Showing papers by "Max Planck Society published in 1975"
TL;DR: Results indicate that the host-versus-graft reaction alone can enihance murine cvtomtiegalovirus in a chronicallY injected host atid maY help explain the high incidence of cvvtomegalov virus infection seen after renal and other allograft transplantation.
Abstract: C3H/He mice chronically infected with murine cYtomegalo virus were given skin allografis fromti histoincompatible BALB/c donors. A significant inicrease in cvtomegalovirus titers occurred within 3 days after placement oJ'the graft in the spleens and kidneYs oJ' the allograft recipients as compared with control aninmals. No significant changes in virus titers were detected in the salivary gland, lung, liver, or blood ofallograJi recipients. These results indicate that the host-versus-graft reaction alone can enihance murine cvtomtiegalovirus in a chronicallY injected host atid maY help explaini the high incidence ofcvvtomegalovirus infection seen after renal and other allograft transplantation
1,083 citations
TL;DR: In this paper, a unified description of many electrical and optical properties of chalcogenide glasses is presented. But the model is based on a lattice-distortion model.
Abstract: A model is discussed which for the first time provides a unified description of many electrical and optical properties of chalcogenide glasses. It is proposed that localized gap states are at dangling bonds, and that lattice-distortion effects are sufficiently strong that these states exhibit an effective negative electron-electron correlation energy.
834 citations
TL;DR: The results suggest that not only testosterone but also other, not yet identified, androgens may be involved in the masculinzation of the brain.
Abstract: Radioimmunological determination of serum LH, FSH, and estradiol concentrations in prepubertal female rats demonstrates the temporal coincidence of increased serum levels of these hormones between days 9 and 21. Serum FSH and estradiol levels are continuously high during that time, whereas interindividual fluctuations in LH levels were enormous. No high LH, FSH, and estradiol levels were observed between day 21 and puberty, during which time serum prolactin and progesterone gradually increased. Serum testosterone in the female immature rats stayed uniformly low. It is suggested that increased serum estradiol levels in the presence of low prolactin levels (between day 10 and 20) act in a positive feedback fashion on the CNS-pituitary axis. The resulting increased gonadotropin levels are later (between day 20 and puberty) decreased by an inhibitory action of prolactin and/or progesterone on pituitary gonadotropin release. In male rats serum FSH and prolactin, which were low during the first 3 weeks, increased later to reach high levels during puberty. Serum LH was slightly elevated during the 2nd and 3rd week of life at which time serum progesterone also increased to reach the highest levels in the prepubertal period. Serum testosterone was higher in male than in female rats for the first 3 weeks of life; the difference between both sexes was significant but not striking. Between day 21 and the prepubertal period the testosterone levels were relatively low, but they increased again during puberty. Sex differences in androgen levels (measured with a less specific antibody) were more pronounced whereas estradiol levels in males showed the same pattern between birth and puberty as in the female littermates. These results suggest that not only testosterone but also other, not yet identified, androgens may be involved in the masculinzation of the brain.
724 citations
TL;DR: The crystal structure of benzamidine-inhibited bovine β -trypsin has been refined by constrained crystallographic refinement at 1·8 A resolution and led to the finding of a single site occupied by calcium.
436 citations
TL;DR: The visual cortex was studied in the mouse by recording from single units, and a topographic map of the visual field was constructed, and more than two‐thirds of cells could also be driven through the ipsilateral eye.
Abstract: The visual cortex was studied in the mouse (C57 Black/6J strain) be recording from single units, and a topographic map of the visual field was constructed. Forty-five percent of the neurons in striate cortex responded best to oriented line stimuli moving over their receptive fields; they were classified as simple (17%), complex (25%) and hypercomplex (3%). Of all preferred orientations horizontal was most common. Fifty-five percent of recpetive fields were circularly symmetric: these were on-center (25%), off-center (7%) and homogeneous on-off in type (23%). Optimal stimulus velocities were much higher than those reported in the cat, mostly varying between 20 degrees and 300 degrees/sec. The field of vision common to the two eyes projected to more than one-third of the striate cortex. Although the contralateral eye provided the dominating influence on cells in this binocular area, more than two-thirds of cells could also be driven through the ipsilateral eye. The topography of area 17 was similar to that found in other mammals: the upper visual field projected posteriorly, the most nasal part mapped onto the lateral border. Here the projection did not end at the vertical meridian passing through the animal's long axis, but proceeded for at least 10 degrees into the ipsilateral hemifield of vision, so that at least 20 degrees of visual field were represented in both hemispheres. The magnification in area 17 was rather uniform throughout the visual field. In an area lateral to area 17 (18a) the fields were projected in condensed mirror image fashion with respect to the arrangement of area 17. Medial to area 17 a third visual area (area 18) was again related to 17 as a condensed mirror image.
413 citations
31 Dec 1975
TL;DR: In this paper, a monograph devoted to the spectral theory of the Sturm-Liouville operator and the Dirac system has been published, with a focus on the spectral properties of the spectral theories of differential operators.
Abstract: This monograph is devoted to the spectral theory of the Sturm- Liouville operator and to the spectral theory of the Dirac system In addition, some results are given for nth order ordinary differential operators Those parts of this book which concern nth order operators can serve as simply an introduction to this domain, which at the present time has already had time to become very broad For the convenience of the reader who is not familiar with abstract spectral theory, the authors have inserted a chapter (Chapter 13) in which they discuss this theory, concisely and in the main without proofs, and indicate various connections with the spectral theory of differential operators
406 citations
TL;DR: In this paper, some aspects of the atom-molecule interactions are extended to include electronic transitions and the main emphasis is directed towards the close relationship between the adiabatic and the diabatic representations.
405 citations
TL;DR: The lipid A which is so far known as a water-insoluble material showed increased solubility when prepared from electrodialyzed lipopolysaccharides, which is related to differences in the sedimentation coefficients of the various salt forms.
Abstract: Ions of low molecular weight like metal cations and basic amines are present in lipopolysaccharides regardless of the isolation procedure employed. They are present in salt form with the acidic groups of the molecule and, partly, bound by chelation. Electrodialysis which removed a large proportion of these basic materials led to acidic lipopolysaccharides often with reduced solubility. Electrodialyzed lopopolysaccharides could be rendered soluble by neutralizing with alkali or with a basic amine. Depending on the base employed for neutralization preparations were obtained which showed in water distinct differences in solubility, viscosity and opalescence. These differences were related to differences in the sedimentation coefficients of the various salt forms. Neutralization with triethylamine led in all cases to highly soluble preparations with low sedimentation coefficients, while, on the other hand, neutralization with Mg(OH)2 led in most cases to insoluble preparations. The acidic lipopolysaccharides obtained by electrodialysis deteriorate on storing in a freeze-dried form. On heating in distilled water autohydrolysis occurs and free lipid A is liberated. The lipid A which is so far known as a water-insoluble material showed increased solubility when prepared from electrodialyzed lipopolysaccharides.
354 citations
TL;DR: In this paper, a theory for optical properties of particles of arbitrary shape, composed of a homogeneous isotropic material with a dielectric constant, was developed for the optical properties.
Abstract: A theory is developed for the optical properties of particles of arbitrary shape, composed of a homogeneous isotropic material with a dielectric constant $\ensuremath{\epsilon}(\ensuremath{\omega})$. The particles are so small that retardation can be neglected. An expression is obtained for the average dielectric constant of a medium containing a small fractional volume of particles. Calculations for a cube show that six resonances contribute to the optical absorption. They span a frequency range such that ${\ensuremath{\epsilon}}^{\ensuremath{'}}(\ensuremath{\omega})$, the real part of the dielectric constant, lies between -3.68 and -0.42, as contrasted with the single resonance for a sphere at ${\ensuremath{\epsilon}}^{\ensuremath{'}}(\ensuremath{\omega})=\ensuremath{-}2$. A comparison of the theory with experiments on the optical absorption of NaCl and MgO cubes shows that the width of the absorption peak can be explained by the frequency range of the cube resonances. Previous theories which assumed spherical particles required an unphysically high damping in $\ensuremath{\epsilon}(\ensuremath{\omega})$ to account for the width.
339 citations
336 citations
TL;DR: In this article, absolute nuclear photon absorption cross sections have been measured for the elements Li, Be, C, O, Al, Si and Ca from 10 MeV up to photon energies beyond the meson production threshold.
TL;DR: Using the simple model of electrons in a box, a dielectric function is derived which should be appropriate for small metal particles as mentioned in this paper. But the model is not suitable for all metal particles.
Abstract: Using the simple model of electrons in a box, a dielectric function is derived which should be appropriate for small metal particles. This dielectric function is used to examine quantum size effects in the optical absorption spectra. For very small particles of uniform size and shape, the plasma resonance absorption should shift and broaden and should show fine structure corresponding to transitions between discrete conduction band energy levels. The size dependence of the shift and broadening was measured and found to be in quantitative agreement with theory.
TL;DR: Carbon isotope values of 260 Precambrian limestones and dolomites (most of them being substantially unaltered) have yielded an overall mean of δ 13 C = + 0.4 ± 2.7 as discussed by the authors.
TL;DR: The data do not give compelling evidence for any formal model of the oscillations driving the activity rhythms, and predictions concerning the relation between phase and activity time derived from a single oscillator model are not matched by the data.
Abstract: 1. The seasonal variations in time of daily onset and end of locomotor activity are described for 3 species of mammals and 5 species of birds kept in captivity at the arctic circle and at lower latitude. These variations are most pronounced at high latitude. 2. The duration of daily activity plotted versus the photoperiod can be described as an S-curve in all species studied so far, both in nature and in captivity. In both male and female fringillid birds activity times were longer before the summer solstice (spring) than after the summer solstice at equal photoperiods. 3. The seasonal changes in activity time result from roughly mirror-image changes in the times of onset and end of activity relative to sunrise and sunset, cancelling out each other. Therefore the midpoint of activity stays relatively stable; remaining minor changes in the midpoint of activity do not produce a general seasonal pattern. 4. At high latitude, a large seasonal fluctuation in the day-to-day variability (or precision) of activity timing is detected. These patterns of precision of the rhythm cannot be attributed to a single Zeitgeber property without complex assumptions. Onset and ends of activity become more precise when occurring during the civil twilight, i.e. at times of day with most rapid changes in light intensity. This may reflect direct action of light on the rhythm rather than a property of the entrainment mechanism. 5. The data do not give compelling evidence for any formal model of the oscillations driving the activity rhythms. Predictions concerning the relation between phase and activity time derived from a single oscillator model are not matched by the data. On the other hand, the general seasonal patterns can be easily described in terms of a two-oscillator model. 6. Seasonal variations in duration of activity are larger in birds than in mammals. Day-to-day variations in timing are larger in mammals than in birds. The implications for photoperiodic time measurement are discussed.
01 Jan 1975
TL;DR: This paper reviews some experiments which have been done to elucidate how a fly looks at its surroundings and considers stimulation for such a study out of the conviction that the neural processing of information in the compound eye might better be unravelled with a precise stimulation of single receptor cells.
Abstract: This paper reviews some experiments which have been done to elucidate how a fly looks at its surroundings. Stimulation for such a study arose out of the conviction that the neural processing of information in the compound eye might better be unravelled with a precise stimulation of single receptor cells and that such a fine stimulation requires a better understanding of the optics.
TL;DR: In this article, a variation in the position of the receptive fields (RF-scatter) of single cells recorded extracellularly is observed in the course of long oblique penetrations through the postlateral gyrus.
Abstract: 1.
In the course of long oblique penetrations through the postlateral gyrus a variation in the position of the receptive fields (RF-scatter) of single cells recorded extracellularly is observed. This is superimposed on the continuous topological representation of the retina. Spezifying the RF-positions by the azimuthal and elevation coordinates of their geometrical centers, the standard deviation (SD) of the mean RF-positions of cells recorded in 200 μm long horizontal sections of cortex is calculated and the total radial scatter of RF-positions (Sanderson, 1971) as defined: \(\sqrt {\left( {{\text{4SD azimuth}}} \right)^2 + \left( {4SD{\text{ elevation}}} \right)^2 } \) is determined. The radial scatter is found to have its smallest value (1 degree visual angle (v.a.)) in the projection area of the functional center of the area centralis increasing to 3–4 degrees v.a. at 10 degrees eccentricity.
2.
The mean RF-diameter as defined: \(\sqrt {{\text{mean RF - area}}} \) is centrally 0.7 degrees v.a. increasing to 2.6 degrees v.a. at 10 degrees eccentricity. The ratio of the largest RF-diameter to the smallest RF-diameter is between 7–9 and remains almost constant over the central 10 degrees of the projection area. The magnification factor (M) as defined: mm Cortex/degree v.a. is centrally 2.3, decreasing paracentrally to 0.6.
3.
The cells in area 17 whose RFs have the same direction in the visual field constitute the spatial subunit of the retinocortical projection. The diameter of the spatial subunit is calculated as: \(\sqrt {\left( {{\text{total radical scatter}}} \right)^2 + \left( {{\text{average RF - diameter}}} \right)^2 } \). The spatial subunit functionally represents, therefore, that part of the visual field whose location and area is calculated by averaging over the RFs of the individuals of its cell population. It is found that the cells belonging to a spatial subunit are distributed within a cortical cylinder of 2.6–2.8 mm in diameter, the peak of the distribution coinciding with the central axis of the cylinder.
4.
Within the projection area of the central 10 degrees of the retina in area 17 the spatial subunits have the same diameter. This suggests that each retinal ganglion cell is functionally connected with an equal number of cells in area 17 irrespective of its position within the retina and that, therefore, the retinocortical projection is organized on the basis of a stereotyped schema if a basic spatial relationship is concerned.
TL;DR: The cyclic peptide phalloidin, one of the toxic components of Amanita phalloides prevented the drop of viscosity of F-actin solutions after the addition of 0.6 M KI and inhibited the ATP splitting of F -actin during sonic vibration.
TL;DR: In this article, the authors extended the single-determinant Hartree-Fock studies on the equilibrium structures and stabilities of H2 O, H3 O+ as well as of the monohydrated ionic systems Li+ · H2O, F− · H 2 O and the hydrogen bonded water dimer, H2 o · HOH, by large scale configuration interaction calculations including all the possible single and double excitations arising from the canonical set of Hartree Fock molecular orbitals.
Abstract: Previous single-determinant Hartree-Fock studies on the equilibrium structures and stabilities of H2 O, H3 O+ as well as of the monohydrated ionic systems Li+ · H2O, F− · H2O and the hydrogen bonded water dimer, H2 O · HOH, are extended by large scale configuration interaction calculations including all the possible single and double excitations arising from the canonical set of Hartree-Fock molecular orbitals. The correlation energy effects on the equilibrium geometrical parameters of the systems under consideration are found to be quite small. The contributions of the correlation energy to the total binding energies of the weakly interacting composed systems are obtained to be of the order of 1 kcal/mole, leading to a considerable increase of the hydrogen bond strength in F− · H2O and H2O · HOH and to a small decrease of the binding energy in Li+ · H2 O. The observed strengthening of the hydrogen bonding interaction due to correlation is shown to be partly compensated by the change in the vibrational zero-point energy of the composed systems compared to the non-interacting subsystems. Approximate force constants corresponding to the intersystem vibrations in Li+ · H2O, F− · H2 O, and H2O · HOH are deduced from the calculated potential curve data on the SCF and the CI level of accuracy.
TL;DR: The results showed that wild-type S strains contain more than one type of lipopolysaccharide, which differ in the length of their O-specific polysaccharid chains.
Abstract: Lipopolysaccharide preparations from R(rough) Escherichia coli O8-,SR(semirough) Salmonella typhimurium and S (smooth) strains E. coli O8 and Citrobacter 396 were disintegrated with sodium dodecylsulfate and subjected to polyacrylamide gel electrophoresis in the presence of 1% sodium dodecylsulfate. The results obtained were compared with those obtained from the same lipopolysaccharide preparations by degradation analysis. In dodecylsulfate gel electrophoresis the lipopolysaccharide preparation from the E. coli R mutant and the S. typhimurium SR mutant showed one band each (R-and SR-band, respectively) with different electrophoretic mobilities. The lipopolysaccharide preparations from the E. coli O8-strain exhibited two bands, one of which had the same electrophoretic mobility as the R-band and the other was identified as S-band. The lipopolysaccharide preparation from the Citrobacter 396-S-strain exhibited four bands: one R-band, one SR-band and two S-bands. The results showed that wild-type S strains contain more than one type of lipopolysaccharide. They differ in the length of their O-specific polysaccharide chains. The lipid A content of the different lipopolysaccharide was expressed in their electrophoretic mobilities.
TL;DR: The uptake of the sugars into the vesicles was osmotically sensitive and independent of glucose metabolism, and transport was Na+-dependent, was inhibited by phlorizin, and showed a transitory vesicle/medium ratio >1, in the presence of an initial Na+ gradient.
Abstract: Uptake studies of D-and L-glucose were performed on vesicles derived from brush-border and basal-lateral membranes. The uptake of the sugars into the vesicles was osmotically sensitive and independent of glucose metabolism. In brush-border vesicles D-glucose but not L-glucose transport was Na-+-dependent, wn the presence of an initial Na+gradient. Basal-lateral membranes take up D-glucose faster than L-glucose, but the D-glucose uptake is significantly less sensitive to sodium removal and only moderately inhibited by phlorzin as compared to the prush-border fraction.
TL;DR: It is established that mixed lecithin-phosphatidic acid membranes exhibit lipid segregation (or a miscibility gap) in the fluid state and suggests the possibility of cooperative conformational changes in the lipid matrix and in the surface proteins in biological membranes.
TL;DR: The results obtained indicate a postischemic depression of protein synthesis due to an inhibition of peptide chain initiation, indicating that during complete cerebral ischemia not only the synthesis but also the catabolism of proteins is inhibited.
TL;DR: P Protein II*, one of the major Escherichia coli outer cell envelope membrane proteins has been characterized and protein-chemical evidence as well as the behavior of two mutant proteins II* very strongly suggest that this protein consists of a single polypeptide chain and that in the strains studied there is no other major protein with similar characteristics.
Abstract: Protein II*, one of the major Escherichia coli outer cell envelope membrane proteins has been characterized. The protein is heat-modifiable and perhaps due to complete unfolding and/or binding of sodium dodecylsulfate only at higher temperatures the modified protein exhibits a higher apparent molecular weight (33000) than the non-modified form (28000). Protein-chemical evidence as well as the behavior of two mutant proteins II* very strongly suggest that this protein consists of a single polypeptide chain and that in the strains studied there is no other major protein with similar characteristics.
For another outer membrane protein, protein III (molecular weight 17000), it has not yet been established if it should be classified as a major protein. Protein III consists of one or perhaps two polypeptide chains. The possibility existed that protein III is bound covalently to lipopolysaccharide, and this has been ruled out. Also, the lipopolysaccharide of the E. coli strains studied does not carry covalently bound protein in amounts anywhere near stoichiometry. Non-protein substituents were neither found in protein II* nor in protein III.
It is concluded that in E. coli B/r and the E. coli K 12 strains used there are three major proteins: I, II*, and IV; protein III may also belong to this class. There are not more major proteins than these. All four proteins are compared and discussed regarding their unknown functions and their relation to E. coli outer membrane proteins studied by other authors.
TL;DR: In this paper, the frequency-dependent mobility of a classical Brownian particle moving in a periodic potential was calculated by applying a generalized version of Mori's continued fraction method, and the results were then used to interpret the observed frequency dependent conductivity for the superionic conductor AgI.
Abstract: We calculate the frequency-dependent mobility of a classical Brownian particle moving in a periodic potential. The problem is solved by applying a generalized version of Mori's continued-fraction method. The results are then used to interpret the observed frequency-dependent conductivity for the superionic conductor AgI.
TL;DR: A model catalyst is described which has properties in common with carbonic anhydrase and demonstrates the availability of a mechanism, previously only hypothetical, for the action of the enzyme.
Abstract: A model catalyst is described which has properties in common with carbonic anhydrase. The model demonstrates the availability of a mechanism, previously only hypothetical, for the action of the enzyme. It also shows, however, that this mechanism alone is not adequate to produce the high activity of the enzyme.
TL;DR: In this paper, a unified microscopic statistical theory of preequilibrium and equilibrium processes of the compound nucleus, valid for mass numbers A ⪆ 40, light incident projectiles (A ′4), and for excitation energies a few MeV above neutron threshold or larger, is presented.
TL;DR: The DNA-Sepharose is stable to high temperature, prolonged storage, and in the case of single-stranded DNA, can be washed with NaOH to destroy nuclease activity and to release any digested oligon nucleotides or mononucleotides.
Abstract: DNA has been covalently linked to insoluble matrices of agarose (Sepharose) in high yield using cyanogen bromide activation. Both double-stranded and single-stranded DNA have been coupled with yields up to 225 nmol/mg dry weight Sepharose or 3–8 μmol nucleotide phosphate/ml bed volume. The DNA-Sepharose has been used for (a) the affinity chromatography of various enzymes (Escherichia coli DNA polymerase I and RNA polymerase) from crude extracts or after initial purification steps, resulting in high yields and degrees of purification, and for (b) nucleic acid hybridization. The DNA-Sepharose is stable to high temperature, prolonged storage, and in the case of single-stranded DNA, can be washed with NaOH to destroy nuclease activity and to release any digested oligonucleotides or mononucleotides.