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  • 1985-1989
  • 1970-1974  (5,505)
  • 1965-1969
  • 1950-1954
  • 1915-1919
  • 1971  (5,505)
  • Chemistry  (5,473)
  • Organic Chemistry  (689)
  • Electron Microscopy
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Years
  • 1985-1989
  • 1970-1974  (5,505)
  • 1965-1969
  • 1950-1954
  • 1915-1919
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 17 (1971), S. 24-36 
    ISSN: 1432-0533
    Keywords: Lafora Bodies ; Glycogenosis ; Branching Enzyme ; Epilepsia ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Lafora-Körperchen sind aus fibrillären und granulären Anteilen in verschiedener Menge zusammengesetzt. Sie sind in Nervenzellfortsätzen und Perikaryen gelegen und häufig mit cytoplasmatischen Elementen durchmischt. Die Bestandteile der Lafora-Körperchen sind elektronenoptisch hell, zeigen wechselnde Affinität zu Osmium und werden nach Bleiacetat-Vorbehandlung mit der klassischen Uranylacetat-Färbung schwach dargestellt. Sie besitzen eine starke Affinität zu Bleihydroxyd und reagieren mit Perjodsäure. Mit der PTA-Methode für basisches Protein und/oder saure Mucopolysaccharide färben sie sich nicht. Diese Befunde stimmen mit chemischen Untersuchungen überein, nach denen die Lafora-Körperchen hauptsächlich aus Polyglucosanen bestehen, und legen nahe, daß sowohl die granulären als auch die fibrillären ultrastrukturellen Anteile Glykolgruppen enthalten. Die Ultrastruktur der Lafora-Körperchen ist jener der Corpora amylacea, der Ablagerungen bei der basophilen Degeneration des Herzmuskels und bei Glykogenose-Typ IV sehr ähnlich.
    Notes: Summary Lafora bodies are composed of fibrillar and granular components in various concentrations. They are located in neuronal cell processes and perikarya and are frequently clearly intermingled with cytoplasmic elements. These components are electron-lucent, show a variable affinity for osmium, and are weakly stained by classical uranyl acetate stain following lead citrate. They exhibit a strong affinity for lead hydroxide and are periodic-acid reactive. They are not stained by the PTA technic for basic protein and/or acidic mucopolysaccharides. These results are in agreement with chemical studies according to which L. B are mostly composed of polyglucosans and suggest that both the granular and fibrillar ultrastructural components contain vic-glycol groups. The ultrastructure of L. B. is very similar to that of corpora amylacea, to deposits in basophilic degeneration of myocardium and in glycogenosis type IV.
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  • 2
    ISSN: 1432-0533
    Keywords: Neuronal Ceroid Lipofuscinosis ; Electron Microscopy ; Membranous and Fingerprint Inclusions ; Hypertrophied Cortical Astrocytes ; Nuclear Bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommaire Deux cas de la maladie de Batten-Spielmeyer-Vogt (idiotie amaurotique familiale juvénile) ont été étudiés en microscopie électronique, histochimiquement et biochimiquement. Le premier cas, dont l'histoire clinique a débuté à l'âge de 3 ans, a révélé des inclusions cytoplasmiques dans les cellules neuronales et gliales, composées de membranes fréquemment disposées en paires. La structure de ces inclusions était identique à l'examen du matériel autopsié six mois plus tard. Dans le deuxième cas, dont l'histoire clinique date de 4 ans et 4 mois, les inclusions étaient plus pléomorphes: elles étaient en général plus denses en électronique et comportaient fréquemment un élément à l'aspect d'«empreintes digitales». Quelques inclusions membraneuses semblables à celles du premier cas y ont également été retrouvées. En outre ont été observées une hypertrophie cytoplasmique prononcée des astrocytes corticaux, et une grande fréquence de cils, de corps basaux et de corps nucléaires dans ces astrocytes. Un paquet de filaments intranucléaires a été observé dans un neuron. Les données neurochimiques n'ont révélé aucune abnormalité dans les lipides ou les protéines du premier cas, ou dans les gangliosides du second. Malgré les différences morphologiques qui les caractérisent, la présence simultanée des deux types d'inclusions cytoplasmiques dans le même cas suggère qu'elles peuvent représenter des stages divers dans l'évolution du même processus fondamental. Il est possible que ce soit l'âge de la cellule nerveuse, lors de l'atteinte métabolique dont elle est l'object, qui détermine ces différences.
    Notes: Summary Electron microscopic, histochemical and neurochemical studies on two cases of Batten-Spielmeyer-Vogt disease (juvenile amaurotic familial idiocy) are presented. In the first case, with the clinical onset at the age of 3 years, cytoplasmic neuronal and glial inclusions consisted of membranous bodies, the membranes of which were frequently paired. The fine structure of these inclusions was unaltered when examined in autopsy material 6 months later. In case 2, with the clinical onset at 4 years and 4 months, the inclusions were more pleomorphic: they were usually more electron-dense, and frequently showed a characteristic “fingerprint” pattern component. A few membranous inclusions resembling those in case 1 were also present. Additional findings included marked cytoplasmic hypertrophy of inclusion-containing cortical astrocytes, and frequent cytoplasmic cilia, basal bodies, and nuclear bodies in the hypertrophic astrocytes. A packet of intranuclear filaments was found in one neuron. Neurochemical studies failed to reveal any abnormality of lipid or protein pattern in case 1, or of ganglioside pattern in case 2. Despite the morphological differences between the two types of cytoplasmic inclusions, the presence of both types within the same case suggests that they may represent different stages in the evolution of a single process. It is conceivable that such differences are related to the age of the neuron when the postulated intracellular defect first becomes manifest.
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  • 3
    ISSN: 1432-0533
    Keywords: Landry-Guillain-Barré Syndrome ; Peripheral Nerves ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Biopsie-Material des N. suralis einer Patientin mit typischem Landry-Guillain-Barré-Syndrom wurde elektronenmikroskopisch untersucht. Es fanden sich degenerative Veränderungen, die sowohl die Myelinscheiden als auch Schwannsche Zellen und unmyelinisierten Nervenfasern betraffen. Vor allem die Veränderungen an unmyelinisierten Nervenfasern scheinen mit der Funktionsstörung autonomer Nerven in Beziehung zu stehen.
    Notes: Summary N. suralis taken from a patient showing the typical Landry-Guillain-Barré Syndrome was examined electron microscopically and showed degenerative changes of the myelin sheaths, Schwann cells, axons and unmyelinated nerve fibres. The changes in the unmyelinated nerve fibres might be concerned with disturbances of autonomic function.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 17 (1971), S. 68-79 
    ISSN: 1432-0533
    Keywords: Transient Cerebral Ischemia ; Pial Circulation ; Neurophysiology ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zuammenfassung Passagere Globalischämie wurde an Katzen durch Unterbrechung der Blutversorgung des Gehirns unter direkter Beobachtung der Piagefäße erzeugt. Die piale Zirkulation konnte nur kurzfristig nach der Ischämie wiederhergestellt werden, doch wurde die postischämische Zirkulation durch intravasale Perfusion des Gehirns mittels verschiedener Salzlösungen beträchtlich verbessert. Der Funktionszustand der neuronalen Aktivität wurde mittels EEG und Pyramidenreaktion (PR) nach elektrischer Reizung des motorischen Cortex geprüft. Perfundierte und nichtperfundierte Katzen wurden im Hinblick auf die Struktur und Funktion des motorischen Cortex in der frühen postischämischen Periode verglichen. Bei perfundierten Tieren kamen die neurophysiologischen Signale nach Ischämie von wesentlich längerer Dauer wieder, als ber nichtperfundierten Katzen. Schwere strukturelle Veränderungen fanden sich an Capillaren, Neuronen und Gliazellen, wenn die Ischämie lange genug anhielt, um die PR zu unterdrücken. Bei perfundierten Tieren fehlten solche Veränderungen selbst nach Ischämie bis zu 30 min Dauer. Die gesteigerte Toleranz des Gehirns gegenüber Ischämie infolge intravasaler Durchströmung erscheint durch zumindest zwei verschiedene Mechanismen bedingt. Die Eliminierung metabolischer Schlackenstoffe verringert vermutlich die Gewebsschäden während der Ischämie und die verbesserte postischämische Zirkulation verhindert sekundäre ischämische Schäden.
    Notes: Summary Transient global ischemia was produced in cats by interrupting the arterial blood supply to the brain under direct observation of the pial vessels. The pial circulation could be restored only for a brief period after ischemia but intravascular rinsing of the brain during ischemia with various saline solutions considerably improved the postischemic circulation. The functional status of neuronal activity was assessed by recording the EEG and the pyramidal response (PR) after electrical stimulation of the motor cortex. Perfused and nonperfused cats were compared with regard to the structure and function of the motor cortex in the early postischemic period. The neurophysiological signals recovered after ischemia of much longer duration in the perfused animals than in the nonperfused cats. Severe structural alterations were seen in capillaries, neurons and glial cells when ischemia was long enough to suppress the PR. In the perfused animals these changes were virtually absent even after ischemia up to 30 min duration. The increased tolerance of the brain to ischemia produced by the intravascular rinsing appears to result from at least two different mechanisms. Elimination of metabolic waste products presumably reduces tissue damage during ischemia and the improved postischemic circulation prevents secondary ischemic lesions.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 17 (1971), S. 234-247 
    ISSN: 1432-0533
    Keywords: Human Foetal Muscle ; Electron Microscopy ; Myotube ; Motor End-Plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An menschlichen Embryonen von 9–16 Wochen Alter wurden elektronenmikroskopische Untersuchungen von Muskeln und peripheren Nerven durchgeführt. Sie zeigten das Auftreten von motorischen Endplatten in der 10. Embryonalwoche, zu einem Zeitpunkt, wo der Muskel noch in myotubulären Stadium ist. Der Unterschied in der Struktur der Nervenfasern zwischen der 9. und der 16. Woche des Fetallebens besteht im Übergang aus der Form eines Multiaxonbündels zu Einzelaxonen, die voneinander durch einen intracellulären, von Kollagenfasern erfüllten Raum getrennt werden.
    Notes: Summary Electron microscopic observations were made on muscle and peripheral nerve of human embryos of the period between the 9th and 16th week. These observations showed the presence of motor end-plates at the 10th week of human embryonic life, at a time when the muscle cells were still in the myotube stage. The difference between the structure of nerve fibres of the 9th and those of the 16th week of foetal life consisted in a change from the form of one multiaxon bundle to single axons separated from each other by an intracellular space filled with collagen fibres.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 19 (1971), S. 129-136 
    ISSN: 1432-0533
    Keywords: Amyloidosis ; Brain ; Dog ; Man ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fluorescent changes in the brains of 4 aged dogs and one senile human were studied with the electron microscope using a special techique to reembed conventional histological sections in plastic (Rossiet al., 1970). Using this method typical amyloid filaments were found in fluorescent leptomeningeal and cortical vessels and in fluorescent plaques in the cerebral cortex. Leptomeningeal and cortical vessels in aged dogs and senile human disclosed dense intercellular accumulation of amyloid extending throughout the whole vessel wall. Contrary to man, perivascular penetration of amyloid filaments were not seen in the dog. They are, however, indicated by the presence of filaments in the adventitia. Senile plaques in both species are formed by the same elements. The central core of the plaque predominantly contains amyloid, while the periphery discloses various dystrophic changes of the ageing brain. Alzheimer filaments clearly distinguished from normal neurofilaments and from amyloid were present in the human brain but were absent in the dog brain.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 17 (1971), S. 287-301 
    ISSN: 1432-0533
    Keywords: Olfactory Bulb ; Radiation ; Synapses ; Degeneration ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les effets d'une seule haute dose de rayons X sur le bulbe olfactif du rat adulte ont été étudiés par la microscopie électronique. Plusieurs éléments caractéristiques de la réponse cellulaire ont été décrits (pyknose neuronale; réponse gliale et accumulation de glycogène; oedème; activité phagocytique). Des approches vers la compréhension des méchanismes sousjacent ces effets et leur signification fonctionelle possible sont dicutées. Le dommage des cellules granulaires internes a donné lieu à la dégénération synaptique au niveau des contacts mitro-granulaires réciproques dans le stratum plexiforme. L'accent est mis sur l'importance que ce travail peut avoir lorsqu'appliqué à l'étude des connections des neurones à cylindre-axe court.
    Notes: Summary Effects of a single high dose of X-rays on the adult rat olfactory bulb have been studied by electron microscopy. Several features of the cell response were described (neuronal pyknosis; glial response and glycogen accumulation; edema; phagocytic activity). Approaches towards understanding the mechanisms underlying these effects and their possible functional significance are discussed. The damage of the internal granule cells gave rise to synaptic degeneration at the level of the reciprocal mitro-granular contacts in the stratum plexiforme. The importance that this work may have when applied to the study of short axon neuron connections is stressed.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 18 (1971), S. 103-112 
    ISSN: 1432-0533
    Keywords: Blood-brain Barrier ; Cerebral Ischemia ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A study was made on the effect of ischemia on the vascular permeability to proteins in the cat brain. Evans blue and horseradish peroxidase were used as protein tracers. They were intravenously injected and localized by fluorescence and electron microscopy. Acute complete cerebral ischemia produced by arterial ligations for 15 min to 3h did not induce extravasation of the tracers. Electron microscopical observations on the cortical vessels showed that this was due to a maintained barrier function of the vascular endothelium. Incomplete cerebral ischemia of corresponding duration produced by an arteriovenous shunt (between one common carotid artery and one femoral vein) caused exceptionally extravasation around cortical vessels. Some cats with long shunting time showed signs of increased vascular permeability in the thalamus where the tracers had accumulated in neurons. Severe swelling of capillary endothelial and perivascular glial cells and changes of their cytoplasmic organelles were present in animals without signs of increased vascular permeability to proteins. A discrepancy therefore exists between the maintained impermeability of the capillary endothelium to protein tracers and the ultrastructural changes of the endothelial cell cytoplasm following acute ischemia.
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  • 9
    ISSN: 1432-0533
    Keywords: Organic Mercury Compound ; Peripheral Nerve ; Regeneration ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ratten wurde oral durch 20 Tage täglich 1 mg organische Quecksilberverbindung verabreicht. Am 7. und 250. Tag nach Ende der Verabreichung wurden die peripheren Nerven untersucht. Am 7. Tag fanden sich Mitosen von Schwannschen Zellen und am 250. Tag deutliche Abnahme der myelinhaltigen Nervenfasern, begleitet von Regeneration der Nervenfasern und Zunahme von Kollagen im intercellulären Raum. Anderseits waren die Ganglienzellen der Hinterwurzeln intakt. Diese Befunde lassen vermuten, daß die Regeneration geschädigter peripherer Nerven nach experimentellen Vergiftung mit organischem Quecksilber durch bis in periphere Abschnitte wachsende Axonsprossen und neugebildete Schwann-Zellen vor sich geht. Die Regenerationstendenz der peripheren Nerven war jedoch im ganzen nicht sehr ausgeprägt.
    Notes: Summary Rats were given 1 mg of organic mercury compound per rat daily by mouth for 20 days. Peripheral nerves were examined on the 7th day and 250 th day after withdrawal of administration. On the 7th day, mitosis of Schwann cells was observed and on the 250 th day, myelinated fibres were noticeably decreased in numbers, with regeneration of nerve fibres and an increase of collagen in the intercellular spaces. Posterior nerve root ganglion cells were however intact. From this it is speculated that regeneration of injured peripheral nerve fibres, experimentally poisoned with organic mercury, is the result of regeneration of axons growing out to the periphery, and by regeneration of Schwann cells. Regeneration of the peripheral nerves was not however a very marked feature.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 17 (1971), S. 37-43 
    ISSN: 1432-0533
    Keywords: Encephalomyelitis, Viral, Experimental ; Group B Arboviruses ; Central Nervous System, Viral Spread ; Neuropil, Extracellular Spaces ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei erwachsenen weißen Mäusen wurde durch intracerebrale Infektion mit dem Zimmern-Virus, ein dem TBE-Komplex angehörendes Arbovirus der Gruppe B, eine Encephalomyelitis erzeugt. Bei ultrastrukturellen Untersuchungen dieses Prozesses konnten einige interessante Beobachtungen gemacht werden. Zimmern-Viruspartikel, welche einen Durchmesser von etwa 400–450 Å haben, wurden nicht nur innerhalb zahlreicher Nervenzellen, sondern wiederholt auch in den Intercellularfugen des Neuropils angetroffen. Aufgrund dieses Befundes ist es sehr wahrscheinlich, daß die extracellulären Räume im ZNS intra vitam wesentlich weiter sind als man sie nach Anwendung der üblichen elektronenmikroskopischen Präparationsverfahren zu Gesicht bekommt. Es liegt somit auch die Annahme nahe, daß die Intercellularspalten als Wege für die Ausbreitung zumindest von kleineren Viren (z. B. Picornaviren und Arboviren der Gruppe B) im eigentlichen Hirn- und Rückenmarksgewebe dienen können.
    Notes: Summary An encephalomyelitis was produced in adult albino mice by intracerebral infection with the Zimmern virus, which is a group B arbovirus belonging to the TBE complex. Ultrastructural studies of this process showed some interesting results. Zimmern virus particles, which measure about 400 to 450 Å in diameter, could be observed, not only inside numerous neurons, but also repeatedly within the intercellular gaps of the neuropil. This finding makes it very likely that the extracellular spaces of the CNS are considerably wider in the intravital state than they appear to be after employing the conventional electron microscopic preparatory techniques. One may also conclude, therefore, that the intercellular clefts can serve as pathways for the spread of at least smaller virions (e. g., picorna viruses and group B arboviruses) throughout the parenchyma of the brain and spinal cord.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 17 (1971), S. 201-219 
    ISSN: 1432-0533
    Keywords: Spinal Muscular Atrophy ; Kugelberg-Welander Syndrome ; Electron Microscopy ; Denervation Atrophy ; Lysosomes ; Sarcoplasmic Reticulum ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In 8 Fällen von gutartiger spinaler Muskelatrophie vom Typ Kugelberg-Welander wurden Muskelbiospien elektronenmikroskopisch untersucht. Progressive Disorganisation und Auflösung der Myofibrille wurde in den atrophischen Muskelfasern gefunden. Sie war verbunden mit dem Auftreten von Lysosomen in diesen Fibrillen. Die frühesten Veränderungen, die wahrscheinlich durch Denervation verursacht sind, waren in Fibrillen normaler Größe oder mit nur geringer Atrophie anzutreffen und bestanden in Erweiterung des sarkoplasmischen Reticulums, Vergrößerung der Mitochondrien und einer relativen Zunahme der Menge des Sarkoplasmas, das Aggregate von Ribosomen enthielt. Muskelfibrillen von normalem oder vergrößertem Umfang enthielten meist beträchtliche Mengen von Glykogen, hatten aber sonst normale Ultrastruktur. Ein kleiner Teil solcher Fibrillen hatte zentrale, im Sarkolemm gelegene Kerne oder zeigte fokale degenerative Veränderungen oder segmentartige hyaline Nekrose mit Unterbrechung der Plasmamembran. Die Befunde werden mit früheren elektronenmikroskopischen Untersuchungen von denervierten Muskeln beim Menschen und im Tierversuch sowie mit den histochemischen Veränderungen in Muskelbiopsien solcher Fälle verglichen.
    Notes: Summary Muscle biopsies from 8 cases of benign spinal muscular atrophy of the Kugelberg-Welander variety were examined with the electron microscope. Progressive disorganisation and dissolution of myofibrils was found in atrophic muscle fibres and was associated with the presence of lysosomes in such fibres. Distinctive nuclear and sarcolemmal changes were also found in atrophic fibres. The earliest changes which were considered to be due to denervation were found in fibres which were slightly atrophied or of normal size and consisted of dilatation of the sarcoplasmic reticulum, enlargement of mitochondria and a relative increase in the amount of sarcoplasm which contained aggregates of ribosomes. Most of the fibres of normal or increased size contained considerable amounts of glycogen but were otherwise normal ultrastructurally. A small proportion of such fibres had internally-situated sarcolemmal nuclei or showed focal degenerative changes or segmental hyaline necrosis with disruption of the plasma membrane. The findings are considered in relation to those of previous electron-microscopic studies of denervated muscle in the experimental animal and in man and to the histochemical changes which are found in muscle biopsies from such cases.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 17 (1971), S. 302-309 
    ISSN: 1432-0533
    Keywords: Synaptic Degeneration ; Tricresylphosphate Intoxication ; Spinal Cord ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine elektronenoptische Untersuchung der Synapsen-Degeneration im Vorderhorn des Rückenmarks vom Huhn wurde nach Gabe einer Einzeldosis von 0,5 cm3 Tricresylphosphat durchgeführt. Die Fixation erfolgte durch Perfusion mit 6% Glutaraldehyd. Degenerative Veränderungen fanden sich in den synaptischen Vesikeln und Mitochondrien des präsynaptischen Abschnittes. Diese Befunde werden mit Läsionen durch mechanische Schädigung und Bestrahlung verglichen. Es wird angenommen, daß sich der toxische Effekt von TCP sicher im Synapsenareal manifestiert. Dieses zeigt dabei Veränderungen ähnlich wie nach mechanischer oder Strahlenschädigung.
    Notes: Summary A study has been made of synaptic degeneration at an ultrastructural level using 6% glutaraldehyde perfusion, fixation method in the anterior horn of hen's spinal cord, after application of a single dose of 0.5 cm3 TCP on the comb. The degenerative changes are seen in the synaptic vesicles and mitochondria of pre-synaptic bag. A comparison of these findings is made with degenerative changes caused by mechanical interference and x-irradiation. It is concluded that the toxic effects of TCP are certainly manifested in the synaptic areas which show changes similar to those caused by the mechanical interference and by x-irradiation.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 18 (1971), S. 34-57 
    ISSN: 1432-0533
    Keywords: Hypertrophic Interstitial Polyneuropathy ; Guillain-Barré Syndrome ; Multiple Sclerosis ; Myelin ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Licht- und elektronenmikroskopische Befunde von zwei N. suralis-Biopsien eines 9 jährigen Knaben mit rezidivierender idiopathischer Polyneuropathie werden beschrieben. Die Biopsien wurden kurz nach einer klinischen Exazerbation und 6 Jahre nach Beginn der Neuropathie durchgeführt. Die Erkrankung hatte akut im Anschluß an Varizellen begonnen. Lichtoptisch fand sich eine aktive primäre Entmarkung bei Auftreten von Infiltraten aus Mononukleären, Lymphocyten und Makrophagen sowie Zwiebelschalenbildung, die in Araldit-Schnitten erkennbar waren. Folgende ultrastrukturelle Veränderungen wurden beobachtet: 1. Der Markzerfall schien durch Makrophagen hervorgerufen, die in intakte Fasern eindringen und in die Markscheiden entlang der minor dense line einbrechen. Myelin und Schwannzellen ohne direkten Kontakt mit den invadierenden Zellen erschienen normal. Extracelluläre bläschenförmige Markauflösung wie beim Landry-Guillain-Barré-Syndrom wurde nicht beobactet. Eine Art von mononukleären Zellen einschließlich solcher nach Art von transformierten Lymphocyten fanden sich im Endoneuralraum und wurden oft in Kontakt untereinander und mit Makrophagen beobachtet. 2. Die Schwannzellen, die Zwiebelschalen-Lamellen bildeten, zeigten wenig morphologische Hinweise auf aktive Proteinsynthese. Sie schienen jene Zellen darzustellen, die ursprünglich die Internoden gestützt hatten und während der Entmarkung und am Beginn der Remyelinisation abgerissen waren. 3. Der mittlere Durchmesser von Axonen in Nervenfasern mit aktiver oder frischer Demyelinisation war geringer als jener in Fasern mit fortgeschrittener Remyelinisierung. Das weist auf eine Querschnittszunahme der Axone während der Remyelinisation hin. Die ultrastrukturellen Befunde werden diskutiert und mit jenen bei anderen nicht-infektiösen entzündlichen primären Entmarkungskrankheiten der peripheren und zentralen weißen Substanz verglichen. Es wird vermutet, daß die rezidivierende idiopathische Polyneuropathie des beschriebenen Typs und die multiple Sklerose verwandte Erkrankungen darstellen.
    Notes: Summary The light and electron microscopical features of two sural nerve biopsies obtained from a nine year old boy with recurrent idiopathic polyneuropathy are described. The biopsies were obtained shortly after an exacerbation of symptoms and six years after the onset of the neuropathy which began acutely following an attack of varicella. Light microscopy revealed active primary demyelination occurring in the presence of an infiltrate of mononuclear cells, lymphocytes and macrophages, with onion-bulb formation discernible in araldite sections. The following fine-structural changes were observed: 1. Myelin breakdown appeared to be initiated by macrophages penetrating intact fibres and burrowing into the myelin sheath along minor dense lines. Myelin and Schwann cells not in direct contact with the invading cell appeared normal. Extracellular vesicular dissolution of myelin, as seen in the Landry-Guillain-Barré syndrome, was not observed. A variety of mononuclear cells including cells with the appearance of transformed lymphocytes were present in the endoneurial space and they were frequently observed to contact each other and macrophages. 2. The Schwann cells forming onion-bulb lamellae showed little morphological evidence of active protein synthesis, and appeared to be effete cells which had originally subserved the internode and which were cast off during demyelination and the commencement of remyelination. 3. The average diameter of axons in nerve fibres showing active or recent demyelination was less than that observed in fibres exhibiting advanced remyelination, suggesting that the diameter of axons increased during remyelination. The ultrastructural findings are discussed with respect to those observed in other noninfectious inflammatory primary demyelinating diseases of peripheral and central white matter, and it is suggested that recurrent idiopathic polyneuropathy of the type described in the present study and multiple sclerosis may be related disorders.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 18 (1971), S. 193-213 
    ISSN: 1432-0533
    Keywords: Glia ; Differentiation ; Tissue Culture ; Autoradiography ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Organotypic cultures of mammalian embryonic spinal cord-dorsal root ganglia combinations treated with H3 thymidine, were studied with light and electron microscopic autoradiography. Cultures pulsed with H3 thymidine for up to six hours showed 0–2% of labelled neuroepithelial cells when fixed immediately thereafter, and 7 to 15 times as many labelled cells when fixed on subsequent daysin vitro (DIV). Cultures exposed to radioactive material for days, at the initiation of the culture, and prior to myelinationin vitro, were compared. The cumulative evidence showed that the peak of proliferative activity occurred not after explantation, but between DIV 7 and DIV 12, which is after synapse formation and prior to myelination. Another smaller proliferative peak occurred after myelination between DIV 15 and DIV 19. Morphological observations with the light microscope revealed labelling of predominantly small dark cells during the first proliferative peak, that is, prior to myelination. Using electron microscopic criteria for identification, these small dark cells were “large glioblasts”, “large glial precursors” and “young” oligodendrocytes, and transitions could be observed between these cells in that order of differentiation. Oligodendrocytes when closely connected with myelin sheaths did not become labelled. Labelling and proliferation of medium large light cells inconspicuously preceded that of oligodendrocytes and their precursors, and continued modestly throughout myelination, achieving a modest peak and predominance during DIV 15 and DIV 19. Astrocytic features could be demonstrated ultrastructurally in these medium large light cells and mitotic division in this type of cell was observed. The possibility that part of this astrocytic population arose from “large glioblasts” was discussed. No labelled cells were seen ultrastructurally fulfilling criteria of amitotic division. No neurons showed labelling with H3 thymidine.
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  • 15
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    Acta neuropathologica 18 (1971), S. 327-341 
    ISSN: 1432-0533
    Keywords: Infantile Neuroaxonal Dystrophy ; Electron Microscopy ; Striated Muscle ; Membranous-Tubular Structures ; Filamentous Structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper deals with the first ultrastructural study of muscle fiber in a child affected by infantile neuroaxonal dystrophy or Seitelberger's disease. In a first step, diagnosis was performed by light and electron microscopy in biopsy and autopsy findings in central and peripheral nervous system. Muscle fiber and axonal changes are very similar. The ultrastructure findings in muscle fiber are as follows: 1. neural atrophy, 2. overproduction of membrano-tubular structures related to sarcoplasmic reticulum hyperplasia, 3. filamentous aggregates by presumed overproduction of myofilaments, 4. overproduction of abnormal mitochondria. These changes, already described in various muscular diseases, are not specific; they seem related to an abnormal muscle fiber reaction in close association to dystrophic axonal endings.
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  • 16
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    Acta neuropathologica 19 (1971), S. 110-120 
    ISSN: 1432-0533
    Keywords: Electron Microscopy ; Motorneurones ; Neurotomy ; Chromatolysis ; Glycogen Deposits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Spinal cord motorneurones of young chickens were examined 2–93 days after section of the brachial plexus nerves. The maximal reaction to axotomy was found 7–14 days after the operation. The majority of cells showed nuclear eccentricity, displacement of Nissl substance towards the periphery and accumulation of mitochondria and other organelles in the cytocentrum. The most conspicuous alteration, however, in a large number of neurones, was the occurrence of numerous dense granules corresponding in size and staining characteristics to glycogen. These granules most often formed large deposits in marginal regions of cells. In the light microscope the presence of polysaccharides, apparently glycogen, was demonstrated with the PAS reaction. From 14 to 93 days after the operation most perikarya regained their normal ultrastructural appearance. Increased amounts of glycogen granules could be seen in some of the cells till the end of the fourth postoperative week. The development of glycogen deposits in axotomized perikarya indicates that considerable alterations in the breakdown and/or synthesis of glycogen apparently occur in young animals after neurotomy.
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  • 17
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    Acta neuropathologica 19 (1971), S. 184-207 
    ISSN: 1432-0533
    Keywords: Haemangioblastoma of the Brain ; Angioblastic Meningioma ; Blastomatous Vessels ; “Zwischenzellen” ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 4 hemangioblastomas of the cerebellum, 1 of the choroid plexus, 1 of the spinal cord, and 3 angioblastic meningiomas of the brain were investigated with the electron microscope. They all show a similar histological arrangement of vessels, intervascular cells (Zwischenzellen), and the intercellular space. The vessels of the tumors regardless where they originate from are identical in their appearance. They differ from autochthonous vessels by the irregular form of the endothelium and the presence of pores. The “Zwischenzellen” of hemangioblastomas are not so uniform as those of angioblastic meningiomas. Corresponding to differences in the nucleus/cytoplasma ratio, the development of the ER and the number of cytofilaments as well as the content of lipid droplets hemangioblastomas can be subdivided in 4 types. Nevertheless they constitute a cytological unity. In 3 hemangioblastomas mast cells were found. glial cells mixed up with tumor cells are present only in the border of tumorous and nervous tissue. The extracellular space is filled either with a protein-rich exsudate or with collagen fibrils. — The electron microscopic findings support the histological identity of hemangioblastomas and angioblastic meningiomas. The relation of “Zwischenzellen” to the vessel walls, their similarity to endothelial cells, and their tendence to form basement membranes indicate that they derive from blastomatous vessels.
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  • 18
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    Acta neuropathologica 19 (1971), S. 343-346 
    ISSN: 1432-0533
    Keywords: Creutzfeldt-Jakob Disease ; Membrane Fragments ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a human case of Creutzfeldt-Jakob disease, fragments of membranes were seen within some vacuoles. They form accumulations of vesicular or curled structures and have to be differentiated from other membranous profiles that one can observe within the large spongy cavities. They are similar to what have been recently described in the experimental disease but their cellular signification is unknown.
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  • 19
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    Acta neuropathologica 19 (1971), S. 290-300 
    ISSN: 1432-0533
    Keywords: Polyneuropathy ; Hyperlipemia ; Electron Microscopy ; Myelin Disorganization ; Membrane Invagination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 73 old patient with very high serum lipids suffered from recurrent peripherad polyneuropathy. Examination of sural nerve showed disorganisation of myelin sheaths ann plasma membrane invaginations into the axons which seems to represent both Schwanl cell and axonal membranes. An extensive basal membrane hyperplasia and perineural connective tissue proliferation were present. The possibility that these changes are related to the patient's hyperlipemia is discussed.
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  • 20
    ISSN: 1432-0533
    Keywords: Subacute Myelo-Optico-Neuropathy ; Peripheral Nerves ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary N. suralis, taken from a patient in the chronic state of “Subacute Myelo-Optico-Neuropathy (SMON)” was examined by electron microscopy. The nerve showed a depletion of myelinated nerve fibres. Vacuoles or degenerated mitochondria were observed in the axis cylinders of myelinated and unmyelinated nerve fibres. Schwann cells were increased in number and many of them were atrophic. Onion-bulb formations were seen diffusely; regeneration of myelinated nerve fibres was sparse.
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  • 21
    ISSN: 1432-0533
    Keywords: Experimental Organic Mercury Poisoning ; Muscles ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In einem Teil des M. gastrocnemius von experimentell mit organischem Quecksilber vergifteten Ratten fanden sich pathologische Veränderungen. Aufgrund dieses Befundes wird vermutet, daß die Vergiftungsläsion zwar die hinteren Nervenwurzelfasern bevorzugt, aber auch Teile der vorderen Nervenwurzelfasern betreffen kann.
    Notes: Summary Pathological changes were found in a part of M. gastrocnemius in rats experimentally poisoned by an organic mercury compound. The authors assume from this that organic mercury mainly affects the posterior nerve root fibres, but some of the anterior nerve root fibres may also be involved.
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  • 22
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    Acta neuropathologica 17 (1971), S. 103-113 
    ISSN: 1432-0533
    Keywords: Tri-Ortho-Cresyl-Phosphate ; Spinal Ganglion ; Neurofilaments ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden Spinalganglien und periphere Nerven von normalen und mit Tri-Ortho-Cresyl-Phosphat (TOCP) vergifteten Hühnern elektronenmikroskopisch untersucht. In den normalen Ganglien fanden sich zwei unterschiedliche Neuronentypen, große Zellen mit hellem Cytoplasma, in dem sich reichlich Neurofilamente fande, und kleinere Neurone, welche wenig oder keine Filamente enthielten. Die “hellen” Zellen reagierten auf TOCP mit einer starken Vermehrung der Neurofilamente, während die dunklen, kleineren Neurone eine Hypertrophie des endoplasmatischen Reticulums zeigten. Diese Veränderungen waren eindeutig nach 15 tägiger TOCP-Applikation sichtbar. An den peripheren Nerven traten bereits nach 6 tägiger Vergiftung deutlichen Reaktionen im Sinne einer Proliferation der glatten Membranen auf. Die möglichen Zusammenhänge dieser Veränderungen werden diskutiert.
    Notes: Summary The spinal ganglia and peripheral nerves of normal and tri-ortho-cresyl phosphate (TOCP)-poisoned chickens were examined with the electron microscope. The normal ganglia contained two main neuron types, a large neuron with light cytoplasm and abundant neurofilaments, and a smaller, darker cell which contained few or no filaments. The “light” neurons reacted to TOCP with a very great increase in the number of filaments present in the cytoplasm, while the darker cells showed a hypertrophy of the endoplasmic reticulum. These changes were not definitely present until 15 days after TOCP ingestion, while the largediameter fibres of the peripheral nerves showed a proliferation of smooth membranes at 6 days. The possible mechanisms for these changes are discussed.
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  • 23
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    Acta neuropathologica 17 (1971), S. 150-155 
    ISSN: 1432-0533
    Keywords: Creutzfeldt-Jakob Disease ; Kuru Plaques ; Electron Microscopy ; Subacute Presenile Polioencephalopathy ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zahlreiche PAS-positive Plaques fanden sich im Kleinhirn eines Falles von Creutzfeldt-Jakob Syndrom. Die licht- und elektronenoptischen Strukturen der Plaques waren identisch mit den bei Kuru-Fällen beschriebenen. Diese Befunde bilden ein weiteres Bindeglied zwischen diesen beiden neurologischen Erkrankungen, die viele gemeinsame klinische, histopathologische und virologische Eigenschaften besitzen.
    Notes: Summary Numerous periodic-acid-Schiff positive plaques occurred in the cerebellum of a patient diagnosed as having Creutzfeldt-Jakob disease. Microscopic and submicroscopic structures of the plaques were identical with those described in Kuru. This is an additional link between these two neurological diseases in which the clinical, histopathological, and virological features are in many respects similar.
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  • 24
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    Acta neuropathologica 17 (1971), S. 353-362 
    ISSN: 1432-0533
    Keywords: Electron Microscopy ; Gamma Irradiated ; Neural Tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die ultrastrukturellen Befunde am retikulären Gewebe der Medulla nach kurzfristiger Gesamtkörper-gamma-Bestrahlung werden beschrieben. 25 erwachsene Ratten wurden in eine Kontrollgruppe und vier bestrahlte Gruppen, die 1000, 2000, 5000 bzw. 10000 rad erhielten, geteilt. Die Gewebepräparation bestand bei allen Gruppen in Immersionfixation in Veronalacetat gepuffertem OsO4 und einer Perfusionstechnik, die s-Collidingepuffertes Glutaraldehyd benützte. Mit einer Ausnahme zeigten die nervösen Ultrastrukturbefunde der Kontrollgruppe Übereinstimmung mit anderen Beobachtungen. Eine Struktur, die sog. konzentrischen Membrankörper (KMK), wurde nach Perfusion der Tiere mit s-Collidin-gepufferter Fixierlösung gefunden. Diese KMK bestehen aus lamellierten Membranen mit einer Intraperiodizität von 40–50Å. In allen bestrahlten Gruppen wurden Membranaggregate gefunden. Es wurde angenommen, daß diese Strukturen in den Gruppen mit niedriger Bestrahlung aus den KMK, hingegen aus KMK und Markscheiden-Zerfallsprodukten in den Gruppen mit höherer Bestrahlungsdosis gebildet wurden. Progressive cytoplasmatische Vacuolisation, Mitochondrien- und Markscheidenschädigung waren abhängig von der Dosishöhe. Da keine Capillarschädigung bei den bestrahlten Tieren gefunden werden konnte, wurde angenommen, daß die beobachteten cellulären Läsionen der Effekt direkter oder lokalisierter Bestrahlungsschädigung waren.
    Notes: Summary The ultrastructural observations recorded after shortterm, whole body gamma irradiation on medullary reticular tissue were evaluated. Twenty-five adult rats were divided into one control and four irradiated groups which received 1,000 rads, 2,000 rads, 5,000 rads, and 10,000 rads, respectively. Tissue preparations in each group consisted of immersion fixation in veronal acetate buffered OsO4 and a perfusion technique utilizing s-collidine buffered glutaraldehyde. The micrographs from the control group revealed conformity to neurological ultrastructures as reported by other authors, with one exception. A structure termed “concentric membranous body” (CMB) was observed in the s-collidine buffered, perfused animals. This structure was noted to be associated with neuronal membranes and to contain laminated repeating intraperiodicity of 40–50Å. In all irradiated groups (1,000, 2,000, 5,000, 10,000 rads) membranous swirls were observed. These structures appeared to be of CMB origin in the lower exposure groups and from both CMB and myelin sheath breakdown in the higher groups. Progressive cytoplasmic vacuolization, mitochondrial, and myelin sheath damage were noted as being related to dose level. Since no apparent capillary bed damage was observed in any irradiated animal, it was concluded that the cellular abnormalities recorded were the result of direct or localized irradiation damage of the brain.
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  • 25
    ISSN: 1432-0533
    Keywords: Astrocytic Organelles ; Lipidoses and Allied Diseases ; Electron Microscopy ; Lipid Synthesis ; Evolution of Intracytoplasmic Lipidoses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The astrocytic organelles in 12 patients with various lipidoses and allied diseases were studied. Histochemically and ultrastructurally, astrocytes contained cytoplasmic inclusions which were identical to those seen in neurons from cases of similar disorders. In the early stage of these disorders, the astrocytic cytoplasm displays a close relationship between increased numbers of mitochondria and dilated smooth portion of the endoplasmic reticulum. In the more advanced stage, the mitochondria decrease in number, and the lipid bodies show close proximity to or continuity with the smooth portion of the endoplasmic reticulum. During the late stages of the disorder, the intracytoplasmic inclusion bodies become numerous, and the mitochondria are further reduced in number. It, therefore, appears that in astrocytes in these disorders the mitochondria and the smooth portion of the endoplasmic reticulum play an important role during the evolution of the intracytoplasmic lipid bodies. On the basis of these observations, the possible morphogenesis of lipid cytosomes is discussed.
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  • 26
    ISSN: 1432-0533
    Keywords: Blood-brain Barrier ; Cerebral Ischemia ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A study was made on the influence of ischemia on the passage of protein tracers across capillaries in certain blood-brain barrier (BBB) injuries. Total cerebral ischemia was produced by arterial ligation and BBB injury was caused by intracarotid injection of mercuric chloride or by acute hypertension. Changes in the vulnerability of the BBB was correlated with the ischemic impact on the brain as revealed by suppression of electroencephalogram (EEG) or of the pyramidal response (PR) after electrical stimulation of the sensorimotor cortex. In cats not subjected to ischemia both the chemical and the hemodynamic lesions invariably caused extensive extravasation of protein tracers (Evans blue and peroxidase). Episodes of ischemia immediately before the chemical and the hemodynamic lesions, long enough to supress the EEG but not the PR, did not change the pattern of protein extravasation. However, when the duration of ischemia was severe enough to suppress both the EEG and the PR (about 9 min) chemical and hemodynamic insults failed to elicit exudation of proteins. Traumatic lesions caused extravasation regardless of the duration of preceding ischemia. The inhibition of protein extravasation induced by ischemia in the chemical and the hemodynamic lesions is probably related to changes in the vascular endothelium but their exact nature remains obscure.
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  • 27
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    Acta neuropathologica 17 (1971), S. 310-320 
    ISSN: 1432-0533
    Keywords: Aging ; Lipofusion ; Centrophenoxine ; Spinal Ganglia ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Aufbau und Vorkommen des Alterspigmentes in Neuronen und Satellitenzellen der cervicalen Spinalganglien seniler Ratten wurde licht- und elektronenmikroskopisch nach 4-, 5-, 8-, 11- und 13 wöchiger Centrophenoxinbehandlung untersucht und mit dem in gleichaltrigen Kontrolltieren verglichen. Lichtmikroskopisch fand sich am PAS-gefärbten Material eine Verminderung des Alterspigmentes nach 8 wöchiger und längerer Behandlungsdauer. Elektronenmikroskopisch ließen sich bereits nach 4 wöchiger Centrophenoxinbehandlung vacuolige Veränderungen an den Pigmentkörpern der Satellitenzellen feststellen. Gleichartige Veränderungen zeigten sich nach 8 wöchiger Behandlung auch an den Pigmenten der Nervenzellen. Gleichzeitig fanden sich die Pigmentkonglomerate in den Typ A-Neuronen in einem Zustand der Disintegration. Die Veränderungen nahmen mit der Dauer der Behandlung zu und führten zu einer Verminderung der Pigmentkörper. Die möglichen Ursachen der Veränderung bzw. Verminderung der Pigmentkörper werden diskutiert und der Weg eines etwaigen Abtransportes der Alterspigmente aus den Nervenzellen erörtert.
    Notes: Summary The appearance and distribution of old age pigment in the neurons and satellite cells of the cervical spinal ganglions of senile rats were examined light- and electronmicroscopically after the rats had been treated for 4, 5, 8, 11 and 13 weeks with centrophenoxine. Untreated rats of the same age were also examined. Light microscopic examination of PAS-stained material revealed a decrease in the amount of old age pigment present in the neurones after eight or more weeks treatment. In the E.M. sections vacuolization of the pigment granules in the satellite cells could already be observed after four weeks treatment. After 8 weeks similar changes could be seen in the neurones, as well as a disintegration of the large accumulations of pigment in the perikarion type A neurones. The changes increased with length of treatment and led to a decrease in the total amount of pigment present. The possible causes of these changes and the probable route for the removal of old age pigment from nerve cells are discussed.
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  • 28
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    Acta neuropathologica 18 (1971), S. 1-16 
    ISSN: 1432-0533
    Keywords: Polymyositis ; Lymphoid Cells ; Electron Microscopy ; Lymphocyte Transformation ; Cytotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Muskelbiopsien von 2 Polymyositisfällen wurden elektronenmikroskopisch untersucht, wobei den Entzündungszellen in den Läsionen besondere Aufmerksamkeit geschenkt wurde. Vergrößerte, möglicherweise „aktivierte Lymphocyten” fanden sich in Kontakt mit dem Endothel kleiner Venolen; man traf sie auch beim Durchtritt durch die Gefäßwand an. Die Endothelzellen der Venolen waren oft vergrößert, die Basalmembran verdoppelt. Die perivasculären und interstitiellen Zellen rekrutierten sich aus kleinen Lymphocyten, größeren Lymphocyten mit den deutlichen morphologischen Zeichen der übergangsformen, pleomorphen Makrophagen sowie einigen Plasmazellen und Granulocyten. Bei einem Fall wurden innerhalb der Basalmembran mehrerer Muskelfasern Zellen gefunden, die primitiven lymphoiden Zellen ähnelten. In der Inkubation mit einem Muskelhomogenat wurden Lymphocyten vom peripheren Blut beider Patienten stimuliert. Die Lymphocyten erwiesen sich auch gegen Kulturen von fetalem quergestreiften menschlichen Muskel als cytotoxisch. Die Bedeutung dieser Befunde wird in Hinblick auf die Pathogenese der Muskelfaserschädigung bei Polymyositis erwogen.
    Notes: Summary Muscle biopsies from two cases of polymyositis were examined with the electron microscope, particular attention being given to the inflammatory cells in the lesions. Lymphocytes which were enlarged and possibly “activated” were found in contact with the endothelium of small venules; they were also seen apparently traversing the vessel wall. Venular endothelial cells were often swollen with reduplication of the basement membrane. Perivascular and interstitial cells comprised small lymphocytes, larger transforming lymphocytes with distinctive morphological features, pleomorphic macrophages and a few plasma cells and granulocytes. In one case cells resembling primitive lymphoid cells were found internal to the basement membrane of several muscle fibres. Peripheral blood lymphocytes from both patients were stimulated on incubation with a crude muscle homogenate. The lymphocytes also appeared to be cytotoxic to cultures of foetal human striated muscle. The significance of these findings is considered in relationship to the pathogenesis of the muscle fibre damage in polymyositis.
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  • 29
    ISSN: 1432-0533
    Keywords: Subacute Sclerosing Panencephalitis ; Electron Microscopy ; Nucleocapsid Structures ; Inclusions ; Nuclear Bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bioptisch gewonnenes Hirngewebe von 3 Patienten mit subakuter sklerosierender Panencephalitis (SSPE) wurde licht- und elektronenoptisch untersucht. Histologisch boten alle Fälle gewisse Läsionen der grauen und weißen Substanz. Einschlußkörper wurden in einem Fall mit nur diskreter Markschädigung gefunden. In den beiden anderen Fällen, in denen Kerneinschlüsse nicht nachweisbar waren, trat die Astrogliaproliferation im Mark stärker hervor. Elektronenmikroskopisch ergaben sich vier abnorme Befunde, die aber nicht in allen Fällen obligat angetroffen wurden. Zwei Typen von Nucleocapsid-Strukturen, kleinere und größere, ähnlich jenen in Masern-infizierten Zellen, wurden in einem Fall gesehen. Die kleineren Nucleocapside bildeten entweder Kern- oder Cytoplasmaeinschlüsse; die größeren waren gewöhnlich im Cytoplasma angehäuft. Kernkörperchen fanden sich in allen Fällen. Gitterartige Strukturen und Bündel von fibrillärem Material wurden ferner in zwei Fällen beobachtet.
    Notes: Summary Brain tissue obtained by biopsy from three patients with subacute sclerosing panencephalitis (SSPE) was examined under the light and the electron microscope. Histologically all the cases showed some degree of abnormality of both the gray and the white matter. Inclusion bodies were found in one case in which changes in the white matter were minimal. In the other two cases, where inclusion bodies were not identified, astrocytic proliferation in the white matter was more conspicuous. In electron microscopy four abnormal findings were observed, but all were not necessarily seen in each case. Two types of nucleocapsid structures, smaller and larger, of the type seen in measles-infected cells, were identified in one case. The smaller nucleocapsids formed either nuclear or cytoplasmic inclusions and the larger ones usually aggregated in the cytoplasm. Nuclear bodies were seen in all the cases. Lattice-like structures and bundles of fibrillar material were also observed in two cases.
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  • 30
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    Acta neuropathologica 18 (1971), S. 150-159 
    ISSN: 1432-0533
    Keywords: Electron Microscopy ; Nerve Regeneration ; Unmyelinated Axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine elektronenmikroskopische Untersuchung über die Regeneration von marklosen Axonen wurde am N. vagus des Kaninchens durchgeführt. Als Folge einer lokalisierten Quetschverletzung des N. vagus am Hals in Höhe der Cartilago thyreoidea wurden die regenerierenden marklosen Axone in den laryngealen Recurrens-Ast abgelenkt, der normalerweise beinahe vollständig aus myelinreichen Fasern aufgebaut ist. Die regenerierenden marklosen Axone kommen um die regenerierenden myelinreichen Axone zu liegen, sind aber mit getrennten Schwannschen Zellen verbunden. Eine mögliche Erklärung für diese aberrierende Regeneration der myelinfreien Axone wird diskutiert, ebenso ihre Bedeutung für die Human-Neuropathologie.
    Notes: Summary An electron microscope investigation has been made into the regeneration of unmyelinated axons in the vagus nerve of the rabbit. Following a localized crush injury of the vagus nerve in the neck at the level of the thyroid cartilage, the regenerating unmyelinated axons become diverted into the recurrent laryngeal branch, which is normally composed almost entirely of myelinated fibres. Here the regenerating unmyelinated axons become arrayed around the regenerating myelinated axons, but are associated with separate Schwann cells. The possible explanation for this aberrant regeneration of the unmyelinated axons is discussed, as is its significance for human neuropathology.
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  • 31
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    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Keywords: Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une concentration moyenne de 2.4×10−8 g U/g de cendre a été obtenue à partir de l'os humain normal. La microdistribution de l'uranium dans l'os indique que cet élément est surtout limité à surface de l'endoste et, en particulier, aux surfaces de l'os lamellaire et aux parois des canaux de Havers, ouverts dans l'os corticol. Cette répartition suggère que l'uranium se présente sous une forme chimique impropre à son incorporation dans l'apatite osseux: il ne semble donc pas exister une distribution diffuse significative de l'uranium dans l'os.
    Abstract: Zusammenfassung Eine mittlere Konzentration von 2,4×10−8 g Uran/g Asche wurde in normalen menschlichen Knochen gefunden. Die Feinverteilung von Uran im Knochen zeigt, daß dieses Element hauptsächlich an der endostalen Oberfläche vorkommt, insbesondere an der Oberfläche des trabeculären Knochens und an den Wänden der offenen Haversschen Kanäle im kortikalen Knochen. Diese Verteilung läßt vermuten, daß Uran in einer chemischen Form vorliegt, welche sich für den Einbau in das Knochenapatit nicht eignet. Daraus folgt, daß keine signifikante diffuse Verteilung des Urans innerhalb des Knochens vorliegt.
    Notes: Abstract A mean concentration of 2.4×10−8 g U/g ash has been obtained for normal human bone The microdistribution of uranium in bone indicates that this element is mainly restricted to endosteal surfaces; in particular the surfaces of trabecular bone and the walls of open Haversian canals in cortical bone. This distribution suggests that uranium is present in a chemical form that is not acceptable for incorporation into bone apatite and consequently there does not appear to be a significant diffuse distribution of uranium throughout bone.
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  • 32
    ISSN: 1432-0827
    Keywords: Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une perte de substance ostéo-cartilagineuse, de taille limitée et identique, est réalisée chez le lapin adulte et la cicatrisation est étudiée histologiquement et par autoradiographie après marquagein vitro au35S-sulfate. Une analyse microchimique est pratiquée pour le contenu et la composition en glycosaminoglycanes. 1. Entre la première semaine et la 4ème et 8ème semaine, un tissu conjonctif non-métachromatique se différencie en un cartilage métachromatique et la quantité de sulfate de chondroitine augmente de façon significative aux dépens des glycoprotéines. 2. Jusqu'à la 4ème semaine, la perte de substance est surtout comblée par de l'os néoformé: après cette période, la région est comblée au delà de la limite de la surface articulaire. 3. Le cartilage hyalin, ressemblant morphologiquement, autoradiographiquement et chimiquement au cartilage articulaire, en ce qui concerne la distribution en glycosaminoglycanes, constitute la surface articulaire de la perte de substance comblée dans un tiers des cas après 8 semaines. Le cartilage hyalin s'observe surtout dans les régions où de l'os néoformé a comblé la cavité médullaire. 4. Dans les deux tiers des cas, après 8 semaines, les surfaces articulaires des zones comblées comportent, non seulement du cartilage, mais aussi du tissu fibreux se formant essentiellement sur les parties latérales et dans les régions, où la cavité médullaire, fliant face, à la surface articulaire, n'a pas été comblée par du tissue osseux. La fraction glycoprotéique augmente par rapport à la fraction chondroitine sulfate. 5. Dans la majorité des cas, après 20 semaines, le cartilage néoformé subit des phénomènes dégénératifs, qui se traduisent par une diminution en chondroitine sulfate.
    Abstract: Zusammenfassung Bei ausgewachsenen Kaninchen wurde ein begrenzter, standardisierter, osteochondraler Defekt hervorgerufen, und das regenerierte Gewebe wurde histologisch und autoradiographisch durch Markierung in vitro mit35S-Sulfat und durch mikrochemische Bestimmung des Gehaltes und der Zusammensetzung der Glykosaminglykane untersucht. Die wichtigsten Befunde waren: 1. Zwischen 1 und 4–8 Wochen veränderte sich nichtmetachromatisches Bindegewebe zu metachromatisch gefärbtem Knorpel, und der Anteil an Chondroitin-Sulfat nahm auf Kosten der Glykoproteine signifikant zu. 2. Bis zu 4 Wochen war der Hauptteil des defekten Gebietes mit neugebildetem Knochen gefüllt; nach dieser Zeit lag dieser Bezirk oberhalb der Verknöcherungsgrenze in Richtung der Gelenkoberfläche. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 4. Nach 8 Wochen bestanden Teile der Gelenkoberfläche des Defektes in zwei Dritteln der Fälle nicht nur aus Knorpel, sondern auch aus fibrösem Gewebe, welches vor allem in den seitlichen Teilen des Defektes und an Stellen vorlag, wo die Markhöhle gegenüber der Gelenkoberfläche nicht mit Knochengewebe verschlossen worden war. Die Glykoproteinfraktion nahm im Vergleich zur Chondroitin-Sulfatfraktion zu. 5. Nach 20 Wochen zeigten sich in den meisten Fällen bei neugebildetem Knorpel degenerative Veränderungen, welche durch eine gewisse Abnahme des Chondroitin-Sulfats wiedergegeben wurden.
    Notes: Abstract A limited, standardized osteochondral defect was created in adult rabbits and the regenerated tissue was examined histologically and autoradiographically after labellingin vitro with35S-sulphate, and microchemically for its content and composition of glycosaminoglycans. The principal findings were: 1. Between 1 week and 4 to 8 weeks, non-metachromatic connective tissue differentiated to metachromatically stained cartilage, and the proportion of the chondroitin sulphate increased significantly at the expense of the glycoproteins. 2. Up to 4 weeks, the major part of the defect area was filled with newly formed bone; after this time, the area lay above the level of the “tidemark”, towards the articular surface. 3. Hyaline cartilage with morphological, autoradiographic and chemical resemblance to the articular cartilage in terms of the distribution of glycosaminoglycans constituted the articular surface of the defect area in one-third of the cases at observation times after 8 weeks. Hyaline cartilage was observed mainly in areas where newly formed bone had closed the medullary cavity. 4. In two-thirds of the cases, after 8 weeks, parts of the articular surface of the defect consisted not only of cartilage but also of fibrous tissue, occurring mainly in the lateral parts of the defect and in areas where the medullary cavity facing the articular surface had not been sealed by bone tissue. The glycoprotein fraction increased relative to the chondroitin sulphate fraction. 5. In most cases after 20 weeks, newly-formed cartilage underwent degenerative changes, which were reflected in some reduction of the chondroitin sulphate.
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  • 33
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    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Keywords: Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Abstract: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notes: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
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  • 34
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    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Keywords: Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un programme d'ordinateur a été mis au point pour calculer les activités ioniques du calcium et l'orthophosphate dans un grand nombre de solutions. Dans le cas de solutions synthétiques, les calculs sont vérifiés en comparant les valeurs de pH, obtenues par ordinateur, avec celles observées expérimentalement. Des essais de ce type, avec des solutions possèdant des concentrations de calcium et d'orthophosphate trouvées dans les liquides biologiques et à des valeurs de pH variant de 3.00 à 10.00, indiquent que le programme est adapté pour des applications biologiques. Le programme n'est pas effectif pour des solutions, dans les lesquelles l'ion bromure est la source principale de la force ionique, sans doute, par manque d'équation étendue de Debye-Hückel dans ces circonstances. Aucune formation de complexe de phosphate de sodium n'a été notée à des concentrations biologiques normales.
    Abstract: Zusammenfassung Es wurde ein Computer-Programm ausgearbeitet, um die Ionenaktivitäten von Calcium und Orthophosphat in einer breiten Varietät von Lösungen zu berechnen. Die Berechnungen wurden bei synthetischen Lösungen durch Vergleiche zwischen den auf diese Weise errechneten pH-Werten und den experimentell gefundenen kontrolliert. Diese Art Kontrollen mit Calcium-und Orthophosphatkonzentrationen, wie sie in biologischen Flüssigkeiten gefunden werden, und mit pH-Werten zwischen 3,0 und 10,0 wies darauf hin, daß das Programm für biologische Anwendungen geeignet war. Das Programm konnte nicht benützt werden für solche Lösungen, bei welchen hauptsächlich das Bromidion zur Einstellung der Ionenstärke verwendet wurde, vermutlich weil die erweiterte Debye-Hückel-Gleichung unter diesen Umständen nicht anwendbar ist. Die Bildung eines Natriumphosphat-Komplexes unter normalen biologischen Konzentrationen konnte nicht nachgewiesen werden.
    Notes: Abstract A computer program has been designed to calculate the ionic activities of calcium and orthophosphate in a wide variety of solutions. In the case of synthetic solutions the calculations were checked by comparing the computed pH values with those observed experimentally. Tests of this type with solutions having the concentrations of calcium and orthophosphate found in biological fluids and with pH values ranging from pH 3.0–10.0 indicated that the program was suitable for biological applications. The program was not effective for solutions in which the bromide ion was a principal source of ionic strength probably because of the failure of the extended Debye-Hückel equation under those circumstances. No evidence for the formation of any sodium phosphate complex at normal biological concentrations could be found.
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  • 35
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    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Keywords: Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Abstract: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notes: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
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  • 36
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    Pflügers Archiv 329 (1971), S. 59-71 
    ISSN: 1432-2013
    Keywords: Myosin Adenosinetriphosphatase ; Cardiac Performance ; Glycogen ; Electron Microscopy ; Skeletal Muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between cardiac function and 1. myocardial glycogen concentration, 2. ultrastructure, and 3. myosin ATPase activity was studied in cats at various times following adrenalectomy. These three variables were also studied in gastrocnemius and soleus muscles from the same cats. Cardiac glycogen concentration was decreased in adrenal insufficient cats 11 days after withdrawal of steroid therapy, a time at which cardiac performance was already severely depressed. Skeletal muscle glycogen levels did not significantly decrease after adrenalectomy. Electron micrographs of the heart and the soleus at 8 days revealed normal myofibrils and mitochondria, but a shorter mean sarcomere length was observed in cardiac muscle. The ATPase activities of myosin isolated from the red fibered cativity of myosin isolated from the predominantly white fibered gastrocnemius muscle appeared to be unaffected by adrenalectomy. Regression analysis of cardiac function on cardiac myosin ATPase activity for adrenalectomized, dexamethasone-treated, and intact control animals revealed a significant correlation (p〈0.001) between cardiac performance and myosin ATPase activity.
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  • 37
    ISSN: 1432-1076
    Keywords: Electron Microscopy ; Surface Spreading ; Critical Point Drying ; Erythrocyte Ghosts ; Virus Particles ; Chromosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Methode der Oberflächenspreitung und der Kritischen Punkt-Trocknung zur elektronenmikroskopischen Präparation ungeschnittener biologischer Objekte wird im einzelnen beschrieben. Die Methode erlaubt, grobmorphologische Veränderungen von Erythrocytenschatten zu beurteilen, Virusteilchen in Zellen nachzuweisen und den inneren Aufbau einzelner Chromosomen zu charakterisieren.
    Notes: Abstract A method for the preparation of unsectioned biological material for whole-mount electron microscopy by surface spreading and critical point drying is described in detail. The applications are demonstrated by showing the three-dimensional structure of erythrocyte ghosts, virus particles, and chromosomes.
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  • 38
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    Biopolymers 10 (1971), S. 1049-1057 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ultrastructural morphology and x-ray and electron diffraction of poly (Gly-Gly-Ala) have been studied. The polymer has two forms; the first, form I possesses a super-folded cross-β structure, long fibers of which show some twisting and intertwining. Form II precipitates in a less distinct fibrous form from aqueous solution. The x-ray diffraction and oriented electron diffraction data suggest that form II is a polyglycine II helix situated in a monoclinic cell with dimensions a = 8.86 Å, b = 22.0 Å, c = 9.42 Å, and β = 90°. Combined with the morphological evidence it appears likely that form II is also in an antiparallel superfolded array.
    Additional Material: 5 Ill.
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  • 39
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    Biopolymers 10 (1971), S. 1099-1101 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 40
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A statistical mechanical model was developed for use in connection with the problem of preferential binding of solvent components to proteins and of conformational transition in water-organic solvent systems. The model is a statistical one for the conformational transition of globular proteins induced by the adsorption of solutes in the solution, considered as a nearest-neighbor problem in statistical mechanics. Although a few illustrative examples are given, the actual interpretations of the experimental data using this theory are reserved for a later paper.
    Additional Material: 7 Ill.
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  • 41
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    Biopolymers 10 (1971), S. 1103-1103 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 42
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    Biopolymers 10 (1971), S. 1121-1138 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concept and representation of a logical tree as defined in computer science is applied to obtain a suitable representation of protein molecules in computer programs which handle or calculate atomic coordinates of protein molecules. On the basis of this analysis and of the analysis of the calculation and modification of the structure of a protein from bond lengths, bond angles, and dihedral angles, which is reproduced in an appendix, program modules which accomplish the various required computations are described. Three such modules are given in Iverson notation; in fact, it is hoped that this article will serve as a reasonably complete basis for the preparation of machine programs by moderately proficient programmers.
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  • 43
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    Biopolymers 10 (1971), S. 1207-1212 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism spectrum obtained from a dilute aqueous solution of poly (ala-gly-gly) resembles that described for charged polypeptides such as the salt form of poly glutamic acid. A similar spectrum is found for films cast from aqueous solution where x-ray studies reported elsewhere have indicated a poly-glycinc II conformation. Evidence is presented for a heat induced poly-glycine II to unordered state transition similar to that described for collagen. The interpretation of this, the first observation of the optical properties of a poly-amino acid in the poly glycine II conformation, is further rationalized on the basis of spectra obtained from a number of polypeptides whose conformation approaches that of a 31 helix.
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  • 44
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    Biopolymers 10 (1971), S. 1229-1242 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of cupric ion on the emission of tryptophan, tyrosine, and serum albumins is studied by emission spectroscopy and lifetime measurements. It is found that whenever cupric ion is bound to tryptophan or tyrosine, their emissions are quenched completely. The quenching may be due to an electron transfer mechanism. The fluorescence of complexes of cupric ions with serum albumins is partially quenched; this is because energy is transferred from tryptophan to the complexed cupric ions by a dipolar energy transfer mechanism. It is deduced from the present study that the tryptophan in the human serum albumin molecule is between 11 and 16 Å from the nearest eupric ion binding sites (assumed to be at the surface of the protein) and that one of the tryptophan in the bovine serum albumin molecule is very close to the cupric ion binding sites and the other is near the center of the bovine serum albumin molecule. It is also found that the deuterium solvent effect on serum albumin fluorescence is very small, and that the quenching of bovine serum albumin fluorescence at the N-F transition is the result of quenching of the fluorescence of both tryptophans. The phosphorescence lifetime apparatus, capable of measuring decay times of signals with intensities changing over a few orders of magnitude, and the ratio spectrofluorometer, both of which were constructed in this laboratory, are also described.
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  • 45
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    Biopolymers 10 (1971), S. 1253-1260 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The measurements were made for the volume and the sound velocity changes (ΔV and ΔU) on titrating the sodium salt of poly (S-carboxymethyl L-cysteine) with dilute HCl. For the reaction, —COO- + H+ → —COOH, ΔV per mole of H+ bound was + 12. 7 ml and +11. 4 ml in salt-free and 0. 2 M NaCl solutions, respectively. Corresponding ΔU was about -13 cm/sec in salt-free polymer solution where 11.5 mM carboxylate ion reacts with equimolar hydrogen ion. ΔV associated with the coil-to-β transition was found to be +2. 35 ml in H2O and +1. 90 ml in 0. 2 M NaCl per mole of amino acid residue, respectively. These values are larger than those obtained for the coil-to-helix transition of poly (L-glutamic acid). ΔU for the transition was about -30 cm/sec in salt-free solution of polymer concentration 0.0115 mole/liter. Possible sources of ΔV and ΔU for reaction; coil → β, are (1) the formation of void volume and (2) the changes in the extent of solvation in amide linkage and in side chain.
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  • 46
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    Biopolymers 10 (1971), S. 1317-1329 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of three aromatic molecules to apomyoglobin has been investigated. In each case equilibrium dialysis studies and tryptophan fluorescence quenching studies indicate that a one to one complex has been formed. The fluorescence quenching studies further suggest that the binding of the aromatic molecules is at the heme site with possible involvement of the arginine CD3. Xenon, which is known to quench the fluorescence of aromatic hydrocarbons, is found to be bound to apomyoglobin-aromatic molecule complexes and quenches the emission of the aromatic molecule in the complexes. Oxygen quenches pyrene fluorescence in water solution but does not quench the pyrene fluorescence from the apomyoglobin-pyrene complex. This is explained by a slower rate of diffusion of oxygen to pyrene in the apomyoglobin-pyrene complex.
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  • 47
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    Biopolymers 10 (1971), S. 1365-1369 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotor speed-dependent aggregation of T4 DNA in the analytical ultracentrifuge is studied in the presence of high pressure generated by compressed nitrogen gas in the cell. The extents of aggregation at various speeds are found to be practically the same in the presence and absence of pressure.
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  • 48
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    Biopolymers 10 (1971), S. 1331-1349 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The time-dependent theory developed in Part I is specialized to treat tetrameric hemoglobin, and the results of the theory for dimeric-and tetrameric hemoglobin are compared with data on the kinetics of the reactions of hemoglobin with carbon monoxide and oxygen at various salt concentrations for the case of large concentration of ligand relative to that of hemoglobin. The fit of the theoretical results to the data suggests that hemoglobin at a 2 M salt concentration is predominantly dimeric and that the tetramer should be taken as the functional unit to explain the kinetics of the reactions of normal hemoglobin. A relationship is established between the time-dependent theory arid Adair's Intermediate Compound Hypothesis (I.C.H.) for hemoglobin, as brought to its present state by Gibson and Roughton. A generalization (G.I.C.H.) of the I.C.H. is presented and is shown to be equivalent to the time-dependent theory in the limit of infinite ligand concentration. The I.C.H. is shown to be an excellent approximation to the centralized theory (G.I.C.H.) in this limit.
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  • 49
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    Biopolymers 10 (1971), S. 1421-1425 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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  • 50
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    Biopolymers 10 (1971), S. 1427-1428 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 51
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    Biopolymers 10 (1971), S. 1429-1454 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of oligodesoxyribonucleotides of various chain lengths to form complexes has been compared with that of oligoribonucleotides. Four series of oligonucleotidcs were prepared and investigated, i.e., dCn at acid pH versus rCn, dAn and dTn versus. rAn and rUn at neutral pH. The results indicate that in dilute solution, the formation of complexes is greatly facilitated in the case of desoxyoligomers and occurs for shorter oligomere than in the corresponding ribooligomers. The spectrophotometric titration of deoxyribooligo C indicates the appearance of two pK values in the 4-5 pH region characteristic of the double-stranded form, which occurs for much shorter dCn than rCn. The circular dichroism (CD.) spectra of deoxycytidylies in dilute solution starting from the trimer are conservative, characteristic of the double-stranded helical form of poly C at acid pH. In contrast, the CD spectra of a series of corresponding ribo Cn, under identical conditions is of nonconservative character similar to that of the single-stranded form of poly C at neutral pH, but differs in the band position. This spectrum is called intermediate. Only at higher concentrations of oligonucleotidcs (i.e., 10-3Minstead of 10-4M) does the circular dichroism spectrum of longer ribocytidylics assume conservative character. Thermal denaturation of deoxycytidylces at acid pH are strongly dependent on chain length and concentration, its one would expect for a cooperative helix-coil transition. The circular dichroism spectra measured at different temperatures shows one isosbestic point. In dilute solution, the standard-state enthalpy change found was 5-6 kcal/mole for higher oligomers (dC7). These properties are all in agreement with a structural transition from the d-Cn double-stranded form to a coil for n 〉 3. Studies of dAn and dTn in solutions of high ionic strength at low temperature indicate that complex formation occurs already at the level of trimer and for high oligomers. Under identical conditions a complex between rAn and rUn is detected only for oligomers longer than the hexamer. The nature of the “intermediate” form of oligoribo C at acid pH and low temperature was investigated by sedimentation and circular dichroism. A model of rCn is proposed of linear molecules which are partially double-stranded and partially single-stranded, which probably are slowly rearranged by “slippage” into a regular-double-stranded helical form.
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  • 52
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The number average molecular weight, Mn, of low molecular weight dextran was determined through endgroup analysis, and the intrinsic, viscosities of these materials in aqueous solution were determined at 25°C. The ultrasonic velocities in their aqueous solutions were also measured at 25 and 45°C. As concerns the molecular weight dependence of the intrinsic viscosity, partial specific compressibility of solute and the hound water around the solute, the following results were obtained. (1) log [η]-log Mn and [η]/Mn0.5 - Mn0.5 plots were in accord with the Mark-Houwink and Stockmayer-Fix-man equations respectively for Mn 〉 2, 000, but these plots deviated from the equations for Mn 〈 2, 000. (2)The partial specific compressibility, β1°, of dextran is expressed by following equation for Mn 〈 2,000: β1° = 10-12 × (13.6 log Mn - 51.7) (cm2/dyne). In contrast, it, becomes the constant value, -- 7.3 × 10-12 cm2/dyne, for Mn 〉 2,000. (3) The amount of bound water of dextran calculated from the sound velocity measurement lakes constant value of 0.17 ml g for Mn 〉 2, 000, but the amount of hydration increase with decreasing molecular weight for Mn 〈 2,000. From these results, a dextran molecule in aqueous solution is expected to change its conformation from random coiling to uncoiling stretched form at the molecular weight of around 2, 000 or about 12 glucose units.
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  • 53
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    Biopolymers 10 (1971), S. 1559-1581 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical rotation studies were performed on five compounds containing two peptide groups. Four of the molecules were confined to restricted regions of conformational space by the presence of closed rings. Solvent and temperature were varied, and theoretical calculations were done for each compound covering the appropriate conformational space. The interpretation which results is qualitatively successful over the conformational regions covered by the compounds. Quantitative correlation between theory and experiment will require compounds of high rigidity.
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  • 54
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    Biopolymers 10 (1971), S. 1617-1623 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energy maps have been calculated for α-D-mannuronic acid (1-4) α-L-guluronic acid and for α-L-guluronic acid (1-4) β-D-mannuronic acid. These have been used, together with maps previously calculated for the homomonomeric dimers, to estimate the characteristic ratios and Kuhn lengths of the alternating copolymer and of a stochastic copolymer similar in composition to that extracted from L. digitata.The results show that the alternating copolymer is less extended than either homopolymer. Kuhn lengths calculated for the stochastic copolymer agree well with experimental results on high ionic strength solutions of alginate isolated from L digitata.
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  • 55
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    Biopolymers 10 (1971), S. 1635-1648 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly-S-carboxyethyl-L-cysteine, a higher side-chain homolog of poly-S-carboxymethyl-L-cysteine, has been prepared from poly-S-carbobenzoxyethyl-L-cysteine with hydrogen bromide in chloroform or acetic acid. The polymer is found to be in the β-conformation of an antiparallel arrangement of polypeptide chains in solid films, both in acid and salt forms, when examined by infrared spectra. Aqueous solutions of t he polymer have been investigated by measurements of rotatory dispersion and circular dichroism as well as by infrared spectra in D2O. These properties show sharp changes around pH 5.5, as the pH of solution is varied. At higher ionization the polymer is randomly coiled, but at lower ionization it is in the β-conformation. Dependence of the rotatory properties upon polymer concentration as well as on ionic strength has been observed even at the lowest degree of ionization attained, and this has been attributed to the formation of intermolecular β-conformation in solutions. The β-structure is characterized by a negative circular dichroic band at 223 mμ and a positive dichroic band at a wavelength lower than 200 mμ, and furt her by a negative bo value, -140°. The pH-induced coil-β transition of the polymer is compared with that of poly-S-carboxymethl-L-cysteine.
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  • 56
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    Biopolymers 10 (1971), S. 1681-1699 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The specific heat, of rat tail tendon at various water contents was measured as a function of temperature. The resulting graphs showed peaks arising from the melting, near 50°C, of helical material in the collagen, and from the melting of absorbed water in the range -40°C to 0°C. The heat of melting of helical material was 11.7 cal per gram of dry tendon. Determination of the heat and temperature of fusion of the absorbed water allowed resolution of the water into four states in the case of tendon before denaturation, and three states after denaturation. The four states are (1) water not freezable on cooling to - 70°C, (2) freezable water with-both heat and temperature of fusion different from the values for ordinary water, (3) freezable water with the heat of fusion of ordinary water, but a different temperature of fusion, and (4) water not distinguished from ordinary water. The fourth state was absent in denatured tendon. The results are discussed in terms of increasing size of clusters of absorbed water molecules.
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  • 57
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    Biopolymers 10 (1971) 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 58
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    Biopolymers 10 (1971), S. 1743-1757 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absorption and rotatory properties of acridine orange-poly-S-carboxymethyl-L-cysteine system in water and in 0.2 M NaCl have been measured at different pH and polymer-to-dye mixing ratios. The absorption spectra indicate that the dyes are bound to the polymer in dimeric or highly aggregated forms. At neutral pH where the polymer is randomly coiled, no optical activity is induced on the absorption bands of bound acridine orange. At acid pH where the polymer has the β-conformation, a pair of positive and negative circular dichroic bands occur at each of the absorption bands, centered around 458 and 261 mμ. The signs of those bands are opposite to those found for α-helical poly-L-glutamic acid. A model for the binding of dye to the β-form polymer is presented, in which dimeric dyes are attached to ionized carboxyl groups and slack one another to form linear arrays on both sides of an extended polypeptide chain. The observed circular dichroism spectra can be explained by the Tinoco's exciton mechanism, based on this model. Low molecular weight poly-S-carboxymethyl-L-cysteine induces quite a different circular dichroism on bound acridine orange.
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  • 59
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    Biopolymers 10 (1971), S. 1853-1863 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dicrosim (CD) spectra of complexes of DNA with ethidiun bromnide, profiavine, 9-aminoacridine and 4-etliyl-9-amino-acridine have been determined between 220 and 450 nm, the range lieing extended to 600 nm for ethidiufm bromide. The variation of the magnitude of the visible and near - ultraviolet CD spectra of ethidium bromide - DNA complexes with the amount of ligand bound (r) suggests a common binding position with profiavine. On the other hand, 4-ethyl-9-aminoacndine complexed to DNA shows CD spectra not distinguishable from those of 9-aminnoacnidmc in both the visible and ultraviolet. The interpretation of these results with respect to the stereochemistry of the DNA-ligand complexes is discussed.
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  • 60
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    Biopolymers 10 (1971), S. 1901-1924 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The various treatments of sedimentation equilibrium are compared on a theoretical and an experimental basis. Particular attention is paid to the polyelectrolyte nature of the problem and the choice of a neutral component. The effective density gradients of several cesium salts for DNA are measured. Two previous theories for the effective density gradient are shown to be equivalent, and the experimental values are interpreted with respect to these theories. It is clear t hat sedimentation equilibrium in a density gradient may be used for the determination of unambiguous molecular weights.
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  • 61
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    Biopolymers 10 (1971), S. 1949-1972 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of friction-limited DNA unwinding is developed explicitly for moderate tind large perturbations. This extension of the earlier theory of the relaxation kinetics is necessary because of the complex nature of the rate limitation for small perturbations. The assumption of the theory that is violated under relaxation conditions is that base pairing reactions occurring at a constant local degree of twist of the strands are fast compared to the net unwinding of the molecule. However, these reactions that are slow for small perturbations have a large activation energy, and become faster than friction-limited un winding for large enough temperature jumps and sufficiently large DXA molecules. Thus only the rate for moderate and large perturbations is clearly limited by frictional resistance to turning the molecule in solution. The model used is a diffusional unwinding of the two strands, driven by the accompanying decrease in free energy. For large perturbations a numerical solution of the diffusion equation is required, since the diffusion coefficient is not constant. Two new parameters must be introduced into the equilibrium statistical theory to describe friction-limited unwinding kinetics. These are the force constant b, for winding up coil regions and the frictional coefficient per base pair βcfor rotating coil regions in solution. We find by fitting the theory to experiment that b = 1.8 × 10-13 ergs/ rad2- and βc = 3.5 × 10-21 erg see/base pair, both for DNA melted in alkali at 0.4.M Na + and ∼30 °C. The latter value is in agreement with predictions based on the viscosity of single stranded DNA in alkali. The quoted value of bcan be interpreted to mean that the number of conformational states of a nucleolide is reduced by an average factor of 1.55 when it is wound around another strand to the degree of twist in a double helix, but without forming a base pair.
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  • 62
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The properties of oligonucleotide helices of adeuylic- and uridylic acid oligomers have been investigated by measurements of hypo-and hyperchromieity. High ionic strengths favor the formation of triple helices. Thus, the double helix-coil transition can be studied (without interference by triple helices) only at low ionic-strength. A “phase diagram” is given representing the Tm-values of the various transitions at different ionic strengths for the system A(pA)17 + U(pU)17. Oligonucleolides of chain lengths 〈8 always form both double and triple helices at the nucleotide concentrations required for base pairing. For this reason the double helix-coil transition without coupling of the triple helix equilibrium can only be measured for chain lengths higher than 7. Melting curves corresponding to this transition have been determined for chain lengths 8, 9, 10, 11, 14 and 18 at different concentrations. An increase in nucleotide concentration leads to an increase in melting temperature. The shorter the chain length the lower the Tm-value and the broader the helix-coil transition. The experimental transition curves have been analysed according to a staggering zipper model with consideration of the stacking of the adeuylic acid single strands and the electrostatic repulsion of tlip phosphate charges on opposite strands. The temperature dependence of the nucleation parameter has been accounted for by a slacking factor x. The stacking factor expresses the magnitude of the stacking enthalpy. By curve fitting xwas computed to be 0.7, corresponding to a stacking enthalpy of about S kcal/mole. The model described allows the reproduction of the experimental transition curves with relatively high accuracy. In an appendix the thermodynamic parameters of the stacking equilibrium of poly A and of the helix-coil equilibria of poly A + poly U at neutral pH are calculated (ΔHA = -7.9 kcal/mole for the poly A stacking and ΔH12 = -10.9 kcal/mole for the formation of the double helix from the randomly coiled single strands). A formula for the configurational entropy of polymers derived by Flory on the basis of a liquid lattice model is adapted to calculate the stacking entropies of adenylic oligomers.
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  • 63
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    Biopolymers 10 (1971), S. 2049-2049 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 64
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    Biopolymers 10 (1971), S. 2071-2077 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The data on the band widths and band shapes of several DNA's at various concentrations in sedimentation equilibrium in a CsCl density gradient have recently become available. In the present report, these literature data are treated in the following manner: (1) based on a theory of isotope-substitution, calculations are made of the molecular weights at infinite dilution, and (2) to explain the concentration dependence of band widths and band shapes, a theory of charge and hydration is put forth, and it is shown that by retaining the terms involving the charge of the macromolecules, it is possible to account for most of the concentration dependence.
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  • 65
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    Biopolymers 10 (1971), S. 2083-2094 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of the unique and specific association of a given amino acid to its t-RNA is investigated by theoretical methods. Several possible schemes are proposed to explain specificity. The physical forces which act within these mechanisms are illustrated by the computer simulation of probable interactions between glycine and nucleotide bases and base pairs. It is demonstrated that glycine has direct and selective affinities for the nucleotide bases and that these interactions are principally determined by the polar groups. Energies have been calculated for the interaction of glycine with several base pairs. From these, the possibility that specificity arises through direct complexing of an amino acid with its anticodon is evaluated.
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  • 66
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    Biopolymers 10 (1971), S. 2147-2160 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equations are developed to describe the shift in the temperature of the helix-coil transition when small molecules bind to nucleic acids. Included are high polymers, oligonucleotides, and oligomer-polymer interactions. The equations prescribe simple ways of plotting experimental data to evaluate transition and binding parameters.
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  • 67
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    Biopolymers 10 (1971), S. 2181-2197 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The helix-coil transitions for poly-L-lysine (PL) were investigated by the methods of spectropolarimetry, viscometry and potentiometric titration in 0.2M NaCl at different temperatures as well as in 0.2MNaBr, 1MKCl, and in mixtures of 0.2MNaCl or NaBr with methanol at room temperature. The enthalpy and entropy differences between the helical and coillike states of uncharged PL molecules in 0.2.M NaCl were determined from the potentiometric titration curves. The cooperativity parameters σ for PL in different solvents were determined by two methods (from the sharpness of the transition and from the dependence of the intrinsic viscosity on the helical content in the transition region). In 0.2MNaCl σ has a value of (2.3 ± 0.5) × 10-4 and does not depend on temperature, i.e., the cooperativity of the helix-coil transition, as for PGA, is mainly of an entropy origin (the initiating of the helical region is accompanied by the entropy decrease ΔSi = -12 eu/mole of helical regions). A comparison of the obtained results for PGA and PL with the molecular theories of the helix-coil transitions shows that the role of dipole-dipole interactions of nonneighboring peptide groups is greatly overestimated in these theories, leading to a considerable enthalpy contribution to the free energy of initiating helical regions which is not observed in the experiment.
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  • 68
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    Biopolymers 10 (1971), S. 2029-2037 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variation of the polarized components of fluorescence of a rodlike particle bearing a fluorescent label upon partial orientation is calculated for some special geometry of the dye macromolecules complexes. Explicit expressions are given for the case where the energy of the molecule in the field depends only on one angle θ, showing that the result is a function of both 〈sin2θ〉 and 〈sin4θ〉. For the case of orientation in an electric field through an anisotropic induced moment, the expressions allow the calculation of this anisotropy of polarizability. The method is applied to the measurement of the polarizability of rodlike fragments of DNA labeled by intercalated molecules of Acridine Orange.
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  • 69
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    Biopolymers 10 (1971), S. 2039-2048 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As the temperature of solid poly(β-benzyl-L-aspartate) (PBLA), (CO.NH.CH.-CH2COOCH2C6H5)n, in the α-helieal form is raised from -150 °C, tlie line width and second moment of the proton magnetic resonance (PMR) signal decrease in stages until the conformational transition to the ω-helix occurs at about 90 °C. A similar temperature dependence of the PMR parameters is observed as the transformed polymer is cooled. Below -100°C (where the lattice is presumed to be rigid), the measured second moments are 9.5 Oe2 and 10.7 Oe2 for the α and ω forms, respectively. Second moments, calculated from the Van Vleck formula for the rigid lattice and also estimated for possible motional cases in which the polymer is taken to be in the ω form, are compared with the PMH data. By combination with the results of X-ray diffraction and infrared spectroscopic measurements, a tentative explanation can be made of the types of motion occurring in PBLA.
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  • 70
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    Biopolymers 10 (1971), S. 2133-2145 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have performed potentiometric titrations of poly-L-lysine. From these data we have calculated the free energy and enthalpy changes for the folding of the random coil to the α-helix in 10% ethanol (-120 and -120 cal/mole) and from the random coil to the β-structure in water (-140 and 870 cal/mole) and in 10% ethanol (-180 and 980 cal mole). Comparison of these values with each other and with values for the coil → α- helix transition in water (-78 and -880 cal/mole) led to the following conclusions. The stabilization by ethanol of ethanol of the α-helix with respect to the coil is that predicted from the known free energy of transfer of the peptide group from water to 10% ethanol. Similar data to explain the enthalpy difference are not available. The thermodynamic functions for the transition from α-helix to β-structure, obtained by subtracting those for the coil → α-helix and coil → β-structure transitions, are explained from a consideration of the structural differences: non bonded interactions of the polypeptide backbone are less favorable in the β-structure than in the α-helix, causing an increase in the energy, while hydrophobic contacts between side chains raise the entropy of the β-structure as compared with the α-helix, so that the free energy difference between the two structures is small, but enthalpy and entropy differences are large. The observation of only small differences in the free energy and enthalpy changes for the transition from coil β-structure upon going from water to 10% ethanol is expected by considering both the free energy of transfer of the peptide group (as for the α-helix) and the free energy and enthalpy of transfer of the apolar part of the side chain involved in hydrophobic bond formation.
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  • 71
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    Biopolymers 10 (1971), S. 2209-2221 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Valine specific transfer RNA (tRNAVal) was isolated from Bacillus stearothermophilus and Escherichia coli by chromatography on benzoylated DEAE-cellulose (BD-cellulose). Likewise isoleucine specific transfer RNA (tRNAIle) was isolated from B. stearothermophilus and from Mycoplasma sp. Kid. The thermal denaturation profiles (melting curves) of the two tRNAVal species in the presence of Mg+ + were nearly identical. However, the Tm for the Kid tRNAIle was about 10°C lower than that for the B. stearothermophilus tRNAIle. A nuclease and tRNA-free aminoacyl-tRNA synthetase (AA-tRNA synthetase) preparation from B. stearothermophilus was able to function efficiently at temperatures up to 80°C in the aminoacylation of all four tRNA species. Determination of the amino acid-acceptor activity of each tRNA species as a function of temperature of the aminoacylation reaction showed in each case a strong correlation between the loss of acceptor activity and the thermal denaturation profile of the tRNA. Evidence is presented that the loss in acceptor activity is most likely due to a change in structure of the tRNA as opposed to denaturation of the enzyme. These results further support the idea that correct secondary and/or tertiary structure must be maintained for tRNA to be active as a substrate for the AA-tRNA synthetase.
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  • 72
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    Biopolymers 10 (1971), S. 2275-2281 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cotton effects of N-acetoacetyl amino acids and derivatives were examined by a circular dichroism technique. A correlation has been established between the sign of the Cotton effect and the absolute configuration of the asymmetric center. The L derivatives show, in dioxane, negative circular dichroism curves, whereas the D antipodes present positive curves. The effect of solvent and pH and influence of alkylation at the amide nitrogen are also discussed.
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  • 73
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    Biopolymers 10 (1971), S. 2345-2358 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The anisotropy of electrical polarizability of rodlike fragments of DNA has been studied by a number of electro-optical methods: Kerr effect (combined with flow birefringence), light scattering, diehroism, and fluorescence in an electric field. The most sensitive technique (Kerr effect) has been used to study the variation of the polarizability with the nature and concentration of counteroins. DNA fragments constitute a truly rigid polyelectrolyte of known structure. The value obtained can then be quantitatively compared to the predictions of those of the theories of the longitudinal polarizability of rigid polyelectrolytes which are based on true molecular parameters. The comparison emphasizes the role of the counterion-counterion repulsion. Oosawa's theory seems to represent the best approach but fails to explain the differences observed between monovalent and divalent ions.
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  • 74
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    Biopolymers 10 (1971) 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 75
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    Biopolymers 10 (1971), S. 2537-2553 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The MCD (magnetic circular dichroism) spectra of Ap, ApA, ApApA, poly A, Up, UpU, poly U and double-stranded poly A:U alternating copoly A-U and alternating deoxyribopoly A-T were measured with a Cary 61 spectropolarimeter fitted with a Varian superconducting magnet at a field strength of 50 Kgauss. The MCD spectra of T2 and T5 DNA at various stages of heal denaturation were measured as a function of hyperchromicity of the sample. MCD spectra of the intact and degraded T2 and T5 phages were used to study the degree of alteration of the DNA inside the phages versus the DNA in vitro. The results for the adenine polymers show that the main MCD bands, B2u(271 nm), B1u(252 nm), and E1u(212 nm), show a decrease in specific magnitude as the length of the polymer is increased, reflecting the degree of stacking of the polymer. In contrast, the uridine series of polymers shows little change of the MCD bands, indicating that there is little interaction between the bases regardless of the length of the polymers. The MCD spectra of poly A:U, alternating poly r(A-U): (A-U), and alternating poly d(A-T):(A-T) show significant differences among themselves in the magnitude of the B2u band and when compared with the sum of the spectrum for the poly A plus poly U. This may indicate the selective effect of hydrogen bonding on the B2u band. Alternatively, the difference may be due to the absence of an n → π* transition in the double-stranded polymer. Measurements of denatured T2 and To DNA's show increases in all MCD bands. The T2 DNA internally packed in phage shows an increase of the B2u and E1ubands, the B2u remaining unchanged. The internal T5 DNA shows an increase of the B1u band only. Thus, the internal DNA structure is altered in a manner quite different from a simple denaturation caused by hydrogen bond breaking. Furthermore, different MCD bands indicate that different modes of DNA packing exist for T2 and T5 phages.
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  • 76
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    Biopolymers 10 (1971), S. 2591-2596 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The infrared absorption of poly-L-proline in concentrated aqueous salt solutions was measured in the fundamental region. Of primary interest were the carbonyl absorption of the peptide linkage and the methylene C-H bending absorption of the pyrrolidine ring. These spectral regions each show an additional component in the concentrated salt solutions. Using the position of the absorptions of poly-L-proline I (cis) and II (trans) as models, we conclude that both cis-trans linkages are present in the peptide in salt solutions. Increasing the temperature shifts the equilibrium slightly in favor of cis.
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  • 77
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    Biopolymers 10 (1971), S. 2619-2621 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 78
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    Biopolymers 10 (1971), S. 2635-2638 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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  • 79
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  • 80
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    Biopolymers 10 (1971), S. 221-224 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 81
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    Biopolymers 10 (1971) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 82
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The base-stacking patterns in over 70 published crystal structures of nucleic acid constituents and polynucleotides were examined. Several recurring stacking patterns were found. Base stacking in the solid state apparently is very specific, with particular modes of interaction persisting in various crystalline environments. The vertical stacking of purities and pyrimidines in polynucleotides is similar to that observed in crystals of nucleic acid constituents. Only partial base overlap was found in the majority of the structures examined. Usually, the base overlap is accomplished by positioning polar substituents over the ring system of an adjacent base. The stacking interactions are similar to those found in the crystal structures of other polar aromatic compounds, but are considerably different from the ring-ring interactions in nonpolar aromatic compounds. Apparently, dipole-induced dipole forces are largely responsible for solid-state base stacking. It is found that halogen substituents affect base-stacking patterns. In general, the presence of a halogen substituent results in a stacking pattern which permits intimate contact between the halogen atom and adjacent purine or pyrimidine rings. Considering differences in the stacking patterns found for halogenated and nonhalogenated pyrimidines, a model is proposed to account for the mutagenic effects of halogenated pyrimidines.
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  • 83
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    Biopolymers 10 (1971), S. 225-242 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The desorption and melting with temperature of proflavine-DNA complexes has been studied by spectrophotometry and spectrofluorometry. Two methods are described to determine at each temperature the concentration of free and bound dye. The first one is based on the quenching of fluorescence of the free dye by the iodine ion, the second on fluorescence polarization measurements. It is shown that the sites where the bound dye fluoresces are thermally less stable than those where it is quenched, in such a way that a redistribution of the dye between the two types of sites occurs at intermediate temperatures, leading to a drop in the total fluorescence. This confirms the nature of the “emitting” sites which correspond to AT-rich region, while “quenched” sites correspond to GC-rich region. The first have a larger binding constant at room temperature, but only the latter are stabilized by dye intercalation. The desorption and melting have also been followed through the relative changes of absorption. The curves obtained at different wavelengths are not superimposed which is at variance with what is observed with complexes of proflavine with poly dAT and poly dG.dC. The beginning of the desorption process corresponds to minor variations at 445 nm, the maximum of absorption of the free dye, but large changes occur at 460 nm, the maximum of the difference spectrum of the complexes proflavine-poly dAT and proflavine-poly dG.dC. The spreading of the melting curves for different wave lengths must therefore reflect the dependence of the absorption spectra of the dye on the nature of the neighboring bases. However, the action spectrum of the fluorescence, which gives the absorption spectrum of the “emitting” sites only, is identical with the total absorption spectrum of the bound dye.
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  • 84
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    Biopolymers 10 (1971), S. 337-355 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical and hydrodynamic properties of T2 bacteriophage DNA have been determined by steady-state flow birefringence and viscosity in glycerol-aqueous buffer solvents at 25°C. Flow birefringence and extinction angle data were obtained over a velocity gradient range of 0.1 to 5 sec-1 and at concentrations from 3 to 55 μg/ml in solvents containing approximately 30, 42, and 48 vol-% glycerol. Large optical backgrounds were observed in the mixed solvent flow birefringence studies which presented special experimental difficulties; these are described and their effect upon the flow birefringence data are discussed. The data on extinction angle provide no evidence for an internal viscosity effect on the stationary-state hydrodynamic properties of high molecular weight DNA over a range of solvent viscosity from 0.9 to 4.6 cP. Both the optical and hydrodynamic properties under present conditions of measurement appear to be self-consistent in terms of the values for these quantities in neutral aqueous buffer solution. Interpretation of the birefringence is complicated by uncertainties inherent in calculating the form anisotropy of DNA in non-aqueous solvents, but the data imply no large changes in helical structure with increasing glycerol concentration. Both intact and slightly degraded DNA samples were investigated, and no significant polydispersity effects were observed under the experimental conditions described.
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  • 85
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    Biopolymers 10 (1971), S. 379-389 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper extends a previous study in which a discontinuity in the specific rotation of open chain α-l,4-linked glucopyranosides in the water-dimethyl sulfoxide (H2O-DMSO) system was attributed to a symmetry change about a polymer chain segment. Optical rotation of amylose, cyclohexamylose, methyl β-maltoside, and dextran was measured in the following mixed solvent systems: formamide-dimethyl sulfoxide (F-DMSO), ethylenediamine-dimethyl sulfoxide (E-DMSO), and hexamethylphosphoramide-dimethyl sulfoxide (HMPA-DMSO). Refractive index measurements were used in an attempt to detect hydrogen bonding between solvent components. The specific rotation of amylose corrected for variation in refractive index (CSR), as a function of solvent composition, showed a discontinuity at solvent compositions corresponding to about 1 mole F to 2 moles DMSO and to 1 mole E to at least 8 moles DMSO. A discontinuity in the CSR function of amylose in the H2O-DMSO mixed solvent that occurs at 25°C is not observed at 70°C. The CSR function of methyl-β-maltoside exhibits a discontinuity in solvent composition corresponding to mole ratios between 2F-DMSO and 3F-DMSO. Present results indicate that an amylose chain segment may undergo a symmetry change in solvent compositions corresponding to mole ratios between F-DMSO and F-2DMSO. Our CSR measurements of amylose and model compounds in E-DMSO and HMPA-DMSO do not permit us to distinguish between possible changes in amylose chain segment symmetry and solvent interactions that could affect symmetry properties of the glucopyranose ring.
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  • 86
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    Biopolymers 10 (1971), S. 547-564 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the effect of polypeptide concentration on the helix-coil transition of poly(γ-benzyl L-glutamate) (PBLG) in both dichloroacetic acid (DCA) and DCA-chloroform (CHF) mixtures. In agreement with other reports, we find the van't Hoff transition enthalpy to be strongly dependent on PBLG concentration. Also, an apparent effect of polypeptide concentration was noted on the transition temperature; however, corrections for finite PBLG concentration on the mole fraction of DCA seem to remove this effect. In order to explain our data, as well as some calorimetric data in the literature, we consider the transition free energy and enthalpy as a sum of three partial terms. These represent the thermodynamic parameters associated with: (1) conformational changes of the polypeptide, e.g. formation or disruption of intramolecular hydrogen bonds; (2) binding by the strong acid to the nonhelical segments of the polypeptide; (3) an overall (weak) interaction of the polypeptide with the nonbound solvent giving rise to dilution parameters that are dependent on the polypeptide conformation. The latter effect is generally ignored, since it is assumed that solvent interactions, other than specific binding, are similar for both the helical and the nonhelical conformation. Striking effects of water (small amounts) and solution aging on the formation of PBLG helices was observed. Water, as expected, acts as a helicogenic solvent when combined with DCA. The processes occurring during solution aging are not known, although the net effect is to stabilize the helical conformation. Finally, we present some rather unique thermally induced transitions of concentrated PBLG (about 200 mg/ml) in DCA. At low temperatures the soluble randomly coiled conformation is present. Heating produces first an isotropic gel, followed at higher temperatures by an isotropic solution consisting of about 70% α-helicity.
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  • 87
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Potential energies of conformation of a dipeptide unit with butyl, seryl, threonyl, eysteinyl, and valyl side groups have been computed by using classical energy expressions. The presence of a γ-atom introduces characteristic restrictions on the backbone rotational angles φ and ψ the γ-atom itself is restricted to three staggered positions about the Cα - Cβ bond. The important results are that a γ-carbon in position I (χ1 ≃ 60°) cannot be accommodated in the standard right-and left-handed α-helices, whereas a γ-oxygen or sulfur could easily be accommodated in the right-handed α-helix. Further, a γ-carbon or a heteroatom in position II (χ1 ≃ 180°) does not favor a conformation ψ ≃ 180°, compared to two other positions. The valyl side group significantly reduces the allowed φ and ψ values and energetically prefers a β-conformation compared to right-or left-handed α-helical conformations. The less favorable α-helical conformation is possible only for γ (III, II) combination of the valyl residue. The observed φ, ψ, and χ1 values of all the amino acid residues in the three protein molecules, lysozyme, myoglobin, and chymotrypsin are compared with the theoretical predictions and the agreement is excellent. The results bring out the important fact that even in large molecules, the conformation of local segments are predominantly governed by the short-range intramolecular interactions.
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  • 88
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    Biopolymers 10 (1971), S. 593-599 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three methods are described for the preparation of oriented samples of DNA molecules in films. The methods involve simple equipment and produce films of good optical qualities, suitable for the determinations of dichroic spectra, for example. To illustrate the quality of the films the dichroism of DNA and of acridine orange-DNA complex are described. Evidence is given that native DNA structure is stabilized by poly-(vinyl alcohol).
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  • 89
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    Biopolymers 10 (1971), S. 699-710 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A molecular conformation of Gramicidin S was derived on the basis of conformational calculations taking into account the available experimental data.The conformation is characterized by a dyad axis which relates the two chemically equivalent halves of the molecule and contains four hydrogen bonds; other structural features agree with experimental results. X Ray Crystallographic evidences for the relative position of the Ornithine residues is also reported which supports an important feature of the structure of Gramicidin S.
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  • 90
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    Biopolymers 10 (1971), S. 657-680 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heat ΔH° for converting an uncharged lysine residue from a coil to an α-helical state in poly-L-lysine in 0.1N KCl has been determined calorimetrically to be -1200 cal/mole at both 15°C and 25°C. Essentially the same value has been obtained for the conversion of an uncharged residue from a coil to a β-pleated sheet state. Titration data provided information about the state of charge of the polymer in the calorimetric experiments, and optical rotatory dispersion data about its conformation. In order to compute ΔH°, the observed Calorimetric heat was corrected for the heat of breaking the sample cell, the heal of dilution of HCl, the heat of neutralization of OH- ion, and the heat of ionization of the ε-amino group in the random coil. The latter was obtained from similar Calorimetric measurements on poly-D,L-lysine, which was shown to be a good model for the random coil form of poly-L-lysine. The measured transition heat was ∼0.7 cal., which is only 7% of the total heat liberated when a 40 ml solution of 0.25% w/v poly-L-lysine is brought, from pH 11 to pH 7; nevertheless it could be determined with a precision of ±8%. The conformation of poly-L-lysine at pH 11 appears to be completely helical at 15°C, but a mixture of 90% α-helix, 5% β form, and 5% coil at 25°C. Since ΔH° ∼ 0 for the α ⇌ β conversion, the polymer behaves like one of 95% α-helix and 5% coil in the calorimeter at 25°C. At neutral pH, poly-L-lysine is an extended coil, like poly-D,L-lysine.
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  • 91
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four fragments (named K, L, M, and N) of Escherichia coli formylmethionine transfer RNA have been prepared by a partial digestion with ribonuclease T1 followed by a chromatographic separation with a DEAE-Sphadex (A-25) column and then a DEAE-cellulose column. The fragment K is the anticodon fragment with 19 nucleotides (previously reported). L is a fragment with 57 nucleotides involving the 3′-terminal (CCA). M is a fragment with 51 nucleotides which is equal to L except that M lacks 6 nucleotides at the 3′-terminal. N is a fragment with 20 nucleotides which involved the 5′-terminal and corresponds to the complementary half to L. The infrared absorption spectrum has been observed of each of these fragments and two equimolar mixtures L + N and M + N in D2O solutions at several temperatures. The results indicate that at 37°C, K has about 4 hydrogen-bonded base-pairs, L about 11, and M about 13. On the other hand, fragment N is found to have only three weak G-C pairs. For both L + N and M + N, 15-17 strong base pairs are found. The observations give direct support to the clover-leaf structure and at the same time provide information on the stability of each of the four arms in the structure.
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  • 92
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    Biopolymers 10 (1971) 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 93
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    Biopolymers 10 (1971), S. 767-775 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The matrix method is used for calculating the grand partition function for the reaction: 2 polymer + solute = complex. The homogeneous polymers are assumed to have two types of sites within each nucleotide unit: sites for the polymer-polymer association, i.e., (p-p) sites; sites for polymer-solute association i.e., (p-s) sites. The respective binding parameters, P and F, and nearest-neighbor interaction parameters, W and S, are assumed independent. Complications due to ring entropy are avoided by rest riding the model to one-solute-stack systems, which are physically realizable when the reciprocal of the solute cooperativity parameter is much larger than the number of nucleotides in the polymer. The 4 × 4 generating matrix is shown to be a tensor product of two 2 × 2 matrices, each the generating matrix of a particular type of site. The scalar product of the 4 × 4 matrix is shown to be equivalent to the scalar product of a 2 × 2 matrix in the weak interaction limit, W ≈ 0. Calculations are presented for the general case which restricts the (p-s) association to occur only with (p-p) associated nucleotide units. The nature of the binding curve in relation to partitioning the total interaction energy (F + P + S + W) among the parameters is discussed. Also presented is a criterion for neglecting possible states in the calculation of the grand partition function.
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  • 94
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    Biopolymers 10 (1971), S. 777-788 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The x-ray scattering method has been used to investigate the structure in two amorphous crosslinked polymers which are regarded as test systems to establish the power of the method as applied to amorphous biologically significant polymer associations. It is shown that structural information can be determined about the rigid regions within the polymer systems, i.e., those regions held in particular configuration by stereochemical effects. Models of such regions extending over distances with dimensions of ca 18 Å are proposed for an Araldite polymer and for crosslinked poly (methyl/butyl methacrylate). The results allow some general statements about the usefulness and limitations of the amorphous x-ray method.
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  • 95
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    Biopolymers 10 (1971), S. 789-794 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectra of proton and deuteron magnetic resonance of water molecules in oriented biopolymer samples (collagen, DNA, cellulose) are interpreted on the basis of a model of molecular Schottki-type diffusion. The presence of narrow splittings are shown to be the result of slight distortions of “ideal” symmetry of orientations of p-p and O-D vectors, corresponding to the point symmetry group of a tetrahedron, one of whose C3-axes is oriented along the fiber axis.
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  • 96
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    Biopolymers 10 (1971), S. 795-808 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The helix-coil transitions of aqueous solutions of poly-α-L-lysine (PLL), poly-α-L-ornithine (PLO), and poly(α,γ-L-diaminobutyric acid) (PLDBA) have been investigated as functions of pH at 25°C and of temperature at pH 11.75, where these polymers are uncharged; in the cases of the latter two polyamino acids, the transitions have also been studied as functions of apparent pH in methanol-water solution (50/50 by volume). The helix stability of the polypeptides is shown to be a direct function of the number of methylene groups on the side chain. From an analysis of potentiometric titration data, we find that the difference between the helix stability of PLL and that of PLO is due to a difference of about 1 e.u. in the ΔS° of the transition. Combining the “melting curves” obtained from optical rotatory dispersion studies with the potentiometric titration data permits evaluation of the initiation parameter Z (or 1/σ½) of the statistical mechanical theories for these transitions. The value obtained for Z in the case of uncharged aqueous PLO is ca. 35.
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  • 97
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    Biopolymers 10 (1971), S. 809-820 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the first time ORD measurements in the near-infrared region from 0.7 to 2.0 μ for well-known polypeptides, namely, poly(γ-benzyl L-glutamate), poly(L-glutamic acid), poly-L-lysine·HCl, poly-S-carbobenzoxymethyl-L-cysteine, and Bombyx mori silk fibroin, were carried out. It was found that the value of the optical activity infrared term, which is proportional to the sum of rotational strengths of vibrational transitions, depends on polypeptide conformation. The optical activity infrared term value is equal to zero for the random-coil conformation, it is small but exceeds the measurement error for the α-helical state, and finally, for the β conformation it is an order of magnitude higher than for the α-helical state. The obtained results permit one to hope that on the basis of ORD measurement in the near-infrared region it will be possible to suggest a method of determining the β-form content in polypeptides and proteins
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  • 98
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    Biopolymers 10 (1971), S. 821-826 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A 95% ethanol solution of the prolamin zein and of the synthetic polymer polyvinyl-pyrrolidone (PVP) can be successfully electrosprayed and a molecular beam, containing ions of these substances in nitrogen carrier gas, formed. Similarly to polystyrene in benzene-acetone solvent, negative beams of zein and PVP have more substructure than beams containing positive ions. The results indicate considerable aggregation in the beam, possibly of six molecular units per aggregate, in addition to the singly charged single molecules.
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  • 99
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sedimentation experiments have been performed on a polydisperse bacterial DNA sample over a wide range of ionic strength (8 × 10-4M to 2M Na+), at very low DNA concentrations (5-30 μg ml). True sedimentation constant distributions were obtained by careful analysis of experimental data and extrapolation to infinite dilution. In order to give a quantitative description of macromolecular shape, the changes of the exponent as in the general equation, s0 = ksMas, have been determined by comparing sedimentation constant distributions obtained at different ionic strengths. as has been found to vary from 0.419 at 2M Na+ to 0.200 at 8 × 10-4M Na+. As well as the decrease of the mean sedimentation constant, this result indicates a pronounced expansion of DNA molecules with decreasing ionic strength. A discussion of the distinct mechanism responsible for the expansion behavior of DNA is given. Furthermore, the dependence of the Mandelkern-Flory parameter β on ionic strength has been calculated by combining the s0 data with the corresponding [η] values of the sample.
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  • 100
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have determined the ultraviolet optical rotatory properties of the cyanogen bromide peptides of myoglobin and reduced, S-carboxymethylated α-lactalbumin in both aqueous and aqueous alcohol solutions. Similar measurements were also made on the tryptic digests of apomyoglobin. In aqueous solutions the α-helicity of the various peptides was between 5 and 15%, while in concentrated ethanol solutions the helicity could be increased significantly, but never to more than about 55%. The maximum helicity attained by the various peptides at high ethanol concentrations, as well as the cooperativity of the coil-to-helix transition (reflected in the slope at the steep portion of the helicity-alcohol concentration curves), does not depend on the number of residues in the peptide in the manner expected. We have used a model which treats proline residues as absolute helix breakers, thus introducing the concept of effective chain length. By applying available theories of helix-coil transitions of short-chain polypeptides to this model, one can satisfactorily describe most of the data on the myoglobin peptides. Significantly, it was possible to predict the helicity of acid-denatured apomyoglobin from the behavior of the shorter fragments. By using the model, the peptides were found to have an equal intrinsic helix-forming tendency which, with only two exceptions, was not raised by the formation of tertiary structure. The exceptions were apomyoglobin and peptide 56-131, which show, respectively, a considerable and a very small helicity attributable to tertiary structure formation in water at neutral pH. These results agree with the demonstrated absence of stable intermediates in protein unfolding equilibria. The results offer a further correlation between helical structure in the native molecule and the tendency to helix formation in isolated peptides. The results do not support the hypothesis that small folded regions are responsible for initiating the folding of the molecule, and an alternate description is proposed which envisages approximately half-folded structures at the rate limiting step in the folding reaction. Helix formation in the 33-residue C-terminal peptide of α-lactalbumin was found to be as easy as in the myoglobin peptides. If the proposed structural analogy between lysozyme and α-lactalbumin is correct, then this is a case where helix formation occurs in a peptide which is not helical in the native protein. On the other hand, an α-lactalbumin peptide corresponding to a region which has β-structure in lysozyme did not lend to form α-helices.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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