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  • Articles: DFG German National Licenses  (3)
  • 1995-1999  (2)
  • 1990-1994  (1)
  • 1970-1974
  • 1965-1969
  • Chemistry  (1)
  • Electrophysiology  (1)
  • Key words Telomerase  (1)
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  • Articles: DFG German National Licenses  (3)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of clinical oncology 4 (1999), S. 338-342 
    ISSN: 1437-7772
    Keywords: Key words Telomerase ; Bile duct carcinoma ; Malignancy grade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background. Studies of human tumors and human tumor cell lines indicate that telomerase activity may play a critical role in the tumor cell growth by sustaining cellular immortality. Telomerase activity has been detected in different percentages in various carcinomas, but the incidence of positive telomerase activity in bile duct carcinomas and surrounding normal bile duct tissues in its relation with malignancy grades of tumors, depth of invasion, lymphatic and vascular invasion, and lymph node metastases has not been studied. Methods. Telomerase activity was assayed in surgically resected specimens of seven human bile duct carcinomas and seven adjacent nonneoplastic tissues using the PCR-based Oncor TRAP (a telomeric repeat amplification protocol)-eze telomerase detection kit. The correlation between the results of telomerase activity and clinicopathological data was examined. Results. The telomerase activity was detected in six of seven (86%) bile duct carcinoma cases with only one negative case in our series, whereas no telomerase activity was detected in nonneoplastic adjacent bile duct tissues. Although the number of cases in our study was small, telomerase activity was regarded as independent of tumor grade, depth of invasion, lymphatic and intravascular invasion, or lymph node metastasis. Conclusions. These results indicate that increased telomerase activity is a common phenomenon in the majority of bile duct carcinomas, and that it is negative in nonneoplastic bile duct tissues.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-136X
    Keywords: Octopamine ; Juvenile hormone ; cAMP ; Cockroach ; Electrophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Juvenile hormone production by the corpora allata of the adult female cockroach, Diploptera punctata, can be modulated by treatment with the biogenic amine, octopamine. Endogenous octopamine has been identified within the CA, using HPLC and electrochemical detection. Treatment with octopamine results in a sinusoidal, dose-dependent inhibition of JH biosynthesis by CA from day 2 virgin females, with maximal inhibition occurring at 10-10 M and 10-4 M. In day 4 and day 8 mated female corpora allata octopamine inhibited JH biosynthesis at 5·10-5 M. Although the elevation of either cAMP or cGMP within the CA is known to be associated with an inhibition of JH biosynthesis, treatment with high concentrations of octopamine results in an increase in the level of cAMP but not cGMP. This effect is both dose- and time-dependent. Octopamine treatment also initiates changes in the passive membrane responses of the CA. Superfusion of CA with octopamine results in a pronounced hyperpolarization of CA cells and an increase in the electrotonic potential (indicative of the degree of electrical coupling between CA cells). This effect could be blocked by the octopamine receptor blocker phentolamine. Treatment with octopamine or phentolamine also blocked the hyperpolarization of CA cells normally associated with electrical stimulation of the axon tracts innervating the CA. We hypothesize that octopamine may be a natural neuromodulator of JH production by CA, regulating ion channels in CA cells themselves as well as release of the inhibitory neuropeptide, allatostatin, from the terminals within the CA.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 28 (1995), S. 291-309 
    ISSN: 0739-4462
    Keywords: juvenile hormone ; methoprene ; pyriproxyfen ; fat body ; locust ; binding protein ; receptor ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Juvenile hormone (JH) binding components from the fat body of the African migratory locust were analyzed in a search for a potential nuclear JH receptor. Biosynthetically prepared 10R[3H]JH III gave a high proportion of specific binding to isolated nuclei and extracted proteins; data obtained with the JH analogs, [3H]methoprene and [3H]pyriproxyfen, on the other hand, were obscured by abundant non-specific binding. The vast majority of the high affinity JH III binding activity present in cytosolic and nuclear extracts was due to a high molecular weight JH binding protein (JHBP) which has previously been identified in locust hemolymph. This protein has several chromatographic forms which interfered in the search for a nuclear JH receptor. When specific antiserum was used to remove JHBP from nuclear extracts, a novel JH binding activity (NBP) was detected. NBP could be separated from JHBP by precipitation with ammonium sulfate. NBP displayed a high affinity for JH III (Kd = 0.25 nM) and JH I and JH II competed strongly for JH III binding, whereas methoprene and pyriproxyfen showed apparent competition when present in 1,000-fold excess. NBP was present in nuclear extracts at approximately 25,000 sites per cell; levels were similar in male and female locusts and were not greatly affected by the presence or absence of JH. The characteristics of NPB make it a strong candidate for a nuclear JH receptor. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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