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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 63 (1985), S. 989-999 
    ISSN: 1432-1440
    Keywords: Dehydration ; Hemodynamics ; Hypertension ; Vasopressin ; Vasopressin antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The two major biological actions of vasopressin are antidiuresis and vasoconstriction. The antidiuretic action of low concentrations of vasopressin is well established and concentrations 10 to 100 times above those required for antidiuresis elevate arterial blood pressure. Antidiuresis is mediated by V2-receptors at the kidney, whereas vasopressin constricts arterioles by binding at V1-receptors. Pharmacological effects of specific antagonists of the vasoconstrictor activity of vasopressin (vascular or V1-receptor antagonists) are presented. Low concentrations of vasopressin do have significant hemodynamic effects. Physiological concentrations of vasopressin cause vasoconstriction and elevate systemic vascular resistance. In subjects with intact cardiovascular reflex activity, however, cardiac output falls concomitantly and blood pressure therefore does not change. In animals with baroreceptor deafferentation or in patients with blunted baroreceptor reflexes (autonomic insufficiency) a rise in plasma vasopressin causes vasoconstriction and an increase in blood pressure, because cardiac output does not fall under these conditions. Vasopressin contributes substantially via increase in systemic vascular resistance to maintain blood pressure during water deprivation. During hemorrhage and hypotension vasopressin has a major role to restore blood pressure. In experimental hypertension vasopressin contributes to the development and maintenance of high blood pressure in DOCA, but not in genetic hypertensive rats. The role of vasopressin in human hypertension is not yet clear. Vasopressin in extrahypothalamic areas of the brain affects circulatory regulation by interaction with central cardiovascular control centers. The exact mechanism of how vasopressin is involved in central regulation of blood pressure remains to be established. In contrast to our previous opinion vasopressin is a vasoactive hormone also at low plasma concentrations. Its cardiovascular action is more complex than previously assumed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: oligonucleotide ; protamine sulfate ; artificial viral envelope ; confocal laser scanning microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The aim of this study was to characterize the intracellular fate and nuclear uptake kinetics of oligonucleotides (ON) that were complexed with protamine sulfate (PS) and negatively charged liposomes at different ratios of ON to PS. Methods. Double-fluorescence labelling of ON and liposomal lipid was applied to simultaneously monitor the interaction as well as the individual fate of active agent and carrier upon intracellular delivery using confocal laser scanning microscopy (CLSM). A DNA-analogue of a 68-mer intramolecular double-stranded RNA:DNA-hybridoligo- nucleotide (chimeraplasts) with unmodified phosphate backbone was employed. This construct was condensed with PS and coated with a liposomal formulation (AVE™-3 = artificial viral envelope). Results. PS-ON complexes and AVE™-3-coated complexes with a defined composition were very effective in nuclear transport of ON for a ON:PS charge ratio of 1:3. Nucleus:cytosol fluorescence ratios peaked at about 10 hrs and started to decrease again at 21 hrs. Conclusions. AVE™ associates with PS-condensed ON, and this complex is able to be taken up by cells and to deliver ON to the nucleus. PS-ON complexes are released from the liposomal formulation, mainly as an extranuclear enzymatic degradation of the liposomal phospholipids. The results of the kinetic analysis can be used to optimize transfection protocols with ON in HepG2 cells.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1440
    Keywords: Hyponatremia ; Vasopressin ; Thirst ; Diuretics ; Cardiac failure ; Cirrhosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Because hyponatremia is frequently associated with preceding diuretic treatment and unrestricted fluid indake — conditions which have not been addressed sufficiently in published literature — we studied the pathophysiology and the clinical setting of such hyponatremia in a large group of internal medicine patients. We observed: a) Of an initial 310 patients with chemical hyponatremia only 204 (64%) had an associated plasma hypoosmolality. Sience a normal plasma osmolality excludes a disturbance of water metabolism only the 204 patients with hypoosmolar hyponatremia were included in the study. This data shows that plasma osmolality is an essential measurement in any evaluation of hyponatremia. b) In 204 consecutive patients with hypoosmolar hyponatremia the electrolyte disturbance was related to advanced congestive cardiac failure in 25%, decompensated liver cirrhosis in 18%, volume contraction in 28%, syndrome of inappropriate antidiuretic hormone secretion in 19% and renal insufficiency in 4%. c) Plasma vasopressin was measurable in 90% of the 204 patients. It is known that radioimmunoassays to measure vasopressin fail to reliably detect low concentrations of circulating vasopressin (〈0.5 pg/ml). It may therefore be stated that hypoosmolar hyponatremia was generally characterized by a failure of antidiuretic hormone suppression. d) Mean daily fluid intake of hyponatremic patients was 2.35±0.15 l. In the presence of stimulated vasiopressin this large a fluid intake is bound to worsen the severity of hyponatremia. e) Of 204 patients 126 were treated with diuretics at the time of study. In these patients hyponatremia worsened during such treatments and was associated with evidence of prerenal azotemia. However there were no significant differences between diuretic-treated and -untreated patients with respect to plasma vasopressin stimulation and amount of fluid intake. In conclusion, stimulated vasopressin and high fluid intake explain the hyponatremia observed in the present study. This applied similary to diuretictreated and -untreated patients.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1238
    Keywords: Key words Intensive care ; Critical care ; Acute respiratory distress syndrome ; Persistent pulmonary hypertension of the newborn ; Feedback inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To examine the kinetics of successful nitric oxide (NO) withdrawal in vivo and in vitro.¶Design and setting: Prospective study in a university pediatric intensive care ward and research laboratory.¶Patients and materials: Nineteen patients with acute respiratory distress syndrome (ARDS) or persistent pulmonary hypertension of the newborn (PPHN). Primary porcine pulmonary artery cells in vitro.¶Interventions: NO inhalation and withdrawal in patients; exposure to NO donor sodium nitroprusside (SNP) and gaseous NO in vitro.¶Measurements and results: In patients: a slight, but significant, increase of oxygenation index (OI) from 4.57 ± 0.24 cmH2O/torr (mean ± SEM) to 4.90 ± 0.26 cmH2O/torr after withdrawal of NO (p 〈 0.001). Recovery of OI (4.43 ± 0.23 cmH2O/torr) 30 min after weaning, a significant drop after 4 h (3.72 ± 0.17 cmH2O/torr; p 〈 0.001), values restored after 12 h.¶In vitro: NO synthase (NOS) activity was significantly lower in SNP-incubated cells (20.0 ± 4.0 μm/min) than in control cells (37.6 ± 7.0 μm/min; p 〈 0.05). Thirty minutes after SNP withdrawal there was NOS activity of 35.8 ± 10.0 μm/min with a significant increase by 4 h (p 〈 0.05). No alteration of endothelial NOS (ENOS) mRNA expression by NO (Northern Blot).¶Conclusion: In patients there is a slight, but significant, reversible increase of OI after successful weaning from NO. In vitro, NO leads to a reversible decrease of ENOS activity on a post mRNA level, resembling clinical observations.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-198X
    Keywords: Hydrochlorothiazide ; Indomethacin ; Nephrogenic diabetes insipidus ; Prostaglandins ; Vasopressin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In four boys with congenital nephrogenic diabetes insipidus, plasma arginine-vasopressin (AVP) and urinary excretion of prostaglandins were studied in response to treatment with hydrochlorothiazide and indomethacin. An abnormal relationship between AVP and urine osmolality was demonstrated in all patients. In the first patient, treatment with indomethacin (3 mg/kg per day) resulted in a drop of the inulin and paraminohippurate clearances. In the other three patients urinary excretion of PGE2 was raised, and fell during treatment with hydrochlorothiazide (2 mg/kg per day) and indomethacin (2 mg/kg per day). Urine flow, free water clearance and osmolar clearance decreased during treatment. A combination of both drugs is more effective than hydrochlorothiazide alone and the effect appears to be additive.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric nephrology 3 (1989), S. 397-400 
    ISSN: 1432-198X
    Keywords: Aldosterone ; Atrial natriuretic peptide ; Chronic renal failure ; Dopamine ; Noradrenaline ; Sodium homeostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to evaluate the possible role of vasoactive hormones in the mechanism of exaggerated sodium loss due to reduced renal mass we measured plasma concentration of atrial natriuretic peptide (ANP), aldosterone, plasma renin activity (PRA), plasma noradrenaline, and dopamine, in 12 children with advanced chronic renal failure (mean CIn17.8-2.6,x± SEM, CPAH93.5±17 ml/min per 1.73 m2, FENa7.0±0.95%). No patient had clinical signs of volume overload. Plasma concentrations of ANP were not significantly different from those of healthy agematched controls (29.2±7.2 vs 23.2±3.1 fmol/ml) and did not correlate with urinary sodium excretion. Plasma concentrations of aldosterone, PRA and noradrenaline, were also within the physiological range, while plasma dopamine levels were elevated (260±36 vs 98±11 pg/ml, 〈0.001). Our data do not support the notion that ANP or the renin-aldosterone axis play a major role in the adaptation of remaining nephrons to maintain long-term sodium balance in normotensive children with chronic renal failure.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-198X
    Keywords: Tubular function ; Atrial natriuretic peptide ; Hypertension ; Acidosis ; Hyperkalaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 14-year-old boy with the syndrome of hypertension and hyperkalaemia with normal glomerular filtration rate (Gordon's syndrome) is described. The patient's clinical symptoms consisted of periodic paralysis, slight metabolic acidosis of the proximal type and hypercalciuria. Prostaglandin excretion was normal. Infusion of atrial natriuretic peptide had no effect on electrolyte excretion or glomerular function although a normal increase in cyclic guanosine monophosphate was demonstrated in plasma and urine. This lack of sensitivity to atrial natriuretic peptide offers a new pathophysiological concept in this syndrome. Treatment with hydrochlorothiazide was successful in this case.
    Type of Medium: Electronic Resource
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