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Biomedical subjects

S Rasmussen

Publications and source records attributed to S Rasmussen.

At least 163 records · Page 9Linked to original sources
PubMed1986

Renal handling of angiotensins I and II in patients with renovascular hypertension.

Plasma renin (PRC) and angiotensin I (pANG I) and II (pANG II) concentrations were determined at renal vein catheterization in 38 hypertensive patients suspected of renal or renovascular aetiology. Veno-arterial differences in pANG I across the affected kidney in patients with lateralization of the renin secretion indicated release of angiotensin I (ANG I) in considerable amounts. Veno-arterial differences in pANG II of around zero indicated that generation and elimination of angiotensin II (ANG II) were equal in that kidney. Across the contralateral kidney the veno-arterial differences in PRC and pANG II were both close to zero, while negative differences in pANG II indicated the removal of ANG II. In patients without lateralization of the renin secretion the veno-arterial differences in pANG I were close to zero or positive, those of pANG II being close to zero or negative. In 14 of the 38 patients, data were obtained either during maintenance treatment with captopril or after a single dose of this converting enzyme inhibitor. Systemic PRC and pANG I values were extremely high and pANG II values low. The pANG I gradient across the affected kidney was further increased compared with pre-captopril levels, whereas the contralateral kidney still eliminated ANG I.

Adolescent↗
PubMed1986

Converting enzyme inhibition in mild and moderate essential hypertension. II.

In 24 patients with mild/moderate essential hypertension, we studied the effects of captopril with/without hydrochlorothiazide (Htz) on blood pressure, the renin-angiotensin system, blood bradykinin concentration (BBK), plasma volume, exchangeable sodium and glomerular filtration. Daily captopril doses of 75 and 150 mg were equally effective in reducing the blood pressure. Addition of Htz caused further blood pressure reductions. Nineteen patients attained a diastolic blood pressure less than or equal to 90 mmHg. Angiotensin converting enzyme inhibition with captopril led to a fall in plasma concentrations of angiotensin II (PAII) and renin substrate, and an increase in plasma concentrations of renin and angiotensin I. Patients starting with Htz had a higher PAII and subsequently a larger fall in blood pressure on captopril than untreated patients. BBK remained unchanged, indicating that the hypotensive action of captopril does not involve an accumulation of circulating kinin. Body fluid volumes and renal function were not affected by the various treatment regimens.

Adult↗
PubMed1986

Haemodynamic and humoral effects of lower body negative pressure in normal, sodium-replete man during angiotensin-converting enzyme inhibition with captopril.

The significance of the renin-angiotensin system (RAS) for circulatory homeostasis during gravitational stress (10 min of lower body negative pressure, LBNP, at -40 mmHg) was investigated in eight men on liberal sodium intake. The function of RAS was inhibited by a single oral dose of 100 mg captopril, an angiotensin-converting enzyme inhibitor. Plasma concentrations of renin and angiotensin I were normal before and increased after captopril and during LBNP. Plasma concentration of angiotensin II was normal before captopril, increased during LBNP, and fell to low values after captopril. Systolic blood pressure decreased more during LBNP after captopril than in the control situation. In three cases, the LBNP experiment after captopril had to be interrupted due to marked hypotension. Heart rate and plasma concentration of adrenaline increased above pre-captopril levels. In six subjects, plasma concentration of noradrenaline increased more during LBNP after captopril, less in two subjects, whereas the arginine vasopressin concentration increased more after captopril in all five subjects where measurements were available. The results demonstrate that RAS participates in blood pressure homeostasis also in sodium-replete, normal man. The enhanced increases in heart rate and plasma catecholamines after captopril do not suggest that sympathetic reflex activity during gravitational stress is blunted after captopril, in contrast to the evidence from animal experiments.

Adult↗
PubMed1986

The influence of the renin-angiotensin system on adrenergic vasoconstrictor responses in the forearm and splanchnic region in sodium deplete man.

In sodium deplete subjects forearm (FBF) and splanchnic (SBF) blood flows were measured at rest and during lower body negative pressure (LBNP) before and during angiotensin II (ANG II) blockade. Both FBF and SBF were reduced by LBNP. Forearm blood flow and forearm vascular resistance were unaffected by ANG II blockade (intra-arterial saralasin, n = 6; i.v. enalapril, n = 9) both at rest and during LBNP. In contrast, resting SBF increased and splanchnic vascular resistance decreased after i.v. enalapril (n = 10). The low resistance was completely unchanged during the following LBNP. It is concluded that acute ANG II blockade has no influence on the vascular resistance in the human forearm, but increases basal SBF in sodium depleted subjects and 'paralyses' the vasoconstrictor response to LBNP.

Angiotensin II↗
PubMed1985

A shear test evaluation of a new, modified, unfilled resin.

A shear test was conducted under simulated oral environmental conditions to examine the retention of a new, commercially available modified unfilled resin in comparison with a conventional unfilled resin provided by the same manufacturer. Within the experimental limits of this study no difference was observed between the retention of the conventional and the modified unfilled resins to enamel specimens. However, for dentin specimens the modified resin was clearly superior to the conventional resin, which gave essentially zero retention. With the recommended procedure, the retention of the modified resin to dentin was 13% of that for the retention of either resin to enamel. It was also observed microscopically that the new resin demonstrated good wetting ability of the dentinal surface. The retention of the two resins to dentin with various surface treatments was determined. The recommended surface preparation procedures of cleaning the dentin surface with hydrogen peroxide followed by a water rinse gave equivalent, if not superior, results to a 1-minute etch with phosphoric acid or citric acid followed by a water rinse.

Acid Etching, Dental↗
PubMed1985

Urinary excretion of kallikrein before and after operation for aldosterone-producing adenoma.

Urinary kallikrein excretion (UKal), determined by the esterase method, was measured in 10 normotensive volunteers, 10 patients with essential hypertension and in 7 patients with primary aldosteronism before and after operative removal of the adenoma. UKal values were low in 5 of the patients with essential hypertension. Preoperative UKal values in the patients with aldosteronism did not differ significantly from those of the normal subjects, but decreased in all after operation in parallel with changes in urinary excretion of tetrahydroaldosterone and plasma aldosterone concentration. The study supports the assumption of an association between the renal kallikrein-kinin system and the mineralocorticoid state in man.

Adenoma↗
PubMed1985

Converting enzyme inhibition in mild and moderate essential hypertension. I. Acute effects on blood pressure, the renin-angiotensin system and blood bradykinin after a single dose of captopril.

The acute effects of 25 mg captopril on blood pressure, heart rate, components of the renin-angiotensin system and blood concentration of bradykinin were followed in a single-blind placebo study of untreated (group A, n = 15) and thiazide-treated (group B, n = 13) patients with mild or moderate essential hypertension. A drug-related fall in blood pressure was seen in both groups. The blood pressure reduction was more marked in group B than in group A. Heart rate remained unchanged. Plasma concentrations of angiotensin II decreased significantly with concurrent increases in plasma concentrations of renin and angiotensin I, indicating the in vivo inhibition of converting enzyme. Blood concentrations of bradykinin showed no systemic changes. The magnitude of blood pressure reduction was correlated both with the pretreatment levels and the concurrent decreases in plasma angiotensin II. Inhibition of angiotensin II formation can explain a large part of the acute hypotensive pharmacological action of captopril. Other vasoactive systems may be involved. The kallikrein-kinin system does not appear to participate as indicated by the unchanged concentrations of kinin in blood.

Adult↗
PubMed1985

Paroxetine in the treatment of depression--a randomized comparison with amitriptyline.

Paroxetine is a new antidepressant drug with potent serotonin (5HT) uptake inhibitory properties. In this double-blind comparative study, the antidepressant effect of paroxetine and amitriptyline has been compared in 44 patients with depressive illnesses of an endogenous nature. Each drug was given for 6 weeks. The 17-item Hamilton Depression Scale was used to measure the antidepressant effect. Reported events were assessed applying a 22-item check list. Non-parametric statistical analyses were applied in the evaluation of treatment outcome for the 30 patients who completed the study. The results showed no significant differences in overall antidepressant efficacy between paroxetine and amitriptyline and that paroxetine displayed significantly fewer instances of dry mouth and orthostatic dizziness than amitriptyline. No obvious relationship was demonstrated between the plasma levels of the drugs and their clinical effects.

Adult↗
PubMed1985

Deterioration of renal function during angiotensin converting enzyme inhibition in hypertensive patients with a poorly functioning solitary kidney.

During treatment with the angiotensin converting enzyme inhibitor, Captopril, glomerular filtration rate (GFR) decreased in three unilaterally nephrectomized hypertensive patients with a poorly functioning remaining kidney. The fall in GFR was not related to changes in the blood pressure, and was reversed when Captopril was stopped. In a fourth nephrectomized patient the initially normal GFR was not affected by captopril. These observations point to a functional reduction in GFR due to a withdrawal of an intrarenal action of angiotensin II. Maintenance of GFR may become critically dependent on a functioning renin-angiotensin system when renal perfusion pressure is reduced to a certain degree. Inhibition of angiotensin II formation may lead to a decrease in GFR in patients with renal hypertension and pre-existing renal insufficiency.

Aged↗
PubMed1984

Dose-response relationship in normal subjects of prenalterol, a beta-adrenergic agonist with positive inotropic and resistance lowering effects.

The acute haemodynamic effects of increasing doses of parenterally administered prenalterol-a beta-adrenergic stimulating drug-were assessed in normal subjects by means of radionuclide ventriculography. Prenalterol induced dose-related increases in the left ventricular ejection fraction and the systolic pressure end-systolic volume ratio. Left ventricular end-systolic and end-diastolic volumes decreased to the same extent accounting for an unchanged stroke volume. Cardiac output increased due to a rise in the heart rate. Systolic blood pressure increased, whereas diastolic and mean blood pressure remained unchanged. Calculated total peripheral resistance decreased significantly. The maximum effect of prenalterol on cardiac performance occurred with a dose of 18 to 36 micrograms/kg. Plasma concentrations of prenalterol showed large interindividual variations. In conclusion, prenalterol improves the pump function of the normal heart and causes a fall in peripheral vascular resistance, implying a reduction of the load on the heart. These effects may prove beneficial in the treatment of acute heart failure.

Adrenergic beta-Agonists↗
PubMed1984

Effect of diethylpyrocarbonate on the biological activities of botulinum neurotoxin types A and E.

The single chain (unnicked) type-E and the dichain (nicked) type-A botulinum neurotoxins were modified with diethylpyrocarbonate (ethoxyformic anhydride), a reagent highly specific for histidine residues. The type-E neurotoxin could be completely detoxified without causing detectable damage to its serological reactivity. Under identical modification reaction conditions, the type A was incompletely detoxified with some alteration in its serological reactivity. Modification of histidine residues was evident from the increase in absorbance at 240 nm, and reactivation of the detoxified proteins by reversing the modification with hydroxylamine. The completely detoxified type-E neurotoxin, used as toxoid, elicited antibodies in rabbits. The antiserum precipitated and neutralized the neurotoxin. This toxoid is homogeneous as tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas the traditional toxoid produced with formaldehyde is heterogeneous.

Animals↗
PubMed1984

Accuracy of absolute left ventricular volumes and cardiac output determined by radionuclide cardiography.

We determined left ventricular (LV) volumes and derived variables by gated equilibrium radionuclide imaging at rest and during exercise in 12 patients without valve disease or intracardiac shunts. LV volume was determined as the product of the background-corrected LV count rate and an individual attenuation correction factor divided by the count rate in peripheral blood. Attenuation correction was based on measurement of LV depth within the chest from an initial first pass study in the left lateral view and a linear attenuation coefficient of 0.156 cm-1 determined in phantom studies. The average LV depth was 8.0 cm (range 6.9-9.1) in agreement with an average depth measured by echocardiography of 8.2 cm (6.3-9.4), P much greater than 0.05. The correlation between radionuclide (RC) and simultaneous thermodilution (TD) measurements was for cardiac output (CO): r = 0.95; CO (RC) = 1.00 X CO (TD) + 0.10 1/min with a standard error of the estimate (SEE) of 0.79 1/min; for stroke volume (SV): r = 0.90; SV(RC) = 0.93 X SV (TD) + 5 ml; SEE = 8 ml; for end-diastolic volume (EDV): r = 0.96; EDV(RC) = 1.06 X EDV(TD) -14 ml; SEE = 27 ml; and for end-systolic volume (ESV): r = 0.98; ESV(RC) = 1.05 X ESV (TD) -6 ml; SEE = 20 ml. The interobserver variation, expressed as the coefficient of variation, was for cardiac output 6%, for stroke volume 6%, for end-diastolic volume 4%, and for end-systolic volume 5%. This method permits non-invasive determination of LV volume and total LV output per beat based exclusively on data obtained during radionuclide imaging.

Adult↗
PubMed1984

Echocardiographic detection of ischemic and infarcted myocardium.

The purpose of this study was to determine the potential of a clinically adaptable two-dimensional echocardiographic system using computer enhancement and a mathematically defined integrated backscatter ratio for the early detection of ischemic and infarcted myocardium. Fifteen dogs had two-dimensional echocardiograms recorded during either open chest coronary occlusion (n = 5), closed chest occlusion (n = 5), occlusion followed by reperfusion (n = 3) or sham coronary occlusion (n = 2). A serial increase in integrated backscatter ratio, representing differences in returned ultrasound intensities between a reference point and specific myocardial regions, was detected between 7 and 12 minutes of complete occlusion in 9 of 12 animals (p less than 0.05), and at minutes 18, 43 and 67 in the remaining 3 animals. Reperfusion after 20 minutes of occlusion in two studies resulted in normalization of the backscatter ratio. An increase in backscatter ratio was not detected when 5 minute occlusion periods were used or during the 5 hour sham occlusion studies. The computer enhancement techniques utilized in this study provided increased visual detail of intracardiac structures over that provided by routine two-dimensional echocardiograms; myocardial tissue was identifiable in what appeared to be echo-free segments; and boundaries that appeared as noncontiguous horizontal lines on the routine echocardiograms were identifiable as trabeculae. The results indicate that: 1) significant increases in backscatter from nonperfused myocardium are detectable echocardiographically within 12 minutes of coronary occlusion and temporal changes can be assessed in the canine model, and 2) the echocardiographic data acquisition and computer analysis system utilized provide a clinically adaptable approach to identify and map myocardial characteristics in human beings.

Animals↗
PubMed1984

The renin-angiotensin system during converting enzyme inhibition with captopril in patients with severe treatment-resistant hypertension.

The effect of captopril on blood pressure (BP) and various components of the renin-angiotensin system was assessed in ten severely hypertensive patients. Captopril acutely reduced the BP with a maximum decrease of 23% at 90-120 min. Maintenance treatment with captopril alone could not control the BP in any of the patients. Addition of hydrochlorothiazide markedly reduced the BP, while supplementation with propranolol caused no consistent changes. Three patients attained a supine diastolic blood pressure (SDBP) less than or equal to 90 mmHg. Only two patients had a fall in SDBP less than 10 mmHg. One patient stopped because of taste disturbances. Monitoring the renin-angiotensin system showed suppressed plasma concentrations of angiotensin II and increased levels of angiotensin I and renin, indicating the inhibition of converting enzyme activity. Plasma concentration of renin substrate decreased significantly. This observation has important implications for the methodology of renin assays. Captopril is an effective alternative in the treatment of hypertensive patients not readily controlled with conventional therapy.

Adult↗
PubMed1984

The influence of ACE-inhibition by captopril on renal formation and metabolism of angiotensins I and II in patients with renovascular hypertension.

Fourteen patients with hypertension of presumed renovascular etiology were studied by renal vein catheterization. Unilateral renin secretion was found in 8 patients. In 4 of these patients a positive veno-arterial difference of plasma angiotensin I concentration (PAI) across the affected kidney increased markedly after a single dose of captopril. Across the contralateral kidney the net veno-arterial PAI difference changed from about zero before captopril to clearly negative values after captopril. The PAI values in the remaining 4 patients, who were already on captopril before the catheterization, were similar to those observed after a single dose of captopril. In patients with bilateral renin secretion the renal veno-arterial PAI differences across the kidneys were positive or close to zero before captopril. After captopril both positive and negative veno-arterial differences of PAI were observed. The plasma angiotensin II concentrations decreased after captopril to low values. These low values together with extremely high PAI values demonstrate effective ACE-inhibition. A high generation rate of angiotensin I in the affected kidney in patients with unilateral renin secretion after captopril is probably explained by activation of the local renin secretion. The angiotensin I "consumption" in the contralateral kidney after captopril in spite of no angiotensin II formation suggests the presence of alternative degradation processes for angiotensin I in the human kidney.

Adult↗