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  • Plasmareninaktivität  (3)
  • chromatin  (3)
  • high-mobility-group (HMG) proteins  (2)
  • 1
    ISSN: 1432-1440
    Keywords: Hypertension ; plasma renin activity ; plasma aldosterone ; salt depletion ; salt loading ; Hypertonie ; Plasmaaldosteron ; Plasmareninaktivität ; Natriumentzug ; Natriumbelastung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 40 Patienten mit primärer Hypertonie Stadium I, 19 Patienten mit primärer Hypertonie Stadium II und III sowie bei 11 Patienten mit renaler Hypertonie (chronische Glomerulonephritis, chronische Pyelonephritis) wurde das Verhalten des Plasmaaldosterons, der Plasmareninaktivität sowie der Elektrolyte im Serum und Urin unter akuter Stimulation durch Salzentzug (Furosemid) und unter akuter Suppression durch Kochsalzinfusion geprüft. Die überwiegende Mehrzahl der Patienten mit primärer Hypertonie Stadium I zeigt eine gute Stimulierbarkeit des Plasmaaldosterons und der Plasmareninaktivität durch akuten Salzentzug. 3 von 40 Patienten mit primärer Hypertonie Stadium I und 13 von 19 Patienten mit primärer Hypertonie Stadium II und III hatten eine nicht stimulierbare Reninsekretion (“low renin hypertension”). Die Stimulierbarkeit des Plasmaaldosterons war jedoch bei allen diesen Patienten intakt. Unter Kochsalzbelastung fanden wir in allen Gruppen eine Supprimierbarkeit des Plasmaaldosterons und der Plasmareninaktivität. Die gute Stimulierbarkeit des Aldosterons bei Patienten mit fehlender Stimulierbarkeit der Plasmareninaktivität zeigt, daß unter unseren Versuchsbedingungen das Renin-Angiotensin-System bei Hochdruckkranken nicht für die gesteigerte Aldosteronsekretion bei Salzentzug verantwortlich sein kann. Wahrscheinlich erfolgt der Plasmaaldosteronanstieg bei Starre der Reninsekretion über den diuretikabedingten Natriumentzug. Ein inadäquates Verhalten der Aldosteronsekretion in Bezug auf akute Kochsalzbelastung besteht bei Patienten mit primärer Hypertonie nicht. Bei renoparenchymalem Hochdruck fand sich eine abgeschwächte Stimulierbarkeit und Supprimierbarkeit der Plasmareninaktivität. Das Plasmaaldosteron stieg auf Natriumentzug ebenfalls nur gering an und der Abfall nach Natriumchloridgabe war statistisch nicht signifikant. Beim renoparenchymalen Hochdruck liegt damit in Bezug auf Natriumchloridentzug und Natriumchloridzufuhr ein inadäquates Verhalten der Aldosteron- und Reninsekretion vor.
    Notes: Summary Plasma aldosterone, plasma renin activity, sodium and potassium in the plasma and the urine were determinated under acute stimulation with saline depletion (furosemide) and under acute suppression with saline infusion in 40 patients with primary hypertension stage I, 19 patients with primary hypertension stages II and III, and II patients with renal hypertension (chronic glomerulonephritis and chronic pyelonephritis). The majority of the patients with primary hypertension stage I showed a good stimulation of the plasma aldosterone and the plasma renin activity under acute salt depletion. Three out of the 40 patients with primary hypertension stage I, and 13 of the 19 patients with primary hypertension stages II and III did not show any stimulation of the renin secretion (“low renin hypertension”). In all these patients the plasma aldosterone stimulation remained intact. With infusion of saline all the groups showed suppression of the plasma aldosterone and the plasma renin activity. A good stimulation of the plasma aldosterone in spite of the lack of stimulation of the plasma renin activity, demonstrates that in our experiments the renin-angiotensin system cannot be responsible for the increase in aldosterone secretion under salt depletion. Most likely the increase of the plasma aldosterone, in spite of the fixed renin activity, is stimulated by the sodium depletion due to diuretics. In all patients with primary hypertension we did not find an inadequate reaction of the aldosterone secretion under saline infusion. The patients with renal hypertension showed a minimal stimulation and suppression of the plasma renin activity. The plasma aldosterone secretion increased only slightly under sodium depletion and the decrease under saline infusion was statistically not significant. Thus we conclude that these patients show an inadequate reaction of the plasma aldosterone and renin secretion under salt infusion and depletion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 55 (1977), S. 351-353 
    ISSN: 1432-1440
    Keywords: Plasma renin activity ; Long-term treatment ; Propranolol ; Essential hypertension ; Propranolol ; Essentielle Hypertonie ; Plasmareninaktivität ; Langzeitbehandlung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 17 Patienten im Alter von 40±9 Jahren mit essentieller Hypertonie wurden mit Propranolol als Monotherapie oral in Dosen von 120, 160 oder 240 mg pro die behandelt. Nach 4wöchiger Behandlung konnten der Blutdruck und die Herzfrequenz statistisch signifikant gesenkt werden und blieben auch bei Fortsetzung der Therapie nach insgesamt 6 Monaten unverändert. Die Plasmareninaktivität betrug vor Behandlungsbeginn 5,7±6,3 ng/ml/h und sank nach 4wöchiger Behandlung auf 1,8±1,3 ng/ml/h ab. 5 Monate später stieg das Plasmarenin im Durchschnitt wieder auf 5,0±0,9 ng/ml/h an. Der erneute Anstieg war ebenfalls statistisch signifikant zu sichern. Von den 17 Patienten hatten nach 6 monatiger Therapie noch 7 (41%) eine niedrigere Plasmareninaktivität als vor Behandlungsbeginn. Davon lagen aber nur 3 (18%) unter dem Wert, der nach 4wöchiger Behandlungsdauer bestimmt wurde. Aus den genannten Befunden wird geschlossen, daß der Wiederanstieg der Plasmareninaktivität möglicherweise ein reaktiver Mechanismus auf die langzeitige Blutdrucksenkung ist. Die Erniedrigung der Plasmareninaktivität nach Kurzzeitbehandlung mit Propranolol kann nicht als ein Mechanismus für den antihypertensiven Effekt dieses Medikaments bei der Langzeitbehandlung angesehen werden.
    Notes: Summary 17 patients (40±9 years) with essential hypertension were included in the study. A monotherapy of 120, 160 or 240 mg propranolol per day was administered orally according to the antihypertensive effect. Four weeks after treatment, blood pressure and heart rate showed a statistically significant decrease and remained unchanged over a period of six months. Plasma renin activity decreased significantly from 5.7±6.3 ng/ml/h at the beginning of the study to 1.8±1.3 ng/ml/h after 4 weeks. 5 months later however plasma renin activity increased again to 5.0±0.9 ng/ml/h. The difference was statistically significant. From 17 patients 7 (41%) had lower levels of plasma renin activity after 6 months treatment when compared with pretreatment values. In only 3 patients (18%) was plasma renin activity lower after 6 months than after four weeks. We conclude that the increase in plasma renin activity is a reactive mechanism to the reduced blood pressure under long-term conditions. The decrease of plasma renin activity in short-term treatment of essential hypertension is not a mechanism responsible for the antihypertensive effect of propranolol during long-term treatment.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 51 (1973), S. 875-882 
    ISSN: 1432-1440
    Keywords: Hypertension ; plasma renin activity ; hydralazine ; theophylline ; sodium restriction ; Hypertonie ; Plasmareninaktivität ; Hydralazin ; Theophyllin ; Natriumentzug
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Es wird über die Plasmareninaktivität im Nierenvenenblut bei 50 Patienten mit primärer und renaler Hypertonie nach Gabe von Hydralazin und Theophyllin berichtet. Die nach diesen Pharmaka beobachtete Stimulation der Reninsekretion beim Gesunden und bei Kranken mit labiler Hypertonie bleibt bei der Mehrzahl der Patienten mit fortgeschrittener primärer Hypertonie aus. Die Stimulierbarkeit bzw. Starre der Reninsekretion durch Natriumentzug zeigt ein analoges Verhalten. 2. Ursächlich kommt für den Plasmareninanstieg nach Hydralazin in erster Linie der Blutdruckabfall in Betracht, der zu einer Erregung der Baroreceptoren im terminalen Vas afferens führt. Für Theophyllin wird eine Erregung der Chemoreceptoren an der Macula densa angenommen. 3. Die fehlende Stimulierbarkeit der Reninsekretion bei Patienten mit fortgeschrittener primärer Hypertonie, die sich sowohl nach Hydralazin wie nach Theophyllin oder Natriumentzug zeigt, führen wir auf eine verminderte Ansprechbarkeit der Receptoren des juxtaglomerulären Zellkomplexes zurück, die als adaptiver Mechanismus aufgefaßt werden kann.
    Notes: Summary 1. Plasma renin activity in venous renal blood was determined in 50 patients with primary and renal hypertension, prior to and following administration of hydralazine and theophylline. While in patients with moderate degrees of hypertension, stimulation of renin secretion occurred in the same manner as in healthy subjects, renin could not be stimulated in the majority of patients suffering from advanced primary hypertension. The responsiveness of renin secretion to sodium restriction showed an analogous pattern. 2. Causally, the increase in the plasma renin activity after administration of hydralazine can be related to the decrease of blood pressure, via the stimulation of baroreceptors in the terminal afferent arteriole. A stimulation of chemoreceptors at the macula densa can be supposed in the case of theophylline. 3. There is some evidence that the lack of response to hydralazine, theophylline, and sodium restriction in renin secretion in patients with advanced primary hypertension, is probably due to a reduced sensitivity of the receptors of the juxtaglomerular cell complex in the sense of an adaptive mechanism.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 41 (1999), S. 351-361 
    ISSN: 1573-5028
    Keywords: chromatin ; gene expression ; high-mobility-group protein HMG1 ; HMGe ; protein stability ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nuclear HMG1 proteins of higher plants are small non-histone proteins that have DNA-bending activity and are considered architectural factors in chromatin. The occurrence of the chromosomal HMG1 proteins, HMGa, HMGc1/2 and HMGd, in various maize tissues was analyzed, and in the course of these studies a novel HMG1 protein, now termed HMGe, was identified. Purification and characterization of HMGe (Mr 13 655) and cloning of the corresponding cDNA revealed that it displays only moderate similarity to other members of the plant HMG1 protein family. The five maize HMG1 proteins could be detected in kernels, leaves, roots and suspension culture cells, indicating that these proteins can be expressed simultaneously and occur relatively ubiquitously. However, the various HMG1 proteins are present in significantly different quantities with HMGa and HMGc1/2 being the most abundant HMG1 proteins in all tissues tested. Furthermore, the relative amounts of the various HMG1 proteins differ among the tissues examined. The HMG1 proteins were found to be relatively stable proteins in vivo, with HMGc1/2, HMGd and HMGe having a half-life of ca. 50 h in cultured cells, while the half-life of the HMGa protein is ca. 65 h. Collectively, these findings are compatible with the concept that the different plant HMG1 proteins might act as general architectural proteins in concert with site-specific factors in the assembly of certain nucleoprotein structures involved in various biological processes.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5028
    Keywords: chromatin ; high-mobility-group (HMG) proteins ; Vicia faba ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromosomal high-mobility-group (HMG) proteins occur ubiquitously in eukaryotes and their common structural and biochemical features indicate a critical role. In this context, we compared structural and functional aspects of HMG proteins from the monocotyledonous plant maize and the dicotyledonous plant Vicia faba. Besides biochemical similarities and immunological differences found between these proteins, the isolation and characterization of a cDNA encoding the V. faba homologue of the maize HMGa protein revealed great similarities between these two proteins, including the HMG-box DNA-binding motif and an acidic domain. Therefore, like the maize HMGa protein, the V. faba HMG protein belongs to the vertebrate HMG1 family, which consists of HMG proteins and transcription factors of various eukaryotes.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 25 (1994), S. 565-568 
    ISSN: 1573-5028
    Keywords: chromatin ; high-mobility-group (HMG) proteins ; protein stability ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromosomal non-histone high-mobility-group (HMG) proteins represent essential components of eukaryotic chromatin and have also been isolated from a variety of plants. In maize, studies on structure and function of the two larger of the four major HMG proteins have recently been performed and are now extended by analysis of theirin vivo stability using pulse-chase experiments in a cell suspension culture. The half-life of the analyzed HMGa and HMGb proteins was found to be 65 h or more than 78 h, respectively.
    Type of Medium: Electronic Resource
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