Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    THE SYNTHESIS OF BRAIN CHROMOSOMAL PROTEINS AFTER A PULSE OF THE NERVOUS SYSTEM-SPECIFIC CARCINOGEN N-ETHYL-N-NITROSOUREA TO THE FETAL RAT (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 27 (1976), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The synthesis of brain chromosomal proteins was investigated after a pulse of the nervous system-specific carcinogen N-ethyl-N-nitrosourea to the fetal BD IX-rat. At different times up to 34 days after the carcinogen pulse, carcinogen-treated and control brain cells were incubated for 6h with [14C] and [3H]leucine, respectively, in a standardized suspension culture system. The relative rates of leucine incorporation into histones F2a1, F2a2. and F3, and into 13 individual non-histone chromosomal proteins, were measured after electrophoretic separation in 15% and 10% polyacrylamide gel, respectively. Both histone and NHP synthesis showed a biphasic response, with a common 2nd maximum as late as 15 days after the carcinogen pulse. A first peak of non-histone chromosomal protein synthesis was seen at 24 h, when histone synthesis had not yet recovered from an initial 48 h depression. The data are discussed in relation to the possible regulatory role of chromosomal proteins in gene transcription during neoplastic transformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1976.tb05157.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    NUCLEAR PROTEIN PATTERNS IN DEVELOPING AND ADULT BRAIN AND IN ETHYLNITROSOUREA-INDUCED NEUROECTODERMAL TUMOURS OF THE RAT (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 24 (1975), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a comparative study, the patterns of histones and non-histone proteins were analysed in the chromatin of foetal (18th day of gestation), 10-day-old, and adult BD IX-rat brain, as well as in the chromatin of two ethylnitrosourea-induced neuroectodermal tumours (TV1A1 and GV1A1) and the corresponding malignant cell culture lines TV1C1 and GV1C1. Separation of nuclear proteins at high resolution was obtained by electrophoresis in 15% and 10% polyacrylamide gels containing urea (2·5 m or 6·25 m). In spite of an overall similarity, significant quantitative and qualitative differences were observed between the respective non-histone proteins banding patterns of normal brain and the neoplastic cells analysed. The non-histone protein banding patterns of brain (∼40 different bands) at different stages of development revealed both quantitative differences and the presence of particular bands characteristic of foetal or adult brain, respectively. Both the‘foetal’and‘adult’non-histone protein bands also appeared in the electrophoretograms of the neoplastic neuroectodermal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1975.tb11892.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Oxygens in DNA are main targets for ethylnitrosourea in normal and xeroderma pigmentosum fibroblasts and fetal rat brain cells (1978)
    [s.l.] : Nature Publishing Group
    Nature 276 (1978), S. 85-88 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The chemical reactions of DNA with carcinogenic N-nitroso alkylating agents have been studied extensively in vitro but to a much more limited extent in vivo (see refs 1-4 for reviews). There are several principal reasons for this contrast. One is the technical problem of obtaining DNA with ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/276085a0
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Cytotoxicity of adriamycin, idarubicin, and vincristine in acute myeloid leukemia: Chemosensitization by verapamil in relation to P-glycoprotein expression (1992)
    Springer
    Annals of hematology 65 (1992), S. 206-212 
    Details
    ISSN: 1432-0584
    Keywords: P-glycoprotein ; Drug resistance ; MTT assay ; Acute myeloid leukemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 4-day colorimetric tetrazolium dye (MTT) assay was used to assess the cytotoxicity of adriamycin (ADM), vincristine (VCR), and idarubicin (IDA) in blasts isolated from 37 patients with newly diagnosed and pretreated acute myeloid leukemia (AML). The effect of verapamil (VRP) as a chemosensitizer was studied in relation to the expression of the membrane efflux pump P-glycoprotein (PGP) as determined by a semiquantitative flow-cytometric procedure. A slight positive correlation was found between the fraction of cells expressing PGP and the ID50 values for ADM and VCR, but not between cellular PGP content and sensitivity to IDA. The overall data showed no significant sensitization effect of VRP. However, in specimens with more than 10% cells expressing PGP, 2μM VRP sensitized cells to ADM and VCR significantly. The median of sensitization ratios (SRs), i.e., the ratios of cytotoxic drug ID50 in the absence/presence of VRP, were 1.89 and 2.0, respectively. No sensitizing effect of VRP on the cytotoxicity of IDA was observed. Related to the clinical status, the median fraction of PGP-positive blasts was elevated fourfold in pretreated patients (n=16) in comparison to patients with de novo AML (n=19). No differences in ID50 values were observed between newly diagnosed and pretreated patients. However, SRs for ADM and VCR were higher in samples of pretreated patients compared with de novo AML. PGP-mediated cellular drug resistance may thus be circumvented in leukemic blasts by application of chemosensitizers or, potentially, alternative anthracyclines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01703946
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    8th International AEK Symposium of the Division of Experimental Cancer Research of the German Cancer Society (1995)
    Springer
    Journal of cancer research and clinical oncology 121 (1995), S. 683-690 
    Details
    ISSN: 1432-1335
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01218527
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Zellproliferation in normalen und malignen Geweben:3H-Thymidin-Einbau in vitro unter Standardbedingungen (1966)
    Springer
    Radiation and environmental biophysics 3 (1966), S. 65-93 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Description / Table of Contents: Summary The introduction of the use of labelled DNA precursors into cell proliferation research has resulted in better techniques for the measurement of cell population kinetics in normal and malignant tissues. There is now an increased chance of being able to successfully deal with the problems of the growth of human tumours. In this context, the characteristics of a standardised in vitro technique for the measurement of3H-thymidine incorporation into expiants of various tissues of rats and mice are described. With the aid of autoradiography and liquid scintillation counting, the kinetics of3H-thymidine incorporation were analysed as was also the distribution of labelled cells in the explants as a function of O2 partial pressure. The relative tritium activity per mg wet weight is proportional to the autoradiographic labelling index for the tissues which were investigated. The applicability of the standardised in vitro technique for the prediction of thymidine labelling indices of tissues with unknown proliferative activities (tumours) is discussed.
    Notes: Zusammenfassung Infolge der Einführung radioaktiv markierter DNA-Vorstufen haben sich die experimentellen Möglichkeiten zur Messung der Zellproliferation normaler und maligner Gewebe verbessert. Besonders auch Probleme des Wachstums menschlicher Tumoren können jetzt mit mehr Aussicht auf Erfolg bearbeitet werden. In diesem Zusammenhang wird über die Charakteristika einer standardisierten In-vitro-Technik zum Einbau von3H-Thymidin in Explantate aus verschiedenen Geweben von Ratte und Maus berichtet. Mit Hilfe von Autoradiographie und Flüssigkeitsszmtillationszählung wurden die Kinetik des3H-Thymidin-Einbaus und die Verteilung der DNA-synthetisierenden Zellen in den Explantaten in Abhängigkeit vom O2-Partialdruck analysiert. Bei den untersuchten Geweben waren die gemessenen Einbauwerte (relative3H-Aktivität pro mg Gewebe) den entsprechenden nach In-vivo-Pulsmarkierung autoradiographisch bestimmten Thymidin-Markierungsindices in guter Näherung proportional. Es wird die Möglichkeit diskutiert, mit Hilfe der verwendeten Methode die mittleren Thymidin-Markierungsindices von Geweben mit unbekannter proliferativer Aktivität (Tumoren) abzuschätzen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01191058
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Characteristics of three nuclear emulsions for autoradiography at the electron microscope (1966)
    Springer
    Radiation and environmental biophysics 3 (1966), S. 123-130 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Description / Table of Contents: Zusammenfassung Drei handelsübliche Kernspuremulsionen, Gevaert NUC 307, Ilford L4 und Kodak NTE, wurden wegen ihrer geringen Korngröße auf ihre Eignung zur elektronenmikroskopischen Autoradiographie untersucht. Korngrößenverteilungskurven wurden aufgenommen und ein geeigneter Entwickler ausgesucht. Zur Bestimmung der Empfindlichkeit dieser drei Emulsionen wurden Einkornschichten im Elektronenmikroskop mit Elektronen einer Energie von 5,7 keV, der mittleren β-Energie des Tritiums, bestrahlt. Anschließend wurden die Emulsionen entwickelt, aber nicht fixiert. Mit dem Anteil der entwickelten AgBr-Körner kann dann über Trefferkurven die Empfindlichkeit der Emulsionen bestimmt werden. Man benötigt zur Bildung eines latenten Bildkeimes für die Ilford L4-Emulsion 1 – 1,4 Elektronen pro AgBr-Korn, für die Gevaert NUC 307-Emulsion 2 – 3 und für die Kodak NTE-Emulsion 4 – 5 Elektronen pro AgBr-Korn. Folgerungen für das Auflösevermögen bei radioaktiven Punkt- und Flächenquellen werden diskutiert. Fortschritte in der Mikroautoradiographie werden von der Entwicklung feinkörniger Emulsionen abhängen, deren Empfindlichkeit bei etwa einem Elektron pro AgBr-Korn liegen sollte.
    Notes: Summary On account of their low grain size three commercial emulsions, Gevaert NUC 307, Ilford L4 and Kodak NTE have been investigated to assess their qualities for electron microscope microautoradiography. Grain size distribution curves were determined and a developer suitable for microautoradiography was selected after having tested different types of developers. In order to investigate the sensitivities of the three emulsions, monolayer preparations were irradiated in the electron microscope, using an energy of 5.7 keV corresponding to the mean β-energy of tritium. After exposure the specimens were developed but left unfixed. The sensitivity may then be determined using the percentage of developed grains. For the formation of one latent image the Ilford L4 emulsion must be hit on the average by 1 – 1.4 electrons per AgBr grain; the corresponding figures for Gevaert NUC 307 and Kodak NTE are 2 – 3 and 4 – 5 respectively. The problem of resolution of point and plane sources of radioactivity is discussed. Future advances in microautoradiography will depend on the development of emulsions with lower grain sizes, but such improvement must not be at the expense of sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01191605
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Molecular and cellular mechanisms associated with pulse-carcinogenesis in the rat nervous system by ethylnitrosourea: ethylation of nucleic acids and elimination rates of ethylated bases from the DNA of different tissues (1974)
    Springer
    Journal of cancer research and clinical oncology 82 (1974), S. 37-64 
    Details
    ISSN: 1432-1335
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Äthylierung von Nucleinsäuren durch das Nervensystem-spezifische Puls-Carcinogen N-Äthyl-N-nitrosoharnstoff (ENU) wurde in verschiedenen Geweben der fetalen, 10 Tage alten und adulten BD IX-Ratte untersucht und mit der Äthylierung von Rattenleber-Nucleinsäuren durch das Lebercarcinogen Däthylnitrosami-1-14C verglichen. Eine Stunde nach einem Puls von ENU-1-14C waren die molaren Anteile von N7-Äthylguanin (N7-EG), O6-Äthylguanin (O6-EG), N3-Äthyladenin (N3-EA) und N7-Äthyladenin (N 7-EA) in der DNS tumorgefährdeter (fetales und 10 Tage altes Gehirn) und nicht tumorgefährdeter Gewebe (z. B. Leber) ähnlich groß und unabhängig von der Höhe des Anteils der zum Zeitpunkt des Carcinogen-Pulses in DNS-Replikation befindlichen Zellen. Die relativen Ausbeuten der verschiedenen äthylierten Purinbasen nach Äthylierung der DNS durch ENU-1-14C in vivo waren im Mittel 54% (N7-EG), 28% (O6-EG), 17% (N3-EA) und ≦ 2% (N7-EA). Ähnliche Werte ergaben sich nach Inkubation von Rattenleber-DNS mit ENU-1-14C in vitro. Der Grad der initialen Purinbasen-Äthylierung in der DNS verschiedener Gewebe bietet somit keine Erklärung für die Nervensystem-Spezifität der carcinogenen Wirkung von ENU. Ein signifikanter Unterschied zwischen Gehirn und anderen Geweben wurde dagegen hinsichtlich der Eliminationsrate von O6-EG aus der DNS beobachtet. Während sich für N7-EG und N3-EA jeweils ähnliche Eliminationsraten ergaben, wurde O6-EG aus Gehirn-DNS sehr viel langsamer eliminiert (t 1/2∼229 Std) als aus Leber-DNS (t 1/2∼36 Std) oder aus der DNS anderer vereinigter Gewebe (t 1/2∼54 Std). Die unterschiedliche Fähigkeit der Zielzellen, O6-EG aus ihrer DNS zu eliminieren, ist daher neben der Häufigkeit der DNS-Replikation möglicherweise ein bestimmender Faktor für die Wahrscheinlichkeit einer neoplastischen Transformation.
    Notes: Summary The ethylation of nucleic acids by the nervous system-specific pulse-carcinogen N-ethyl-N-nitrosourea (ENU) was investigated in different tissues of the fetal, 10-day-old, and adult BD IX rat, and compared with data on the ethylation of rat-liver nucleic acids by the hepatocarcinogen diethylnitrosamine-1-14C. One hour after a pulse of ENU-1-14C, the molar fractions of N7-ethylguanine (N7-EG), O6-ethylguanine (O6-EG), N3-ethyladenine (N3-EA), and N7-ethyladenine (N7-EA) were similar in the DNA of “high-risk” (fetal or 10-day-old brain) and “low-risk” tissues (e.g. liver), and independent of the fraction of cells engaged in DNA replication at the time of the ENU pulse. The average relative yields of these ethylated bases after ethylation of DNA by ENU-1-14C in vivo were 54% (N7-EG), 28% (O6-EG), 17% (N3-EA) and ≦ 2% (N7-EA). Similar values were obtained after incubation of rat liver DNA with ENU-1-14C in vitro. The initial degree of base ethylation in the DNA of different tissues does not provide an explanation for the nervous system-specificity of the carcinogenic effect of ENU. It was, therefore, of interest to find a significant difference between brain and other tissues with regard to the elimination rate from DNA of O6-EG. While the respective elimination rates of N7-EG and N 3-EA were similar, O6-EG was removed from brain DNA much more slowly (t 1/2∼229 h) than from liver DNA (t1/2∼36 h) or from the DNA of other pooled tissues (t1/2∼54 h). The capacity of the target cell to eliminate O6-EG from its DNA, together with the frequency of DNA replication may be an important factor in determining the probability of neoplastic transformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304382
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Synchronisation in vivo: Temporäre Inhibition der DNA-Synthese durch Hydroxyharnstoff in normalen und malignen Säugerzellsystemen (1971)
    Springer
    Journal of cancer research and clinical oncology 76 (1971), S. 266-292 
    Details
    ISSN: 1432-1335
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Bearbeitung einer Reihe von Problemstellungen der experimentellen und klinischen Krebsforschung setzt die Möglichkeit einer Synchronisation proliferierender Zellsysteme in vivo voraus. Dies gilt z. B. für die Frage, ob bei Säugerzellen als Funktion ihrer Position im Zellcyclus Empfindlichkeitsunterschiede vorhanden sind, und zwar sowohl hinsichtlich der Auslösbarkeit des Prozesses der malignen Transformation durch Cancerogene, als auch in bezug auf die Inaktivierbarkeit maligner Zellen durch cytocide Agentien oder ionisierende Strahlung. In der vorliegenden Arbeit wird über Untersuchungen zur in vivo-Synchronisation verschiedener Gewebe (Embryo; Leber; Milz; transplantabler BICR/M1R-Tumor) der Ratte durch temporäre Blockade der DNA-Synthese mit Hydroxyharnstoff (HU) berichtet. HU inhibiert die DNA-Synthese in vivo spezifisch, rasch und nahezu vollständig. Das rasche Absinken der HU-Konzentration im Organismus unter den zur Hemmung der DNA-Synthese erforderlichen Schwellenwert gestattet eine hinreichend verzögerungsfreie Beendigung von DNA-Syntheseblocks, wie sie für eine effektive Synchronisation erforderlich ist. Nach ein- oder mehrmaliger Pulsapplikation von HU sind die Halbwertszeiten (t1/2) für die HU-Konzentration in BICR/M1R-Tumorgewebe und Blut annähernd gleich. Die t1/2-Werte im Blut von Maus (13 min), Ratte und Mensch verhalten sich wie etwa 1∶2∶8. In den gemessenen Zellsystemen der Ratte erfolgte die Aufhebung der DNA-Syntheseblocks bei Unterschreiten einer HU-Konzentration von 1–5×10−5 Mol/103 g (Ausnahme: Rattenembryo, ∼2×10−4 Mol/103 g). Die Inhibitorwirkung einer bestimmten, im Blut gemessenen HU-Konzentration kann mit Hilfe des 3H-Thymidineinbaus durch Inkubation entsprechender Blutplasmaproben mit Referenzzellen in vitro bestimmt werden. Cytotoxische Effekte von HU, die wahrscheinlich vorwiegend auf blockierte S-Zellen beschränkt sind, waren besonders deutlich bei Zellen vom lymphatischen Typ. Als Modellsystem für die Analyse der Proliferationskinetik nach ein- und mehrmaligen DNA-Syntheseblocks von verschiedener Dauer diente der BICR/M1R-Tumor. Die Ergebnisse zeigen, daß durch Anwendung eines Inhibitors der DNA-Synthese vom Typ des HU unter kontrollierten Bedingungen eine partielle Synchronisation proliferierender Zellen in vivo erreicht werden kann.
    Notes: Summary The synchronous passage of proliferating cells through defined phases of the cell cycle is a prerequisite for the study of a number of problems associated with carcinogenesis and cancer therapy. It is particularly required for investigations of the differential sensitivity of mammalian cells in specific phases of the cell cycle to agents capable of initiating the process of malignant transformation, or causing cell death. The present study is concerned with the in vivo synchronisation of different rat tissues (embryo; liver; spleen; transplantable BICR/M1R tumor) by temporary specific inhibition of DNA synthesis with hydroxyurea (HU). In the cell systems investigated, HU inhibited DNA synthesis rapidly and almost completely. On the other hand, the short half-life (t1/2) of the inhibitor in the organism permitted a termination of blocking periods without delay, as required for effective synchronisation. Following single or multiple doses of HU, the t1/2 values for the HU concentration in BICR/M1R tumor tissue and rat blood were nearly identical. t1/2 in rat and human blood exceeded the corresponding value for the mouse (13 min) by factors of about 2 and 8, respectively. In the rat cell systems investigated, DNA synthesis resumed when the HU concentration decreased below a level of 1–5×10−5 moles/103 g (exception: rat embryo; ∼2×104 moles/103 g). The inhibitory effect of a specific blood concentration of HU on cellular DNA synthesis after in vivo administration of the inhibitor can be measured by the reduction of 3H-thymidine incorporation in reference cells exposed to the respective blood plasma samples in vitro. Cytotoxic effects of HU, which are often confined to cells blocked in S, were particularly evident in cells of the lymphatic type. The BICR/M1R tumor served as a model cell system for the analysis of the kinetics of cell proliferation after single and multiple blocks of varying duration. The results show that partial synchronisation of proliferating cells in vivo can be obtained by temporary inhibition of DNA synthesis under controlled conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304031
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Sensitization of clonogenic malignant cells to hyperthermia by glucose-mediated, tumor-selective pH reduction (1982)
    Springer
    Journal of cancer research and clinical oncology 104 (1982), S. 23-30 
    Details
    ISSN: 1432-1335
    Keywords: Neurogenic rat tumors ; Clonogenic tumor cells ; Glucose ; Tumor-selective pH reduction ; Hyperthermia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fraction of clonogenic cells (as assayed by colony formation in semisolid agar medium) in neurogenic TV1A tumor transplants carried subcutaneously by hyperglycemic BDIX rats (serum glucose concentration 50 mmoles/l; average intratumoral pH 6.1) was reduced by a factor of approximately 2.5x103 after in vivo exposure to 42.2°C for 1 h. The corresponding reduction factor for TV1A tumors in normoglycemic rats was about 20 (serum glucose concentration 6 mmoles/l; average intratumoral pH 6.9). Hyperglycemia without hyperthermic treatment reduced clonogenicity by a factor of about 18 (“glucose-mediated suicide”).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402050
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...