Abstract: Résumé Les arcs de nivelage de fils d'acier tressés ont été comparés avec les fils nickel-titane de la nouvelle génération, se distinguant par leur mémoire de forme, superélasticité et capacité excellente de rappel. Les valeurs relevées au cours de l'essai de pliage ont été enregistrées statistiquement et ont montré une caractéristique linéaire du tracé de force des fils d'acier tressés. Les fils nickel-titane ont cependant montré une déviation significative en présentant non une linéarité mais un tracé curviligne. A côté de leur caractéristique atypique de leur tracé de force avec un dégagement constant de force au centre de la courbe, ces fils ont produit la même force, indépendamment, du degré d'activation (c.-à-d., indépendamment du fait que l'espace entre les brackets fut de 1 ou 4 mm). Plus l'activation était grande entre les brackets, plus la zone du dégagement de la force constante-la superélasticité, paraissait longue sur le diagramme. C'est pourquoi ces fils sont indiqués pour de fortes différences de niveau ou déflexions importantes. En cas d'activation peu considérable, le tracé est très raide et presque linéaire. Dans ces cas, la préférence doit être accordée aux fils d'acier tressés, en raison de leur force élastique et flexibilité inférieures.
    Notes: Zusammenfassung Nivellierungsbögen aus verseilten Stahldrähten wurden mit Nickel-Titanium-Drähten der neuen Generation, ausgezeichnet durch Formgedächtnis, Superelastizität und exzellentes Rückstellvermögen, verglichen. Die im Biegeversuch ermittelten Werte wurden statistisch aufbereitet und ergaben eine lineare Kraftweg-Kennlinie der verseilten Stahldrähte. Die Nickel-Titanium-Drähte zeigten aber eine deutliche Abweichung von der Linearität mit kurviger Verlaufsform. Neben der atypischen Kraftweg-Kennlinie mit einer konstanten Kraftabgabe im Mittel der Kurve gaben diese Drähte, unabhängig vom Aktivierungsgrad (das heißt unabhängig davon, ob die Stufe zwischen den Brackets 1 oder 4 mm betrug), dieselbe Kraft ab. Je größer die Aktivierung zwischen den Brackets war, desto länger stellte sich der Bereich der konstanten Kraftabgabe-die Superelastizität-im Diagramm dar. Daher eignen sich die Drähe für große Niveauunterschiede oder Deflektionen. Bei geringer Aktivierung verläuft die Kennlinie sehr steil und annähernd linear. In diesen Fällen ist verseilten Stahldrähten aufgrund ihrer kleineren Federrate und Flexibilität der Vorzug zu geben.
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  • 4
    ISSN: 1432-1440
    Keywords: Respiration control ; Sleep apnea ; CO2 and oxygen response ; Hypoxia ; Sudden infant death syndrome ; Atemsteuerung ; Schlafapnoen ; Hypoxie ; CO2- und O2-Antwortkurven ; plötzlicher Kindestod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wir untersuchten das Verhalten verschiedener Variabler, die mit der Atemregulation bei Säuglingen bis zu einem Alter von 6 Monaten in Verbindung stehen, um ein eventuelles Risiko für das Auftreten eines SIDS-Ereignisses (sudden infant death syndrome) identifizieren zu können. Bei 23 von insgesamt 114 untersuchten Säuglingen waren bereits ernste oder lebensbedrohende Apnoeanfälle während chirurgischer Eingriffe unter Narkose beobachtet worden. Diese Babies wurden als Risikogruppe bezeichnet, während die restlichen untersuchten Säuglinge als Kontrollgruppe galten. Wir konnten zeigen, daß praktisch alle Risikosäuglinge Apnoen während des Schlafes hatten, die eine Länge von 8 s überschritten. Lediglich 22% aller Kontrollsäuglinge hatten Apnoen dieser Länge. Von den aufgezeichneten Atemkurven berechneten wir als statistischen Parameter den mittleren Atemsausfall in s pro min (MA-Wert). Dieser MA-Wert war bei der Risikogruppe im Vergleich mit der Kontrollgruppe statistisch signifikant erhöht. Durch kontinuierliche Aufzeichnungen der transkutanen $$P_{O_2 } $$ -Werte konnte darüber hinaus noch gezeigt werden, daß die Babies der Risikogruppe zu einer Hypoxämie während des Schlafes neigen. Übereinstimmend mit dieser Beobachtung ist auch der Anstieg der 2,3-DPG-Konzentration und der Abfall der Dichte der Erythrocyten bei Risikosäuglingen. Verabreichung leicht hypoxischer Gasgemische führte besonders bei der Risikogruppe
    Notes: Summary We have examined the behavior of several variables which are related to respiratory control in 114 infants (up to 6 months of age) in order to assess the risk for the sudden infant death syndrome (SIDS). 23 of the infants had already had demonstrable serious or life threatening apneas or respiratory problems during surgical anesthesia. These infants were assigned as a risk group, and the rest of the investigated babies was taken as a control group. We found that practically all infants of the risk group had apneas during sleep, which lasted longer than 8 s each. Only 22% of the infants of the control group had apneas of such a duration. As a statistical parameter, calculated from at least 1 hour recording of respiration, we defined the mean apnea duration (MA-value) as average value of apnea duration time in seconds per minute of recording. The MA-value proved to be significantly elevated in the infants of the risk group. The trend to hypoxia in the infants of the risk group was also indicated by the observation of lower transcutaneous $$P_{O_2 } $$ -values (tc- $$P_{O_2 } $$ ) during sleep, when compared with control infants. In agreement with this observation is the increase of the 2,3-DPG concentration and the decrease of the density of erythrocytes of the infants of the risk group. Breathing hypoxic gas mixtures tended to depress respiration in all infants tested, and, especially in the risk group, to elicit irregular respiratory patterns. On the other hand, we observed that inhalation of pure oxygen markedly stimulated respiration in all infants investigated. We conclude from these observations that a risk for SIDS may be related to a particular response pattern of the respiratory center during the early postnatal life. We are able to distinguish infants with a higher risk for SIDS from other children by determination of the MA-value during sleep.
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  • 5
    ISSN: 1439-6327
    Keywords: Exercise tests in children ; Heart rate index ; Regression analysis ; Physical working capacity ; Leistungstests bei Kindern ; Leistungspulsindex ; Regressionsanalyse ; Körperliche LeistungsfÄhigkeit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung E. A. Müller hat 1950 eine Methode zur Messung des Leistungspulsindexes eingeführt, die auf der Bestimmung der linearen Regression zwischen Pulsfrequenzanstieg und Leistung beruht. Unsere Untersuchungen bei zehn- und elfjÄhrigen Kindern haben ergeben, da\ die AbhÄngigkeit des Pulsfrequenzanstieges von der Leistung besser durch eine nichtlineare Regression, insbesonders durch eine überlappende Knickregression beschrieben werden kann. Hierzu werden durch die gekrümmte Kurve zwei einander überlappende Geraden mit den Steigungen b 11 und b 12 angepa\t. Wir schlagen vor, da\ bei diesen nichtlinearen gekrümmten Kurven nur der Regressionskoeffizient b 11 für den ersten Abschnitt der Knickregression als LPI zu bezeichnen ist. Bei der Untersuchung zehn- und elfjÄhriger Knaben war ein linearer Pulsfrequenzanstieg vom Ende der zweiten bis zur sechsten Belastungsminute, bei gleichaltrigen MÄdchen nur bis zur Versuchsminute 3,8 feststellbar, die Streuungen betrugen jeweils ±1,4 min. Aus unseren Resultaten ergeben sich Konsequenzen für die Bestimmung weiterer Parameter aus dem LPI, so da\ z. B. in allen FÄllen, in denen die Beziehung zwischen Leistung und Herzfrequenz nicht linear verlÄuft, eine lineare Extrapolation zur Berechnung der PWC170 nicht möglich scheint. Wir stellen zur Diskussion, den Knick als überschreitung der Dauerleistungsgrenze zu interpretieren.
    Notes: Summary E. A. Müller (1950) has introduced a procedure for the measurement of the “Leistungspulsindex” (LPI) based on the determination of a linear regression between heart rate increase and work load. For this purpose the work load on a bicycle ergometer is increased in proportion to time (about 10 W/min) and the heart rate is recorded continuously. We have performed measurements in children (10–11 years of age) and found that the above mentioned regression is markedly nonlinear and can be described best by two overlapping linear regression lines with different slopes (b 11 and b 12). We propose that under these conditions the regression coefficient b 11 of the first part of the relation can be assumed as LPI. In our analysis we found the linear part of the heart rate to increase between the end of min 2 and min 6 (±1.4) of the experiment in boys. In girls we found the linear part of the regression only until min 3.8 (±1.4). One consequence of our results is related to the calculation of the PWC170 by linear extrapolation which appears to be impossible in all cases in which the relation between work load and heart rate is nonlinear. It seems possible to relate that part of the heart rate increase where the slope suddenly changes to the endurance limit.
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  • 6
    ISSN: 1437-160X
    Keywords: Gout ; Triglycerides ; HDL-cholesterol ; HDL-phospholipids ; Apolipoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Serum lipid and lipoprotein values of 32 male patients suffering from gout were quantitated and compared with corresponding values of a random control group which did not differ significantly with regard to age, body weight index and socio-economic status. All patients were on therapy with allopurinol which lasted on average for 6 years. The most striking differences between patients and controls were the increased triglyceride and apo B values and the decreased HDL-cholesterol (HDL-C) and HDL-phospholipid (HDL-PL) values in the patient group. The values of total cholesterol, LDL-cholesterol, apo A-I and Lp (a) were not significantly different between patients and controls. The great differences in the ratios of apo B/LDL-C, apo A-I/HDL-C and apo A-I/HDL-PL values suggest that gout is connected with changes in the chemical composition of the major lipoprotein classes. In three normolipemic individuals who were treated for 3 weeks with allopurinol no changes in lipoproteins and apolipoproteins were apparent. The results are discussed in view of the atherosclerosis risk of patients suffering from gout.
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  • 7
    Electronic Resource
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    Springer
    Infection 11 (1983), S. 104-113 
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Untersuchung zellulärer und humoraler immunologischer Parameter (T- und B-Lymphozyten und Immunglobuline) im Hinblick auf post-operative Infektionen bei Kindern ließ vorwiegend Veränderungen der T-Lymphozyten erkennen. Präoperative Komplikationen (Ileus, Schock, Infektionen), Narkose und Operation führen zu einer vorübergehenden Immunsuppression. Diese T-Zell-Suppression ist altersabhängig; sie hält am längsten bei Neugeborenen an (im Mittel bis drei Wochen) und am kürzesten bei älteren Kindern (im Mittel eine Woche). Die IgA- und IgG-Konzentrationen zeigen nur geringe abnorme Veränderungen; IgM dagegen steigt während der postoperativen Periode in allen Altersgruppen signifikant an. Prophylaktische und therapeutische Überlegungen zur Prävention und Behandlung postoperativer Infektionen lassen sich von den immunologischen Veränderungen im Zusammenhang mit Operationen ableiten.
    Notes: Summary The investigation of cellular and humoral immunologic parameters (T and B lymphocytes and immunoglobulins) with respect to postoperative infection in children revealed changes in the T lymphocytes in particular. Preoperative complications (ileus, shock, infection), anesthesia and surgery lead to transient immunosuppression. The duration of this T cell suppression is age-dependent; suppression is longest in newborns (up to three weeks on the average) and shortest in older children (one week on the average). IgA and IgG concentrations show only slight abnormal changes; IgM concentrations, however, increase significantly during the postoperative period in all age groups. Prophylactic and therapeutic measures for the prevention of post-operative infections can be considered on the basis of immunologic changes related to surgery.
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  • 8
    ISSN: 1435-1803
    Keywords: frequency-potentiation ; pseudo-random stimulation ; isolated myocardial strips ; regression model ; time series analysis ; Frequenzpotenzierung ; Pseudozufallsstimulation ; isolierter Herzmuskelstreifen ; Regressionsmodell ; Zeitreihenanalyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Um den Einfluß der Stimulationsfolge auf die Kontraktilität von isolierten Herzmuskelstreifen zu untersuchen, wurden isolierte Herzmuskelstreifen von Meerschweinchen nach einer Pseudozufallsfolge von Intervallen stimuliert. Mittels dieser Stimulationsmethode, die einer RR-Intervallsequenz während kardialer Arrhythmie analog ist, erhält man Kontraktionen stark unterschiedlicher Amplitude. Durch Anwendung von Methoden der Korrelations- und Regressionsanalyse und insbesondere der Zeitreihenanalyse ist es möglich, die Beziehung und die Eigenschaften aufeinanderfolgender Kontraktionen zu studieren. Um die Zeitfolge der isometrischen Kraftentwicklung zu beschreiben, wurde ein Zeitreihenmodell entwickelt. Die Modellparameter werden aus der Pseudozufallsfolge der Kontraktionen bestimmt, die Eingangsvariablen, die wesentlichen Einfluß auf die Eigenschaften von Kontraktionen haben, werden mittels eines ökonomischen Parametersuchverfahrens identifiziert. Als Resultat dieser Prozedur fanden wir, daß die Eigenschaften von mindestens 4 bis 6 vorhergehenden Kontraktionen einen wesentlichen Einfluß auf eine bestimmte nachfolgende Kontraktion haben. Es ist mit freiem Auge nicht möglich, Anhaltspunkte für eine Frequenzpotenzierung aus einer Pseudozufallsfolge abzulesen. Wir können das Vorhandensein der Frequenzpotenzierung nachweisen, wenn das Verhalten der Kontraktionen durch Anwendung eines Regressivmodells simuliert wird, als dessen Eingangsvariable die Intervalle verschiedener Stimulationsfrequenzen eingegeben werden. Die Ergebnisse bestätigen, daß für die Effekte der Frequenzpotenzierung Vorgänge eine Rolle spielen, die länger als eine Kontraktion anhalten.
    Notes: Summary To analyze the influence of the pattern of stimulation on contractility, isolated myocardial strips of guinea pigs have been stimulated in a pseudo-random sequence of intervals. By this stimulation method, which is analogous to the RR-interval sequence during cardiac arrhythmia, it is possible to get a large variety of different contractions. Using methods of correlation and regression analysis, and especially methods of time series analysis, it is possible to study the relations between properties of succeeding contractions. To describe the time course of the isometric force, a multiple regression model was established. The model parameters are estimated from a pseudo-random sequence of contractions, and in an economical parameter selection procedure the input variables, which have a substantial influence on the properties of one contraction, are identified. As a result of this procedure we found that at least properties of 4 to 6 preceding contractions have a substantial influence on one contraction. It is not possible to find indicators for frequency potentiation by free eye in the pseudo-random sequence of contractions. We can show that these effects are present when the behaviour of the contractility is simulated using the regression model, whose input variables are the intervals for different stimulation frequencies. This indicates that processes lasting longer than one contraction are responsible for the effects of frequency potentiation.
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  • 9
    ISSN: 1435-1803
    Keywords: Mechanical restitution ; postextrasystolic potentiation ; interval-force relationships ; transfer function modelling ; LVdP/dtmax
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Objectives The purpose of this study was to explore the physiology underlying the beat-to-beat variations of ventricular function during atrial fibrillation (AF). Methods Left ventricular pressure, and its first derivative (LVdP/dtmax, an index of contractility, and aortic blood velocity (and its integral AVI, an ejection index), were recorded using cathetermounted transducers in 15 patients with AF during cardiac catheterisation. Transfer function modelling was used to examine the influence of preceding intervals on LVdP/dtmax, and of LVdP/dtmax on AVI. The technique also allowed simulation of the behaviour of LVdP/dtmax in response to specific manipulations of interval. Results The variations in LVdP/dtmax recorded from the AF patients were shown to be dependent on up to six preceding intervals; a maximum of 91 % of the variation was explicable in this way. The influences of mechanical restitution (MR, the relationship between preceding interval and contractility), postextrasystolic potentiation (PESP, the inverse relationship between pre-preceding interval and contractility) and the decay of that potentiation were all demonstrated. These influences collectively appeared to be powerful determinants of AVI. Simulations of LVdP/dtmax, following single interval perturbations, were entirely consistent with these interval force effects. Conclusions The cardiac interval force relationship in man is an important determinant of the beat-to-beat variations of contractile and ejection function during AF: the beat-to-beat variations in contractile (or inotropic) function are independent of changes in ventricular filling or fibre-length.
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