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Aim of this cross-sectional study was the investigation of associations between different rheumatoid arthritis (RA)-related blood parameters and periodontal condition as well as selected periodontal pathogenic bacteria in RA patients under methotrexate (MTX) immunosuppression.

Maximal oxygen uptake (VO2max) is one of the most distinguished parameters in endurance sports and plays an important role, for instance, in predicting endurance performance. Different models have been used to estimate VO2max or performance based on VO2max. These models can use linear or nonlinear approaches for modeling endurance performance. The aim of this study was to estimate VO2max in healthy adults based on the Queens College Step Test (QCST) as well as the Shuttle Run Test (SRT) and to use these values for linear and nonlinear models in order to predict the performance in a maximal 1000 m run (i.e. the speed in an incremental 4×1000 m Field Test (FT)). 53 female subjects participated in these three tests (QCST, SRT, FT). Maximal oxygen uptake values from QCST and SRT were used as (a) predictor variables in a multiple linear regression (MLR) model and as (b) input variables in a multilayer perceptron (MLP) after scaling in preprocessing. Model output was speed [km·h−1] in a maximal 1000 m run. Maximal oxygen uptake values estimated from QCST (40.8 ± 3.5 ml·kg−1·min−1) and SRT (46.7 ± 4.5 ml·kg−1·min−1) were significantly correlated (r = 0.38, p < 0.01) and maximal mean speed in the FT was 12.8 ± 1.6 km·h−1. Root mean squared error (RMSE) of the cross validated MLR model was 0.89 km·h−1while it was 0.95 km·h−1for MLP. Results showed that the accuracy of the applied MLP was comparable to the MLR, but did not outperform the linear approach.

Hintergrund: Mit der neuen ÄAppO wurde an den Medizinischen Hochschulen u.a. auch in der Allgemeinmedizin die Durchführung eines benoteten Blockpraktikums verbindlich eingeführt. In den Akademischen Lehrpraxen besteht dabei eine auffällige Tendenz zu überwiegend sehr guten Beurteilungen. Es stellte sich die Frage, in wie weit die dort vergebenen Noten zuverlässig die klinisch-praktische Kompetenz des Studierenden widerspiegeln. Methoden: Zur Klärung dieser Frage wurden 98 Studenten, die im Wintersemester 2006/2007 ihren Kurs Allgemeinmedizin erfolgreich abgeschlossen hatten und danach in ein einwöchiges Blockpraktikum gingen, zu Beginn des folgenden Semesters in einem OSCE (Objective Structured Clinical Examination), bestehend aus vier Stationen, geprüft. Ergebnisse: Während die Verteilung der Notenhäufigkeiten in den Praktikumsnoten eine starke Lastigkeit in Richtung sehr guter Bewertungen zeigte, war diejenige des OSCE eindeutig realistischer. Im Blockpraktikum betrug der Mittelwert der vergebenen Noten 1,27, im OSCE lag dieser bei 2,41. Nur ca. ein Viertel der Prüfungsteilnehmer hatten im OSCE gleich gute oder sogar bessere Noten als im Blockpraktikum. Die überwiegende Mehrheit zeigte eine um ein bis zwei Stufen schlechtere Benotung. Schlussfolgerungen: Obwohl ein OSCE große Anforderung an Planung, Durchführung und auch finanziellen Aufwand stellt, ist er als klinischpraktische Prüfung auf hohem Kompetenzniveau in der studentischen Ausbildung nicht mehr wegzudenken. Dabei macht auch ein nur aus wenigen Stationen bestehender OSCE durchaus Sinn. Wünschenswert wäre die Durchführung eines „großen“ OSCE, der die Blockpraktika mehrerer Fächer gleichzeitig abprüft, gleichsam als Kompetenz-Check vor Beginn des Praktischen Jahres.

Summary: Mechanical behavior of dense packing spheres with small irregularities is investigated in this paper. A generalization of the hertzian contact model for surfaces of the form x k yields a normal contact force F n , which is proportional to ζ1+1/ k , with the normal displacement ζ. For oblique forces, the frictional force can be calculated, [10]. Different load cases are explained in detail. It is shown that the stress-strain curve during initial loading of the packing is identical with the force-displacement relation at the contact point, using an appropriate constant. The results for uniaxial loading, unloading and reloading are illustrated. As experimentally observed, the axial pressure in unloading is smaller than during loading, while the lateral pressure increases. The stress-strain relation is compared with well-known empirical relations of rock and soil mechanics, and the wave velocity for spherical irregularities agrees with earlier geomechanical theories for random packing of smooth spheres.

In experimentally naive monkeys the horizontal vestibulo-ocular-reflex (VOR) has a time constant which is in the range of 40–60 s. It can be measured as the nystagmus decline after pulses of angular acceleration, or from the transfer functions obtained from sinusoidal rotation with different frequencies. When frequencies below 0.1 Hz are applied, sinusoidal rotation leads to a pronounced phase advance, a decrease in gain and a shortening of the pre- and post-rotatory nystagmus time constant. Even very low frequencies (e.g., 0.002 Hz) are effective where the phase advance of eye relative to head velocity is already 90 ° in the naive animal. Exposing the animal to stimulation only at a single frequency shifts the whole frequency curve towards a greater phase advance. These results are consistent with habituation experiments in which steps of angular velocity have repeatedly been applied. In these experiments nystagmus duration is shortened, whereas the initial response at the end of acceleration does not change. This corresponds to a phase shift and a gain reduction in the low frequency range (below 0.1 Hz) which we have also observed during sinusoidal rotation.

We present a new model for E. colityrosine aminotransferase based on the X-ray structures of the wild type and Val 39Leu mutant of E. coliaspartate aminotransferase and computer simulation studies. Active site characteristics of the model are correlated with experimental observations on the specificity of these enzymes towards aromatic/dicarboxylic acid substrates.

The reverse transcriptase from human immunodeficiency virus type 1 is a heterodimer consisting of one 66-kDa and one 51-kDa subunit. The p66 subunit contains both a polymerase and an RNase H domain; proteolytic cleavage of p66 removes the RNase H domain to yield the p51 subunit. Although the polymerase domain of p66 folds into an open, extended structure containing a large active-site cleft, that of p51 is closed and compact. The connection subdomain, which lies between the polymerase and RNase H active sites in p66, plays a central role in the formation of the reverse transcriptase heterodimer. Extensive and very different intra- and intersubunit contacts are made by the connection subdomains of each of the subunits. Together, contacts between the two connection domains constitute approximately one-third of the total contacts between subunits of the heterodimer. Conversion of an open p66 polymerase domain structure to a closed p51-like structure results in a reduction in solvent-accessible surface area by 1600 A2 and the burying of an extensive hydrophobic surface. Thus, the monomeric forms of both p66 and p51 are proposed to have the same closed structure as seen in the p51 subunit of the heterodimer. The free energy required to convert p66 from a closed p51-like structure to the observed open p66 polymerase domain structure is generated by the burying of a large, predominantly hydrophobic surface area upon formation of the heterodimer. It is likely that the only kind of dimer that can form is an asymmetric one like that seen in the heterodimer structure, since one dimer interaction surface exists only in p51 and the other only in p66. We suggest that both p51 and p66 form asymmetric homodimers that are assembled from one subunit that has assumed the open conformation and one that has the closed structure.

Summary: Nonrotating half-planes in contact under oblique loading are investigated in this paper. The solution is based on the influence integrals of the Flamant solution. The problem is determined by two integral equations for the normal and tangential stresses, which are uncoupled for special cases, as bodies of similar material in contact. In order to simplify the singular integrals, the method of superposition of flat punches is used. The result for the symmetric case is almost identical with the axisymmetric solution. For polynomial profiles of the form x s , the Muskhelishvili potentials can be written in terms of a complex hypergeometric function. The interior stress field is illustrated for an example.

In this article, the collison of two geometrically and materially similar elastic spheres, which are rotating around the common normal of their contact area, is analysed. The solution of the static problem, when the spheres are pressed together by a constant normal force and are then subjected to a monotonously increasing torsional couple about the contact normal, has been found by Lubkin. Superposition of Lubkin's solutions for varying contact areas yields the general contact law for finite sequences for normal and torsional displacement increments. The torsional rotation at the end of impact is obtained from numerical integration of the angular equation of motion and the contact law. The Nassi-Shneiderman diagrams of the contact algorithm and the impact algorithm are presented. Some results are plotted and compared with an asymptotic theory for complete adhesion and complete sliding in the contact area.

We present a new model for E. colityrosine aminotransferase based on the X‐ray structures of the wild type and Val39Leu mutant of E. coliaspartate aminotransferase and computer simulation studies. Active site characteristics of the model are correlated with experimental observations on the specificity of these enzymes towards aromatic/dicarboxylic acid substrates.

Two axi-symmetric bodies are pressed together, so that their axes of symmetry coincide with the contact normal and the normal force is held constant. A small torque about the contact normal or a small tangential force is applied. For bodies of equal material, the normal and tangential stress states are uncoupled, and can solved separately. The surfaces of the bodies are thought as a superposition of infinitesimal rigid flat-ended punches. Consequently, the normal stress distribution can be calculated as a summation of differential flat punch solutions. A formula results, which is identical with the solution of Green and Collins. After application of a torque an annular sliding area forms at the border of the contact area. For reasons of symmetry, the common displacement of the inner stick area must be a rigid body rotation. Similarly to the normal problem, the solution can be thought as a superposition of rigid punch rotations. The tangential solution can be derived analogically, in form of a superposition of rigid punch displacements. The present method also solves the problem of simultanous normal and torsional or tangential loading with complete adhesion. As an example, Steuermann's problem for polynomial surfaces of the formA2nr2nis solved. The solutions for constant normal forces can be used as basic functions for loading histories with varying normal and tangential forces.

An investigation is made of the phenomena occurring at the contact of elastic spheres, subjected to forces with varying tangential component, in one direction, with changing sign, and varying normal component. The contact law is based on the assumption, introduced by H. Hertz [3], that both bodies behave physically like elastic half-spaces. We assume constant stress directions in the slip area in order to use so-called Cattaneo-Mindlin functions to solve the tangential boundary value problem. The stress distribution of the Cattaneo-Mindlin theory [2], [8] is rotational symmetric and has a typical break at the border of the stick area at ?=a1* fora1*1, with the radiusa1* of the stick area and the radiusa1 of the contact area. The general solution of the tangential contact problem can be written as a sum of Cattaneo-Mindlin functions. The appropriate superposition of two Cattaneo-Mindlin functions yields a new Cattaneo-Mindlin function, which simplifies the calculation of the force and the displacement. We will arrive at a formula for the force-displacement relation of general load-histories, which can be reduced to the compliances of Mindlin & Deresiewicz [9] by differentiation. In contrast to Mindlin & Deresiewicz our formula depends only on the points of instantaneous adhesionPi, for 1?i?N-1, and the current displacements ?N, ?N in tangential and normal direction of the initial contact point, which simplifies the solution. It also allows a generalization for oblique load-histories with elliptical contact areas and tangential forces in varying directions [4]. Finally an algorithm is given, which determines the essential number of Cattaneo-Mindlin functions.

The dipyridodiazepinone Nevirapine is a potent and highly specific inhibitor of the reverse transcriptase (RT) from human immunodeficiency virus type 1 (HIV-1). It is a member of an important class of nonnucleoside drugs that appear to share part or all of the same binding site on the enzyme but are susceptible to a variety of spontaneous drug-resistance mutations. The co-crystal-structure of HIV-1 RT and Nevirapine has been solved previously at 3.5-A resolution and now is partially refined against data extending to 2.9-A spacing. The drug is bound in a hydrophobic pocket and in contact with some 38 protein atoms from the p66 palm and thumb subdomains. Most, but not all, nonnucleoside drug-resistance mutations map to residues in close contact with Nevirapine. The major effects of these mutations are to introduce steric clashes with the drug molecule or to remove favorable protein-drug contacts. Additionally, four residues (Phe-227, Trp-229, Leu-234, and Tyr-319) in contact with Nevirapine have not been selected as sites of drug-resistance mutations, implying that there may be limitations on the number and types of resistance mutations that yield viable virus. Strategies of inhibitor design that target interactions with these conserved residues may yield drugs that are less vulnerable to escape mutations.

We have investigated the internal vibrations of metal hydrate complexes in ionic single crystals and their interactions with the phonon system of the lattice, by observing the Raman spectra and infrared reflection spectra with polarized light at different temperatures T(2 K ≦ T ≦ 300 K). As special systems the octahedral nickel hydrate complexes in NiSnCl6 · 6 H2O, NiSnCl6·6 D2O and in NiSO4 · 6H2O. NiSO4 · 6D2O have been chosen. For NiSnCl6·6 aqu a complete interpretation of the spectra is given, starting from the assumption of isolated metal hydrate complexes and SnCl6-- -ions as structural units. The discussion of the spectra of the sulfate crystal is based on the corresponding assumption. However, here an unambiguous assignment of all lines observed was not possible.

The absorption spectra of CeCl3·7 H2O, LaCl3·7 H2O, CeCl3·7 D2O and LaCl3·7 D2O have been measured at low temperatures in the region of the 4 f→4 f infrared transitions. The energy levels of the Ce3+-ion in these compounds have been derived. The infrared phonon transitions have also been determined from the reflection spectra of these crystals measured in the region between 4000 cm−1 and 50 cm−1.

Wie in der vorstehenden Arbeit [1] werden Reflexionsspektren von einkristallinem, orthorhombischem MgSO4·7H2O und MgSO4·7D2O beschrieben. Die Spektren wurden in polarisiertem Licht bei einer Probentemperatur von 300°K, 80°K und ca. 14°K im Wellenzahlenbereich zwischen 4000 cm−1 und 400 cm−1 gemessen. Mit den Kronig-Kramers-Relationen wurden die Frequenzen der ultrarotaktiven Übergänge ermittelt. Die Spektren und ihre Temperaturabhängigkeit werden Reflexionsspektren von wasserfreiem orthorhombischem Cs2SO4 gegenübergestellt, die praktisch keine Temperaturabhängigkeit zeigen.

An einkristallinem BeSO4·4H2O und BeSO4·4D2O wurden in polarisiertem Licht Reflexionsspektren gemessen bei Probentemperaturen von 300°K und 14°K im Wellenzahlenbereich zwischen 4000 cm−1 und 300 cm−1. Mittels einer Kronig-Kramers-Analyse wurden die Frequenzen der ultrarotaktiven Übergänge bestimmt. Diese Übergänge werden inneren Schwingungen der Wassermolekeln und der Sulfationen zugeordnet, im Bereich zwischen 1000 cm−1 und 300 cm−1 außerdem noch inneren und äußeren Schwingungen der tetraedrischen Be++·4aqu-Komplexe. Die Schwingungsformen dieser Komplexe bestehen aus einer Überlagerung von Translations- und Librationsschwingungen der Wassermolekeln und Translationsbewegungen des zentralen Be++-Ions.

Die Möglichkeiten der Benzo(a)pyrenbestimmung durch Fluorescenzmessung in schwefelsaurer Lösung wurden untersucht. Die Stabilität der Fluorescenz, die Isolierung der Benzo(a)pyrenfraktion durch Dünnschicht-Chromatographie sowie der Einfluß fluorescenzlöschender Substanzen wurden geprüft und die Ergebnisse diskutiert. Die relative Standardabweichung des Verfahrens beträgt 2,9 und 5,9% für Benzo(a)pyrenmengen von 265 bzw. 68 ng.