Showing papers by "Ludwig Maximilian University of Munich published in 1980"
TL;DR: In this paper, a variety of classical as well as quantum-mechanical models for which kinetic equations can be derived rigorously are discussed and the probabilistic nature of the problem is emphasized: the approximation of the microscopic dynamics by either a kinetic or a hydrodynamic equation can be understood as the approximate approximation of a non-Markovian stochastic process by a Markovian process.
Abstract: Dynamical processes in macroscopic systems are often approximately described by kinetic and hydrodynamic equations. One of the central problems in nonequilibrium statistical mechanics is to understand the approximate validity of these equations starting from a microscopic model. We discuss a variety of classical as well as quantum-mechanical models for which kinetic equations can be derived rigorously. The probabilistic nature of the problem is emphasized: The approximation of the microscopic dynamics by either a kinetic or a hydrodynamic equation can be understood as the approximation of a non-Markovian stochastic process by a Markovian process.
1,068 citations
TL;DR: Eicosapentaenoic acid (C20:5 omega 3), which is present in high concentration in certain salt-water fish, may reduce the incidence of cardiovascular disease in Greenland Eskimos by reducing platelet aggregation and adhesion.
538 citations
TL;DR: It is shown that the combination of optical elements and low amounts of FITC-Dextran improved the contrast of the televised image without changing macro- and microhemodynamic parameters, and blood plasma was delineated as bright structure against the substantially darker background of red blood cells and surrounding tissue.
Abstract: An experimental model was designed for direct, quantitative studies of hemodynamic and morphologic parameters in the microcirculation. It consists of implanting a modified Algire chamber in the dorsal skin flap of hamsters and the implementation of two permanent catheters in jugular vein and carotid artery. The microcirculation was studied using intravital microscopy and television techniques for in situ measurements of blood cell velocity and vascular diameters.
428 citations
TL;DR: In this article, it was shown that the rate-determining step in ammonia synthesis over iron catalysts is the chemisorption of nitrogen, and the question as to whether the nitrogen species involved on the surface is molecular or atomic is still not conclusively resolved.
Abstract: About 5 years ago a Battelle Colloquium on “The Physical Basis of Heterogeneous Catalysis” was held in honor of Professor Emmett where he presented an introductory talk on ″Fifty Years of Progress in the Study of the Catalytic Synthesis of Ammonia″ [1], a field to which he had made significant contributions during this whole period. So why another report on this topic? Justification can perhaps partly be obtained by some of Professor Emmett's concluding remarks which were not completely decisive with respect to the mechanism of this reaction: 'The experimental work of the past 50 years leads to the conclusion that the rate-determining step in ammonia synthesis over iron catalysts is the chemisorption of nitrogen. The question as to whether the nitrogen species involved on the surface is molecular or atomic is still not conclusively resolved. In fact, our own work in this field was mainly induced by this paper, and continuing discussions and correspondence with Professor Emmett were extremely help...
416 citations
TL;DR: The similarity of the morphology and of DNA composition, the homology of the component patterns of DNA-dependent RNA polymerases and their immunochemical crossreactivity support the conclusion that several extreme thermoacidophiles are related to each other.
Abstract: The similarity of the morphology and of DNA composition, the homology of the component patterns of DNA-dependent RNA polymerases and their immunochemical crossreactivity support the conclusion that several extreme thermoacidophiles are related to each other. We name two new species of the genus Sulfolobus. The first, Sulfolobus solfataricus (DSM 1616 and DSM 1617) has the same GC content in its DNA and the same general properties as S. acidocaldarius, but differs significantly from the latter species in the molecular weights of the 11 components of its RNA polymerase and in the salt requirements of this enzyme. The second, Sulfolobus brierleyi, DSM 1651, differs from S. acidocaldarius in several respects. The cells show much less stability at neutral pH. The GC content is significantly lower. The RNA polymerase lacks two components present in the enzymes from the other species. The residual 9 components show larger size differences from the homologous subunits of the S. acidocaldarius enzyme. Like the enzyme from S. solfataricus, the polymerase from S. brierleyi yields an incomplete immunochemical crossreaction with an antibody against the RNA polymerase from S. acidocaldarius. The isolates DSM 1616 and DSM 1617 of Sulfolobus solfataricus are probably identical with or similar to the “Caldariella” strains MT 3 and MT 4, isolated by de Rosa et al. (1975). Like all other known archaebacterial RNA polymerases the enzymes from these species are insensitive to rifampicin and streptolydigin.
386 citations
TL;DR: The findings suggest that patients with endogenous depression are characterized by a subsensitivity of postsynaptic alpha-receptors or of structures related to them, and the clonidine test shows promise as an indicator of vulnerability to endogenous depression.
Abstract: The stimulation of human growth hormone (HGH) release by clonidine (0.15 mg i.v.) was studied as a test of the postsynaptic α-receptor sensitivity of psychiatric patients. In this test, endogenous depressives showed a significantly reduced HGH response to clonidine as compared to normal controls, neurotic-reactive depressives, and schizophrenics. However, no differences were found between the endogenous depressives and a group of schizoaffective patients. HGH response to clonidine was not correlated with plasma levels of noradrenaline, serum cortisol, free fatty acids, or blood glucose. Within the group of normal control subjects, a reduced HGH response was found in most postmenopausal women and in some regular users of alcohol. Our findings suggest that patients with endogenous depression are characterized by a subsensitivity of postsynaptic α-receptors or of structures related to them. The clonidine test shows promise as an indicator of vulnerability to endogenous depression.
367 citations
TL;DR: In this paper, the authors studied the energetic, kinetic and structural properties of hydrogen chemisorbed on a Pd(100) surface by means of thermal desorption, work function and LEED measurements.
345 citations
TL;DR: A functional analogy of the ‘uncoupling protein’ as an anion carrier to the ADP, ATP carrier of mitochondria, as well as the fact that both proteins bind specifically nucleotides and have about the same MW suggested certain similarities between this protein and the ADp, ATP carriers.
251 citations
TL;DR: The properties of the transport have first been elucidated on isolated mitochondria with a still largely intact inner membrane, which contain an endogenous pool of adenine nucleotides which interacts directly with the ADP-ATP carrier.
Abstract: In eukaryotic aerobic cells, mitochondria supply the major portion of the ATP consumed in the cytosol for the multitude of energy-consuming processes. For this symbiosis mitochondria are equipped with a transport system for adenine nucleotides which shuttle ADP and ATP through the inner mitochondrial membrane (Fig. 1)~. Phosphate is transported by a separate system which can be differentiated from the ADP-ATP carrier by inhibitors. The properties of the transport have first been elucidated on isolated mitochondria with a still largely intact inner membrane. These mitochondria contain an endogenous pool of adenine nucleotides which interacts directly
239 citations
TL;DR: By applying the well known techniques of the planar process: oxide passivation, photo engraving and ion implantation, Si pn-junction detectors were fabricated with leakage currents of less than 1 nA cm−2/100 ωm at room temperature as mentioned in this paper.
235 citations
TL;DR: In this article, the authors present a method by which one-dimensional nonlinear soliton and kink Schrodinger equations can be solved in closed form, by inverting the procedure.
Abstract: We present a method by which one-dimensional nonlinear soliton and kink Schrodinger equations can be solved in closed form. The hermitean nonlinear soliton operator may contain up to second derivatives of the wave function and the vanishing condition must hold. The method is applied to solve known nonlinear Schrodinger equations for one-soliton and one-kink solutions and, by inverting the procedure, to derive new operators with wave packet solutions of algebraic and arbitrary shapes. One of them is equivalent to the Derivative Nonlinear Schrodinger equation.
TL;DR: In this article, the oxidation states and compositions of the surfaces of CuAl2O4 and NiO promoted CuAl 2O4 were investigated by X-ray photoelectron spectroscopy (XPS).
TL;DR: In this article, the authors examined the chemisorption of hydrogen on pure and Cu-covered Ru(0001) surfaces by means of low energy electron diffraction (LEED), work function (Δϑ) measurements, and thermal desorption spectroscopy (TDS).
TL;DR: A plethora of studies of this nature has in the past been performed on simple proton spectra as mentioned in this paper, which has led to a significant reduction of the effort required for the quantitative dynamic evaluation of NMR spectra arising from complex spin systems or involving other nuclei.
Abstract: In addition to the static parameters of the chemical shifts and coupling constants, which serve as a source of knowledge for molecular structure and stereochemistry, an NMR spectrum can frequently furnish dynamic quantities characterizing relaxation and exchange phenomena. The information about nuclear switching processes has proved to be particularly useful in practice for the detection of internal molecular motions and for the estimation or determination of the corresponding energy barriers. A plethora of studies of this nature has in the past been performed on simple proton spectra. Methodological developments of recent years have led to a significant reduction of the effort required for the quantitative dynamic evaluation of NMR spectra arising from complex spin systems or involving other nuclei. In many cases it has, moreover, become possible to extract detailed mechanistic information inaccessible by other means. The practical execution of such analyses will be explained and illustrated by a selected number of applications.
TL;DR: It is concluded that the causes of the induction lag in protoplasts can differ from those in isolated chloroplasts, and it is suggested that fructose-1,6-bisphosphatase and ribulose- 1,5-bisPhosphate carboxylase may limit flux in the Calvin cycle during induction.
TL;DR: An ultrathin layer, horizontal polyacrylamide gel system for electrophoresis, isoelectric focusing and two-dimensional techniques is described, greatly simplified and performed in a fraction of the time needed for conventional, thick gels in the 1-2 mm thickness range.
TL;DR: In this paper, thin copper overlayers on a Ru single-crystal surface were prepared as models for Cu/Ru “bimetallic cluster” catalysts, and various amounts of copper were deposited at 540 K on a ruthenium(0001) crystal surface.
TL;DR: The presence of parvocellular vasopressin‐ and neurophysin‐ containing neurons in the suprachiasmatic nucleus (SCN) was investigated in 13 mammalian species representing six mammalian orders, using specific antisera to vasopresses in the unlabelled antibody‐enzyme immunoperoxidase method.
Abstract: The presence of parvocellular vasopressin- and neurophysin- containing neurons in the suprachiasmatic nucleus (SCN) was investigated in 13 mammalian species representing six mammalian orders (marsupials, rodents, lagomorphs, artiodactyls, carnivores, and primates), using specific antisera to vasopressin and neurophysin in the unlabelled antibody-enzyme immunoperoxidase method. In all mammals examined, including man, parvocellular vasopressin and neurophysin neurons were found in the SCN. Only a portion of SCN neurons contain vasopressin and neurophysin, the number varying with species. Cell counts comparing the number of immunoreactive to Nissl-stained neurons showed averages of 17% immunopositive neurons in the rat SCN, and 31% in the human SCN. No oxytocin-containing SCN neurons were observed. These findings suggest that parvocellular vasopressin and neurophysin neurons are widely represented in mammals.
TL;DR: The results demonstrated that peroxidative break-down of lipids is an ongoing post-transcriptional process of ageing and the possible role of protective repair mechanisms is discussed.
TL;DR: From birth to adulthood, marked evolutional changes were observed in the basal plasma concentrations of all physiologically important unconjugated corticosteroids and progestins in normal children.
Abstract: Plasma Levels of Aldosterone, Corticosterone, 11-Deoxycorticosterone, Progesterone, 17-Hydroxyprogesterone, Cortisol, and Cortisone During Infancy and Childhood
TL;DR: It is demonstrated that ribulose 1,5-bisphosphate, ATP, ADP, AMP, inorganic phosphate, hexose phosphate, triose phosphate and 3-phosphoglycerate can be reliably recovered in the subcellular fractions isolated from protoplasts, and measured by enzymic substrate analysis.
Abstract: A method for determining the subcellular metabolite levels in spinach protoplasts is described. The protoplasts are disrupted by centrifugation through a nylon net, releasing intact chloroplasts which pass through a layer of silicone oil into perchloric acid while the remaining cytoplasmic components remain over the oil and are simultaneously quenched as acid is centrifuged into them. Cross-contamination is measured and corrected for using ribulose 1,5-bisphosphate as a chloroplastic marker and phosphoenolpyruvate carboxylase as a cytoplasmic marker. A method for separation of intact protoplasts from the medium by silicone oil centrifugation is described, which allows a correction to be made for the effect of free chloroplasts and broken protoplasts. Methods for inhibiting chloroplast photosynthesis, without inhibiting protoplasts, are presented. It is demonstrated that ribulose 1,5-bisphosphate, ATP, ADP, AMP, inorganic phosphate, hexose phosphate, triose phosphate, fructose 1,6-bisphosphate, and 3-phosphoglycerate can be reliably recovered in the subcellular fractions isolated from protoplasts, and measured by enzymic substrate analysis.
TL;DR: The esterification of chlorophyllide a was investigated an irradiated etioplast-membrane fractions from oat seedlings and a new chlorphyll esterified with farnesol was detected which does not occur in intact plants.
Abstract: The esterification of chlorophyllide a was investigated in irradiated etioplast-membrane fractions (‘broken etioplasts’) from oat seedlings (Avena sativa L.). As a substrate, [1-3H]geranylgeraniol and its monophosphate and diphosphate derivatives were prepared by chemical synthesis. Geranylgeraniol and its monophosphate derivative are incorporated into chlorophyll only in the presence of ATP whereas the diphosphate derivative is incorporated also without ATP. The yield of esterified chlorophyll is 80–90% of chlorophyllide with saturating substrate concentrations. The term ‘chlorophyll synthetase’ is used to describe this enzyme activity which is different from chlorophyllase. Other substrates are phytol and farnesol either with ATP or as the diphosphate derivatives. The relative specificity of ‘chlorophyll synthetase’ for these substrates is geranylgeraniol: phytol: farnesol = 6:3:1.
In these experiments in vitro, a new chlorophyll esterified with farnesol was detected which does not occur in intact plants. Geraniol and n-pentadecanol are no substrates for the enzyme. Proto-chlorophyllide which is present in non-irradiated etioplast membrane fractions is not esterified under the same conditions.
TL;DR: Results indicate that inhibition by ouabain of active cation transport is not a mandatory prerequisite of its positive inotropic effect, at least in the rat heart.
TL;DR: Not only the absorptive but also the metabolic efficiency greatly contributed to zinc homeostasis and total true efficiency of zinc utilization and its component factors, true absorption and metabolic efficiency, were studied.
Abstract: Total true efficiency of zinc utilization and its component factors, true absorption and metabolic efficiency, were studied in relation to dietary zinc supply in a 15-day experiment with 36 weanling rats in six groups. After day 3, the initial supply of 18.2 ppm zinc in the diet for all groups was changed to 5.6, 10.6, 18.2, 39, 70 and 141 ppm. in groups 1 to 6, respectively. During the 6-day balance period after day 9, zinc in take was proportional to dietary zinc concentration. Mean daily rates of weight gain and apparent zinc retention increased from a near zero level in group 1 to a high plateau from group 4 to 6. True absorption rate steadily rose and reached about twice that of apparent absorption in group 6. This difference in rates was due to endogenous zinc excretion. Percent total utili zation and percent true absorption steadily declined from a mean of about 100 in groups 1 and 2 to nearly 15 and 30, respectively, in group 6. Meta bolic efficiency, reflecting true retention of absorbed zinc, similarly de clined as percent true absorption did. The major conclusion was that not only the absorptive but also the metabolic efficiency greatly contributed to zinc homeostasis and total true efficiency of zinc utilization. J. Nutr. 110: 469-480, 1980.
TL;DR: In this article, a clear distinction of 6 subgroups of patients with acute lymphoblastic leukemia (ALLA) was possible: (1) common null-cell or cALL (cALL) was recognized in some patients of the c-ALL group, but was not analyzed consistently); and (6) pre-B-cell and pre-T-cell were detected in 32 leukemias no surface marker could be demonstrated.
TL;DR: In this paper, anioncharakters and ringoffnungen in the Hetero-Reihe eignet sich as Ordnungsprinzip.
Abstract: Das Prinzip der Orbitalkontrolle pericyclischer Reaktionen vertiefte das Verstandnis vom Reaktionsgeschehen und bot eine uberlegene Klassifikation dieser einstufigen Prozesse. Der elektrocyclische Ringschlus vom Typ Pentadienyl-Anion ⇌ Cyclopentenyl-Anion ist relativ unbedeutend in All-Kohlenstoff-Systemen und beim Stammkohlenwasserstoff nicht einmal realisiert. Fur eine Fulle von Ringschlussen und Ringoffnungen in der Hetero-Reihe eignet sich diese elektrocyclische Reaktion jedoch als Ordnungsprinzip. Dazu ersetzt man die Kohlenstoffatome des Pentadienyl-Anions schrittweise durch Heteroatome. Dieser Austausch kann isoionisch, d. h. unter Erhaltung des Anioncharakters, oder isoelektronisch vorgenommen werden. Ein isoelektronischer Ersatz von CR2 in 1-Position gegen NR2 oder OR sowie von CR in 3-Position gegen NR oder O ermoglicht es, eine ladungsfreie Grenzformel der offenkettigen Spezies zu schreiben; die Ladungswanderung bei der Elektrocyclisierung hat die Korrelation mit einem cyclischen Zwitterion zur Folge. Umgekehrt fuhrt der isoelektronische Austausch von CR in 2-Stellung gegen NR oder O zum konjugierten 1,3-Dipol, der zum ladungsfreien ungesattigten Funfring cyclisiert. Bei zweifachem isoelektronischem Austausch findet das ganze Geschehen im Kation statt. Ausgewahlte Beispiele machen mit Systematik und Triebkraft dieser elektrocyclischen Reaktion vertraut.
TL;DR: Nisin inhibits murein synthesis with concomitant accumulation of undecaprenyl-pyrophospho-MurNAc(pentapeptide) (lipid intermediate I) and this latter complex is not formed since lipid intermediate II is no longer synthesized.
Abstract: Nisin inhibits murein synthesis with concomitant accumulation of undecaprenyl-pyrophospho-MurNAc(pentapeptide) (lipid intermediate I). This inhibition is caused by the formation of a complex between the antibiotic and lipid intermediate I. Undecaprenyl-pyrophospho-MurNAc(pentapeptide)-GlcNAc (lipid intermediate II) also forms a complex with nisin. However, when murein synthesis is inhibited by nisin, this latter complex is not formed since lipid intermediate II is no longer synthesized.
TL;DR: The results described here agree with the hypothesis that an additional function of the decarboxylase could be the transport of Na’ through the membrane just as ATP energy is used to drive Na' and K’ transport by the adenosintriphosphatase.
01 Apr 1980-Zentralblatt für Bakteriologie: I. Abt. Originale C: Allgemeine, angewandte und ökologische Mikrobiologie
TL;DR: The subdivision into two main groups was found to correlate with the electrophoretic type of the L-lactic acid dehydrogenase and several features of the cell wall chemistry, whereas no phenotypical characters were found to distinguish the homology subgroups from each other, so the subgroups were not named.
TL;DR: From measurements of plasma concentrations of adenosine and inosine in the sinus sagittalis superior it is concluded that seizure is also accompanied by an enhanced release ofadenosine from the brain.
Abstract: In order to elucidate whether adenosine may be involved in the increase in cerebral blood flow (CBF) during functional hyperemia, cortical tissue levels of adenosine, inosine and hypoxanthine were measured in the cat following bicuculline (3 mg/kg)-induced seizure. In addition, the subcellular distribution of 5′-nucleotidase in the cortex was determined by histochemical techniques. Experiments were performed on anaesthetized and immobilized cats and tissue samples to be analyzed for the different purine compounds were obtained by freezing through the trepanized and non-trepanized skull. Control values for adenosine, inosine and hypoxanthine on the trepanized side were 1.31, 1.12 and 3.79 nmoles/g, respectively. The cortical content of adenosine increased to 3.85 nmoles/g, 15 s after beginning of seizure activity and remained elevated for 20 min. Inosine and hypoxanthine also increased, exhibiting highest values after 20 min. Values for adenosine and lactate were found to be generally higher when analysis was performed from tissue frozen through the intact skull bone. In all experiments the adenosine content correlated with lactate levels. From measurements of plasma concentrations of adenosine and inosine in the sinus sagittalis superior it is concluded that seizure is also accompanied by an enhanced release of adenosine from the brain. Localization of 5′-nucleotidase by electron-microscopic cytochemistry revealed that this enzyme is associated almost exclusively with plasma membranes of glial cell membranes including perivascular astrocytes. Thus high concentration of adenosine can be expected to accumulate locally in the brain cortex. In view of the well known increase in CBF during onset of seizure and the time course of adenosine formation, our findings support the view that adenosine may be involved in the initial phase of seizure-induced functional hyperemia of the brain.