Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The α,α-Dimethyl-3,5-dimethoxybenzyloxycarbonyl (Ddz) Residue, an N-Protecting Group Labile toward Weak Acids and IrradiationThe synthesis of α,α-dimethyl-3,5-dimethoxybenzyloxycarbonyl azide (7) and its reactions with several amino acids are described. It is shown that the N-acyl residue can easily be cleaved from the Ddz-amino acids under weakly acidic conditions. Moreover it is possible to eliminate the protecting group by UV-irradiation in a continuous procedure without side reactions. Fission products of the acyl residue are isolated and identified.
    Notes: Die Synthese des α.α-Dimethyl-3.5-dimethoxybenzyloxycarbonylazids (7) und seine Umsetzung mit einer Reihe von Aminosäuren zu den Ddz-aminosäuren wird beschrieben. Es wird gezeigt, daß der neue N-Acyl-Rest leicht unter schwach sauren Bedingungen abgespalten werden kann. Außerdem ist es möglich, die Schutzgruppe in einem kontinuierlichen Verfahren durch Bestrahlung mit UV-Licht ohne Nebenreaktionen zu entfernen; dabei entstehende Spaltstücke der Schutzgruppe werden isoliert und identifiziert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antamanide, XI. - Merrifield Synthesis of Tyrosine-containing Analogues of AntamanideAnalogues of antamanide (AA) in which the phenylalanines in positions 5, 6, 9 and 10 are replaced by tyrosine are synthesized by punched tape programmed automatic synthesis on polystyrene resins. Tyrosine is used as its O-benzyl derivative: Tyr5-AA (1), Tyr6-AA (2), Tyr9-AA (3), Tyr10-AA (4), Ile1. Tyr6-AA (5), Ile1. Tyr5. Tyr10-AA (6), Gly1. Gly4. Tyr5-AA (7), Gly1. Gly4. Tyr6-AA (8), and Tyr9. de-Ala-AA (9). The cyclopeptides 1, 2 and 5 like AA protect in a dose of 0.5-1 mg per kg the white mouse from being killed by 5 mg phalloidine per kg, the analogue 3 with 2 mg per kg; 4 and 6 have the same effect with 5 mg per kg and the glycine-containing tyrosine-antamanides 7 and 8 are ineffective even with 20 mg per kg. The cyclononapeptide 9 without Ala4 of the antamanide sequence is found to be the first effective shortened analogues of AA with a protecting dose of 5-10 mg per kg.
    Notes: Analoge des Antamanids (AA), in denen die Phenylalanine der Positionen 5, 6, 9 und 10 durch Tyrosin ersetzt sind, werden durch Lochstreifen-programmierte, automatische Synthese der linearen Decapeptide-Vorstufen an Polystyrolharzen unter Verwendung von O-Benzyl-tyrosin aufgebaut und zwar: Tyr5-AA (1), Tyr6-AA (2), Tyr9-AA (3), Tyr10-AA (4), Ile1. Tyr6-AA (5), Ile1. Tyr5. Tyr10-AA (6), Gly1. Gly4. Tyr5-AA (7), Gly1. Gly4. Tyr6-AA (8), und Tyr9. des-Ala-AA (9). Die Cyclopeptide 1, 2 und 5 schützen wie Antamanid mit ca. 1 mg pro kg die weiße Maus vor dem Tod durch 5 mg Phalloidin pro kg, die Variante 3 mit 2 mg pro kg; 4 und 6 wirken mit 5 mg pro kg, während die Glycin-haltigen Tyrosin-Antamanide 7 und 8 noch mit 20 mg pro kg unwirksam sind. Im Cyclononapeptid 9, dem das Ala4 der Antamanidsequenz fehlt, liegt das erste wirksame, verkürzte Antamanid-Analog vor; es schützt die Maus bei einer Dosis von 5-10 mg pro kg.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1573-6903
    Keywords: Chromaffin cells ; cell culture ; defined media ; neuronotrophic factors ; catecholamines ; neuronal plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Adult bovine and young rat chromaffin cells cultured in serum-free medium were examined for their survival and differentiation following exposure to various additives, trophic agents and conditioned media. Adrenal chromaffin cells dissociated from 8 day old rats were maintained by dexamethasone, NGF and CNTF or without any additives in an N1-supplemented medium in similar numbers as in serum-containing medium for up to 6 days. Neuritic growth elicited by NGF or CNTF was enhanced in the absence of serum. Medium conditioned by purified bovine chromaffin cells improved cell survival and caused neurite outgrowth in a dose-dependent manner. The activiti(es) was sensitive to heat and trypsin and not blocked by the addition of anti-NGF antibodies. Bovine chromaffin cell survival was reduced by 30% when cells were maintained for one week in the absence as compared to the presence of serum. Addition of insulin, the N1 supplement, dexamethasone or dbcAMP single or in combinations improved the survival to different extents. A combination of insulin (5 μg/ml) and dexamethasone (5×10−6M) proved to be optimal in this respect. However, these supplements failed to restore the cellular catecholamine, noradrenaline and adrenaline contents to levels seen in the presence of serum. This was also true for a chromaffin cell-conditioned medium, which improved survival without elevating the catecholamine contents. Conditioned medium, however, partly restored a more physiological adrenaline-noradrenaline-ratio.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...