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  • 1990-1994  (3)
  • Nitrate (as inductor)  (2)
  • Renal insufficiency
  • 1
    ISSN: 1432-2048
    Schlagwort(e): Glutamine synthetase ; Nitrate (as inductor) ; Nitrite reductase ; Phytochrome (as inductor) ; Sinapis (nitrate assimilation)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The extent to which the appearances of nitrite reductase (NIR; EC 1.7.7.1) and glutamine synthetase (GS; EC 6.3.1.2) are coordinated was studied in mustard (Sinapis alba L.) seedlings. It was established by immunotitration that the increased activities of NIR and GS in the presence of light and nitrate can be attributed to the de-novo synthesis of enzyme protein. The bulk of the NIR and GS was found in the developing cotyledons. In the absence of nitrate in the growth medium there was no coordinate appearance of NIR and GS. While light strongly stimulated the appearance of GS, the level of NIR was hardly affected and remained low. On the other hand, in the presence of nitrate in the medium the appearances of NIR and GS were strictly coordinated, the GS level being considerably above that of NIR. It is argued that phytochrome-controlled synthesis of GS in the absence of nitrate is part of the mechanism to reassimilate ammonium liberated during proteolysis of storage protein and metabolism of the resulting amino acids, whereas the strictly coordinated synthesis in the presence of light and nitrate indicates the dominance of nitrate assimilation under these circumstances. The fact that the level of GS was always considerably above that of NIR appears to be a safety measure to prevent ammonium accumulation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-2048
    Schlagwort(e): Glutamine synthetase ; Nitrate (as inductor) ; Nitrite reductase ; Phytochrome (as inductor) ; Sinapis (nitrate assimilation)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The extent to which the appearances of nitrite reductase (NIR; EC 1.7.7.1) and glutamine synthetase (GS; EC 6.3.1.2) are coordinated was studied in mustard (Sinapis alba L.) seedlings. It was established by immunotitration that the increased activities of NIR and GS in the presence of light and nitrate can be attributed to the de-novo synthesis of enzyme protein. The bulk of the NIR and GS was found in the developing cotyledons. In the absence of nitrate in the growth medium there was no coordinate appearance of NIR and GS. While light strongly stimulated the appearance of GS, the level of NIR was hardly affected and remained low. On the other hand, in the presence of nitrate in the medium the appearances of NIR and GS were strictly coordinated, the GS level being considerably above that of NIR. It is argued that phytochrome-controlled synthesis of GS in the absence of nitrate is part of the mechanism to reassimilate ammonium liberated during proteolysis of storage protein and metabolism of the resulting amino acids, whereas the strictly coordinated synthesis in the presence of light and nitrate indicates the dominance of nitrate assimilation under these circumstances. The fact that the level of GS was always considerably above that of NIR appears to be a safety measure to prevent ammonium accumulation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    ISSN: 1432-1440
    Schlagwort(e): Endothelin ; Hypertension ; Coronary artery disease ; Renal insufficiency ; Rheumatoid arthritis ; Lupus erythematodes ; Liver cirrhosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Plasma concentrations of the recently isolated potent vasoconstrictory peptide endothelin were measured in 382 patients. The investigations were performed by means of a sensitive radioimmunoassay specific for Endothelin-1, 2. The results from 110 healthy volunteers displayed a normal range of 44.67±3.51 pg/ml. Significantly raised levels were found in 33 patients with chronic end-stage renal failure both before and after hemodialysis. In contrast, 35 patients with compensated renal insufficiency did not differ from the normals. Sixty-five patients after kidney transplantation revealed significantly elevated levels, as did 27 patients with acute myocardial infarction, 8 after coronary bypass surgery, and 5 with liver cirrhosis. The mean values of 27 patients with untreated hypertension, 22 with secondary hypertension, of various causes and 16 with coronary artery disease were comparable to the normal population. The values were significantly decreased in 9 pregnant women with hypertension and proteinuria. A marked decline was found in 5 patients with systemic lupus erythematodes, while 20 patients with rheumatoid arthritis demonstrated only a slight decrease. The pathophysiological role of endothelin as a local or circulating hormone in regulating systemic blood pressure or release of other hormones remains to be determined.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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