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Biomedical subjects

A Rappelli

Publications and source records attributed to A Rappelli.

At least 91 records · Page 5Linked to original sources
PubMed1982

Active and inactive renin during acute reduction of renal perfusion pressure in essential hypertensives.

Arterial and renal venous active and inactive renin were studied in 5 patients with long established moderate hypertension following unilateral acute reductions of renal perfusion pressure (15% and 70% of control) by inflating a balloon catheter introduced into the right renal artery. This procedure failed to induce the expected release of active renin; total and inactive renin levels were also unchanged. On the contrary in a single normotensive patient smaller reductions of the renal perfusion pressure (-15% and -30%) were able to acutely increase the release of active renin with a concurrent conversion of inactive renin but without inducing blood pressure changes. These findings show that the renin pattern typical of unilateral renovascular hypertension, including the intrarenal activation of inactive renin, could be reproduced acutely in a normotensive subject. Moreover, a complete reversal of the above mentioned active and inactive renin pattern was observed in a recent onset renovascular hypertensive patient within 30 min from successful percutaneous transluminal dilation. The negative results observed in our hypertensive patients suggest that structural changes induced by the long duration of hypertension might have reduced the sensitivity of the baroceptors involved in renin release.

Adult↗
PubMed1982

Persistence of unilateral secretion and contralateral renin suppression after successful percutaneous transluminal dilatation in a normotensive patient.

We describe a case of a 26-year old woman with severe fibromuscular renal artery stenosis whose blood pressure was well controlled with atenolol but that remained normotensive also after discontinuation of the drug. In addition her renal vein renin pattern was typical of renovascular hypertension and an intrarenal activation of inactive renin was also present. This renin pattern remained unchanged soon after successful percutaneous transluminal dilatation whereas 15 days later both active and inactive forms of renin were found to be released by the previously stenotic kidney. This case casts doubts upon the relationships between renal artery stenosis, renin secretion and high blood pressure.

Adult↗
PubMed1982

Multicenter evaluation of mepindolol and of mepindolol plus hydrochlorothiazide in essential hypertension.

The effect on systolic (SAP) and diastolic (DAP) arterial blood pressure of 5 mg mepindolol daily vs 12.5 mg hydrochlorothiazide daily vs 5 mg mepindolol plus 12.5 mg hydrochlorothiazide daily was evaluated in this multicenter study. After a 2-week washout period with placebo, 138 patients with mild to moderate essential hypertension (WHO Class I and II), homogeneous for age and blood pressure values, were randomly allocated to one of the three treatment groups. Arterial blood pressure and heart rate were obtained at the beginning and at the end of the washout placebo period, and after 2, 4, and 6 weeks of active treatment. At the beginning and at the end of the study, all patients underwent a thorough clinical and laboratory evaluation, including blood chemistry, electrocardiogram, and chest roentgenogram. A trend toward normalization of blood pressure was defined as a lowering of DAP to 90 mmHg or at least a 10-mmHg decrease from the control value. Statistical analysis was performed on all the data. After 6 weeks of treatment, SAP and DAP values were significantly reduced in 67% of the patients in all groups. In 71% of patients on mepindolol plus hydrochlorothiazide a particularly more marked decrease in DAP was observed. Mepindolol was well tolerated: side effects were generally mild and inconsequential. The results show that mepindolol, given as a single oral dose of 5 mg, is an effective agent in the treatment of mild to moderate essential hypertension. Because of its efficacy, the advantage of single daily administration, and lack of important side effects, it can increase compliance to therapy. Moreover the association of mepindolol plus hydrochlorothiazide appears to be safe and effective.

Blood Pressure↗
PubMed1981

Optimum tryptic activation of inactive renin in human plasma is independent of endogenous anti-tryptic activity.

1. Plasma samples from 31 normal subjects were treated (at 4 degrees C, pH 7.0, for 2 min) with different concentrations of trypsin (500, 1000, 2000, 3000 and 4000 microgram/ml) in order to assess which concentration yielded the maximum activation of inactive renin. 2. Endogenous antitryptic activity was also measured in all samples; the mean value +/- SD (in microgram of trypsin inhibited by 1 ml of plasma) was 953 +/- 550 microgram/ml (range 34-1800 microgram/ml). 3. In the entire group of subjects the values of trypsin-activated renin measured with trypsin at 2000 microgram/ml were significantly higher than those obtained with lower or higher trypsin concentrations. 4. With subjects divided into subgroups according to their endogenous anti-tryptic activity, the maximum yield of activation was reached with trypsin at 2000 microgram/ml. 5. No significant correlations were found between single values of active, inactive or trypsin-activated renin and the corresponding levels of endogenous anti-tryptic activity. However, a weak but significant correlation (r = 0.39, P less than 0.05) was found between single values of anti-tryptic activity and the corresponding percentage of activation of inactive renin. 6. Thus the maximum activation of inactive renin at 4 degrees C for 2 min is obtained with trypsin at 2000 microgram/ml independently of the corresponding endogenous anti-tryptic activity. It is not excluded that the content of protease inhibitors in human plasma might affect the proportion in vivo of circulating active and inactive renin.

Adult↗
PubMed1981

Trypsin activation of inactive renin in human plasma. An assessment of some methodological aspects.

The following methodological aspects of the use of trypsin as activator of inactive renin in human plasma have been studied: a) the effect of SBTI on renin activity and angiotensin; b) the reaction velocity of trypsin on inactive renin; c) the optimum trypsin concentration; d) the ability of human plasma to neutralize exogenous trypsin. Our results show that: 1) Some commercially available SBTI may exert an angiotensinase-like effect which can be abolished by PMSF. 2) At 4 degrees C activation of inactive renin reached a maximum within the first two minutes then no further activation could be demonstrated. 3) Trypsin 2 mg/ml yielded more inactive renin than trypsin 1 or 0.5 mg/ml. A higher concentration (3 mg/ml) gave substantially equivalent activation as (with) trypsin 2 mg/ml whereas when using a still higher concentration (4 mg/ml) a degradation of the renin system components could be noted. 4) Endogenous trypsin inhibitors can eventually inactivate exogenous trypsin up to 3 mg/ml. About 20% of renin is destroyed by trypsin 4 mg/ml within 2 min at 4 degrees C while an additional 40% is lost during the incubation at 37 degrees C if no SBTI is added.

Enzyme Activation↗
PubMed1981

[Role of renin profile and age in the choice of the therapeutic approach of arterial hypertension (author's transl)].

A group of 116 patients with grade I-II (W.H.O.) essential hypertension was studied. A diuretic treatment was instituted as a first step of therapy in 50 patients while the remaining 66 were firstly treated with beta-blockers. After 6 weeks of treatment the drugs were combined in those patients who did not achieve blood pressure control; this combination therapy was again maintained for 6 weeks and, if necessary, a vasodilating agent was added thereafter. The results show that with diuretic treatment alone diastolic blood pressure was brought to normal values (less than 95 mmHg) in 3/4 of our low renin patients, in 2/3 of normal renin and in 1/3 of high renin hypertensives. On the contrary among the group of patients treated with a beta-blocker alone more than half of the high and normal renin patients were controlled whereas this goal was achieved in only 1/4 of the low renin patients. Similar behaviour was observed subdividing the subjects in young (less than 35 yrs), middle-aged (36-49 yrs) and older (greater than 50 yrs) patients. In conclusion our data indicate that age must be taken into account in classifying hypertensive patients in renin subgroups. In addition if a renin-sodium profile is available, it can be useful in choosing between diuretics or beta-blocker as a first step treatment. Alternatively, younger patients are more likely to have better hypotensive responses with beta-blockers whereas in older patients antihypertensive treatment should preferentially be started with diuretics alone.

Adrenergic beta-Antagonists↗
PubMed1980

[Methodology of renal vein renin study: comparison between simultaneous and sequential sampling (author's transl)].

Purpose of this study has been to compare the results obtained using two different procedures in blood sampling from the renal veins for measuring renal venous renin. The first is the classical procedure which employs three catheters for simultaneous sampling from both renal veins and from the inferior vena cava, or from an artery. The other one is a simplified procedure which employs a single catheter that allows blood to be collected in the following rapid sequential manner: right renal vein, inferior vena cava, left renal vein, inferior vena cava. We have studied 13 patients (8 with essential hypertension, 5 with unilateral renal artery stenosis). Two catheters were introduced through a femoral vein and inserted into both renal veins; a third catheter was inserted into the femoral artery; then the blood sampling was performed strictly simultaneously. Soon after, the blood sampling was repeated according to the above mentioned sequential single catheter procedure. PRA was measured by Angiotensin I radioimmunoassay, then the Renal Vein Ratios (RVRR) were calculated. Even though as average of less than 20 seconds elapsed between the blood sampling in a renal vein and that in inferior vena cava, our results demonstrate that the release of renin can vary so quickly that erroneous informations may be obtained unless a strictly simultaneous sampling of blood is performed. In conclusion, our study demonstrates that the only reliable renal vein renin sampling procedure must employ the simultaneous renal venous and arterial (or inferior vena cava) blood collection.

Adult↗
PubMed1978

Effects of levodopa alone and in combination with dopa-decarboxylase inhibitors on plasma renin activity in patients with Parkinson's disease.

Plasma renin activity (PRA) of patients with Parkinson's disease was measured in recumbency, upright position, and after frusemide administration. The results show that the renin responses to both stimuli are significantly reduced as compared with those obtained in a group of normal subjects, while recumbent PRA levels of Parkinsonism patients are not significantly lower than those found in recumbent normal subjects. Levodopa treatment, alone or in combination with two different dopa-decarboxylase inhibitors, benserazide and carbidopa, does not modify the renin response to posture or to frusemide. Although the reduced activity of the renin-angiotensin system can play some role in the genesis of orthostatic hypotensive episodes encountered in patients with Parkinsonism, the greater incidence of orthostatis hypotension in patients treated with levodopa seems to be unrelated to any effect of this drug on the renin release.

Adult↗
PubMed1975

[Coronary risk factors in 287 cases of myocardial infarct treated in a coronary unit].

The main coronary risk factors were estimated in a series of 287 myocardial infarct patients admitted to a coronary unit. Particular attention is drawn to smoking, arterial hypertesion, diabetes and hypercholesterolaemia in this respect. 24 cases in patients under 40 yr where cigarette smoking was by far the most important factor are examined more closely.

Adult↗
PubMed1975

Heart block and hyperthyroidism. Report of two cases.

In two patients with hyperthyroidism who had no signs of heart disease, first-degree heart block with tall and large P waves occurred. In one patient, a left bundle-branch block and transient complete heart block with Stokes-Adams episodes also occurred, although there was no verifiable evidence of acute inflammatory disease.

Adams-Stokes Syndrome↗