Showing papers by "University of Tübingen published in 1973"

Binding of 14C-Carbon Tetrachloride to Microsomal Proteins in vitro and Formation of CHCl3 by Reduced Liver Microsomes

Abstract: 1. Addition of CCl4 to suspensions of reduced liver microsomes produces a difference spectrum with max. absorption at 454 nm. This absorption develops within approx. 5 min (37°).2. Dehalogenation of CCl4 to CHCl3 by NADPH reduced liver microsomes displays similar kinetics.3. The irreversible binding of 14CCl4 to microsomal proteins proceeds more slowly than CHCl3 formation.4. The first step in CCl4 liver toxicity is the very rapid formation of fast reacting intermediates. This step might occur between the binding of CCl4 to cytochrome P-450 and the release of CHCl3. The primary intermediates bind to liver lipids and proteins and also initiate lipid peroxidation.

Profile of volatile metabolites in urine by gas chromatography-mass spectrometry.

Abstract: Profiles of volatile metabolites of 150 urine samples from normal individuals and 40 samples from subjects with diabetes mellitus have been studied by gas chromatography and mass spectrometry. The technique involves adsorption of the urinary headspace volatiles on Tenax GC, heat desorption with helium, trapping on a cooled precolumn, and chromatography on 100-m X 0.50-mm i.d. nickel columns. Individual profiles were observed over a period of 2 months. Characteristic constituents in normal urines are 2-butanone, 2-pentanone, 4-heptanone, dimethyl disulfide, several alkyl furans, pyrrole, and carvone. In subjects with diabetes mellitus under insulin treatment, high concentrations of pyrazines, cyclohexanone, lower aliphatic alcohols, and octanols were found.

Animal bone finds and economic archaeology: a critical study of 'osteo-archaeological' method.

Abstract: This paper describes how the study of animal bones from archaeological sites ('osteo‐archaeology') may contribute to our reconstruction of cultural and economic history. Methods of identification, quantification and sex and age determination are critically reviewed. The basic problem of relating bone debris at archaeological sites to a prehistoric animal population is discussed.

Metabolic activation of halothane and its covalent binding to liver endoplasmic proteins in vitro.

Abstract: 1. In suspensions of rabbit liver microsomes reduced by dithionite or NADPH, halothane produces a difference absorption spectrum with a maximum at 473 nm and a minimum at 408 nm. The “optical affinity” (Ks) was in the region of 3–6×10−6 M for dithionite reduced microsomes. The maximal absorption with dithionite reduced microsomes for halothane (473–550 nm) was 0.017–0.019 and for CCl4 (454–500 nm) 0.04–0.05 per nmol of cytochrome P-450. The appearance of the difference absorption with halothane is faster than that with CCl4. 2. During anaerobic incubation with NADPH-reduced liver microsomes from phenobarbital pretreated rabbits, 14C-labelled halothane (1 mM) was covalently bound to microsomal proteins at a rate of 2 nmol/mg protein in 30 min (CCl4: 11 nmol/mg protein in 30 min). Reduction by dithionite was ineffective. The binding of halothane was 60% inhibited in a gas phase of air, 75% by CO, 55% in the presence of 1 mM metyrapone, 50% by CCl4, but only 20% by red. glutathione. The binding of the radioactivity from labelled halothane and CCl4 to proteins of isolated rabbit lung and kidney microsomes was approximately proportional to the concentrations of cytochrome P-450 in the organ fractions. 3. Like CCl4, halothane (1 mM) inhibited several microsomal drug oxidation reactions. 4. Irreversible binding of halothane or its metabolite(s) to endoplasmic proteins might be connected with halothane liver damage.

Evolution or revolution of ammonoids at mesozoic system boundaries

Abstract: Summary 1. Biological revolutions at major stratigraphical boundaries have been given numerous explanations involving endogenous biological, exogenous ecological, physical, and cosmic, as well as sedimentary or chemical factors. In an attempt to elucidate the true nature of these faunal revolutions and to assess the possible influence of biological and/or physical factors, the evolution of ammonites at the boundaries of Mesozoic stratigraphical Systems is reviewed. It is believed that the more detailed data now available can give a clearer impression of evolutionary events at these boundaries. 2. It can be demonstrated that there is neither an abrupt and world-wide extinction, nor a spontaneous replacement by new elements at these caesuras as had been generally supposed to have occurred at the Triassic-Jurassic boundary, for example. Instead, one can recognize three distinct phases in the sequence of events: (1) a continuous disappearance of the ‘antique’ faunal elements; (2) a similarly continuous, gradual, and largely synchronous appearance of, or substitution by, qualitatively distinguishable ‘modern’ elements in small populations, yet in various parallel lineages (mosaic evolution); (3) a quite revolutionary, and quantitatively very sudden, diversification of these new elements, occurring at or with some delay above the boundary. 3. Thus one can demonstrate both continuous evolution of the modern faunas (‘preadaptational phase’), as well as ‘discontinuous’ spontaneous revolution, which does not produce qualitatively new characters and must be explained by diversification or adaptive radiation. This means that no further explanation by internal factors or by higher mutation rates resulting from the impact of cosmic rays becomes necessary. It is believed that, preceded by high extinction rates, world-wide ecological factors promoting higher niche diversity suffice to explain these adaptive radiations. The high degree of provincialism, endemism and specialization of the ‘antique’ faunas and the constant survival of smooth oxycones — regarded as inhabitants of a deep-sea environment — demonstrate that marine regressions and transgressions were the most effective ecological factors. 4. If there is not too much time involved between the two events, the caesura (Faunenschnitt) between final extinction of the old faunas and the radiation of the new is the most appropriate point by which to define System boundaries.

Thermal expansion and glass transition temperatures of synthetic glasses of plagioclase-like compositions

Abstract: The glass transition temperatures and the thermal expansions both below and above the glass transition temperature region of synthetic glasses of compositions close to those of plagioclases have been determined. The linear thermal expansion coefficient of the rigid glasses decreases on average from 7.4×10−6/dgC for albite glass to 4.9×10−6/dgC for glass close to anorthite composition. The glass transition temperature of the glasses initially decreases from 763° C for albite glass to 752°C for An9.7 glass and then increases nearly linearly with further increasing anorthite content to 813° C for glass close to anorthite composition.—Measurements made for comparison on a glass prepared from Madagascar orthoclase yielded a linear thermal expansion coefficient of 6.1×10−6/dgC and a glass transition temperature of 905° C.

Über den ovipositor der neuropteroidea und coleoptera und seine phylogenetische bedeutung (Insecta, Holometabola)

Abstract: 1. Bei den Megaloptera besteht der Ovipositor aus zwei medial miteinander verschmolzenen Labien, die die Legespalte zwischen sich fassen. Sie Bind durch Verschmelzung der Gonocoxite und Gonostyli des Segmentes 9 entstanden. Das Endglied der Gonostyli blieb als Taster erhalten. Die Gonapophysen der Segmente 8 und 9 fehlen. Die Labien werden durch ein kraftiges Lateralsklerit versteift, das mit einem Fortsatz des Tergum in gelenkiger Verbindung steht. 2. Die Legeapparate der Planipennia entsprechen den Verhaltnissen der Megaloptera. Insgesamt gesehen erscheinen die Legeapparate der ursprunglichen Planipennia-Familien weniger weit zuruckgebildet als diejenigen der Megaloptera. 3. Bei den Raphidioptera besteht der Legeapparat aus Anhangen des 8. und 9. Segmentes. Genauso wie bei den Megaloptera und den Planipennia wird auch bier der rinnenformige Korper des Legeapparates von den Gonocoxiten und Gonostyli des 9. Segmentes gebildet. Ein unpaarer Anhang des 8. Segmentes ubernimmt den ventralen Verschlus des Legeapparates. Beide Bauelemente sind durch eine Falzvorrichtung (Olistheter) miteinander verbunden. Auch bei den Raphidioptera bleiben die Endglieder der Gonostyli erhalten. Das Lateralsklerit ist bis auf eine schmale Skleritstange in quergestellte Spangen aufgelost. 4. Der unpaare Anhang des 8. Segmentes der Raphidioptera konnte sich offenbar nur parallel mit dem eigentlichen Korper des Legeapparates entwickeln. Es erscheint als ausgeschlossen, das der Anhang nachtraglich in einen Ovipositor vom Neuropteroidea-Typ „einwachsen” konnte. Hieraus folgt, das die Planipennia und Megaloptera den unpaaren Anhang des 8. Segmentes verloren haben. 5. Es kann als wahrscheinlich angesehen werden, das der Olistheter der Raphidioptera eine Sekundarbildung darstellt. 6. Bei den Coleoptera wird die weibliche Genitaloffnung von tasterformigen Vaginalpalpen flankiert. Es handelt sich um die mit den Gonocoxiten verschmolzenen Gonostyli des Segmentes 9. 7. Gegenuber den Coleoptera sind die Neuropteroidea durch die Verschmelzung ihrer Gonostyli and durch die Entwicklung einer legerohreigenen Muskulatur starker abgeleitet. Es wird als sicher angesehen, das these Ubereinstimmungen auf Verwandtschaft beruhen. Infolgedessen kann die Moglichkeit ausgeschlossen werden, das die Coleoptera mit einer Teilgruppe der Neuropteroidea naher zusammenhangen. 8. Es wird die Hypothese vorgetragen, das der Ovipositor der Neuropteroidea ein vaginalpalpenartiges Stadium durchlaufen habe. 9. Es ware vorstellbar, das der Vaginalpalpus der Coleoptera eine plesiomorphe Differenzierungsstufe des Neuropteroidea-Ovipositors reprasentiert. 10. Die aufgewiesenen Sachverhalte lassen sich am besten unter der Annahme verstehen,das die Coleoptera den Neuropteroidea als Schwestergruppe gegenuber-stehen.

The Embedding of Quasinormal Subgroups in Finite Groups.

Abstract: A subgroup of a group G is called quasinormal in G if it permutes with every subgroup of G. For a finite group G it is well known that quasinormal subgroups are not far from being normal: It6 and Sz6p [3] have shown that a quasinormal subgroup of G containing no nontrivial normal subgroup of G is always nilpotent. In this paper we shall prove a stronger result, namely: Theorem. If Q is a quasinormal subgroup of the finite group G, then Q~/QG is contained in the hypercentre Zoo (G/Q~) of G/Q~.

Interaction of H+ and Ca++ in the regulation of local pial vascular resistance.

Abstract: Mock CSF of various compositions was injected into the perivascular space of different small pial arteries by means of micropipettes. Acid CSF (pH 6.5) caused local vascular dilatation, as did normal CSF with the addition of EDTA or EGTA. Systemic acidosis caused by CO2 respiration also caused pial vasodilatation. Tiny silver-chloride electrodes were placed directly on the surface of small pial arterioles. Current-constant stimulation with series of DC-impulses (2–5 mA strength, duration 1 ms/imp.; stimulation lasted 10 sec) caused local vasoconstriction of the stimulated vessel. The constricted region of the vessel was of a different shape. Most frequently spindle-shaped constrictions with an extention not exceeding the length of the indifferent electrode were seen. In some cases the constriction was unilaterally placed near the different electrode (100 μm ∅) and in a few cases the constriction was propagated along the whole vessel. Stimulation after application of acid CSF or during CO2-respiration caused a constrictory action of about the same degree as in normal CSF. The acidotic dilatation, however, remained visible because the resulting vascular diameter after stimulation remained greater than in the controls with normal CSF. In Ca++-free CSF the stimulation elicited a small response and during EGTA no constriction appeared after stimulation. In CSF with EDTA the constrictory response was distinctly diminished. From the experiments it cannot be excluded that the constriction of pial vessels caused by electrical stimulation is based on another mechanism than that caused by extravascular alkalosis. Ca++ is necessary for both mechanisms.

Linear Magnetic Birefringence in the Antiferromagnetic Iron Group Difluorides

Abstract: The linear optical birefringence of the iron-group difluorides (rutile-type) has been determined between 5 and 700 K. A magnetic contribution to the birefringence occurs during the ordering of the antiferromagnetic compounds MnF2, FeF2, CoF2, and the weak ferromagnetic NiF2; the linear magnetic birefringence (LMB) can be well separated from the temperature dependent natural optical anisotropy. Both the magnetic short-range as well as the long-range order contribute to the LMB. The temperature derivative of the LMB follows the course of the magnetic specific heat to a very good degree. It is shown that this proportionality is to be expected if all spin pair correlation functions exhibit the same temperature behaviour. Whether this condition is valid for the lattice distortions is discussed using the existing structural data. Assuming the observed LMB is mainly due to spontaneous lattice distortions, the influence of the fluorine parameter seems to play an important role. An den Difluoriden der Eisenreihe wurde zwischen 5 und 700 K der Verlauf der linearen Doppelbrechung bestimmt. Der bei den Antiferromagneten MnF2, FeF2, CoF2 sowie beim schwachen Ferromagneten NiF2 gefundene magnetische Beitrag zur Doppelbrechung (LMB) ist gut vom Temperaturverlauf der naturlichen optischen Anisotropie zu trennen. Magnetische Nah- und Fernordnung tragen zur LMB bei. Die gefundene magnetische Doppelbrechung, nach der Temperatur differenziert, stimmt ausgezeichnet mit dem Verlauf der magnetischen spezifischen Warme uberein. Es wird gezeigt, das diese Proportionalitat zu erwarten ist, wenn alle Spm-Paar-Korrelationen gleiches Temperaturverhalten aufweisen. Die Gultigkeit dieser Bedingung auch fur die Gitterdeformationen wird an Hand vorliegender Strukturdaten gepruft.

New aspects of the intrafilamental vascular system in gills of a euryhaline teleost, Tilapia mossambica.

Abstract: The non-respiratory vascular system of T. mossambica gill filaments was studied in serial longitudinal and cross sections. Comparatively few scattered vascular communications occur between the afferent filament artery and the central venous sinus (AVAaff). The efferent filament artery, however, is connected by regularly arranged anastomoses (AVAeff), directly, and sometimes indirectly via nutritive vessels, to the central sinus. These AVAeff are about as numerous as lamellae counted on one side of each filament, although they diminish slightly in number towards the filament base. The relation AVAeff to AVAaff was 17.6:1 in the distal and 17.8:1 in the basal filamental region, while in the tip region of 7 filaments 126 AVAeff but only 1 AVAaff were encountered. No direct connection between the lamellar lacunae and the central sinus was detected. According to these results, non-respiratory intrafilamental blood shunting appears unlikely. AVAeff are assumed to be the main route for blood entering the central venous sinus which would consequently flow into the branchial veins.

Age-dependent changes of plasma renin concentration in humans.

Abstract: 1. Plasma renin concentration (PRC) in newborns greatly exceeded PRC in children and adults. PRC in cord plasma of newborns was higher than peripheral venous PRC in their mothers. PRC in the newborns increased further in the first 48 h post partum and then gradually decreased. 2. The mean PRC of healthy children and adults on free sodium intake decreased with age by an exponential function. 3. The absolute increase of PRC in response to upright posture (PRC upright — PRC recumbent ) decreased with age. The relative increase of PRC in response to upright posture (PRC uprjght :PRC recumbent ) remained unchanged with age, the PRC in upright posture being about twice the basal PRC in all age groups.

Recent Iron Sediment Formation at the Kameni Islands, Santorini (Greece)

Abstract: Iron-rich sediments are now forming in several bays of the Kameni Islands within the Santorini caldera by precipitation from warm submarine springs which represent a phase of late volcanic activity. From one bay of Palaea Kameni several cores from the soft, up to 3 m thick sediment have been taken and the analyses of four of them are reported in this paper. The composition of the gel-like silica-rich substance is not homogeneous. In the uppermost part, ferric hydroxide prevails. Down to approximately half a meter ferrous carbonate occurs. Underneath this layer, iron occurs as ferrous hydroxide, basic sulfate, or water-rich ferrous silicate gel. Only in the uppermost parts of the layers ferrous sulfide forms locally by the activity of sulfate reducing bacteria. Possibilities of the origin of the material precipitated in this bay, mode of transport, and stability relationships relative to Eh and pH values are discussed.

Light-Induced Phase Shifts of Circadian Leaf Movements of Phaseolus: Comparison with the Effects of Potassium and of Ethyl Alcohol

Abstract: Leaves of Phaseolus coccineus were exposed to high concentrations of KCl (0.1-0.3 M) for periods of 4-5 hr, or to ethyl alcohol (5-30%) for periods of 2 hr. The treatment started at various phases of the free-running circadian rhythm in continuous light. Whereas the K+ pulses induced only advance phase shifts, i.e., shortening of the periods, the alcohol pulses caused stronger advances and also slight delays, i.e., lengthening of the periods. These delays became stronger with lower concentrations of alcohol (1.7%) applied for a longer time. The lengthening effect by alcohol supplied continuously depends on the intensity of light. The rather high intensity of 3500 lux, resulting in very long free-running periods of about 29 hr, inhibits a further strong lengthening by alcohol. The phases reacting with advances to K+ and to alcohol are about the same phases that respond to light pulses with advances. The advances are reached at earlier phases of the circadian cycle when the concentration of alcohol or the strength of the light pulse is increased. The phases that respond with advances are those which, according to earlier publications, are within the energy-independent part of the cycle. The phases responding with delays belong to the energy-requiring part of the cycle. Consequently, it is suggested that advances are due to accelerated membrane depolarization and delays are due to stabilizing effects on membranes.

Adenosine 3′,5′-monophosphate in cultured neuroblastoma cells: Effect of adenosine, phosphodiesterase inhibitors and benzazepines

Abstract: The effect of various neurohormones on intracellular levels of adenosine 3′,5′-monophosphate were evaluated in a neuroblastoma cell line both, in the presence and in the absence of the phosphodiesterase inhibitors isobutylmethylxanthine and papaverine. Without the phosphodiesterase inhibitors only prostaglandin E1 increased intracellular adenosine 3′,5′-monophosphate levels. In the presence of isobutylmethylxanthine and/or papaverine, however, adenosine stimulated adenosine 3′,5′-monophosphate formation and the effect of prostaglandin E1 was greatly potentiated. Treatment of the cells with dopamine, 5-hydroxytryptamine, noradrenaline, adrenaline, histamine and prostaglandin F1α was without effect on adenosine 3′,5′-monophosphate levels either in the presence or absence of the phosphodiesterase inhibitors. The adenosine concentration for a half maximal effect was about 75 μM. The effect of 0.1 mM adenosine was not antagonized by 1 mM theophylline. Several adenosine analogs were tested and found to have little or no effect on adenosine 3′,5′-monophosphate levels in neuroblastoma N4TG3. Diazepam and to a lesser extent chlordiazepoxide act like phosphodiesterase inhibitors when incubated together with prostaglandin E1.

On the theory of lateral inhibition.

Abstract: Das mathematische Modell fur das Prinzip der lateralen Inhibition in der Theorie der optischen Perzeption fuhrt auf ein System nichtlinearer Gleichungen fur n reelle Variable. Dieses System wird auf Losbarkeit und eindeutige Losbarkeit untersucht. Es zeigt sich, das die Gleichung als Bedingung fur die stationaren Zustande eines geeigneten zeitabhangigen Systems zu deuten ist. Hier kann man ein diskretes und ein kontinuierliches Modell einfuhren. In beiden Fallen kann die Frage der Existenz der Losungen und der Stabilitat einigermasen vollstandig geklart werden. Eine Verallgemeinerung auf kontinuierlich viele Raumvariable ist moglich.

Gaschromatographie und Massenspektrometrie trifluoracetylierter Kohlenhydrate

Abstract: Zucker werden im Mikrogramm-Masstab in die Per(trifluoracetyl)-(TFA)-Derivate uber-gefuhrt, die anschliesend gaschromatographisch-massenspektrometrisch identifiziert werden. Die Massenspektren zeichnen sich durch relativ ubersichtliche Fragmentierung aus. Eine Unterscheidung von Aldosen und Ketosen sowie von Pyranosen und Furanosen ist durch das Auftreten einiger intensiver Fragment-Ionen im oberen Massenbereich gewahrleistet. Die erstaunlich hohe Fluchtigkeit macht die TFA-Derivate besonders gut geeignet fur gas-chromatographische Untersuchungen. Das Anomerengleichgewicht der Zucker wird bei der Umsetzung zu Trifluoracetylderivaten in den meisten Fallen nicht verandert. Das Fragmentierungsverhalten von trifluoracetylierten Desoxyzuckern, Methylglycosiden und von Disacchariden wird ebenfalls diskutiert. Gas Chromatography and Mass Spectrometry of Trifluoroacetylated Carbohydrates The trifluoroacetyl (TFA) derivatives of sugars are synthesized on a microgram scale and subsequently identified by means of gas chromatography and mass spectrometry. The mass spectra show easily interpretable fragmentation pathways. Aldoses and ketoses as well as furanoses and pyranoses can be distinguished by a number of intense fragment ions in the high mass range. The surprisingly high volatility of the TFA derivatives makes them well suited for gas chromatography. In most cases the equilibrium of anomers is not effected by the formation of the TFA derivatives. The fragmentations of the trifluoroacetyl derivatives of deoxysugars, methyl glycosides, and disaccharides upon electron impact arc discussed.

Simultaneous inclusion of the zeros of a polynomial

Abstract: A family of inclusion sets for the zeros of a complex polynomial is derived from the Lagrangean interpolation formulas. The optimization of the inclusion leads to a special type of matrix eigenvalue problem previously considered by several authors in connection with minimal Gershgorin discs.