Showing papers by "University of Basel published in 1973"
TL;DR: Whether a given aromatic or olefinic compound produces such an effect would depend on a variety of factors, such as the relative rate of formation and degradation of the intermediate oxirane, on its stability with respect to spontaneous isomerization to the corresponding phenol and on its chemical electrophilic reactivity.
Abstract: 1. Several aromatic and olefinic compounds are converted to intermediate arene and alkene oxides by mammalian mono-oxygenases. Intermediate arene oxides rearrange non-enzymically to phenols. Arene and alkene oxides are converted by epoxide hydrases to vicinal diols and by glutathione S-epoxide conjugases to glutathione conjugates. Due to their high electrophilic reactivity, such oxiranes also bind to proteins, RNA and DNA. Mutagenic, carcinogenic and cytotoxic effects of several aromatic and olefinic compounds appear to be due to the formation of intermediate epoxides and their reaction with tissue constituents. Whether a given aromatic or olefinic compound produces such an effect would thus depend on a variety of factors, such as the relative rate of formation and degradation of the intermediate oxirane, on its stability with respect to spontaneous isomerization to the corresponding phenol and on its chemical electrophilic reactivity.2. Epoxide hydrases, which convert such intermediate oxiranes t...
805 citations
TL;DR: Young male rats were treated for various periods with several doses of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) or disodium dichloromethylene diphosph onate (Cl2MDP) and the effects of treatment on the changes in the thickness, growth and mineralization of proximal growth plate and metaphysis of the tibia were assessed histologically and by micro-radiography.
Abstract: Young male rats (70–90 g) were treated for various periods with several doses of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) or disodium dichloromethylene diphosphonate (Cl2MDP). Effects of treatment on the changes in the thickness, growth and mineralization of proximal growth plate and metaphysis of the tibia were assessed histologically and by micro-radiography. High doses (10 or 30 mg P/kg/day) of EHDP impaired mineralization of the growth cartilage, which became increased in thickness, and of the osteoid in the metaphysis and diaphysis. Matrix formation continued, although at a diminished rate. High doses (10 or 30 mg P/kg/day) of Cl2MDP produced a different effect. There was no inhibition of mineralization, but there was a marked impairment of normal metaphyseal remodelling, with persistence of columns of calcified cartilage. Resorption at the periosteal surface in the metaphysis was also inhibited, so that the metaphysis became club-shaped. Osteoclasts were present in large numbers in the metaphysis, but their appearance was abnormal and similar to that seen in human osteopetrosis.
457 citations
181 citations
TL;DR: In this article, the correlation of the π-ionization potentials of ethylene (1), butadiene (2), and trans-1, 3, 5-hexatriene (4) was analyzed.
Abstract: It is shown that the correlation of the π-ionization potentials of ethylene (1), butadiene (2) and trans-1,3,5-hexatriene (4) favours the orbital sequence π, π, σ in butadiene and π, π, σ, π in the hexatriene in excellent agreement with the results of SPINDO calculations. Within the experimental error the π-ionization potentials of cis-1,3,5-hexatriene (3) and trans-1,3,5-hexatriene (4) are the same. Methyl-substitution of 2 lowers the π-ionization potentials I1(π) and I2(π). For 1 and/or 4 substitution the difference I2(π)−I1(π) remains constant (≈ 2.5 eV). On the other hand 2 and/or 3 substitution leads to a smaller gap of I2(π)–I1(π) ≈ 1.6 to 2.0 eV without changing the mean π-ionization potential I(π) relative to the corresponding 1,4 substituted derivatives. This result is rationalized in terms of a through space interaction between double bond π-orbitals and non-bonded pseudo-π-orbitals of the substituting methyl groups.
The reduced split I2(π)–I1(π) in cyclopentadiene is attributed to hyperconjugation across the methylene group.
177 citations
TL;DR: The isolation of a second macromolecular component, other than AF, which is necessary for reaggregation, and which seems to remain on the surface of the cell after removal of the aggregation factor, and to interact with intercellular AF is described.
Abstract: SPONGE cells dissociated by means of seawater containing no calcium or magnesium release a large molecular factor (AF) which is required for specific reaggregation at 4° C into multicellular agglomerations the size of small sponges1. The function of the aggregation factor (AF) in Microciona prolifera is dependent on a specific carbohydrate2. Here we describe the isolation of a second macromolecular component, other than AF, which is necessary for reaggregation, and which seems to remain on the surface of the cell after removal of the aggregation factor, and to interact with intercellular AF. Until its function is clearly understood, we shall describe it as a baseplate.
143 citations
141 citations
01 Jan 1973
TL;DR: In this article, the authors consider holomorphic modular forms with respect to the congruence subgroup of the modular group Γ, where the holomorphy condition includes the cusps.
Abstract: In the following article we consider holomorphic modular forms with respect to the congruence subgroup \( \Gamma _0 (N) = \{ (\begin{array}{*{20}c} a & b \\ c & d \\ \end{array} ) \in \Gamma :c \equiv 0\bmod N\} \) of the modular group Γ. Of course the holomorphy condition includes the cusps. By Sk(Γ0(N),χ) we denote the space of these forms of weight k and character χ, i.e. those satisfying
$$ f(\frac{{az + b}} {{cz + d}})(cz + d)^{ - k} = \chi (a)f(z) $$
for all substitutions of Γ0(N), which vanish in the cusps.
141 citations
TL;DR: Surface components have been obtained from chick neural retina6 and mouse cerebrum7 which preferentially enhance the aggregation of cells from the homologous tissue, which was found to be organ specific.
Abstract: THE coordinated cell interactions which occur during development are thought to be due to molecular gradients throughout critical tissue zones1 or to specific cellular adhesions2,3. A model system of the latter was described in 1907 by H. V. Wilson4–5 who dissociated a yellow and a red species of marine sponge, mixed the cell suspensions and found that the cells sorted into species specific aggregates of the two separate colours. Such sorting out occurs also in embryonic vertebrate cells2 and was found to be organ specific3. Specific reaggregation and sorting out are assumed to be guided by specific macromolecular components of the cell surface. Surface components have been obtained from chick neural retina6 and mouse cerebrum7 which preferentially enhance the aggregation of cells from the homologous tissue.
105 citations
TL;DR: In a recent paper, Tullock as discussed by the authors pointed out a possible relation between the Arrow-paradox and logrolling and showed that as soon as side-payments are aUowed, Pareto-optimality will result from logrolling.
Abstract: The phenomenon of logrolling has enjoyed increasing interest in the last one and a half decades. There has been a discussion about this subject in the literature by Gordon Tullock (1959, 1961) and Anthony Downs (1961). In this discussion Tullock asserts that logrolling necessarily leads to negative consequences for the respective community, whereas Downs believes that negative results of parliamentary logrolling are not important in reality because legislators are in an indirect democracy controlled by voters. The position of Tullock is taken up again by Buchanan and Tullock (1962), where an extensive examination of logrolling can be found (compare especially chapters 10-12). The authors, however, try to show that as soon as side-payments are aUowed, Pareto-optimality will result from logrolling. In a recent paper, Tullock (1970) points to a possible relation between the Arrow-paradox and logrolling:
95 citations
TL;DR: It is concluded that the variations in the level of lung inflation lead to a reduction in the available diffusion capacity by as much as 50 to 75 percent as compared to the values obtained on completely unfolded lungs.
93 citations
TL;DR: Structural similarities between Anelytropsis, Dibamus, feyliniids and snakes show interdigitation of the periventricular gray zones of the optic tectum and enlargement of lamina 7 of the posterior colliculus, may suggest common ancestry between Dibia and snakes rather than parallelism.
Abstract: Anatomical analysis of the forebrain and midbrain of Anelytropsis, Dibamus and feyliniids reveals structural similarities with those of skinks and snakes. Skinks and feyliniids are probably derived from a common ancestral stock. This is suggested by mutual reduction of several telencephalic nuclei, by similar trends in the development of the dorsal thalamus, and by similarities in the lamination of their optic tecta. Anelytropsis, Dibamus, feyliniids and snakes show interdigitation of the periventricular gray zones of the optic tectum and enlargement of lamina 7 of the posterior colliculus. Of these three taxa, Dibamus is most similar to burrowing snakes and many of its brain characters are intermediate between skinks and burrowing snakes. These similarities may suggest common ancestry between Dibamus and snakes rather than parallelism.
TL;DR: In this article, the technical realisation of the shell model with arbitrary fields is presented in detail, with special emphasis of the unusual and large deformations of the nuclear shape as they may occur in the fission process.
TL;DR: The absolute configurations of two cy tochalasans (phomin and a cytochalasin D derivative) have been established by X-ray analysis, and it is probable that all Cytochalasan have a common biogenetic scheme.
Abstract: A series of cytostatically active metabolites have been isolated from microorganisms in recent years. These compounds, which are chemically closely related, are of a new structural type. A highly substituted hydrogenated isoindolone unit is fused to an 11- to 14-membered macrocycle. The large ring may be carbocyclic or heterocyclic (lactone or carbonic diester). The absolute configurations of two cytochalasans (phomin and a cytochalasin D derivative) have been established by X-ray analysis. The biogenesis of phomin (cytochalasin B) is broadly known, and it is probable that all cytochalasans have a common biogenetic scheme. All the compounds of this class have a more or less pronounced specifically cytostatic action.
TL;DR: In this paper, the authors calculate the tensor of effective mass which has six independent components for three shape degrees of freedom, among them is the reflection asymmetry, and with these mass parameters and the Strutinsky deformation energy the lifetimes for spontaneous fission are calculated in WKB approximation.
TL;DR: In this article, the averaging procedure in Strutinsky's method of shell corrections is formulated for a general type of averaging function, and the method is proved analytically to give the same results as semiclassical methods.
TL;DR: In this article, the influence of vibrational motion on structural parameters is discussed, and the transformations from the observed effective NMR structures to average structures are compared with corresponding ones from electron diffraction or from optical or microwave spectroscopy.
TL;DR: In this article, the π-ionization potentials of unsubstituted acetylenes can be parametrized in terms of a LCBO-model using the PE-spectra of triacetylene, methyldiacetylene and dimethylacetylene.
Abstract: The PE.-spectra of triacetylene 1 (3), methyldiacetylene 2 (2), dimethylacetylene 3 (1) and dimethyldiacetylene 3 (2) have been recorded. The π-ionization potentials of the unsubstituted acetylenes can be parametrized in terms of a LCBO-model.
TL;DR: It is postulated that τ-particles produced by 24 − mutants can serve as precursors to mature phage heads if the functional gene 24 product is supplied, as well as during infection with wild-type phage.
TL;DR: The photoelectron spectra of benzo[b]thiophene (2), thieno[3,2-b] thiophene(4) and thienobene[2,3-b], together with 2,1, 3-benzothiadiazol (6), benzofurazan (7) have been recorded and the first three bands have been assigned to π-orbitals on the basis of band shapes and semiempirical calculations.
TL;DR: The transcription phase of trans-synaptic induction of tyrosine hydroxylase (TH) seems to be completed by 24 h after stress, which implies that the turnover of the (messenger) RNA involved is slow enough to allow an increased synthesis of TH 24 h beyond the termination of the regulatory step at the transcription level.
Abstract: The trans-synaptic induction of tyrosine hydroxylase (TH) in the peripheral sympathetic nervous system is a slow process. The present experiments were performed to establish the time required to accomplish the single steps of TH induction, i.e. duration of the increased preganglionic activity and of the resulting changes at the transcription and translation levels. An intermittent swimming stress of 1 h was sufficient to lead to a statistically significant (P<0.05) increase in TH activity in the adrenal medulla 48 h later. A 2-h swimming stress was necessary to produce the same effect in the superior cervical and stellate ganglia. Administration of a ganglionic blocking agent (chlorisondamine 5 mg/kg i.p) immediately after and 1 h after termination of the swimming stress significantly (P<0.05) reduced the increase in TH activity, whereas 2 h after the stress this drug was without effect, indicating that the enhanced preganglionic activity exceeded the end of the swimming stress by 1 to 2 h, or that normal ganglionic transmission represents a permissive prerequisite for the initiation of the induction process. Treatment of rats with a single dose of actinomycin D (0.8 mg/kg s.c.) immediately before or after the swimming stress completely abolished the increase in the TH activity. If actinomycin D was injected 6 or 12 h after the stress the increase in TH was reduced but not abolished, whereas treatment with actinomycin D after 24 h had no effect. Thus, the transcription phase of trans-synaptic induction seems to be completed by 24 h after stress. The fact that an increased rate of TH synthesis continued up to 48 h implies that the turnover of the (messenger) RNA involved is slow enough to allow an increased synthesis of TH 24 h beyond the termination of the regulatory step at the transcription level.
TL;DR: The predilection shown by several Ctenuchids, and the related Arctiids, for foodplants containing cardiac glycosides or pyrrolizidine alkaloids is discussed.
Abstract: Syntomeida epilais sequesters and stores several cardiac glycosides from its food plant Nerium oleander L. Unlike the other insects previously examined which feed on oleander, this moth stores oleandrin in its body tissues. Amata phegea, feeding on non-poisonous plants, contains a histamine-like substance which increases capillary permeability in rats. Both species are repellent to many avian predators. The predilection shown by several Ctenuchids, and the related Arctiids, for foodplants containing cardiac glycosides or pyrrolizidine alkaloids is discussed.
TL;DR: The photoelectron spectra of bicyclo[3.2]nonane and its five dehydrogenated analogues are reported in this article, where it is shown that the unsymmetrical diene 5 retains the natural order of the π-orbitals present in the lower homologues, i.e. the in-phase below the out-of-phase combination of the basis πorbitals πa and πc.
Abstract: The photoelectron spectra of bicyclo[3.2.2]nonane and its five dehydrogenated analogues are reported. Analysis of the π-bands reveals that the unsymmetrical diene 5 retains the ‘natural order’ of the π-orbitals present in the lower homologues, i. e. the in-phase below the out-of-phase combination of the basis π-orbitals πa and πc. The isomeric diene 4 is the first member of the symmetrical homologous series (I), which inverts this order, so that a1(π) (in phase!) lies above b2(π) (out-of-phase!).
TL;DR: It is concluded that either cyclic AMP is not involved in trans-synaptic induction of TH or that changes in a small pool are essential and are overshadowed by a much larger pool of cyclicAMP not reacting in the same way.
Abstract: Changes in the levels of cyclic AMP were studied in the superior cervical ganglion and adrenal medulla of male Sprague-Dawley rats under experimental conditions which lead to a trans-synaptic induction of tyrosine hydroxylase (TH) in these organs.
TL;DR: Among the eight species of the fern genus Dryopteris which have been recorded from Kenya (East Africa), the group of D. inacqualis, D. pentheri and D. schimperana is regarded as critical, and the hypothesis that the latter is an allotetraploid derived from the diploids 6 and 7 is supported.
Abstract: Among the eight species of the fern genus Dryopteris which have been recorded from Kenya (East Africa), the group of D. inacqualis, D. pentheri and D. schimperana is regarded as critical. There is no agreement among experts as to whether D. inaequalis s. str. is restricted to South Africa and whether it should be separated specifically from D. pentheri
Chemical and, as far as possible, cytological investigations of available material showed that the following taxa of Dryopteris occur in Kenya (ploidy in brackets) : 1. D. athamantica (2 × );2. D. callolepis (4 × ); 3. D. inaequalis (4 × ); 4. D. kilenzensis (2 × ); 5. D. manniana (4 × ); 6. D. pentheri (2 × ); 7. D. schimperana (2 × ); 8. D. sp. RBF-71/885 (TR-330.5) (4 × ); 9. D. squamiseta(ploidy not determined). The nomenclature of the four critical taxa, 3, 6, 7 and 8 is provisional. For comparison, two taxa from the Canary Islands, 10. D. ‘dilatata’ (4 × ) and 11. D. oligodonta (2 × ) were also investigated.
Among the nine taxa from Kcnya, two (4 and 9) did not contain any phloroglucides. Dryopteris kilomensis must be regarded as one of the few representatives of the genus Dryopteris which lacks such compounds. On the other hand, the negative result for 9 is in agreement with the fact that this species has recently been transferred to a new genus Nothopevanema.
The following three new compounds havc been isolated: Trisaspidinol (8), from D. inaequalis; Pentherin-I (not quitc pure) and Pentherin-I1 (hypothetical partial formula 25), from D. pentheri. Pentherin-I is also present in D. sp. RBF-71/885. Chemical and cytological results are compatiblc with the hypothesis that the latter is an allotetraploid derived from the diploids 6 and 7. The chemical patterns of 6, 7 and 8 show similarities to that of D. manniana, which in turn also shows similarities to the European D. filix-mas. Dryopteris ‘dilatata’ from the Canary Islands is chemically different from Europcan D. dilatata s. str. in lacking para-aspidin, while D. oligodonta gave results rather different from D. inaequalis or other East African species, and also from known European taxa.
TL;DR: In this paper, angeordneten Basen (Konfiguration wie sie in den Nukleinsauren gefunden wird) are shown to be befahrungen.
Abstract: Studien anhand vonDreiding Stereomodellen zeigen, dass die Bildung von helixartigen Sekundarstrukturen durch Basenpaarung und Basenstapelung nicht auf Polynucleotide mit β-standig angeordneten Basen (Konfiguration wie sie in den Nukleinsauren gefunden wird) beschrankt ist. Auch Polymere aus lauter α-Nucleotideinheiten scheinen dazu befahigt zu sein.
01 Nov 1973
TL;DR: In this article, the Rydberg spectrum of acetylene has been reexamined and a new interpretation for the 1250 to 1360 A region is proposed, and it is suggested that the D state is 1 Πg(σ☆u←πu); G could be 1Πu(δ*g←piu).
Abstract: The Rydberg spectrum of acetylene has been reexamined. A new strong Rydberg series and a weak one are found and a new interpretation for the 1250 to 1360 A region is proposed. It is suggested that the D state is 1Πg(σ☆u←πu); G could be 1Πu(δ*g←πu).
TL;DR: In this article, the photoelectron spectra of bicyclo[4.1.1] and bicyclo-2 6.3.2 were used to obtain further information concerning the interaction between Walsh-orbitols of conjugated cyclopropane rings.
Abstract: To obtain further information concerning the interaction between Walsh-orbitols of ‘conjugated’ cyclopropane rings, the photoelectron spectra of the following compounds have been recorded: bicyclo[4.1.0]heptane 1, cis- and trans-tricyclo[5.1.03, 5]octane 2, 3, diademane 4, trans-pentacyclo[3.3.2.02, 9.04, 10, 06, 8]decan 5 and bicyclo[4.1.0]heptene-2 6. The first bands in the PE.-spectra of these compounds have been assigned on the basis of a ZDO HMO-approximation. For 2 and 4 the value for resonance integral between linked 2p atomic orbitals of two adjacent eclipsed cyclopropane rings is found to be −1.73 eV.
TL;DR: In this paper, a systematic study of collective states excited by 209 MeV inelastic electron scattering in even single-closed-shell nuclei is presented, and the experimental results are compared with the theoretical microscopic vibrational model.