Showing papers by "University of Lausanne published in 1968"
TL;DR: In this article, the methylester of cyclodopa (5.6-dihydroxy-indoline-2-carboxylic acid) is achieved by oxidative conversion of dopa methyl ester to dopachrome methyl esters and its subsequent reduction at pH 8, using respectively potassium hexacyanoferrate(III) and sodium dithionite.
Abstract: The synthesis of the methylester of cyclodopa (5.6-dihydroxy-indoline-2-carboxylic acid) is achieved by oxidative conversion of dopa methyl ester to dopachrome methyl ester and its subsequent reduction at pH 8, using respectively potassium hexacyanoferrate(III) and sodium dithionite. The efficiency of the oxidation step was found to be dependent on the rather low concentration of the reactants and the very short reaction time involved. After its production cyclodopa methyl ester was stabilized by immediate protonation followed by acetylation leading in a high yield to O,O,N-triacetyl cyclodopa methyl ester. By partial hydrolysis this derivative gives an O,N-diacetyl cyclodopa methyl ester and further N-acetyl cyclodopa methyl ester. Cyclodopa methyl ester and cyclodopa are obtained by prolonged anaerobic hydrolysis. Micro-separation procedures, nmr-, uv-spectra and chiral-optical properties of cyclodopa and its derivatives are reported and discussed. It is shown by nmr evidence that under acidic conditions the aromatic proton on C(7) of cyclodopa slowly exchanges with deuterium. When an alcoholic solution of cyclodopa methyl ester and semicarbazide is allowed to oxidize in the air, the semicarbazone of dopachrome methyl ester forms.
46 citations
TL;DR: Several 7-aza-norbornadiene-derivatives have been synthesized and their UV-and NMR-data are reported as mentioned in this paper ; see Section 2.1.
Abstract: Several 7-aza-norbornadiene-derivatives have been synthesized. Their UV.- and NMR.-data are reported.
44 citations
TL;DR: In this paper, the intramolecular thermal [2π + 2σ]-cycloaddition reactions in the tricyclo[3.2.1.0] oct-6-ene system are described.
Abstract: Intramolecular thermal [2π + 2σ]-cycloaddition reactions in the tricyclo[3.2.1.02,4]-oct-6-ene system are described. Within a certain set of conditions no [2π + 2σ]-additions within some tricyclo[5.1.0.03,5]octane derivatives could be achieved.
39 citations
TL;DR: The movement of ( 14)C from IAA-(14)C was studied in sections of Lens and Phaseolus roots, using a system 20 or more times as sensitive as any previously used.
Abstract: A critical review of the few papers on IAA-14C movement in roots revealed apparent contradictions, as well as flaws in experimental design that would be apt to cause artifacts. The movement of 14C from IAA-14C was studied in sections of Lens and Phaseolus roots, using a system 20 or more times as sensitive as any previously used. To make sure that our results with roots could be compared validly with published work on petioles and stems, we used the same techniques as we had earlier used for shoot structures. The results with Lens were similar in many ways to those for shoots: net movement into receiver blocks was very strongly polar, followed a linear course for several hours, and showed a velocity of the same order of magnitude as in shoots (and, in fact, very close in absolute value to that found in Coleus stem cylinders). Also, as with shoots, all the radioactivity in receiver blocks ran to the RF of IAA. The time-course of loss of counts from donor blocks was similar to that found in shoots. The 2 most striking differences from shoots were 1) the very low percentage of added 14C that was moved into the receivers (about one-tenth of the values for bean petioles), and 2) the fact that the polar movement was acropetal in roots, rather than basipetal as in shoots. Results with Phaseolus roots were similar to those for Lens, although an additional complication with Phaseolus roots was the indication of a transitory stage of weak basipetal polarity in the first few hours after excising the section. This stage was followed in a few hours by a stronger acropetal polarity.
35 citations
TL;DR: In this article, a model of low-energy S-wave pion-pion scattering is constructed, which fulfills rigorous conditions (resulting from axiomatic field theory) on the non-physical interval 0 ⩽ s⩽ 4.
34 citations
TL;DR: These Ecole polytechnique federale de Lausanne EPFL students studied polymer engineering at the same time as the rest of the world, in order to develop a new generation of engineers.
Abstract: These Ecole polytechnique federale de Lausanne EPFL, n° 77 (1969) Reference doi:10.5075/epfl-thesis-77Print copy in library catalog Record created on 2005-03-16, modified on 2016-08-08
31 citations
TL;DR: Based on the principle of silver chloride precipitation in the presence of chloride ions, the procedure showed positive results in the “chloride cells” of eels adapted to sea water, having thereby the aspect of a secretory product.
Abstract: The ultrastructure of “chloride cells” in the gills of eels kept in artificial sea water and of a control animal kept in fresh water was studied. In addition to glutaraldehydeosmium tetroxide and simple osmium tetroxide fixation, a special method for the demonstration of chloride ions was used (Komnick, 1962, 1963). Based on the principle of silver chloride precipitation in the presence of chloride ions, the procedure showed positive results in the “chloride cells” of eels adapted to sea water. Smooth-surfaced tubules of the endoplasmic reticulum contained a material of medium to strong electron density, that was often in communication with the plasma membrane. The same material, always of very high density, was present in the intercellular spaces, thus forming conspicuous lines around cells. The silver precipitate was found very often in large quantities in the “pits” of “chloride cells”, having thereby the aspect of a secretory product. However, a direct communication between the system of endoplasmic reticulum tubules containing the silver reaction product with the above-mentioned masses of silver chloride was not demonstrated.
27 citations
TL;DR: In this article, photochemical cycloaddition reactions in anellated oxanorbornadiene derivatives have been investigated in the manner of a bis-homo-furan system.
Abstract: Photochemical cycloaddition reactions in anellated oxanorbornadiene derivatives have been investigated In the case of 7a the tetracyclic isomer 8a can be isolated which adds dimethylacetylenedicarboxylate in the manner of a bis-homo-furan system On thermal activation 8a yields the thiepino-oxepin derivative 9a In contrast, on direct photoexcitation of the benzoxanorbornadiene the primary photoproduct cannot be identified, the reaction leading directly to the benz[d]oxepin
24 citations
TL;DR: In this paper, the ASE2 mechanism was applied to the secondary deactivated aliphatic diazo compounds (diazo-ketones RCOCN2R′, ROOCCHN2 and CF3 CHN2) and showed that the secondary diazonium ion reacts with a nucleophile in a bimolecular displacement step.
Abstract: Secondary deactivated aliphatic diazo compounds (diazo-ketones RCOCN2R′; diazo-esters ROOCCN2R′; 1, 1, 1-trifluoro-2-diazopropane) are hydrolysed by the ASE2 mechanism comprising rate determining protonation of the substrate, followed by decomposition. Product analysis shows that the decomposition of the secondary diazonium ions is monomolecular, without intervention of a nucleophile.
The corresponding primary diazo compounds (RCOCHN2, ROOCCHN2 and CF3CHN2) are hydrolysed by the A-2 mechanism comprising preequilibrium protonation; the primary diazonium ion reacts with a nucleophile in a bimolecular displacement step. The only exception observed is found in p-nitrophenyl-diazomethane, which follows ASE2 mechanism.
The observations are discussed in terms of the stability of the corresponding secondary resp. primary α-keto-carbonium ions.
23 citations
22 citations
TL;DR: Experiments with trypsin-dissociated heart muscle cells have shown two distinct processes, aggregation and agglutination, to be involved in the socalled reaggregation of cells.
TL;DR: In this paper, the Darstellung der 6-Vinyl-bicyclo[3.1.0]-hexen-Derivat 40a fuhrender Mechanismus wird diskutiert.
Abstract: Die Darstellung der Tricyclo[3.2.1.02.4]octen-Derivate 20a, 21a, 22a und 23a, wird beschrieben. Wahrend 21a und 23a thermisch bis mindestens 270° stabil sind, erfahren 20a und 22a schon knapp oberhalb 200° eine tiefgreifende Skelettumwandlung: als Pyrolyseprodukte werden 25a, 26a und 27a bzw. 30a und 31a identifiziert. Ein uber das 6-Vinyl-bicyclo[3.1.0]-hexen-Derivat 40a fuhrender Mechanismus wird diskutiert.
TL;DR: The ultrastructure of the lungs of an adult pigeon, sparrow and hen, and of foetal chickens and chicks of different ages were studied and it seems that this layer is secreted by the air capillary epithelial cells, which is most probable to be merocrine.
Abstract: The ultrastructure of the lungs of an adult pigeon, sparrow and hen, and of foetal chickens and chicks of different ages were studied. The presence of a noncellular continuous film on the air capillary surfaces, i.e. on the effective respiratory surfaces, was established at all stages of development as well as in three observed avian species. This film was bilaminar, of a thickness of approximately 100–150 A. The upper and lower layers are strongly osmiophilic, the intermediate layer is of low electron density. This membrane is lacking in all respiratory passages with the exception, mentioned above, of air capillaries. The lung tissue was examined by the periodic acid-silver methenamine technique for the demonstration of polysaccharides and by the colloidal iron method (Mowry's modification of Hale's method) for the detection of acid mucopolysaccharides. After the first mentioned reaction, the picture corresponding to the visualization of “carbohydrate-rich cell coat” (Rambourg, 1967) was obtained. The reaction with colloidal iron was strongly positive at the air capillary surfaces. Nevertheless, the weakly expressed positive reaction was also present at the endothelial cell surfaces. It was assumed that the bilaminar osmiophilic lining film did not contain polysaccharides. Furthermore, this film was also shown to be present in the chicken's lung which had been rinsed several times with saline before fixation. It seems that this layer is secreted by the air capillary epithelial cells. We consider the type of secretion to be merocrine. In view of its behaviour in response to certain histochemical techniques and on the basis of electron microscope investigation its lipoproteinous nature is most probable.
TL;DR: In this article, the Valenzisomerisierung der Homovinyl-cyclopropan-systeme 7, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 34, 35, 36, 37, 38, 39, 40, 41, 42, 50, 51, 52, 53, 54, 55, 56, 57
Abstract: Durch direkte Lichtanregung gelingt die Valenzisomerisierung der Homovinyl-cyclopropan-systeme 7, 15 und 16 zu den Bis-homo-cyclopentadien-Derivaten 9, 17 und 20. Der Anteil dieser [2°+2σ]-Cycloadditionen am photochemischen Geschehen wird wesentlich durch stereoelektronische Faktoren und durch Milieueinflusse bestimmt.
TL;DR: The three ternary limiting isotherms of the system KCI-RbCI-CsCI-H2O are given for 25°; in the latter the incorporation is almost negligible; they belong to ROOZEBOOM's type IV.
Abstract: The three ternary limiting isotherms of the system KCI-RbCI-CsCI-H2O are given for 25°. The system KCI-RbCI-H2O, with only one solid phase present, belongs to the type I of the ROOZEBOOM classification. A large miscibility gap is present in the systems RbCI-CsCI-H2O and KCI-CsCI-H2O; in the latter the incorporation is almost negligible; they belong to ROOZEBOOM's type IV.
TL;DR: In this paper, models of the low-energy S-wave π0-π0 scattering amplitude in the neutral theory are constructed, which satisfy conditions which have been deduced rigorously from axiomatic field theory.
Abstract: Models of the low-energyS-wave π0-π0 scattering amplitude in the neutral theory are constructed. In the nonphysical interval 0≤s≤4, these models satisfy conditions which have been deduced rigorously from axiomatic field theory. The models are based on a parametrization of the inverseK-matrix element ϕ(s)=1/2(s−4)1/2ctgδ(s) which is consistent with its analyticity properties and its threshold behavior ats=0. Three models are investigated, characterized by the number of poles of ϕ(s). In each case, the values of the parameters are strongly restricted. Systematically, some rigorous inequalities are nearly saturated. The results have no direct extension to the realistic charged theory.
01 Mar 1968
TL;DR: In 12 ausgewahlten Hodenbiopsien von Knaben im Alter of 3 bis 14 yearsren with kryptorchen, abdominal, inguinal or ektopisch gelegenen Hoden wurde die raumliche Struktur von 53 Ringtubuli systematisch in Serienschnitten untersucht as mentioned in this paper.
Abstract: In 12 ausgewahlten Hodenbiopsien von Knaben im Alter von 3 bis 14 Jahren mit kryptorchen, abdominal, inguinal oder ektopisch gelegenen Hoden wurde die raumliche Struktur von 53 Ringtubuli systematisch in Serienschnitten untersucht. Diese sog. Ringtubuli entsprechen in Wirklichkeit kugeligen oder langsovoiden Auftreibungen eines Samenkanalchens, die im Zentrum immer ein oder mehrere Konkremente enthalten. Die Auftreibungen konnen an drei verschiedenen Stellen im Verlauf des Tubulus sitzen, namlich am blinden Ende eines Tubulus, im sonst intakten und durchlaufenden Tubulus als umschriebene, segmentformige Auftreibung oder an Tubulusverzweigungen. Gelegentlich findet man auch Kombinationsformen mit besonders bizarren Strukturen. Nomenklatur und Gestalt dieser Misbildungen werden diskutiert.
TL;DR: Several of the frozen heart muscle cells of 8-day chick embryos regained beating activity after thawing, proving that the faculty of autonomous pulsation of these isolated cells can, in principle, withstand freezing.
01 Mar 1968
TL;DR: In einer Gruppe von 28 ausgewahlten autopsien von Mannern im Alter zwischen 15 und 33 Jahren, die an den Folgen eines Unfalls, an einem Suicid oder an einer schweren Systemkrankheit starben, wurden die hypoplastischen Zonen, die in einem oder beiden normal descendierten Hoden der Verstorbenen nachgewiesen werden konnten, auf ihre raumlic
Abstract: In einer Gruppe von 28 ausgewahlten Autopsien von Mannern im Alter zwischen 15 und 33 Jahren, die an den Folgen eines Unfalls, an einem Suicid oder an einer schweren Systemkrankheit starben, wurden die hypoplastischen Zonen, die in einem oder beiden normal descendierten Hoden der Verstorbenen nachgewiesen werden konnten, auf ihre raumliche und mikroskopische Struktur untersucht. Vier hypoplastische Kanalchen aus je einem Hoden zweier verschiedener Patienten konnten auf Serienschnitten in ihrer ganzen Lange verfolgt werden. Es zeigt sich, das die hypoplastischen Zonen im normal descendierten Hoden fehlentwickelte Teile sonst normaler Tubuli sind. Wahrend sich weder Form noch Durchmesser des durch die Tunica propria gebildeten Schlauches beim Ubergang vom normalen auf den hypoplastischen Bezirk wesentlich andern, wechselt das Bild im Innern des Schlauches schlagartig. Das Keimepithel geht in einen dunnen, soliden, kernreichen Zellstrang uber, der innerhalb der Tunica propria dicht liegende Windungen beschreibt und nicht selten Konkremente enthalt.
01 Mar 1968
TL;DR: In two cases the PAS positive bodies, usually intracellular and seen frequently in granulomatous orchitis, occasionally contain also calcium and iron, a finding which suggests a certain similarity with the Michaelis-Gutmann bodies of malakoplakia.
Abstract: Die Untersuchung umfast 26 Falle granulomatoser Orchitis. Nach dem Verlaufe lassen sich 2 Gruppen bilden, Patienten mit Schwellung des Scrotums und ausgepragtem Entzundungszeichen oder Patienten mit einem sich allmahlich entwickelnden harten „Hodentumor“. Histologisch liegt eine chronische, diffuse oder herdformige, vorwiegend intratubulare Entzundung mit Beteiligung der Lamina propria und des Zwischengewebes vor, die wegen der intratubularen Lokalisation in den Schnittpraparaten Granulome imitiert. Diese bauen sich aus grosen eosinophilen histiocytaren Zellen, Lymphocyten, Plasmazellen, polynuclearen Leukocyten, Fibroblasten, Riesenzellen, kollagenen sowie retikularen Fasern und Capillaren in wechselnder Verteilung auf. Nekrosen fehlen.
TL;DR: The low temperature Hall effect, transverse magnetoresistance, and electrical resistivity has been measured as a function of temperature and sample thickness on a high purity polycrystalline Ni plate as mentioned in this paper.
TL;DR: In this paper, low temperature specific heat measurements have been made on Ni, three dilute Ni based alloys, and three high solute content pseudonickels (Ni 1−3 x Cu 2 x Fe x ).
01 Sep 1968
TL;DR: In the testes of boys from 0 to 18 years of age the presence of intratubular bodies in so-called “ring-like tubules” is determined and a count per square millimeter permits the conclusion that I.B. are not only a congenital malformation, but they are also produced at the same rate after birth during normal development.
Abstract: In Hoden von Knaben im Alter von 0–18 Jahren wurde die Haufigkeit von Ringtubuli mit intratubularen Korperchen und ihre Dichte im Hodengewebe bestimmt. Es standen autoptisch gewonnene Hoden von 716 Knaben mit normal gelagerten Testes und 18 Falle mit fehlgelagerten Gonaden zur Verfugung. Die Untersuchungen wurden durch die Kontrolle von Biopsien aus den Testes von 191 Knaben mit Kryptorchismus im Alter von 4–18 Jahren erganzt. Die Resultate lassen erkennen, das tubulare Auftreibungen mit zentralen Konkrementen in fehlgelagerten Hoden haufiger sind als in normal gelagerten. Sie liegen meist an der Hodenperipherie und werden deshalb bei Hodenbiopsien relativ haufig erfast. Die Tatsache, das die Anzahl derartiger Gebilde pro Hodenquerschnitt trotz des Hodenwachstums nicht abnimmt, last darauf schliesen, das es sich nicht nur um angeborene Misbildungen handelt, sondern auch um tubulare Neubildungen anlaslich der Hodenentwicklung. Aus den Untersuchungen geht hervor, das die Haufigkeit intratubularer Korperchen keine direkten Beziehungen zu Alter, Grundkrankheit oder ubrigen Misbildungen hat.
TL;DR: In this article, the velocity of oxygen exchange between several substituted p-benzoquinones and H218O has been measured at 25°C in neutral tetrahydrofuran containing 2 to 5% water.
Abstract: The velocity of oxygen exchange between several substituted p-benzoquinones and H218O has been measured at 25°C in neutral tetrahydrofuran containing 2 to 5% water. Halogen substituents accelerate the exchange (Cl > Br), methyl groups slow it down. The reaction was found to be second or third order in [H2O].
TL;DR: Wahrend der periodischen lichtmikroskopischen Pinocytoseruhe in einer Zellkultur von HeLa-Zellen und isolierten Herzmuskelzellen besteht noch eine ausgepragte Micropinocytose.
Abstract: Wahrend der periodischen lichtmikroskopischen Pinocytoseruhe in einer Zellkultur von HeLa-Zellen und isolierten Herzmuskelzellen besteht noch eine ausgepragte Micropinocytose.
TL;DR: The development of a system inhibitory for IAA oxidase in lightgrown organs or plants is linked to the presence and the amount of chlorophyll, which may be due to an increase in polyphenols which is dependant on the photosynthetic rate.
Abstract: The development of a system inhibitory for IAA oxidase in lightgrown organs or plants (roots of Lens, seedlings of tobacco) is linked to the presence and the amount of chlorophyll. This correlation may be due to an increase in polyphenols which is dependant on the photosynthetic rate.