Showing papers by "Humboldt University of Berlin published in 1975"
TL;DR: The control theory of steady states, previously presented for linear enzymatic systems (Heinrich and Rapoport, 1974) is extended to nonlinear systems and a new procedure for the calculation of the control strength and the control matrix is developed.
Abstract: The control theory of steady states, previously presented for linear enzymatic systems (Heinrich and Rapoport, 1974) is extended to nonlinear systems. On the basis of three theorems a new procedure for the calculation of the control strength and of the control matrix is developed. The theory is applied to the extended model of glycolysis of erythrocytes, which includes also ATP-consuming processes. Also in this model the glycolytic flux is mainly controlled by the hexokinase-phosphofructokinase-system. The control strengths of the pyruvate kinase and of the enzymes of the 2.3 P2G-bypass are negligibly small. The control strength of the ATPase is negative, i.e. an activation of this enzyme leads to a decrease of the flux.
For transition states of multienzyme systems definitions are given for the mean time required for the transition of the metabolites and for the “transient control” of enzymes. Enzymes with a pronounced influence on the transition time are called time-limiting enzymes. Enzymes which excert strong control on the time-dependent processes may have little influence under steady state conditions and vice versa. The transition times of ATP have been calculated for transient states of glycolysis.
133 citations
TL;DR: The strong effect of the compound on Ehrlich ascites carcinoma cells is not the result of an anomalously high sensitivity of these cells in the culture conditions used, but is a more general phenomenon also found with other cell lines and in vivo.
Abstract: WE have described1 the discovery of cytostatic action on cultured Ehrlich ascites carcinoma cells of a series of deoxyuridines substituted in the carbon-5-position (for example, 5-hydroxymethyl-, 5-mercaptomethyl-, 5-cyano-, 5-thiocyanato- and 5-vinyl-2′-deoxyuridine), the strongest effect being shown by 5-hydroxymethyl-2′-deoxyuridine (HMUdR). Although Green et al. reported2 that the compound inhibits growth and cell division of Escherichia coli , no reports of any inhibitory properties have to our knowledge appeared since 1957. It was found, however, that HMUdR is a normal constituent of the DNA of certain Bacillus subtilis phages3–5, in which it replaces all the thymidine, and a number of reports have described its chemical synthesis6–11. We indicate here, however, that the strong effect of the compound on Ehrlich ascites carcinoma cells is not the result of an anomalously high sensitivity of these cells in the culture conditions used, but is a more general phenomenon also found with other cell lines and in vivo.
57 citations
TL;DR: A mathematical model for the glycolysis of human erythrocytes is presented which takes into account ATP-synthesis and -consumption and gives a good agreement of theoretical predictions with the measured metabolite concentrations.
Abstract: A mathematical model for the glycolysis of human erythrocytes is presented which takes into account ATP-synthesis and -consumption A set of three differential equations describes the steady states and the time-dependent changes of the metabolite concentrations under blood storage conditions For a given parameter combination there are in general three stationary points of the system, one of which is unstable At a low ATP-need the ATP-level is relatively constant for variations in the rate constant of the ATP-consuming processes Above a critical level of the energy consumption the system breaks down An important role of the 23P2G-bypass of the erythrocytes is its action as an "energy buffer", wasting ATP in case of ATP-overproduction and producing ATP in case of underproduction A parameter combination consistent with the data on the isolated enzymes was found which gives a good agreement of theoretical predictions with the measured metabolite concentrations Under blood preservation conditions the difference of the rates of ATP-production and -consumption is the most important factor for a high ATP-level over long periods
46 citations
TL;DR: In this paper, a Lemma zur p-desingularisierung is given for allgemeine Eigenschaften von Ringen with strenger approximation-seigenschasenschaft.
Abstract: 1. Einleitung . . . . . . . . . . . . . . . . . . . . . . . . 145 2. Allgemeine Eigenschaften von Ringen mit strenger Approximationseigenschaft . . . . . . . . . . . . . . . . . . . . . 148 3. Beweis des Hauptresultates . . . . . . . . . . . . . . . . . 149 4. Ein Lemma zur p-Desingularisierung . . . . . . . . . . . . . 162 5. Nerons p-Desingularisierung . . . . . . . . . . . . . . . . 165 6. Anhang . . . . . . . . . . . . . . . . . . . . . . . . . 173
45 citations
TL;DR: The results corroborate earlier fluorescence microscopic findings of a uniform protein distribution, provided that a number of conditions are fulfilled.
Abstract: Proteins were covalently attached to Sepharose by the CNBr method. Their distribution across the carrier beads was studied at the electron microscopic level. The approach has been to ferritinstain and to section the gel beads. Ferritin was either coupled directly to the polysaccharide backbone of the carrier or conjugated with pure rabbit anti-aminopeptidase in order to visualize covalently bound leucine aminopeptidase by the immunferritin technique. The results corroborate earlier fluorescence microscopic findings of a uniform protein distribution, provided that a number of conditions are fulfilled.
40 citations
TL;DR: In this article, an explanation of the differences between the Stevens-exponents revealed by estimation vs. production methods is proposed, based on Teghtsoonian's description of intramodal range effects and a modified version of Helson's theory, which works on the level of stimulus ratios.
32 citations
TL;DR: In this paper, the functional dependence of the parameters of the diffusion layers at ion-echange membranes has been theoretically investigated by means of the laser-interferometric method, and their temporal dependence at constant current density is represented.
27 citations
TL;DR: The diminished content of linoleic acid in PCh of neonatal and dystrophic muscle cannot be interpreted as expression of a corresponding or similar lipid metabolism in both tissues and was discussed as proof of the authors' thesis that the basic defect in p.
Abstract: The fatty acid distribution of the main lipid fractions: triglycerides (TG), phosphatidylcholine (PCh), phosphatidylethanolamine (PE), and sphingomyelin (Sph) of muscle from 6 patients with progressive muscular dystrophy (p.m.d.), Duchenne, 8 to 12 years old was estimated and compared with normal controls of different age. In view of the results of several authors about varied fatty acid distribution in immature muscle a third group comprising samples of neonatal muscle was studied. 1. The fatty acid pattern of the lipid fractions TG, Sph, and PE from muscle of patients with p.m.d. shows no important variation in comparison to normal controls. In contrast to this the fatty acid distribution in PCh is extremely varied: the percentage of 18:2 is decreased and corrrespondingly the content of 18:1 is increased. In view of the high percentage (nearly 10%) in which linoleic acid is substituted by oleic acid in PCh, effects on the plasma membrane are to be expected. 2. The fatty acid pattern in neonatal muscle shows in narly all positions of the fractions TG, Sph, PE, and PCh a different distribution from normal or dystrophic muscle. In view of the most important variation in dystrophic muscle it must be stated that generally 18:2 is decreased. This deficit was replaced by an increase of all other fatty acids (not only at a substitution by 18:1 as given in p.m.d.). Therefore the diminished content of linoleic acid in PCh of neonatal and dystrophic muscle cannot be interpreted as expression of a corresponding or similar lipid metabolism in both tissues. The results were seen as signs of significant qualitative alterations especially of PCh in p.m.d. They were discussed as proof of our thesis that the basic defect in p.m.d. concerns the specific acylation of PCh with linoleic acid.
24 citations
TL;DR: In this article, it was found that a large proportion of the radioactive amino acids were absorbed as early as after 0.5 hr and reached a peak value after 14-24 hours; in the case of 14C activity this peak value amounted to 25.4% of the administered dose.
Abstract: Male Albino rats (90-100 g) were fed ad libitum (with limited periods of feeding) for 14 days. The diets were adjusted to a crude protein content of 10%. Powdered whole egg, fish meal, yeast and gelatine were used as protein sources. Additionally, one group of rats was fed a protein-free diet. On the 15th day of experiment the rats were fed a test diet at a level of 2 g per 100 g of body weight. 2 hrs after that the rats received 25 muCi of 3H glycine and 5 muCi of 14C-L-Leucine per 100 g of body weight administered by way of intragastric infusion. It was found that a large proportion of the radioactive amino acids were absorbed as early as after 0.5 hr. The highest rate of absorption was observed in animals fed dietary proteins of poor quality or a protein free diet, so that in animals receiving a gelatine diet or a protein-free diet only 68.4% or 56.4% of the administered amount of 14C activity were detected inside the gastro intestinal tract after 0.5 hr. Analogous data for the 3H activity were 52.4% and 25.3%. Maximum absorption occurred after 3-7 hrs. Following this the level of radioactivity in the intestinal contents again increased reaching a peak value after 14-24 hrs; in the case of 14C activity this peak value amounted to 25.4% of the administered dose in animals fed the gelatine diet and 32.8% in the group receiving the protein-free diet. It was established that the major proportion of the resecreted amount of 14C activity was present in leucine. Until 72 hrs after the intake of 14C activity the level of radioactivity was again found to decline, a processes which was induced by processes occurring in the large intestines. Moreover, evidence was obtained in confirmation of previous findings, indicating that the composition of faecal amino acids was constant and unaffected by dietary proteins.
20 citations
TL;DR: In this paper, the influence of strong electric field on the form and magnitude of the scattering cross section of the Raman spectrum has been investigated and the polarization dependence of these electronic Raman transitions is stated.
Abstract: Interband electronic resonance Raman scattering for excitation from the split-off valence band to the light-hole and heavy-hole band and from the light-hole band to the heavy-hole band in p-type semiconductors with diamond or zincblende structure has been studied. The polarization dependence of these electronic Raman transitions is stated. The influence of a strong electric field on the form and magnitude of the scattering cross section is calculated. The Raman spectrum will be depressed in the presence of the strong electric field. All explicit results are given for band parameters of Ge.
Die elektronische Interband-Resonanz-Ramanstreuung wird fur eine Anregung vom ab-gespaltenen Valenzband in die Bander der Ieichten und schweren Locher und vom Band der lcichten Locher in das Band der schweren Locher in p-leitenden Halbleitern mit Diamantoder Zinkblendestruktur untersucht. Es wird die Polarisationsabhangigkeit dieser elektronischen Ramanubergange bestimmt. Der Einflus eines starken elektrischen Feldes auf die Form und Grose des Streuquerschnitts wird berechnet. Bei Anwesenheit eines starken elektrischen Feldes wird das Ramanspektrum unterdruckt. Alle expliziten Ergebnisse werden fur die Bandparameter von Ge angegeben.
19 citations
TL;DR: In this paper, the ion induced electron emission was investigated when (001) cleavage surfaces of some alkali halides (KBr, KCl, NaCl, LiF) are bombarded with He +, Ne +, Ar +, Kr +, and Xe + ions in the energy range 1,5-25 keV at normal incidence and a residual pressure of about 10 −10 torr.
TL;DR: In this paper, the influence of different random bending of the valence and conduction band edges on the interband dielectric function and its external field induced change Δe(ω) are calculated in the oneelectron approximation for a semiconductor with fluctuating band edges presented by smooth random Gaussian fields.
Abstract: The interband dielectric function e(ω) and its external field induced change Δe(ω) are calculated in the one-electron approximation for a semiconductor with fluctuating band edges presented by smooth random Gaussian fields. The influence of different random bending of the valence and conduction band edges one(ω) and Δe(ω) is investigated. The corresponding plots are presented. A broadening of the line shape Δe(ω) is obtained if the band bending becomes different. This broadening might be obtained in electromodulation experiments of crystals propagated by an internal acoustic noise flux. Application of the model to amorphous semiconductors is discussed.
Der Interbandanteil der dielektrischen Funktione(ω) und ihre feldmodulierte Anderung Δe(ω) werden in der Einelektronennaherung fur Halbleiter mit fluktuierenden Bandkanten, die durch glatte zufallige Felder mit Gauss-Statistik gegeben sind, berechnet. Der Einflus der verschiedenen zufalligen Bandkantenverschiebung des Valenz- und Leitungsbandes aufe(ω) unde(ω) wird untersucht. Die entsprechenden Darstellungen fure(ω) und Δe(ω) wer- den gezeigt. Eine Verbreiterung der Linienform Δe(ω) wird fur den Fall unterschiedlicher Verschiebung der Kanten gefunden. Diese Verbreiterung konnte bei Elektromodulationsexperimenten an Kristallen, die ein intensiver akustischer Rauschstrom durchlauft, festgestellt werden. Es wird die Anwendung des Modells fur amorphe Halbleiter diskutiert.
TL;DR: In the present paper, paranoid states are discussed with regard to their clinical pictures and their good prognoses, and the cycloid psychoses, which confirm the cycloids and disprove schizophrenias.
Abstract: Scandinavian psychiatrists acknowledge endogenous psychoses which are neither schizophrenic nor manic-depressive, i.e., above all the "reactive psychoses" and the "schizophreniform psychoses", both of which differ from schizophrenia in their features as well as in their good prognoses. These Scandinavian diagnoses bear relationships to psychoses, which I separate from schizophrenia. In the present paper, paranoid states are discussed with regard to their clinical pictures and their good prognoses. Among these are the "cycloid psychoses". Patients suffering from these diseases recover from every phase, though most of the German psychiatrists consider them schizophrenic. Among the cycloid psychoses, the "ansiety happiness psychosis" shows ideas of reference on the one hand and ecstatic ideas on the other. In "inhibited confusion psychosis", the patients are suffering from ideas of reference and ideas of significance; in "excited confusion psychosis", from misidentifications of persons. The other symptoms which occur--anxiety, happiness, stupor, incoherent pressure of speech--confirm the cycloid psychoses and disprove schizophrenias. Besides the already mentioned psychoses, there is a monopolar psychosis, "suspicious depression", in which ideas of reference and ideas of guilt mix. It is extremely important, not only for theoretical but also practical reasons, to separate from schizophrenia paranoid states which terminate in complete recovery from every phase.
TL;DR: In this article, the authors investigated the correlation of excitonic molecule emission in CdS single crystals under stationary (high pressure mercury lamp) and pulse laser (400 kW N2 laser) excitation in a very extended range of excitation intensities at 1.8 K.
Abstract: An investigation is made of the correlation of excitonic molecule emission in CdS single crystals under stationary (high pressure mercury lamp) and pulse laser (400 kW N2 laser) excitation in a very extended range of excitation intensities at 1.8 K. It is shown that the discrepancies existing in the literature up to now due to the appearance of different molecule lines under different excitation conditions can be resolved assuming a model for molecule annihilation which involves both Γ6-excitons and Γ5-polaritons.
Es wurden in einem ausgedehnten Bereich von Anregungsintensitaten bei 1,8 K Unter- suchungen zum Zusammenhang der Exzitonenmolekulemission in CdS-Einkristallen bei stationarer (Quecksilberhochdrucklampe) und Impulslaser-Anregung (400 kW N2-Laser) durchgefuhrt. Es wird gezeigt, das die Diskrepanzen, die bis jetzt in der Literctur durch das Auftreten von verschiedenen Molekullinien unter verschiedenen Anregungsbedingungen bestehen, in einem Modell fur die Molekulannihilation, welches sowohl Γ6-Exzitonen als auch Γ5-Polaritonen berucksichtigt, beseitigt werden konnen.
TL;DR: In this paper, a theoretical treatment of continuous electronic and discrete one-phonon Raman scattering for the case that the two scattering processes give rise to nearly the same Raman shifts is given.
Abstract: A theoretical treatment is given of continuous electronic and discrete one-phonon Raman scattering for the case that the two scattering processes give rise to nearly the same Raman shifts. By using a Green's function formalism the final state interaction due to the interband electron–phonon coupling is described and it is found that the resulting line shape is similar to that of Fano's theory. A discussion is given of the frequency and the concentration dependence of the characteristic parameters.
Eine theoretische Behandlung von kontinuierlicher elektronischer und diskreter Ein-Phonon-Raman-Streuung wird fur den Fall gegeben, das die beiden Streuprozesse naherungsweise zu den gleichen Frequenzverschiebungen fuhren. Unter Verwendung des Formalismus der Greenschen Funktionen wird die Wechselwirkung der Elementaranregungen, die in den beiden Streuprozessen angeregt werden, uber die Elektron–Phonon-Kopplung behandelt. Es wird gezeigt, das die Linienform des Interferenzspektrums der der Fanoschen Theorie ahnlich ist. Die Frequenz- und Dotierungsabhangigkeit der charakteristischen Parameter wird diskutiert.
TL;DR: In this article, a chlor-fluor-Austausch an C-Cl-Bindungen mit Hilfe von Antimon(V)halogeniden wird hinsichtlich Kinetik und Mechanismus diskutiert.
TL;DR: In this article, Dimroth rearrangement occurs to yield S-methyl derivatives, which can then be methylated with dimethyl sulphate to the Smethyl derivatives and cyclized with one equivalent of aqueous hydrogen bromide.
Abstract: On heating compounds4 a-f in alcohols, Dimroth rearrangement occurs to yield5 a-f, which can be methylated with dimethyl sulphate to the S-methyl derivatives6 a, b, d, f. 6 a, b can be cyclized with one equivalent of aqueous hydrogen bromide to9 a, b. 9 a could not be prepared by reacting 3-methylthio-5-amino-1,2,4-triazole (10) with phenacyl bromide.
TL;DR: The cyclotron resonance of electrons in semimetallic BiSb alloys was investigated within a range of 0 to 4 at % antimony at 35 GHz in three crystallographic planes as discussed by the authors.
Abstract: The cyclotron resonance of electrons in semimetallic BiSb alloys is investigated within a range of 0 to 4 at % antimony at 35 GHz in three crystallographic planes. A nonlinear dependence of the cyclotron masses on the antimony concentration (x at %) is found. The analysis of spectra indicates limiting-point resonances being associated with the cyclotron wave propagation.
Im Bereich von 0 bis 4 At % Antimon wird bei 35 GHz die Zyklotronresonanz der Elektronen in halbmetallischen BiSb-Legierungen in drei kristallographischen Ebenen untersucht. Es wird eine nichtlineare Abhangigkeit der Zyklotronniassen von der Antimonkonzentration (x At %) gefunden. Die Analyse der Spektren weist auf Grenzpunktresonanzen hin, die mit Zyklotronwellenausbreitung verbunden sind.
01 Jan 1975
TL;DR: In this article, the ionization potentials are obtained as eigenvalues of a special matrix and the results for the elements of this matrix are derived for systems having a doublet ground state.
Abstract: The application of Koopmans' theorem to open shell systems shows — compared with closed shell systems — an important difference: a mixture of one-electron-states of theN-electron system is needed for the quantum mechanical description of the (N – 1)-electron system. The ionization potentials are obtained as eigenvalues of a special matrix. Equations for the elements of thisI-matrix were derived which are applicable to systems having a doublet ground state. The derivation was carried out for the procedures developed by Roothaan, Kruglyak, McWeeny, Longuet-Higgins, and Pople and Nesbet using the density matrix formalism. First numerical calculations suggest that the effects which are taken into account in the exact form of Koopmans' theorem are important.
TL;DR: In this article, anodische Verhalten einiger 5,5-disubstituierten N-Aryl-Δ 2 -pyrazoline (1a)-(1d) wurde in 0.1 M N(C 2 H 5 ) 4 ClO 4 /Acetonitril unter Zusatz von Pyridin, α-Picolin and Collidin with Hilfe der Voltammetrie and der Oszillopolarographie an der rotierenden Pt-Scheibenelekt
TL;DR: The mean generation time of endothelial cells increases with advancing age, as deduced from the decrease in the 3H-thymidine labelling index and in the mitotic rate, and raised endothelial turnover in the area of the iliac bifurcation requires further studies.
TL;DR: In this article, the authors investigated the electrochemical luminescence of aromatic compounds in aprotic solvents using the following semiconductor electrodes: n-GaP, n-ZnO and n-SnO 2.
TL;DR: A synthetic two stage procedure for the preparation of perfluoroalkylated derivatives of uracil and its nucleosides is described and it is shown by mass spectra that the substitution always takes place at the 5-position of the pyrimidine.
Abstract: In the paper a synthetic two stage procedure is described for the preparation of perfluoroalkylated derivatives of uracil and its nucleosides. Using copper bronze a perfluoroalkyl-copper-complex is formed from perfluoralkyl iodides in polar aprotic solvents, such as DMSO, and under inert conditions. The reaction of this complex with uracil, uridine and 2-deoxyuridine leads to the corresponding 5-substituted perfluoralkyl derivatives. It is shown by mass spectra that the substitution always takes place at the 5-position of the pyrimidine. The chemical and physical properties of the formed compounds are described.
TL;DR: In this article, a theoretical analysis of the interband resonance Raman scattering in small gap semiconductors is given, and the possibilities of an experimental observation of the predicted effects are discussed for some representative small-gap semiconductor devices.
Abstract: A theoretical analysis is given for the interband resonance Raman scattering in small gap semiconductors. For a certain interval of incident photon energies the scattering spectrum shows a strong resonance peak. By measurements in the visible frequency region, especially the energy gap can be determined from the scattering spectrum. The possibilities of an experimental observation of the predicted effects are discussed for some representative small-gap semiconductors.
Die Interband-Resonanz-Raman-Streuungin Halbleitern mit schmaler Energielucke wird theoretisch analysiert. Fur ein bestimmtes Intervall der einfallenden Photonenenergie wird im Streuspektrum ein starkes Resonanzmaximum beobachtet. Durch Messung im sichtbaren Spektralbereich kann aus dem Streuspektrum insbesondere die Energielucke bestimmt werden. Fur einige reprasentative Halbleiter mit schmaler Energielucke werden die Moglichkeiten einer experimentellen Beobachtung der vorhergesagten Effekte diskutiert.
TL;DR: In this article, it was shown that P 4 O 6 can be continuously prepared with yields of about 70 mole-%, based on introduced phosphorus, and selectivities up to 95 per cent.
Abstract: Phosphorus(III)oxide, P 4 O 6 , can be continuously prepared with yields of about 70 mole-%, based on introduced phosphorus, and selectivities up to 95 per cent. Its thermal decomposition gives phosphorus(III/V)oxides, being also formed on interaction of P 4 O 6 -solutions in CCl 4 with oxygen. Reaction of P 4 O 6 with HCl yields phosphorus(III) chloride and phosphorous acids: with HF phosphorus(III) fluoride and fluorophosphorous acids result. Interaction with halogens gives phosphorus(III/V) oxide halides. Highly dispersed P 4 O 6 reacts with water to form immediately high-concentrated solutions of pure phosphorous acid. Alcoholysis, performed in the reaction products as solvent medium, yields pure equimolar mixtures of phosphorous acid mono- and diesters; as an intermediate product, polymeric phosphorous acid can be obtained. Monocarboxylic acids give acyl phosphites which may be quantitatively transformed to alkanehydroxy-diphosphonic acids. Aliphatic amines yield mono- and diamides of phosphorous acid. Reaction of P 4 O 6 with sulphur allows continuous preparation of the oxide sulphide P 4 O 6 S 4 . All these reactions of P 4 O 6 are strongly exothermic and of a high rate. The reactions yielding phosphorus(III) compounds may be explained by a nucleophilic attack on the P 4 O 6 molecule.
TL;DR: Requirements for the content of sulfur-containing amino acids in the protein were shown to be independent of the protein content of the diet, and were found to vary between 4.4% and 4.7% of the crude protein.
Abstract: Experimental rats (weighing 50-100 gm) received semisynthetic diets containing 8%, 10%, or 12% of crude protein (Soya protein) These were supplemented with graded amounts of L- or DL methionine After a 5-day feeding period the rats were injected 35S methionine Subsequently, the levels of urinary 35S excretion were determined over a period of 4 days after methionine injection The level of urinary 35S excretion was found to be clearly increased if methionine supplementation exceeded the methionine requirements of the animals Supplementation with 015% methionine was just enough for diets containing 8-10% crude protein 02% methionine had to be supplemented to meet the methionine requirements of the animals if the diet contained 12% crude protein Requirements for the content of sulfur-containing amino acids in the protein were shown to be independent of the protein content of the diet, and were found to vary between 44% and 47% of the crude protein The needs for methionine supplementation were independent of the fact whether L methionine or DL methionine was added It is definite advantage of the present method that methionine demands are determined in close correlation with metabolic processes, including the maintenance metabolism
TL;DR: In this paper, both the thickness of the diffusion layer and the amount of the concentration shift in diffusion layer at a cation exchange membrane depend on current density, and the dependence of the parameters of diffusion layer is experimentally investigated by means of the laser-interferometric method.
TL;DR: In this paper, a lineare Freie-Enthalpie-Beziehung zwischen dem Logarithmus der k 1 and den anodischen Halbstufenpotentialen zeigt, dass dieser Teilschritt um so schneller ablauft, je mehr die Bildung der Radikalkationen unter dem Einfluss von Substituenten zu positiven Potentialen verschoben wird.
TL;DR: The quenching effect of the divalent metal ions can be exploited as a simple routine activity measurement for various kinases and phosphohydrolases.