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  • Phosphorus  (6)
  • hypertension  (5)
  • Springer  (11)
  • PANGAEA
  • 1980-1984  (11)
  • 1983  (11)
Sammlung
Verlag/Herausgeber
  • Springer  (11)
  • PANGAEA
Erscheinungszeitraum
  • 1980-1984  (11)
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 70 (1983), S. 107-124 
    ISSN: 1573-5036
    Schlagwort(e): Citrate ; Iron ; Lupins ; Lupinus albus L. ; Phosphorus ; Polymers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Large quantities of citrate ions have been shown to be secreted by the roots ofLupinus albus. It is postulated that these react in the soil to form ferric hydroxy phosphate polymers which diffuse to the root surface where they are degraded by the action of reducing agents in the presence of an Fe II uptake mechanism balanced by hydrogen ion secretion. Some known chemical behaviour of Fe III and citrate which supports this postulate is reviewed. Evidence is also presented which suggests that much of the Fe absorbed circulates within the root system and is subsequently precipitated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 24 (1983), S. 15-19 
    ISSN: 1432-1041
    Schlagwort(e): hypertension ; mianserin ; clonidine ; methyldopa ; depression ; α2 receptors ; interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The concurrent administration of tricyclic antidepressants has been shown in man to result in a clinically significant impairment of the antihypertensive effect of clonidine. This interaction is thought to be related to competition for central α2 receptors where clonidine acts as an agonist and the tricyclics act as antagonists. Although it seems to cause less cardiovascular effects than tricyclic antidepressants, the tetracyclic antidepressant, mianserin also has been reported to be an α receptor antagonist and may, therefore, also interfere with the antihypertensive activity of centrally-acting drugs. This study investigates the effects of acute and chronic mianserin administration in patients with essential hypertension established on long term treatment with either clonidine or methyldopa. The first dose of mianserin was not associated with an increase in blood pressure and during a further two weeks of mianserin therapy there were no significant alterations in blood pressure, supine or erect. Similarly, mianserin did not alter heart rate either after acute or after chronic administration. Mianserin itself had a sedative effect but there was no interference with the sedation attributable to clonidine or methyldopa. Mianserin caused no reduction in salivary flow and did not influence the reduced saliva production caused by clonidine. Both clonidine and methyldopa are associated with a reduction in sympathetic outflow but there was no evidence in this study of any further change in plasma noradrenaline or 24 h urinary catecholamine excretion. This study demonstrates that if mianserin is given acutely or chronically, it does not interfere with the effects of the centrally acting antihypertensive drugs, clonidine and methyldopa. Mianserin may therefore be a suitable antidepressant for patients receiving these antihypertensive agents if drug treatment for depression is indicated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 25 (1983), S. 463-466 
    ISSN: 1432-1041
    Schlagwort(e): guanfacine ; hypertension ; phenobarbital ; withdrawal syndrome ; enzyme induction ; pharmacokinetics ; renal insufficiency
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The unusual observation of a withdrawal syndrome due to guanfacine in a hypertensive patient with chronic renal failure led to a study of the kinetics of the drug in this patient. The principal pharmacokinetic parameters of guanfacine were greatly altered, with extended biotransformation and a decrease in the half-life compared to the values observed in other cases of severe renal insufficiency. Associated treatment with phenobarbital had had a considerable effect, as shown by the results of a further kinetic study 2 months after withdrawal of the phenobarbital. The findings then were in good agreement with reference values which strongly suggests a consequence of the enzyme inducing effect of phenobarbital. Advice about the dosage regimen in such cases is given.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 25 (1983), S. 481-490 
    ISSN: 1432-1041
    Schlagwort(e): propranolol ; pharmacokinetics ; pregnancy ; hypertension ; naphthoxylactic acid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of propranolol (P) and its major metabolites, propranolol glucuronide (PGLUC), 4-hydroxypropranolol (4OHP), 4-hydroxypropranolol glucuronide (4OHPGLUC) and naphthoxylactic acid (NLA), (Walle et al. 1972) were determined, whenever possible, in the first, second and third trimesters of pregnancy in thirteen patients and also when these patients were at least three months post-partum. No correlations were found between the mean arterial blood pressure (post-therapy) or the fall in blood pressure as a result of the P therapy (p〉 〉0.05) and P dose, peak P plasma concentrations, peak 4-hydroxypropranolol (4OHP) plasma concentrations or peak (P plus 4OHP) plasma concentrations. However, a positive nonlinear relationship was found between the daily P dose (independent variable) and peak P plasma concentrations over the daily dose range 30–160 mg/day. The elimination half-lives of NLA for patients in the third trimester of pregnancy were significantly shorter (p=0.072, df=13) than those when the patients were at least three months post-partum. Also, the areas under the plasma level-time curves of NLA were significantly less (p〈0.05, df=13) for patients in the third trimester of pregnancy than when these patients were at least three months post-partum. The results of this study indicate that the pharmacokinetics of P, PGLUC, 4OHP and 4OHPGLUC are not significantly altered by pregnancy. However, the kinetics of NLA do appear to be altered. The formation of NLA by N-dealkylation of P and further oxidation, appears to be competitively inhibited by unidentified substances, perhaps endogenous steroids, especially in the third trimester when compared to at least three months post-partum.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 25 (1983), S. 571-575 
    ISSN: 1432-1041
    Schlagwort(e): beta-blocker ; felodipine ; calcium antagonist ; hypertension ; vasodilator ; side effects ; plasma levels ; metoprolol ; propranolol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In a double-blind, cross-over trial, 10 men with primary hypertension, not adequately controlled with a β-blocker alone, were also given felodipine or placebo for periods of one week. Placebo was administered single-blind for 2 weeks and 1 week, respectively, before randomization and between treatments. The dose of felodipine ranged from 6.25 mg to 25 mg. The addition of felodipine resulted in a pronounced (20%), statistically significant reduction in blood pressure (BP) and a small but significant increase in heart rate (HR). The effects were seen within 1–2 h and were maximal after 3–4 h. During steady state treatment the duration of BP reduction was at least 12 h. No orthostatic reaction was seen. There was a significant correlation between the plasma concentration of felodipine and change in BP. The most frequently reported side-effects were headache and ankle oedema, the latter probably being due to pronounced pre-capillary vasodilatation. There was no weight increase and thus no indication of general water retention. No clinically significant change in laboratory variables and no influence on the P-Q time were seen. Thus, felodipine in combination with a β-blocker seems to be a useful addition to the treatment of hypertensive patients whose BP is not adequately controlled with a β-blocker alone.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1432-1041
    Schlagwort(e): furosemide ; hypertension ; plasma renin activity ; plasma adrenaline ; plasma noradrenaline ; body fluid loss ; diuretic response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary To evaluate the role of adrenergic mechanisms in the acute response of renin to furosemide, plasma renin activity (PRA) and plasma catecholamine concentrations were measured for 3 h after i.v. administration of furosemide 1 mg/kg to 8 patients with mild essential hypertension. Furosemide induced a prompt and long-lasting increase in renin, with PRA more than doubled at all times. The increase in PRA within the first 30 min paralleled the peak increases in urinary water and sodium flow rates, and significant decreases in plasma volume and central venous pressure. There was no change in plasma catecholamine concentrations. Plasma noradrenaline was increased significantly at 60 min and adrenaline at 90 min, once furosemide had induced a marked loss of body-fluid and ∼65% decrease in central venous pressure. Both catecholamines remained elevated until the end of the study, whereas urinary water and sodium flow rates had returned to their pre-treatment values by 150 min. Mean blood pressure was essentially unchanged throughout the study, whereas heart rate increased significantly after 90 min. The findings suggest that in mildly hypertensive patients adrenergic mechanisms are not involved in the initial renin response to furosemide, but they come into play later, probably as a result of reflex sympathetic activation triggered by marked volume depletion.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 71 (1983), S. 23-35 
    ISSN: 1573-5036
    Schlagwort(e): Apple ; Mycorrhizas ; Phosphorus ; Root activity ; Root growth ; Water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The paper reviews information, much of it obtained from studies using the East Malling root observation laboratories, on the growth and development of the fruit tree root system. The production of new white root varies from year-to-year, generally being highest in the early years. As trees age, woody roots constitute an increasing fraction of total root length although the contribution made by new root growth to the total root length of established trees is also affected by soil management, being higher for trees under grass than under herbicide. Soil management also affects the balance of short (lateral) to long (extension) roots; under grass there are more lateral roots. Calculation of the rate of water uptake per unit root length needed at various times in the year to meet transpirational demand, suggests that woody roots, which recent experimental work has shown to be capable of absorbing water, must be responsible for much of total water supply. Measurements of VA mycorrhizal infection in field-grown trees indicated, for part of the season, higher per cent infection in trees grown under irrigated grass than under herbicide management. It is suggested that this, which is associated with raised leaf phosphorus levels, may be due at least partly to higher numbers of lateral roots, the root type which becomes infected. The growth and functioning of the root system under field conditions depend upon the production and integration of a range of root types.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 72 (1983), S. 85-90 
    ISSN: 1573-5036
    Schlagwort(e): Chickpea ; Manganese ; Phosphorus ; Yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Phosphorus and Mn relationship was studied in chickpea at two stages of growth in pot culture using 0, 7.5, 15 and 30 ppm P and 0, 5, 10 and 15 ppm Mn. The dry matter yield increased with P at both stages of growth. Manganese improved the yield only in the first stage. Initial levels of Mn enhanced while higher levels had a depressing effect on tissue P. Addition of 7.5 ppm P enhanced Mn concentration at first stage and at higher levels a marked reduction in Mn content was observed at both the stages.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 71 (1983), S. 463-467 
    ISSN: 1573-5036
    Schlagwort(e): Anion uptake ; Barley ; Hordeum vulgare ; Mycorrhiza ; Phosphorus ; pH Rhizosphere ; Triticum aestivum ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary In two field experiments sown in 1982 to test the effect of vesicular-arbuscular mycorrhizas (VAM) on growth and phosphorus nutrition of (i) spring wheat and spring barley, (ii) winter wheat and winter barley, we measured the concentrations of the major cation (K+, Ca2+, Mg2+ and Na+) and anions (Cl−, SO4 2−, H2PO4 − and NO3 −) in shoot tissue. In all cases the sum of the anion concentrations (ΣA) was increased strongly by mycorrhizal infection but not by P additions, confirming earlier observations2 on spring wheat. The concentration of total cations (ΣA) was generally reduced by P additions, hence P and VAM both reduced the cation excess (ΣC−ΣA) but by different mechanisms. These results suggest that increased uptake of anions by plants with VAM may be a general phenomenom which would have important implications for the elemental composition of crops. The effect may also be manifested by other types of mycorrhizal association.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 1573-5036
    Schlagwort(e): Ammonification ; Eh ; Flooded soils ; Iron ; Manganese ; Nitrate reduction ; Phosphorus ; pH ; Salinity and extractable cations ; Zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The electro-chemical and chemical kinetics of six California rice soils were significantly influenced by the presence of salts up to an EC of 9 mmhos/cm in saturation extract (ECe). Subsamples of each soil salinity treatment were incubated for periods up to 10 weeks after flooding. Most of the changes in Eh and pH values took place in the first 3–4 weeks after submergence. Salinity decreased pH values, but slightly increased the redox-potential. Both ammonification and nitrate reduction were significantly decreased, by increasing soil salinity. Salinity up to 9 mmhos/cm did not affect levels of Bray and Kurtz extractable P, but increased the water extractable Ca, Mg, K and Mn. In DTPA extract, salinity in incubated soils had no effect on Zn in 4 soils, but it decreased Fe in acid and neutral soils. Possible explanations for the electro-chemical and chemical kinetic changes due to flooding and salinity are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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