Showing papers by "Ludwig Maximilian University of Munich published in 1983"

Familial hemophagocytic lymphohistiocytosis

Abstract: Familial hemophagocytic lymphohistiocytosis (FHL) is probably a genetically transmitted disease affecting infants and very young children. Cardinal symptoms are fever, hepatosplenomegaly, and pancytopenia. Frequently meningeal involvement is seen, manifested by neurologic symptoms and a lymphohistocytic pleocytosis with increased protein levels in the cerebrospinal fluid. Characteristic laboratory findings in FHL are hypertriglyceridemia and hypofibrinogenemia, which are reversible with treatment. The disease has been rapidly fatal in most patients, but recently longterm remissions have been achieved with cytotoxic agents.

Optical bistability and mirror confinement induced by radiation pressure

Abstract: This paper reports the observation of optical bistability due to a radiation-pressure-induced change of the length of a Fabry-Perot resonator. In addition, for higher laser powers, a purely optical mechanism leading to the stabilization of the resonator has been observed.

RNA polymerase from Rhizobium japonicum

Abstract: DNA-dependend RNA polymerase (EC 2.7.7.6) from Rhizobium japonicum was purified. The subunit structure was found to be ββ′α2σ, with the following apparent molecular weights determined by electrophoresis: Mr (β and β') 150,000 each, Mr (σ) 96,000, Mr (α) 40,000, Mr (holoenzyme) 490,000, Mr (core enzyme) 380,000. The recovery of σ was 28%. RNA polymerase from aerobically grown R. japonicum cells and from nitrogen-fixing cells have the same electrophoretic properties suggesting that no chemical modification of the enzyme occurs when cells undergo this metabolic differentiation.

Hadronic Collisions: A Quarkonium Factory

Abstract: Hadronic collisions are quite efficient in producing new quark flavours due to the large gluon content of ordinary hadrons. In particular, one may expect sizable yields of heavy quark-antiquark bound states with various spin and orbital quantum numbers. Using perturbative QCD in combination with the nonrelativistic quarkonium model we present a fairly complete and detailed picture of charmonium and bottomonium production. We compare our results on inclusiveJ/ψ and γ distributions with high energypp data and make predictions onηc and χ production.

Phosphorus Ylides in the Coordination Sphere of Transition Metals: An Inventory

Abstract: Phosphorus ylides are not only classical reagents in organic chemistry, but also play an increasingly important role as novel components in organometallic compounds. These metallic “ylide complexes” are either synthesized from “preformed ylides” and coordination compounds by addition or substitution, on the building block principle, or they are formed, in sometimes complicated reactions, from phosphanes, metal complexes, and C1 substrates in the coordination sphere of the metals. The resulting metal-carbon bonds are greatly modified in their properties by the immediate presence of the phosphonium center and often belong to the most stable of M-C structural units. The metal can come from any group of the periodic table, including the lanthanoids and actinoids. Numerous preparative and structural studies are gradually enabling us to gain an overall picture of the scope of this area of research.

Power, luck and the right index

Abstract: We have pointed out the theoretical drawbacks of the traditional indices for measuring a priori voting power inasmuch as they are implied in considering the coalition value a private good. This criticism caused us to view the coalition outcome as a public good. From this aspect and additional considerations with respect to power, luck, and decisiveness, we obtained a “story” describing the characteristics of an adequate measure of a priori voting power. These characteristics were found to be fulfilled by an index presented by Holler (1978). Through the above analysis this index has received its theoretical justification. An independent view of this index was then provided by means of an axiomatic characterization. This characterization makes possible abstract comparison of the index with previously established “private good” indices. While we have restricted our attention to simple games, the index presented can be generalized to provide a “value” on games in characteristic function form. We leave this topic for future conideration.

Variations in magnetization intensity and low-temperature titanomagnetite oxidation of ocean floor basalts

Abstract: The remanent magnetization of the oceanic crust exhibits a systematic long-term variation which correlates with the amplitudes of marine magnetic anomalies. After a sharp initial decrease of natural remanent magnetization intensity, a minimum is reached at ∼20Myr, followed by a gradual increase up to ages of 120 Myr. The progressive sea floor alteration of the magnetic minerals carrying the crustal magnetism is proposed as a cause for this behaviour.

Chromophore structure of the physiologically active form (P(fr)) of phytochrome.

Abstract: Chromopeptides were prepared by proteolytic digestion of phytochrome (far-red absorbing form, Pfr) and of phycocyanin. The phycocyanobilin peptide, the chromophore of which is Z,Z,Z-configurated, was modified to the Z,Z,E isomeric chromophore. It has been demonstrated earlier that the Pfr chromopeptide and the Z,Z,E-configurated phycocyanin chromopeptide behave similarly with regard to spectral and chromatographic properties and reactivity. We present evidence here, obtained by high-resolution 1H NMR spectroscopy, that both the modified phycocyanobilin chromophore and the phytochrome chromophore obtained directly from Pfr are 15E-configurated.

Nipple Location By Newborn Rabbits: Behavioural Evidence for Pheromonal Guidance

Abstract: In einem mit Glasboden versehenen Nistkasten wurde das Saugverhalten neugeborener Hauskaninchen von unten beobachtet (3 Wurfe). Durch Experimente, in denen der Bauch der Hasin rasiert und in verschiedener Weise abgedeckt worden war, wurden die relevanten Reize fur das Auffinden der Zitzen untersucht (16 Wurfe). 1. Kaninchenjunge konnen bereits wenige Sekunden nach Ankunft der Mutter Zitzen finden und besaugen. Auf Vibrations- und Beruhrungsreize reagieren sie mit AufrichtBewegungen. Sobald sie mit dem Fell der Hasin in Kontakt kommen, stosen sie ihre Schnauzen tiefer und fuhren die fur Zitzensuchverhalten typischen, senkrechten (Proben) und seitlichen Kopfbewegungen aus, bis sie eine Zitze ergriffen haben. 2. Das Zitzensuchverhalten wird durch Geruchsstoffe der Haut ausgelost und aufrecht erhalten. Die Starke des Geruchs scheint in Richtung Zitzen zuzunehmen und besonders hohe Konzentrationen an der Zitzenbasis oder ein moglicher zweiter Geruch losen das Ergreifen der Zitzen aus. 3. Wegen der geringen Reichweite des Geruchs hilft wahrscheinlich das Fell der Mutter den Jungen Kontakt mit der Bauch aufzunehmen und zu bewahren, und durch Verstarkung der seitlichen Kopfbewegungen den Geruchsgradienten zu entdecken. Jedoch sind fur das Auffinden der Zitzen weder der Fellstrich noch Temperaturgradienten der Haut wichtig. 4. Von der gesamten Saugezeit, pro Tag 3-4 Minuten, benotigten die Hasinen im Mittel 5,2 sec, um die Saugehaltung einzunehmen, die Jungen 11,5 sec (Median), um das Bauchfell der Mutter zu erreichen und 6,0 sec (Median), zum Zitzen zu finden und zu ergreifen. Unerwartet war, das Kaninchenjunge haufig Zitzen loslassen und wechseln, im Mittel 2,5 mal pro Minute, wodurch sich die an Zitzen insgesamt verbrachte Zeit weiter reduzierte. Jedoch nahm mit dem Alter auch die Leistungsfahigkeit der Jungen zu und der relative Anteil der eigentlichen Saugezeit erhohte sich wahrend der ersten 12 Lebens-tage von circa 47% auf 72%. 5. Der Zitzensuchverhalten auslosende Geruch kann als ein Pheromon im eigentlichen Sinn angesehen werden, da ein stereotypes Verhalten reproduzierbar ausgelost wird.

In vitro activity of ciprofloxacin, norfloxacin and nalidixic acid

Abstract: The in vitro antibacterial activity of the new quinoline derivative ciprofloxacin (BAY 0 9867) was evaluated in comparison to norfloxacin and nalidixic acid using 495 clinical strains of gram-negative and gram-positive bacteria. The compound was highly active againstEnterobacteriaceae, with MICs ranging from 0.008 mg/l to 4 mg/l, whereas the MICs of norfloxacin ranged from 0.03 mg/l to 16 mg/l. All strains ofPseudomonas aeruginosa andAcinetobacter calcoaceticus were inhibited with a concentration of 2 mg/l ciprofloxacin and 32 mg/l norfloxacin. Ciprofloxacin was also active against gram-positive cocci. The MICs forStaphylococcusaureus, Staphylococcus epidermidis, andStreptococcus faecalis ranged from 0.008 to 2.0 mg/l. The activity of ciprofloxacin was only slightly influenced by inoculum size, whereas an acid environment caused a noticeable decrease in the activity. Ciprofloxacin would seem to be a promising antibacterial agent for the treatment of urinary tract infection.

Indole alkaloids from cell suspension cultures of Tabernaemontana divaricata and Tabernanthe iboga.

Abstract: From cell suspension cultures of Tabernaemontana divaricata and Tabernanthe iboga grown under standard conditions, six monoterpenoid indole alkaloids have been isolated and identified. T. divaricata synthesized apparicine, catharanthine, coronaridine, conoflorine, tubotaiwine and vinervine, whereas T. iboga produced tubotaiwine and conoflorine. Both cultures are a reasonable source for conoflorine, which is expected to be a good candidate for studying the mechanism of Aspidosperma type alkaloid formation at the cell-free level.

Semi-infinite systems with first-order bulk transitions

Abstract: Semi-infinite systems are considered which undergo a first-order transition. The global phase diagram is discussed within the framework of Landau theory. Several types of phase transitions are found. At some of these transitions, critical surface phenomena occur since a variety of surface exponents may be defined although there are no bulk exponents.

Influence of pollen feeding and physiological condition on pesticide sensitivity of the honey bee Apis mellifera carnica.

Abstract: In two consecutive years heavy bee mortality at end April/early May followed the use of pesticides classed as harmless for bees along road verges. It was thought that old weak winter bees had succumbed to a preparation otherwise innocuous. Extensive tests to reveal any links between the bees' physiological condition and pesticide sensitivity involved 6 hormone herbicides, 11 fungicides and 2 insecticides, all approved harmless for bees and functioning on them wholly or mainly as stomach poisons. As a rule bee sensitivity was measured as LD 50 per os, in smaller tests as percentage mortality. Amount and quality of pollen ingested in the first days of life affected the pesticide sensitivity of young and older bees. Bees fed adequate high quality pollen are less sensitive than counterparts fed inadequate or inferior pollen or pollen substitute; such differences persisted if the LD 50 was calculated for the same body weight. Pesticides containing manganese are an exception. To these, bees fed inadequate pollen are no more or even less sensitive than comparable well-fed bees. Pesticide sensitivity decreases generally from early to late summer. Quality of pollen available for larvae has no effect on poison sensitivity of imagines. Food supply conditions however exert a clear influence: tested with the same pesticides, hive bees from colonies having had a rich early food supply, and young bees bred then, are less sensitive than their counterparts having had moderate or no early food supply. Poison sensitivity of summer bees increases with age; most sensitive are old winter bees which had practiced broodcare in early spring. Inadequate pollen intake can be regarded as causing protein deficiency. Investigation of this in mammals and man indicate that the higher poison sensitivity in bees results from inhibition of the enzymatic decomposition of pesticides. For practical bee protection it is important that all organic fungicides tested are effectively harmless. Hormone hebicides can be ranked as practically harmless even for bees inadequately protein-fed, as long as the approved concentrations are observed. Our tests raised doubts however about the registration as harmless for bees of insecticides based on Endosulfan and Phosalon. Of interest in practice and for the official testing of pesticides are also the high pesticide sensitivity of old winter bees, the decrease in sensitivity of bees on a stable feed from early to late summer, and the sensitivity-reducing influence of pollen-rich food supply promoting development. It is important ecologically that pollens of different plant species vary in nutrient quality for the honey bee: there are perfectly worthless (conifers), poor-to-medium, and highly effective pollen types. As shown in this paper, these differences are relevant not only for the development of the physiological condition and breeding potential of the bee, but also for pesticide sensitivity. That bees gather worthless and poor-quality, sometimes even poisonous, pollen (some Ranunculus sp.) is evidently due to the phagostimulant present in all pollen types.

Transition Metal Carbene Complexes

Abstract: By using an optically active metal-carbene complex we were able to isolate an optically active cyclopropane from the reaction of diethyl fumarate with [(−) (R)-methylphenylpropylphosphine] (phenylmethoxycarbene) tetracarbonylchromium. In addition to being synthetically useful for the preparation of cyclopropanes of optical activity, this reaction demonstrates that no free carbene is involved in the mechanism for the reaction.

Chemical composition and structure of cell wall teichoic acids of staphylococci

Abstract: The cell wall teichoic acid structures of 22 staphylococci including 13 type strains were determined. Most of the strains contain a poly(polyolphosphate) teichoic acid with glycerol and/or ribitol as polyol component. The polyolphosphate backbone is partially substituted with various combinations of sugars and/or amino sugars. Most of the substituents occur in a monomeric form but some strains also contain dimers of N-acetylglucosamine as substituents. Staphylococcus hyicus subsp. hyicus NCTC 10350 and S. sciuri DSM 20352 revealed rather complex cell wall teichoic acids. They consist of repeating sequences of phosphate-glycerol-phosphate-N-acetylglucosamine. The amino sugar component is present in this case as a monomer or an oligomer (n less than or equal to 3). Moreover, the glycerol residues are partially substituted with N-acetylglucosamine. The cell wall teichoic acid of S. auricularis is a poly(N-acetylglucosaminyl-phosphate) polymer similar to that found in S. caseolyticus ATCC29750. The cell wall teichoic acid structures for type strains of S. auricularis, S. capitis, S. cohnii, S. haemolyticus, S. hominis, S. hyicus subsp. hyicus, S. sciuri, S. xylosus and S. warneri were determined for the first time in detail. The structures of some of the previously described teichoic acids had to be revised (S. epidermidis, S. simulans, S. aureus phage type 187).

Effective field theory for interface delocalization transitions

Abstract: Semi-infinite systems are considered which give rise to a delocalization transition of the interface between two coexisting phases. Since the interface position becomes a zero mode at the transition, interface fluctuations invalidate mean-field theory for space dimension $dl~3$. An effective field-theoretic model for this zero mode is obtained via the collective-coordinate method. Results for a simplified version of this model in $d=2$ and in $d=3$ are reported.

Multicritical behaviour at surfaces

Abstract: The critical behaviour of a semi-infiniten-vector model with a surface term (c/2) ∫dSφ2 is studied in 4-e dimensions near the special transition. It is shown that all critical surface exponents derive from bulk exponents and η∥, the anomalous dimension of the order parameter at the surface. The surface exponents and the crossover exponent Φ for the variablec are calculated to second order in e. It is found that Φ does not satisfy the relation Φ=1-ν predicted by Bray and Moore. The order-parameter profilem(z)= is calculated to first order in e. In contrast to mean-field theory,m(z) is not flat nor does it satisfy a Neumann boundary condition. General aspects of the field-theoretic renormalization program for systems with surfaces are discussed with particular attention paid to the explanation of the unfamiliar new features caused by the presence of surfaces.

Nature of surface-enhanced-Raman-scattering active sites on coldly condensed Ag films

Abstract: Evidence is presented that coldly deposited Ag films are highly porous and that the pores persist up to 170 K but are heated out at 250 K. Diffusion of adsorbed pyridine into the pores is negligible below 60 K but readily takes place at 130 K. Theoretical results on the classical electromagnetic enhancement of the Raman cross section within the pores as well as a survey of published surface-enhanced Raman-scattering data lead the authors to conclude that the surface-enhanced Raman-scattering active sites of coldly deposited Ag films are within the pores.

The role of peristomatal transpiration in the mechanism of stomatal movement

Abstract: Abstract. Peristomatal transpiration is defined as the relative high local rate of cuticular water loss from external and internal surfaces around the stomatal pore and its decisive role in the control of stomatal movement is re-emphasized. As the resistance towards changes in air humidity is low in the pore surroundings, the state of turgor is particularly unsteady there. Due to the inherent instability the guard cell ‘senses’ fluctuations in the supply-demand relationship of water and is thus the control unit proper. The environmental variables (supply and demand) are cross-correlated within the subsidiary cell and the information is transmitted to the guard cell through the water potential gradient between the two cells. A conceptual segregation of a ‘humidity response’ by ‘passive’ stomatal movements is rejected. As ions always accumulate at the most distant point of the liquid path and as this point varies with pore width according to the prevailing water potential gradients, it is felt that the water stream is causing the characteristic pattern of ion distribution within the epidermis. Passive import of ions is attributed to local concentration gradients which are steepened by continuous supply and by water uptake into the guard cell in response to starch hydrolysis. A mechanistic model supplements the discussion.

On the redox control of synthesis of anaerobically induced enzymes in enterobacteriaceae

Abstract: Mutants of Escherichia coli were isolated in which transcription of the structural genes for hydrogenase (hyd) and for one of the components of formate dehydrogenase (fdh) (of the formate hydrogen-lyase complex) is coupled with that of the lacZ gene. They were — together with lac fusions of the nifH and nifL genes from Klebsiella — used to study regulation by redox control, of the expression of the respective structural genes. The following results were obtained: (i) β-galactosidase synthesis was fully repressed in the presence of O2 or nitrate (anaerobically), and induced in the absence of an external electron acceptor. Fumarate as terminal electron acceptor only marginally affected nif expression and partially repressed hyd and fdh expression. Redox control of the synthesis of hydrogenase and formate dehydrogenase, therefore, (as well as that of nif) acts at the level of transcription; the size of the redox potential seems to be correlated with the amount of repression; (ii) β-galactosidase synthesis in the hyd:: lac and fdh::lac fusion strains is induced by formate. At high concentrations formate reverses the repression by nitrate and fumarate but not that by oxygen.

Egyptian blue — Cuprorivaite a window to ancient Egyptian technology

Abstract: Egyptian Blue, a multicomponent synthetic blue pigment has been recorded in ancient Egypt since the Fourth Dynasty of the Old Kingdom (2600–2480 B.C.). The pigment consisting of cuprorivaite (CaCuSi4O10) with variable amounts of wollastonite (CaSiO3), Cu-rich glass and cuprite (Cu3O) or tenorite (CuO) was prepared by melting the copper-rich ingredient with lime and desert sand. Low melting temperatures (below 742 °C) were achieved by addition of flux-like plant ashes. The high quality of the pigments collected from monuments of the Fifth Dynasty (2480–2320 B.C.) may indicate that the first manufacture was in early dynastic or perhaps predynastic eras. During the reign of Thutmosis III (18th Dynasty, 1490–1436 B.C.) probably bronze filings were first applied as starting material, thus indicating a technological innovation. This new method was employed till the Roman times.