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  • 1
    ISSN: 1432-1041
    Keywords: converting enzyme inhibitor ; CGS 14824A ; pharmacodynamics ; plasma renin ; plasma angiotensin ; aldosterone ; side-effects ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The converting enzyme inhibitor CGS 14824A was evaluated in 15 healthy male volunteers. First, the efficacy of a single 5 or 10 mg oral dose in antagonizing the pressor response to exogenous angiotensin I was tested in 2 subjects. Blood pressure and heart rate were monitored continuously through an intra-arterial catheter. CGS 14824A 5 mg reduced the response to angiotensin I within 75 min to 50%, and 10 mg within 1 h to less than 25%, and for a period of more than 4 h. Subsequently, plasma renin and converting enzyme activity, plasma angiotensin I, angiotensin II and aldosterone were measured serially before and up to 72 h following oral administration of 2, 5, 10 or 20 mg CGS 14824A to groups of 5 volunteers. Plasma converting enzyme activity fell to well below 10% of baseline within 1 h after administration of 5 mg or more CGS 14824 A. Within 2 h following 2 mg p.o., a similarly low level was reached. Twenty four hours following the 20 mg dose, plasma converting enzyme activity was still below 10%. As expected, plasma renin activity and angiotensin I rose while angiotensin II and aldosterone fell following the 2 mg dose. This pattern of effects was enhanced by increasing the dose. Nonetheless, 24 h after the 20 mg dose, plasma angiotensin II and aldosterone had returned to their baseline levels. No side-effects occurred. Thus, in normal volunteers, CGS 14824A was an effective, potent and long acting converting enzyme inhibitor.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 58 (1980), S. 1233-1241 
    ISSN: 1432-1440
    Keywords: Lymphocyte transformation ; Methylguanidine ; Phenol ; Urine metabolites ; Lymphozytentransformation ; Methylguanidin ; Phenol ; Urinmetabolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zur Differenzierung des bekannten hemmenden Effektes der potentiellen niedermolekularen „Urämietoxine“ Methylguanidin und Phenol auf die Lymphozytentransformation wurden beide Substanzen in steigender Konzentration Lymphozytenkulturen zugesetzt und3H-Thymidineinbau sowie LDH-Aktivität im Kulturmedium als Parameter des laufenden Lymphozytenuntergangs nach fünftägiger Inkubation gemessen. Für beide Substanzen findet sich sowohl in spontan transformierenden Kulturen als auch nach PHA-Stimulation eine dosisabhängige Transformationshemmung und ein ebenfalls dosisabhängiger Anstieg der LDH-Aktivität mit nahezu spiegelbildlichem Kurvenverlauf, so daß der Effekt beider Toxine offensichtlich in überwiegend cytotoxischer Herabsetzung der lymphozytären Überlebensdauer bestehen dürfte. In analoger Versuchsanordnung wurden weiterhin höhermolekulare Metabolite aus dem Urin von Gesunden und Patienten mit chronischer Niereninsuffizienz (kompensierte Retention) in steigender Konzentration Lymphozytenkulturen zugesetzt. Der auch hier zu registrierende dosisabhängige Abfall der spontanen und PHA-stimulierten Transformation sowie der spiegelbildliche LDH-Anstieg ist beim niereninsuffizienten Kollektiv in gleicher Konzentration gegenüber Gesunden leicht verringert, so daß eine Verschiebung zugunsten nichttoxischer Komponenten anzunehmen ist. Die um das 20–30fach höhere Exkretion dieser Metabolite bei diesen Patienten schließt aber eine Zuordnung zu den „Urämietoxinen“ im Sinne einer Retention im Serum aus.
    Notes: Summary In order to investigate the depressive effect of the hypothetical low molecular weight “uremic toxins” methylguanidine and phenol on lymphocyte transformation these substances were added to lymphocyte cultures with increasing concentrations.3H-thymidine uptake and LDH-activity in the supernatant culture medium as a parameter of continuous cell destruction were analyzed after incubation for 5 days. Both substances induced in spontaneous as well as in PHA-stimulated cultures dose-dependent depression of3H-thymidine uptake and a simultaneous increase in LDH-activity. Thus the effect of both toxins may be cytotoxic depression of lymphocyte viability. Furthermore in the same arrangement-way higher molecular weight metabolites from urine of healthy and chronic uremic persons were added in increasing concentrations to lymphocyte cultures. The same result: dose-dependent depression of transformation and increase of LDH-activity was slightly diminished by urine metabolites from uremic patients as compared to healthy persons. This may be due to a shift towards non-toxic compounds. But as these metabolites are excreted in 20–30 fold larger quantities in chronic renal insufficiency, an accumulation in the serum and classification as “uremic toxins” can be excluded.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1041
    Keywords: converting enzyme inhibitor ; blood pressure decrease ; exogenous angiotensin ; plasma angiotensin I and II ; plasma renin ; aldosterone ; healthy male volunteers ; CGS 13928C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The converting enzyme inhibitor CGS 13928C was evaluated in 15 healthy male volunteers. First the efficacy of a single oral dose of 0.5, 1, 2 or 5 mg in antagonizing the pressor response to exogenous angiotensin I was tested with continuous monitoring of the blood pressure and heart rate by an intraarterial catheter. CGS 13928C 1, 2 and 5 mg consistently reduced the response to angiotensin within 2 to 3 h and for a period exceeding the 4 h of monitoring. The 2 mg dose was hardly more effective than 1 mg and 5 mg did not further enhance the blockade. Subsequently, plasma renin and converting enzyme activity, angiotensin I, angiotensin II and aldosterone were measured serially before and up to 72 h following oral administration of either 1 mg (n=7) or 2 mg (n=8) CGS 13928C. As expected, plasma renin activity and angiotensin I rose, while plasma converting enzyme activity, angiotensin II and aldosterone fell following both doses of the drug. No side-effects occurred. In normal volunteers CGS 13928C is an effective and extremely potent, orally active converting enzyme inhibitor.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1041
    Keywords: converting enzyme inhibitor (CGS 14824A) ; blood pressure ; renin-angiotensin system ; healthy volunteers ; aldosterone ; haemodynamic effects ; plasma angiotensin II ; angiotensin converting enzyme ; plasma renin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A new, orally active angiotensin converting enzyme (ACE) inhibitor, CGS 14824A, was evaluated in 12 healthy male volunteers. Two groups each of 6 volunteers were given 5 or 10 mg once daily p.o. for 8 days. Four hours after the first and the last morning doses, plasma angiotensin II, aldosterone and plasma converting enzyme activity had fallen, while blood angiotensin I and plasma renin activity had risen. Throughout the study, more than 90% inhibition of ACE was found immediately before giving either the 5 or 10 mg dose and 50% blockade was still present 72 h following the last dose. Based on the determination of ACE, there was no evidence of drug accumulation. No significant change in blood pressure or heart rate was observed during the course of the study. CGS 14824A was an effective, orally active, long-lasting and well tolerated converting enzyme inhibitor.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1440
    Keywords: Uremia toxins ; lymphocyte transformation ; autohemolysis ; Urämietoxine ; Lymphozytentransformation ; Autohämolyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zur Frage einer toxischen Wirkung höhermolekularer Urinmetabolite durch Retention bei Urämie wurde der Effekt auf Lymphozytentransformation und Autohämolyse inkubierter Erythrozyten untersucht. Nach viertägiger Dialyse gegen Wasser wurde das lyophilisierte, nicht dialysable Retentat aus dem 24 Std Urin gesunder Personen mit einer Konzentration von 2,22 mg/ml in Medium TC 199 bzw. physiologischer Kochsalzlösung gelöst und davon steigende Mengen (0,1 bis 1,0 ml) Lymphozytenkulturen (3 × 106 Zellen in 4 ml Medium) und Erythrozyten (3 ml Vollblut nach Separation der Granulozyten) von 6 gesunden Blutspendern zugesetzt. Die durch Messung des3H-Thymidineinbaus nach fünftägiger Inkubation ermittelte spontane Lymphozytentransformation zeigte eine deutliche, dosisabhängige Hemmung bis auf 30,4% des Ausgangswertes, während der Abfall nach Stimulation mit 400 µg PHA nur bis 65,2% nachweisbar war. Die als Parameter des Zelluntergangs im Kulturmedium gemessene LDH-Aktivität wies in beiden Fällen einen dosisabhängigen Anstieg auf. Die negative Korrelation zu den3H-Thymidinwerten läßt als Hauptursache der verminderten Transformation einen vermehrten Zelluntergang annehmen. Die Autohämolyse der Erythrozyten zeigte einen dosisabhängigen Abfall bis auf 59,3% des Ausgangswertes. Höhermolekulare Urinmetabolite kommen demnach als Retentionsprodukte lediglich für die zytotoxische Teilwirkung urämischen Serums auf kultivierte Lymphozyten in Frage, während die gesteigerte Autohämolyse durch Toxine geringerer Molekülgröße ausgelöst wird.
    Notes: Summary Possible toxic effects of lyophilised not dialysable residue from urine of healthy persons obtained by 4 days dialysing against water were investigated. Therefore, the substance dissolved at a concentration of 2.22 mg/ml in Medium TC 199 respectively in physiological saline solution was added with increasing quantities (0.1 to 1.0 ml) to lymphocyte cultures (3 × 106 cells in 4 ml medium) and to erythrocytes (3 ml of blood after separation of granulocytes) from healthy persons. Spontaneous3H-thymidine uptake of the lymphocytes ascertained 5 days after beginning of incubation was markedly depressed with dependence upon the doses up to 30.4% of the control value, whereas only 65,2% was reached after stimulation with 400 µg PHA. In both cases LDH activity in the supernatant culture medium measured as a parameter of cell destruction showed a dose-dependent increase with inverse trend as compared to3H-thymidine uptake levels. This negative correlation may be due to impaired cell viability as the main cause for depressed lymphocyte transformation. The autohemolysis of the erythrocytes was diminished with dependence upon the doses until to 59.3% of the control value. Therefore, only cytotoxic effects of uremic serum on the lymphocytes may be due to higher molecular urine metabolites retained in uremia whereas increased autohemolysis will be induced by toxins of lower molecular weight.
    Type of Medium: Electronic Resource
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