Showing papers by "University of Düsseldorf published in 1976"

Two cases of phosphoenolpyruvate carboxykinase deficiency.

Abstract: . Two children are described who suffered from hypoglycemia and liver impairment. Assays of gluconeogenic enzymes in liver samples taken immediately after death demonstrated a deficiency of phosphoenolpyruvate carboxykinase, a key enzyme of gluconeogenesis. Post mortem examination demonstrated massive fat deposition in liver and kidney and to a lesser extent in other tissues. The fatty changes in liver and kidney could be explained by the absence of phosphoenolpyruvate carboxykinase, which would cause an alteration in the mitochondrial-cytosolic processes related to gluconeogenesis.

Differential shaping of EEG theta rhythms.

Abstract: Heart rate, EEG, frontal EMG, and forearm EMG were recorded in 20 subjects for 3 baseline, 8 feedback, and 2 postbaseline sessions in order to compare two biofeedback methods of teaching subjects to increase theta EEG activity. Subjects were divided into high- and low-EMG groups. Five high-EMG subjects, and 5 low-EMG subjects then received 8 sessions of strictly theta feedback. The remaining 10 subjects, 5 from the high-EMG group, and 5 from the low-EMG group, received a “graduated” training which involved shaping the target response. This procedure consisted of 4 initial sessions of EMG feedback, followed by a second phase consisting of 4 sessions of theta feedback. Results showed a clear relationship between subjects' baseline frontal EMG levels and the effect of the training methods. Although subjects with high-EMG baseline increased their theta output only with the two-phase training, subjects with low-EMG baseline levels performed better when given theta feedback only. This result shows not only that amounts of theta can be reliably increased, but that training techniques should be adapted to the physiological characteristics of the individual—in this case, baseline levels of frontal EMG levels.

Elimination of spontaneous and chemically induced chromosome aberrations in mice during early embryogenesis.

Abstract: NMRI mice (ΦΦ) were treated with 0.25 mg/kg body weight Trenimon (2,3,5-triethyleneiminobenzoquinone-1,4) in the preovulatory phase just before ovulation. Then they were mated with untreated males. The female mice were dissected 45 h after application of this mutagen. The preimplantation embryos, being in a 2-cell stage, were flushed out of the oviduct and cultured in vitro for 60 h. Of the cultured embryos 87.7% reached the blastocysts stage in the control series, whereas only 49.7% did so in the experiments. Some of the females were dissected on the 14th day post conception (p.c.) and the number of dead and living implants was determined. Furthermore, the 9.5- and 13.5-day-old embryos were cytologically investigated, to determine the frequency of chromosomal aberrations. Of the unfertilized oocytes 76.2% deriving from mice treated with 0.25 mg/kg Trenimon, were aberrant in the stage of metaphase II (Rohrborn and Hansmann, 1971). Comparing Rohrborn's and Hansmann's results (1971) to our own findings a continous elimination of chromosome aberration is clearly to be seen during early embryogenesis. The biological selection takes place in the pre- as well as in the early and late postimplantative phase.

On the frame dependence of electric current and heat flux in a metal

Abstract: The ideas and methods of the kinetic theory of metal electrons are used to show that Ohm's law of electric conduction and Fourier's law of heat conduction in a metal both contain frame dependent terms. It follows that the principle of material objectivity does not hold rigorously.

I. Lineare Fehlerminimisierung Ein Verfahren zur Eigenwertberechnung bei Schrödinger‐Operatoren

Abstract: A variational principle is derived from the spectral theorem of self-adjoint operators. The principle allows to calculate simultaneously upper and lower bounds for each point of the spectrum. For Schrodinger operators this method of error minimization is reduced to a series of matrix diagonalizations using an iterative process and is linearized in this way. The convergence of this method and the equivalence with the nonlinear problem of variation are proven.

Molecular basis of a control mechanism of DNA synthesis in mammalian cells.

Abstract: Personal observations made on the model of isoproterenol-stimulated DNA synthesis have pointed out the following: 1) cell hypertrophy precedes constantly the onset of DNA synthesis; 2) the length of the G1 phase is mass-dependent; 3) accumulation of ribosomes is needed for cell progress through G1; 4) ribosomal protein synthesis is involved in cell growth activation. These results together with a consideration of the pertinent literature allow us to formulate a hypothesis on the control of cell division in mammalian cells.DNA synthesis might be the terminal event in a chain of metabolic processes whereby a cell adjusts itself to increased functional demands (Increased Functional Demand Hypothesis). The main points of this model are the following: the interaction of the extracellular effector on the target cells first activates the pre-existent protein-synthesizing apparatus of the cell, which in turn brings about the activation of the “translation-transcription connecting mechanism” whereby the cells adjusts itself to an increased need for protein synthesis. Such a mechanism is characterized by cytoplasmic signals arising from the protein-synthesizing apparatus of the cell which reach the nucleus and call forth a messenger RNA for ribosomal proteins. The latter, once synthesized, protect the nascent ribosomal RNA from nuclease attack, resulting in an accumulation of ribosomes in the cytoplasm. Once the ribosomes have reached a “critical amount”, the cell is triggered to enter DNA synthesis. As a link between the enhanced ribosomal RNA synthesis and DNA synthesis a reduction in the capacity of the ribonucleotide pool as source of DNA precursors has been suggested.

The Green' function forwaves in a homogeneous anisotropic absorbing plasma

Abstract: The Green's function (or matrix) for a source of sinusoidal time dependence in an infinite homogeneous absorbing magneto-ionic plasma is written as a Fourier integral over wavenumber space. It is shown that this Fourier integral solution exists, and is unique as a generalized function. By extending the Fourier integral to complex wavenumbers, it is shown that the far-field expression for the Green's function may be written as an integral over sections of the dispersion surface, which in this case is a complex sub-manifold of the space of three complex variables. Use of the saddle-point method in two dimensions allows a further simplification of the far-field result. The matrix coefficients in the resulting expression are shown to represent a decomposition into modes. Corresponding results are also obtained for sources with spatial dependence, described by either functions of compact support or rapidly decreasing functions.

II. Eigenwertberechnung beim Dreikörperproblem

Abstract: The convergence and the quality of approximation of the variational method developed in part I are tested using the He atom as an example. For the three-body problem the inner products and the norms were explicity expressed as functions of the optimization parameters. The method permits calculation of upper and lower bounds for the ground state of helium.

Miscellaneous arc devices

Abstract: Steady arc discharges at about normal pressure exposed to magnetic fields and flows are studied. In particular, a cylindrical, wall stabilized arc and a free burning arc between fixed electrodes are considered and the different modes of operation are investigated. In a second section the transition of a wall stabilized straight arc into a helical shaped discharge is discussed. Finally phenomena occurring in an arc column under influence of a longitudinal magnetic field are reviewed.

A ray expansion with matrix coefficients for sourcesin absorbing anisotropic media

Abstract: A ray or quasi-optical approximation is developed, using complex rays. The ‘amplitude’ terms are matrices, rather than vectors that represent the wave polarization. Thus, the way the propagation resolves a source into various modes is described. The second term in the amplitude series is shown to include a type of inter-mode coupling. It is shown that initial values needed to integrate along the rays can be chosen so that the leading term of the approximation agrees with the far-field solution for localized sources in a homogeneous medium. By invoking the ‘canonical problem’ method, the result is extended to give an approximation for the Green's matrix in a slowly-varying medium.

Der Einfluß von Azetylsalizylsäure und Dipridamol auf die Abstoßung allotransplantierter Hundenieren bei präsensibilisierten Empfängern

Abstract: The effect of antiaggregating agents - acetylsalicyclic acid (ASA) and dipyridamol - on the rejection of allotransplanted canine kidneys in presensitized animals were studied. Blood flow dropped more markedly in the control group than in the group treated with ASA and dipyridamol. 24 hours after transplantation the blood flow in this group was significantly higher than in the control group (p 2,5 %) and in the third group treated with dipyridamol alone. The cellular rejection started earlier and was more pronounced in the control group. Only in this group vascular rejection and microthrombi were demonstrated. Urine output ceased 24 to 60 hours after transplantation. The immunosuppressive, antiphlogistic and platelet antiaggregating effect of the combined ASA and dipyridamol therapy is thought to be responsible for the better results in this group. In this experimental model the combined treatment of ASA and dipyridamol results in a later onset of cellular rejection, in better blood-flow of the kidney and later onset of anuria.

Metabolic research in monozygotic twins with diabetes mellitus: progress report.

Abstract: An intravenous and oral glucose tolerance test and an intravenous tolbutamide test have been performed in 11 MZ twin pairs, discordant for diabetes mellitus. Blood sugar, immunoreactive insulin, and free fatty acids were determined. The research aimed at finding out whether prediabetic subjects may show any characteristic parameter which could be suggestive of the hereditary disposition. Three MZ twins of juvenile diabetics showed a normal blood glucose, immunoreactive insulin, and free fatty acids during the glucose and tolbutamide loads within a maximum of 10 years observation.