Showing papers by "University of Cologne published in 1981"

Activation of mouse complement by monoclonal mouse antibodies.

Abstract: The ability of monoclonal mouse IgM, IgD and IgG anti-(4-hydroxy-3-nitrophenyl) acetyl (NP) antibodies to activate mouse complement was studied using a hemolytic assay. Efficient hemolysis was obtained with IgG2a, IgG2b and IgG3 antibodies but no lysis was observed using a monoclonal IgD. Of several IgG1 antibodies tested, three gave no detectable hemolysis, although weak but significant hemolysis was obtained with two other IgG1. IgM was found to be powerfully hemolytic in that it was effective at lower concentrations than were IgG. However, using complement from mouse strains carrying the H-2k haplotype it was found that, under conditions of complement limitation and saturating antibody, a fixed amount of complement could lyse about 3 to 4 times as many IgG-coated sheep red cells as IgM-coated red cells. This discrimination between IgM and IgG as regards the efficiency of complement utilization is controlled by a gene in the S region of H-2 and is not apparent with complement from mice carrying the b, d or s allele at that locus.

Chemical control of Al-solubility in orthopyroxene and its implications on pyroxene geothermometry

Abstract: Two suites of spinel peridotites of the Westeifel/West Germany were found to have equilibrated in a narrow temperature interval each. Temperatures calculated from the CaO-solubility in orthopyroxene using experimental data of Lindsley and Dixon (1976) are 945° C to 980° C for the amphibole bearing Ia-suite and 1,150° C to 1,165° C for the Ib-suite. From the study of phase equilibria in both series it appears that Al-solubility in orthopyroxene is controlled by the composition of the coexisting spinel. Temperatures calculated from Al-solubility in orthopyroxene using an equation of Fujii (1976) derived from the univariant reaction en+sp↔fo+Al-en in the MgO-Al2O3-SiO2 system show a clear dependence on the FeCr2O4 component in the spinel phase, although ideal solution correction allowing for additional components was made. Temperatures obtained for the most chromite rich spinel — orthopyroxene pairs are 1,370° C and 1,240° C, respectively. These temperatures are by 220° C higher than those from Cr-poor pairs and those obtained from Ca solution in orthopyroxene. For practical purposes of geothermometry in spinel peridotites, an empirical equation $$T({}^oC) = \frac{{4.59 + ln K - 1.552Y_{C_r }^{sp} }}{{0.0025}}$$ allowing for the mole fraction of FeCr2O4 in spinel has been derived by a linear least squares fit to the orthopyroxene — spinel compositional data and temperatures calculated from the CaO-solubility of orthopyroxene in the present paper.

The antiplatelet and cardiovascular actions of a new carbacyclin derivative (ZK 36 374)--equipotent to PGI2 in vitro.

Abstract: The vascular and antiplatelet activities of a new, chemically stable carbacyclin derivative (ZK 36 374) were investigated and compared to PGI2. ZK 36 374 dose-dependently relaxed bovine coronary artery strips in vitro but was without direct effects on strips of bovine coronary veins which were contracted by PGI2. ZK 36 374 dose-dependently inhibited the ADP-, thrombin- and collagen-induced platelet aggregation in human platelet-rich plasma and disperded preformed platelet aggregates in whole blood of cats ex vivo. The IC50 was 0.2–1.1 (antigaggregation) and 13 (disaggregation) nM, respectively, and in the same range as PGI2. The maximum antiplatelet dose of ZK 36 374 (resolution of platelet aggregates) in anaesthetized cats in vivo was 0.45 nmoles/kg x min, and could be increased up to 3 nmoles/kg x min, i.e. 6–7-fold without significant changes in arterial blood pressure and heart rate. This indicates an appreciable dissociation between antiplatelet and blood pressure-lowering activities of this compound, at least in this model. It is concluded that ZK 36 374 is the first, chemically stable prostacyclin-mimetic agent that is equipotent to PGI2 in vitro and might be superior to PGI2 in vivo because of a reduced blood pressure-lowering activity.

Phase diagram for three-dimensional correlated site-bond percolation

Abstract: The Coniglio-Stanley-Klein model is a random bond percolation process between the occupied sites of a lattice gas in thermal equilibrium. Our Monte Carlo simulation for 403 and 603 simple cubic lattices determines at which bond thresholdp Bc , as a function of temperatureT and concentrationx of occupied sites, an infinite network of active bonds connects occupied sites. The curvesp Bc (x, T) depend only slightly onT whereas they cross over if plotted as a function of the field conjugate tox. Except close toT c we find 1/p Bc to be approximated well by a linear function ofx, in the whole interval between the thresholdx c (T) of interacting site percolation atp Bc =1 and the random bond percolation limitx=1 atp Bc =0.248±0.001. Thisx c (T) varied between 0.22 forT=0.96 (coexistence curve) and 0.3117±0.0003 forT=∞ (random site percolation). At the critical point (T=T andx=1/2) we confirmed quite accurately the predictionp Bc =1-exp(−2J/k B T c ) of Coniglio and Klein. As a byproduct we found 0.89±0.01 for the critical exponent of the correlation length in random percolation.

Metric-affine variational principles in general relativity II. Relaxation of the Riemannian constraint

Abstract: We continue our investigation of a variational principle for general relativity in which the metric tensor and the (asymmetric) linear connection are varied independently. As in Part I, the matter Lagrangian is minimally coupled to the connection and the gravitational Lagrangian is taken to be the curvature scalar, but we now relax the Riemannian constraint as far as possible—that is, as far as the projective invariance of the assumed gravitational Lagrangian will allow. The outcome of this procedure is a gravitational theory formulated in a volume-preserving space-time (i.e., with torsion and tracefree nonmetricity). The vanishing of the trace of the nonmetricity is due to the remaining vector constraint. We also discuss the physical significance of the relaxation of the Riemannian constraint, the possible relaxation of the vector constraint, the notion of the hypermomentum current, and its possible relation to elementary particle physics.

Evidence for Deformed Ground States in Light Kr Isotopes

Abstract: The levels in $^{74,76}\mathrm{Kr}$ were studied with in-beam $\ensuremath{\gamma}$-spectroscopy techniques and the ${\ensuremath{\beta}}^{+}$ decay of $^{76}\mathrm{Rb}$. The energies of the ${2}_{1}^{+}$ states in $^{74,76}\mathrm{Kr}$ deviate from smooth behavior compared with the higher spin levels. The yrast cascade $B(E2)$'s are highly collective. The $^{74,76}\mathrm{Kr}$ ground states have unusually large deformation. The origin of this deformation and of shape coexistence in this region is described in terms of the protons driving the deformation.

Propagation of foreign DNA in plants using cauliflower mosaic virus as vector

Abstract: Cauliflower mosaic virus (CaMV) is the best analysed member of the caulimoviruses, a group of small isometric plant viruses that contain a circular double-stranded genome (for review see ref. 1). As most plant viruses have an RNA rather than a DNA genome, caulimoviruses have attracted considerable interest due to their potential use as genetic vectors for plants. DNA purified from CaMV particles can infect plants and cause virus production when rubbed over the surface of susceptible leaves2. Moreover, the entire chromosome of several CaMV strains can be propagated through bacterial hosts by plasmid and phage λ vectors and has been used successfully to infect plants3,4. Recently, Howell et al.5 reported the insertion of an 8-base pair (bp) EcoRI linker molecule into the large ‘intergenic’ region of cloned CaMV strain CM 4-184 DNA without impairment of infectivity. Here we report the successful propagation of foreign DNA in plants using cauliflower mosaic virus as vector. We find that the size of foreign DNA that can be successfully propagated through virus particles has an upper limit of ∼250 base pairs.

Mass Spectrometry of Negative Ions

Abstract: “It appears that negative ion mass spectra measured with a commercial instrument and the electron energies used (20–70 eV) are not suitable either for molecular weight or for structure determination—”. This was the conclusion of a paper appearing in 1965 which expressed the then almost universal opinion on the importance of negative ion mass spectrometry in the structure analysis of organic compounds[8]. The fact that quinones and aromatic nitro compounds were exceptions to this rule was rather taken as substantiation of this opinion. The potential value of the work originating from the laboratories of Manfred von Ardenne was first realized with the development of chemical ionization. This technique gave a firm foundation to negative ion spectrometry in the area where it is complementary to that of positive ions.

Positional Specificity and Fatty Acid Selectivity of Purified sn-Glycerol 3-Phosphate Acyltransferases from Chloroplasts.

Abstract: Soluble acyl-CoA: sn -glycerol 3-phosphate acyltransferases (EC 2.3.1.15) which are localized in chloroplasts were purified from leaves of Pisum sativum and Spinacia oleracea and obtained free from interfering activities. The purification raised the specific activities by factors of about 1,000 for pea and 200 for spinach preparations. In pea chloroplasts, acyltransferase activity occurs in two soluble forms with apparent isoelectric points of 6.3 and 6.6. For both forms, the same molecular weight of about 42,000 was determined. The enzyme from spinach chloroplasts showed a slightly higher molecular weight and a lower isoelectric point of 5.2. The enriched enzyme fractions possessed a specificity for glycerol 3-phosphate as acyl acceptor and did not use dihydroxyacetone phosphate. Besides acyl-CoA, acyl-acyl carrier protein also can function as acyl donor. With acyl-CoA as acyl donor, the enzyme shows a high positional specificity, since the predominant product is 1-acylglycerol 3-phosphate. Different acyl-CoAs, when offered separately, were all accepted as substrates, whereas incubations with mixtures of palmitoyl-, stearoyl-, and oleoyl-CoA demonstrated a preference for oleic acid. The acyltransferase from spinach displays higher selectivity than does the enzyme from pea and, therefore, may be responsible for the preferred esterification of oleic acid at the C—1 position in chloroplast lipids and the exclusion of palmitic acid from this position as observed during in vivo labeling experiments.

Some Recent Explanations of Income Inequality

Abstract: This article attempts to evaluate five alternative explanations of the size distribution of income. It is based on a regression analysis of inequality data from 71 countries and different explanatory variables taken from various theoretical approaches. Also, the proper specification of the relationship between economic development and income inequality is used. The following tentative conclusions are reached: First, the most important correlate or determinant of inequality is the level of economic development; divergent conclusions in other studies are the result of improper specification. Second, communist countries have a more equal distribution of income than other societies. Third, high military participation ratios contribute to income equalization. Fourth, judgment about democratic performance has to be postponed because democracy seems to contribute to a more egalitarian distribution of income in one data set, but not in the others. Fifth, the three versions of dependency theory under consideration—Galtung's (1971), Rubinson's (1976), and Bornschier and Ballmer-Cao's (1979) have failed to contribute significantly to the explanation of income inequality.

Grüneisen parameter of cerium compounds with unstable 4f shells

Abstract: We give experimental results of magnetic susceptibility, thermal expansion and elastic constant measurements for CeSn3 and CePd3. We interpret these results with a phenomenological scaling function for the free energy and we include a brief discussion of CeAl3. The coupling between the electronic system and the lattice can be described by an electronic Gruneisen parameter Ωg associated with the unstable 4f system which turns out to become a system specific constant far below the fluctuation temperatureT0. The coupling parameter T0Ωg is an order of magnitude larger than the coupling constant for stable valentRE systems extracted from crystal field effects. A generalization to include magnetic field dependent effects is also given.

Idiotypic regulation by isologous monoclonal anti-idiotope antibodies.

Abstract: The network hypothesis1 proposes that internal antibody interactions are crucial in the regulation of the immune system. Thus, injection of minute amounts of anti-idiotypic antibodies (antibodies specific for a particular set of antigenic determinants (idiotopes) associated with the variable region of a particular antibody or set of antibodies) can enhance or suppress the production of the corresponding set of idiotopes (the idiotype) in subsequent antibody responses of the animal2–5. We have recently shown that idiotope expression can be enhanced and suppressed by monoclonal anti-idiotope antibodies of the IgG1 class in concentrations approaching those of natural antibodies6. We now demonstrate that these regulatory effects are not due to differences in the constant parts of the injected antibody and antibodies of the IgG1 class in the recipient. Also, an IgG2a anti-idiotope antibody raised in C57BL/6 mice suppresses the expression of the corresponding idiotope in animals of the same strain when minute amounts are injected 2–8 weeks before the test immunization with antigen. These results indicate that antibody-mediated network interactions are physiologically important and suggest that the class of isologous anti-idiotypic antibodies may influence their regulatory properties. Finally, the enhancement and suppression of idiotope expression by IgG1 anti-idiotopes and the suppression by IgG2a is almost exclusively at the level of IgG but not IgM antibodies.

Mycoplasma contamination in human tumor cell lines: effect on interferon induction and susceptibility to natural killing.

Abstract: Cleaning of human tumor cell lines from arginine-dependent nonfermentative Mycoplasma orale 1 (MO1) by a recently developed technique profoundly altered several in vitro properties of the cell lines. Four melanoma lines (Mel I, Mel St, Mel K, IGR3) and 1 ovarian carcinoma line (Ro) induced human leukocyte interferon (IFN-alpha) only in the mycoplasma-infected state and not in the mycoplasma-free state. MO1-infected tumor lines were generally more susceptible to natural killer (NK) cell-mediated lysis than their mycoplasma-free counterparts. Reinfection of cleaned tumor lines with MO1 restored their interferonogenicity and the increased susceptibility to NK lysis. Thus, the amplifying role of MO1 infection on NK target lysis occurred in connection with an increased production IFN-alpha during the assay period. The human erythroleukemia cell line K562 was exceptional in that it also induced high levels of IFN in an apparently mycoplasma-free state and was unaffected in its susceptibility ot NK lysis by infection with MO1. Possible implications of these findings for the biologic significance of the NK reaction are discussed.

Lambda chain expression at different stages of ontogeny in C57BL/6, BALB/c and SJL mice

Abstract: In C57BL/6 and BALB/c mice, 2–3% of immunoglobulin-positive cells express λ1 and 1–2% λ2 chains at the cell surface. These percentages are constant from the time around birth until adult age. The levels of λ1 chains in serum antibodies correspond closely to those in the B cell population in both mouse strains whereas in the case of λ2 chains, they are three times lower in serum antibodies than in the B cell population. In strain SJL, λ2-bearing B cells occur in similar frequencies as in BALB/c and C57BL/6, both in newborn and adult animals. However, the level of λ2-bearing immunoglobulins in the serum is 30 times below that expected on the basis of the cellular analysis and 10 times lower than in BALB/c and C57BL/6. B cells expressing λ1-like light chains were found in normal frequency in newborn SJL mice with a monoclonal rat anti-λ1 antibody. In adult animals such cells were present in a frequency 100 times below that characteristic for BALB/c and C57BL/6 mice. The concentration of immunoglobulin reactive with rat anti-λ1 antibody was 300 times lower in SJL than in BALB/c and C57BL/6 serum, in accord with previous data (W. Geckeler et al., J. Exp. Med. 1978. 148: 1122). The notion that in SJL mice a control mechanism specifically suppressess λ chain expression is further supported by an analysis of the early primary anti-(4-hydroxy-3-nitro-phenyl)acetyl (NP) response. We show that this response is initially dominated by antibody-forming cells secreting antibodies with λ1-like light chains. These cells rapidly disappear and appear to be selected against particulary in the IgG response. The monoclonal SJL anti-λ1 antibody Ls136 (M. Reth et al., Eur. J. Immunol. 1979. 9: 1004) does not stain any B cells in SJL mice, whereas it detects λ1-bearing cells in C57BL/6 and BALB/c animals in the expected frequency.

Some Recent Explanations of Income InequalityAn Evaluation and Critique

Abstract: This article attempts to evaluate five alternative explanations of the size distribution of income. It is based on a regression analysis of inequality data from 71 countries and different explanatory variables taken from various theoretical approaches. Also, the proper specification of the relationship between economic development and income inequality is used. The following tentative conclusions are reached: First, the most important correlate or determinant of inequality is the level of economic development; divergent conclusions in other studies are the result of improper specification. Second, communist countries have a more equal distribution of income than other societies. Third, high military participation ratios contribute to income equalization. Fourth, judgment about democratic performance has to be postponed because democracy seems to contribute to a more egalitarian distribution of income in one data set, but not in the others. Fifth, the three versions of dependency theory under consideration-Galtung's (1971), Rubinson's (1976), and Bornschier and Ballmer-Cao's (1979) have failed to contribute significantly to the explanation of income inequality.

Carbon metabolism and strobilation in Cassiopea andromedea (Cnidaria: Scyphozoa): Significance of endosymbiotic dinoflagellates.

Abstract: Scyphopolyps and scyphomedusae of Cassiopea andromeda Forskal (Cnidaria, Scyphozoa) containing dinoflagellate endosymbionts (zooxanthellae) were investigated for rates and pathways of carbon fixation. Photosynthesis by the algae, accounting for 80 and 15 μmol C h-1 on a dry weight basis in medusae and polyps, respectively, by far exceeds dark incorporation of inorganic carbon by the intact association. Photosynthetic carbon fixation is operated via C3 pathway of carbon reduction. DCMU-treatment (1×10-6 M and 1×10-5 M) completely inhibits light-dependent carbon assimilation. Major photosynthates presumably involved in a metabolite flow from algal symbionts to animal tissue are glycerol and glucose. A total of 5–10% net algal photosynthate appears to be seleased in vivo to the host. This is probably less than the energy supply ultimately required for the nutrition of the polyps and medusae. The presence of zooxanthellae proved to be indispensable for strobilation in the scyphopolyps. However, photosynthesis by algal symbionts as well as photosynthate release is obviously not essential for the initiation of ephyrae as is shown by DCMU-treatment, culture in continous darkness, and aposymbiotic controls. It is therefore concluded that strobilation is supported, but not triggered by algal photosynthetic activity. The induction of strobilation thus seems to depend on a more complex system of regulation.

ESR-dating of the fossil hominid cranium from Petralona Cave, Greece

Abstract: The age of the hominid cranium discovered in 1960 in a limestone cave near Petralona (Greece) is a continuing cause of controversy. The age of the skull, which was apparently encrusted by brown calcite soon after the death of the individual concerned, has been variously estimated at between 70,0001 and 700,0002 yr. Here we show using electron spin resonance (ESR) measurements of the calcite encrustation and of bone fragments that the age of the Petralona hominid lies between 160,000 and 240,000 yr. We also demonstrate, by trace element analysis, that the composition of the calcite encrustation is the same as that of the very top of the travertine floor.

The sequence of IS4.

Abstract: IS-elements are devoid of easily recognizable transacting functions and exert their visible effects in the position cis only (recent reviews Calos and Miller 1980; Starlinger 1980). It has been a matter of debate, whether these elements encode functions for their own transposition. In the case of the E. coli IS-elements this could not easily be determined by genetic methods, because most of these elements are present in several copies (Saedler and Heiss 1973; Deonier et al. 1979). In the case of the IS-elements flanking transposons, evidence has recently been brought forward that these carry the transposition specificity (Rothstein et al. 1980; Kleckner 1980; Grindley 1981).

Control of idiotope expression by monoclonal anti-idiotope and idiotope-bearing antibody.

Abstract: Preinjection of C57BL/6 mice with nano-to microgram amounts of a monoclonal IgG1 antibody directed against a binding site-related idiotope of the anti-NP [(4-hydroxy-3-nitro-phenyl)acetyl] antibody B1-8 results in enhancement or suppression of the corresponding and of another B1-8 idiotope in a subsequent anti-NP response, depending on the dose of the injected anti-idiotope antibody The enhancing and suppressive effects appear two weeks after anti-idiotope administration and are maximal after 6-8 weeks They are predominantly expressed at the level of IgG, not IgM, antibodies Enhancement of idiotype expression, ie idiotypic memory, can also be induced by the injection of idiotypic antibody of the IgM class, namely antibody B1-8 This effect might represent one of the general mechanisms by which immunological memory is established

A shortest augmenting path method for solving minimal perfect matching problems

Abstract: An efficient procedure for solving minimum weight perfect matching problems is presented. Starting from the empty matching the optimal matching is constructed by successively augmenting along shortest augmenting paths. Such paths can be determined via a special labeling technique. The algorithm is motivated by purely combinatorially natured optimality criteria using the concept of admissible transformations of the cost coefficients. We report on some experience with computer implementations of two different versions of this method and an implementation of Edmonds' BLOSSOM-algorithm which makes use of Lawler's labeling technique. Though all three methods are comparable with respect to computational complexity the results indicate that the shortest augmenting path method is superior with respect to running time and that even larger problems may be solved in a reasonable amount of time.