Showing papers by "University of Konstanz published in 1975"

Influence of intermittent long-term stimulation on contractile, histochemical and metabolic properties of fibre populations in fast and slow rabbit muscles.

Abstract: Slow (m.soleus) and fast (m.tibialis anterior) muscles of the rabbit were subjected to indirect long-term intermittent stimulation (3 weeks, 8 hrs daily) with a frequency pattern of 10 imp/sec. Whereas no changes were observed in case of the slow muscle, stimulation induced profound changes in the fast tibialis anterior muscle. These consisted in a rearrangement of the enzyme activity pattern of energy-supplying metabolism, e.g. decrease in glycogenolytic and glycolytic enzyme activities and severalfold increase in key enzymes of aerobic endoxidation of substrates in beta-oxidation and the citric acid cycle. Concomitant with the increase in aerobic oxidative capacity, there was an increased resistance to fatigue. Histochemical studies revealed a strong increase in mitochondria of all fibres. The bimodal distribution of fibre cross-sectional area in the normal tibialis anterior muscle was changed by stimulation into a more homogeneous population of fibres with a smaller cross-sectional area. Despite a 50% increase in time to peak of isometric twitch contraction no changes were observed in the fibre population with regard to myofibrillar ATPase reaction in quantitative evaluation of whole cross-sections of the muscles. The percentage of fibres histochemically classified as slow amounted to 2.8% and 3.1% in control and stimulated tibialis anterior muscle. Nevertheless the data suggest a transformation of the fibre population under the influence of long-term intermittent stimulation.

Ir-gene control of immunogenicity of insulin and A-chain loop as a carrier determinant.

Abstract: IT is generally believed that the B cells produce antibody against certain antigens after the helper cells recognise a determinant on the carrier part of the antigen. The immune response in mice against several antigens is controlled by Ir-genes which map in the major histocompatibility (H-2) locus of the IXth mouse linkage group. Details of the function of the Ir-genes are still unknown, but it is generally accepted that they control the recognition of carrier determinants1,2.

Bilateral Motor Interaction: Perceptual-Motor Performance of Partial and Complete “Split-Brain” Patients

Abstract: In recent years VOGEL and BOGEN, both neurosurgeons at the White Memorial Hospital in Los Angeles, have used surgical division of the neocommissures to treat a number of patients for intractable epilepsy. This measure was always a last effort to alleviate advancing, life-threatening convulsions and for most patients so far has brought remarkable improvements (BOGEN et al., 1965; BOGEN and VOGEL, 1962). This review is based on tests with ten of these patients, eight of whom underwent a complete commissurotomy, i.e. the corpus callosum in its entirety, the anterior and hippocampal commissure, as well as the massa intermedia (when present) were sectioned in a single operation. In the other two patients (N. F., D. M.) only a partial division of the neocommissures, including the anterior two thirds of the callosum and the anterior commissure, was performed (case histories: BOGEN, 1969; GORDON et al., 1971).

Correlation analysis of electrical noise in lipid bilayer membranes: kinetics of gramicidin A channels.

Abstract: If a membrane contains ion-conducting channels which form and disappear in a random fashion, an electric current which is passed through the membrane under constant voltage shows statistical fluctuations. Information on the kinetics of channel formation and on the conductance of the single channel may be obtained by analyzing the electrical noise generated in a membrane containing a great number of channels. For this purpose the autocorrelation function of the current noise is measured at different concentrations of the channel-forming substance. As a test system for the application of this technique we have used lipid bilayer membranes doped with gramicidin A. From the correlation time of the current noise generated by the membrane, the rate constants of formation (kR) and dissociation (kD) of the channels could be determined. In addition, the mean square of the current fluctuations yielded the single-channel conductance Λ. The values ofkR,kD, and Λ obtained from the noise analysis agreed closely with the values determined by relaxation measurments and single-channel experiments.

Two approaches to estimating public expenditures

Abstract: Traditionally, the demand for public expenditures has been estimated using as explanatory variables the average values of per capita income, as well as other variables. The results of this approach are disappointing which is due to the lacking theoretical basis. The public choice model, on the other hand, uses the political decision-making process (median voter model) to explain expenditures. Taking the same set of data, it is shown that the public choice approach yields superior results. It also offers a solution to the unfruitful discussion about the influence of political determinants of public expenditures.

Masked auditory thresholds, critical ratios, and scales of the basilar membrane of the housemouse (Mus musculus)

Abstract: 1. Masked auditory thresholds were determined for the housemouse (Mus musculus, outbred strain NMRI) between 1 kHz and 80 kHz and for four noise spectrum levels. 2. Critical ratios (K, K1) after Fletcher (1940), which represent bands of summated sound evaluation, were calculated. For frequencies (f) below 15 kHz critical ratios (CR-bands) remain constant (K = 35 dB;K1 = 3162 Hz). Above 15 kHz the relation between CR-bands andf can be expressed by the following functions:K = 13.27·Ig f−19.87;K1 = 0.456·f −2836. 3. From these functions the width in kHz and the number of CR-bands in the acoustic system of the mouse could be derived. The ear ofMus musculus is able to form maximally 10 CR-bands between 0.8 kHz and 115.4 kHz. 4. The width and number of CR-bands could be used to calculate a function for frequency distribution along the basilar membrane of the mouse, or to estimate fitting factors for Greenwood's (1961) equation respectively. The following function is proposed to be the best approximation:f = 3350·(100.21x−1),x = distance from the helicotrema. 5. Equidistant scales for the basilar membrane ofMus musculus are constructed. 6. The comparison of data on man, cat, and mouse shows that the CR-bands of these mammals are equal to a width of 0.67 mm on all respective basilar membranes. Thus accuracy of sound evaluation in mammals is directly proportional to the length of the respective basilar membranes.

Immunofluorescent localization of glycogenolytic and glycolytic enzyme proteins and of malate dehydrogenase isozymes in cross-striated skeletal muscle and heart of the rabbit.

Abstract: Specific antisera against glycogen phosphorylase, phosphofructokinase, aldolase, glyceraldehyde-phosphate dehydrogenase, enolase, lactate dehydrogenase, cytosolic and mitochondrial malate dehydrogenase from rabbit muscle were obtained from sheep. The gammaglobulins were used for indirect immunofluorescent localization of the respective enzymes in rabbit skeletal muscle and heart. In stretched skeletal muscle a cross-striation like distribution was observed for all enzymes studied. In the case of mitochondrial malate dehydrogenase this pattern is due to the staining of I-band mitochondria. In cross-sections, an intense staining of the sarcolemma and of subsarcolemmal mitochondria was observed. Comparative analyses with polarized light revealed that the cytosolic enzymes under study are distributed in the relaxed muscle fibre predominantly within the isotropic zones. The same distribution holds also for heart. In contracting muscle a decrease in cross-striated fluorescence and a faint staining of the interfibrillar spaces suggests a location also within the interfibrillar space.

Cobalt sulphide staining of optic fibres in the brain of the cricket, Gryllus campestris.

Abstract: Neuronal projections from one optic lobe to other parts of the brain were stained in the cricket Gryllus campestris using the cobalt sulphide technique and Timm's sulphide-silver method. The results are: Four tracts directly connect the medulla with the lobula and medulla of the contralateral optic lobe. Direct medullar projections end mainly in the non-glomerular neuropile of the protocerebrum, but also penetrate the calyx of the mushroom bodies, pons and central body in small numbers. A few somata which send fibres into the medulla lie in the pars intercerebralis, in the protocerebrum ventral to the opposite β-lobe, the outer margin of the medulla of the contralateral optic lobe and between deutoand tritocerebrum. The anatomical and physiological relevance of the stained connections is discussed.

Noradrenaline induces morphological alterations in nucleated and enucleated rat C6 glioma cells

Abstract: GILMAN and Nirenberg1 have reported that catecholamines induce a striking increase in intracellular cyclic AMP concentration in cultures of rat and human glioma cells. They concluded that this activation of the adenylate cyclase was mediated through the β-adrenergic receptor, since the effect was inhibited by the β-receptor blockers sotalol and dichloroiso-proterenol. Another report2 showed that cultured human glioma cells treated with cyclic AMP derivatives resumed the typical morphology of the normal counterparts, that is, having multiple processes extending from a compact cell body. I have therefore compared the effects of noradrenaline, a β-adrenergic stimulator, on the morphology and cyclic AMP level in rat C6 glioma cells.

Investigation of the symmetry of oligomeric enzymes with bifunctional reagents.

Abstract: 1 The symmetry of proteins composed of identical polypeptide chains has been investigated by means of cross-linking with bifunctional reagents and subsequent sodium dodecylsulfate–poly-acrylamide gel electrophoresis. The majority of the investigations were performed with diimidates of different chain lengths (C3–C12), which react exclusively with amino groups. Aldolase, catalase, fumarase, pyruvate kinase, tetrameric proteins with identical polypeptide chains, reveal a D2 symmetry, i.e. they appear to be composed of two pairs of polypeptide chains. The validity of this conclusion is demonstrated with lactate dehydrogenase. This enzyme, shown by X-ray analysis to have a D2 symmetry, yields after cross-linking and subsequent polyacrylamide electrophoresis the band pattern expected for a protein with this quaternary structure and similar to the pattern obtained with the above enzymes. 2 The influence of the experimental conditions on the cross-linking reaction has been investigated. The selectivity of the bifunctional reagent for the different contact domains within the quaternary structure of a protein depends on the reaction time, the chain length and on the concentration of the reagent. In general the D2 symmetry becomes more obvious with increasing chain length and with increasing concentration of the diimidate. Diethylpyrocarbonate showed very little selectivity. 3 Problems and limitations of the method have been investigated. The four polypeptide chains of β-galactosidase could not be cross-linked with the investigated reagents. Glyceraldehyde-phosphate dehydrogenase barely showed the predicted cross-linking pattern, although its D2 symmetry has been demonstrated by X-ray analysis. Yeast alcohol dehydrogenase shows a pattern which did not indicate any substructure with respect to the quaternary structure. Catalase yielded a complicated band pattern indicating that the cross-linking prevented complete unfolding of the polypeptide chains in sodium dodecylsulfate. These pattern did not occur after cross-linking with diethyl pyro-carbonate. 4 The applicability of molecular-weight determinations with sodium dodecylsulfate–polyacrylamide gel electrophoresis to cross-linked proteins has been investigated. Calibrations obtained with cross-linked proteins are very similar to that obtained with non-cross-linked polypeptide chains. Even with catalase the RF values of the predominant bands fit into this calibration.

The interaction of hydrophobic ions with lipid bilayer membranes.

Abstract: Electrical relaxation studies have been made on lecithin bilayer membranes of varying chain length and degree of unsaturation, in the presence of dipicrylamine. Results obtained are generally consistent with a model for the transport of hydrophobic ions previously proposed by Ketterer, Neumcke, and Lauger (J. Membrane Biol.5:225, 1971). This model visualizes as three distinct steps the interfacial adsorption, translocation, and desorption of ions. Measurements at high electric field yield directly the density of ions adsorbed to the membrane-solution interface. Variation of temperature has permitted determination of activation enthalpies for the translocation step which are consistent with the assumption of an electrostatic barrier in the hydrocarbon core of the membrane. The change of enthalpy upon adsorption of ions is, however, found to be negligible, the process being driven instead by an increase of entropy. It is suggested that this increase may be due to the destruction, upon adsorption, of a highly ordered water structure which surrounds the hydrophobic ion in the aqueous phase. Finally, it is shown that a decrease of transient membrane conductance observed at high concentration of hydrophobic ions, previously interpreted in terms of interfacial saturation, must instead be attributed to a more complex effect equivalent to a reduction of membrane fluidity.

Intramolecular addition of the riboflavin side chain. Anion-catalyzed neutral photochemistry.

Abstract: The presence of higher (greater than 0.2 M) concentrations of divalent anions A2- (hydrogenphosphate, sulfate) is found to accelerate as well as to change entirely the course of riboflavin photolysis: instead of 10-dealkylation to yield lumichrome, intramolecular addition of the 2'-hydroxyl group is found to occur at the peri-position C(9). The reaction is analogous to the "photohydration" of the flavin nucleus in the cationic state as described by Schollnhammer and Hemmerich [Eur. J. Biochem. (1974) 44, 561-577]. The final product of the new addition reaction arises from autoxidation of a dihydroflavin intermediate and exhibits the structure. It is thus representative for a new class of flavins ("cyclo-dehydroflavins"). Earlier reports on "anomalous" flavin photodegradation products absorbing around 410 nm [Holmstrom (1964) Ark. Kem. 22, 281; Massey and Atherton (1962) J. Biol. Chem 237, 2965] are readily explained. The reaction is found to depend strictly on the presence of a nucleophilic function in the N(10)-side chain, e.g. N(10)-CH2-C(OH)RR' or even N(10)-(CH2)2-SO3-. Quenching experiments suggest that the new reaction occurs via the singlet state 1FLox while the normal photolysis is mediated by the triplet 3Flox. The new photoaddition is though to occur via a Flavin-A2- complex which creates sterically favorable conditions for C(9)/O(2'alpha)-interaction.

Leg co-ordination during walking in the crab,Uca pugnax

Abstract: 1. Cine films of fiddler crabs (Uca pugnax) walking sideways on land were analysed frame by frame in order to study the co-ordination of the legs both during normal walking and following amputation (induced autotomy) of one of the 3rd pair of legs. 2. Although the average gait of unoperated animals approximates to an alternating tetrapod rhythm, equivalent to the alternating tripod gait of insects (Figs. 3–7), the stepping order of legs on leading and trailing sides of the animal is different. The dominant sequence on the leading side is 2435 (legs numbered from front to rear), that on the trailing side 2534 (Table 1), the chelae (leg 1) being usually held off the ground. 3. Stepping parameters also change with walking speed (Figs. 8, 10), the most clear-cut of these changes being the reduced relative duration of the power stroke at high walking speeds. At low walking speeds, clear-cut metachronal co-ordination is sometimes seen in trailing legs (Fig. 9), but the data nevertheless do not fit Wilson's 1966 metachronal model for insect locomotion. 4. Amputation of one of the 3rd pair of legs causes adaptive changes in the gait. The most obvious of these changes are that the chelae are now frequently used in walking and legs 4 and 2 on the operated side of the animal now alternate whereas before they moved together (Figs. 11–13, Table 2). Evidence is presented to show that these changes are brought about by the changed sensory input and are not due either to the effects of axon section on motorneurone electrical excitability, or to the animal walking more slowly and using a different but normally occurring gait.

Nuclear protein kinases from murine cells.

Abstract: Three protein kinase activities are found in nuclei from three different murine cells (Ehrlich ascites cells, mouse L cells and rat glioma cells). Two of these activities are soluble, one is bound to chromatin. The soluble enzymes are similar, if not identical, to the cytoplasmic protein kinases. The chromatinbound, adenosine-cyclic-3′: 5′-monophosphate-independent enzyme is not found in the cytoplasm. This enzyme is composed of one subunit with a molecular weight of 80000–90000. Some biochemical properties of this enzyme are described. A brief description of a nuclear enzyme, which dephosphorylates phosphorylated histones, is also given

Changes in the flight motor pattern during the development of the australian plague locust,Chortoicetes terminifera

Abstract: The establishment of the characteristic adult flight and its motor pattern has been followed behaviourally and electrophysiologically in locusts of exactly known ages. In the last two larval instars there is repetitive firing in the flight muscles but the alternation of antagonists typical of adult flight is not present (Pig. 3). Alternation can first be seen late in the last larval instar and the full adult pattern is recognizable in most animals by day 3 of adult life. Competent flight behaviour is established by day 4 or 5. In this period the coupling between elevator and depressor neurones improves and the pattern stabilizes (Figs. 4 and 6) but the time course of the whole process varies considerable between individuals. After this the only major change is an increase in wingbeat frequency from about 15–20 Hz at fledging to 25–35 Hz in the second or third week (Fig. 5).

Ir gene control of carrier recognition. I. Immunogenicity of bovine insulin derivatives

Abstract: 2,4-Dinitrophenyl-lysin B29 -bovine insulin was used as immunogen to investigate the carrier function of insulin in the induction of immune response. Experiments with backcross mice suggest that this is controlled by autosomal Ir genes. The response pattern shown by congenic mice demonstrate the linkage of these genes to the H-2 complex. With a standard dose of 20 μg per mouse, strains with the H-2 haplotypes d,b,v respond to this carrier. All other strains tested, with the H-2 haplotypes a,k,u,r,s,q, are nonresponders. The two Ir genes, Ir-insulinBov (H-2d) and Ir-insulinBov (H-2b), which are associated with H-2d and H-2b respectively, can be distinguished from one another on a functional basis. Only H-2d mice respond to an appreciable extent when B. pertussis organisms are the adjuvant. With complete Freund's adjuvant, H-2d and H-2b mice give high antibody titers, but with low doses of antigen only H-2d mice respond. In contrast to H-2d mice, H-2b mice do not respond to trifluoresceinthiocarbamyl insulin, suggesting that the dimeric insulin might be the immunogenic form in these mice. Furthermore, as has been shown earlier (Nature, 1975. 254: 78.), the A-chain loop is needed as a carrier determinant only in H-2b mice. Experiments with recombinant strains localize Ir-insulinBov (H-2b) to the left of Ir-1B, probably in Ir-1A. H-2k mice are strict nonresponders, even when other proteins such as bovine IgG, methylated bovine serum albumin or rabbit IgG are provided as carriers complexed with insulin. However, if proinsulin is used as the antigen, anti-insulin antibody can easily be raised in these strains.

Flavin-nicotinamide biscoenzymes: models for the interaction between NADH (NADPH) and flavin in flavoenzymes. Reaction rates and physicochemical properties of intermediate species.

Abstract: 1 Flavin-nicotinamide biscoenzymes covalently linked by two, three or four methylene groups through positions N(10) of the flavin (F1) and N(1) of the nicotinamide (Nic) form long-wavelength-absorbing, intramolecular complexes when the flavin part of the molecule is reduced specifically. The energy of the long-wavelength transition is minimal and its intensity maximal for Nic+ox-(CH2)3-FlredH− (λmax= 600 nm; ɛ= 1200 M−1× cm−1). 2 The increasing proximity of the positively charged nicotinamide lowers the pK-value of dihydroflavin deprotonation up to 1.7 units and the flavin oxidation-reduction potential becomes more positive up to 116 mV. 3 Specific reduction of the nicotinamide part of the biscoenzymes yields transient, long-wavelength-absorbing complexes. The energy of the long-wavelength transition is minimal and its intensity maximal for the complex NicredH-(CH2)3-Flox (λmax= 575 nm; ɛ= 650 M−1× cm−1). 4 The rate of intramolecular flavin-dependent dihydronicotinamide dehydrogenation is highest for NicredH-(CH2)3-Flox (345 s−1), about 3 times slower for NicredH-(CH2)4-Flox and 100 times slower for NicredH-(CH2)2-Flox. 5 The results obtained in this study are consistent with a reaction mechanism that involves formation of a charge transfer complex between reduced nicotinamide and oxidized flavin and rate-limiting heterolytic breakdown into products.

An extended kinetic analysis of valinomycin-induced Rb-transport through monoglyceride membranes.

Abstract: The time course of the current following a voltage jump, which is applied to monoglyceride bilayers in the presence of valinomycin, shows two relaxation times. This is basically in agreement with a simple carrier model which has been described in full detail formerly. Relaxation times and amplitudes allow a calculation of the rate constants of the transport model. The presented data supplement an analysis which was hitherto based only on the slower relaxation process and on information derived from the nonlinearity of currentvoltage characteristics. The additional resolution of the faster relaxation time allowed an approximate determination of the voltage dependence of the translocation rate constant for the carrier-ion-complex and provided evidence for a small voltage dependence of the interfacial reaction. The dependence of the relaxation parameters on the ion concentration in the aqueous phase was interpreted assuming a saturation of the ion concentration at the reaction plane at high bulk concentrations.

On the modelling of politico‐economic interdependence*

Abstract: Various analytic and simulation models designed to integrate the political and economic sectors are surveyed, stressing the interacting links going from the economy to the polity through the popularity function and in the reverse direction through the government's reaction function. Partial politico-economic models concentrate on a particular trade-off between goals, in particular between inflation and unemployment. The models of total politico-economic interdependence study the interrelationship of the economy as a whole with the polity. They are studied theoretically and by simulation techniques. Ongoing research by the authors indicates that such models can be applied empirically; as an example an already existing econometric model of the German economy is extended by an endogenous government sector.

Studies of Glutamate Dehydrogenase: Analysis of Functional Areas and Functional Groups

Abstract: 1 It is shown by limited tryptic digestion of beef liver glutamate dehydrogenase under native conditions that the amino terminus of the polypeptide chain is located at the surface of the molecule. End-group analysis after trypsin treatment yields aspartic acid as the new N-terminal amino acid while the C-terminal threonine remains unchanged. 2 NADH, especially in the presence of 2-oxoglutarate, protects the enzyme against tryptic degradation. In the absence of the coenzyme, glutamate dehydrogenase is rapidly inactivated. 3 The regulatory effects of ADP and GTP are only slightly altered by trypsin. A small shift of the pH dependence of the activation by ADP is observed. 4 The quaternary structure of the unimer of the enzyme is not affected by limited tryptic digestion indicating that the N-terminal part of the polypeptide chain is not located in the contact domains between the polypeptide chains. The association of the hexamer to large associated particles is reduced but not abolished. 5 It is shown by treatment of the enzyme with iodo[2-14C]acetic acid as well as with Ellman's reagent that the six –SH groups of the polypeptide chain are buried and not accessible to these reagents in phosphate buffer. In Tris buffer they become exposed and react in the order 89, 55, 197, 115, 270, 319. This together with the result that in Tris buffer the rate of inactivation caused by trypsin is higher than in phosphate buffer indicates that Tris buffer changes drastically the properties of the enzyme. 6 Cross-linking of the enzyme molecule with bifunctional reagents and subsequent dodecyl-sulfate-polyacrylamide electrophoresis shows that the six identical polypeptide chains are arranged in two groups of three. 7 The implications of these results for the tertiary and quaternary structure of beef liver glutamate dehydrogenase are discussed.