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Biomedical subjects

B Waeber

Publications and source records attributed to B Waeber.

At least 379 records · Page 21Linked to original sources
PubMed1984

Hypotensive effect of human factor XII active fragment in conscious normotensive rats: role of bradykinin.

The active fragment derived from factor XII (factor XIIf) was purified from human plasma and administered intravenously to normotensive conscious rats. Factor XIIf-mediated hypotension was dose-dependent and augmented by pretreatment with captopril, an inhibitor of the bradykinin-processing enzyme kininase II. These results therefore suggest that factor XIIf-mediated hypotension is due to the formation of bradykinin.

Animals↗
PubMed1984

Long-term follow-up study of hypertensive patients by practicing internists after a controlled drug trial.

Thirty patients with uncomplicated essential hypertension were treated for an average of 44 months by 14 internists in private practice. All patients had previously participated in a controlled comparative trial of antihypertensive drugs carried out by the same physicians in their offices. During the long-term follow-up period, ie, after completion of the initial trial, the physicians administered antihypertensive therapy based on their best judgment; the drugs they most commonly prescribed were diuretics (80% of patients) and beta-blocking agents (60% of patients). Although 80% of the patients received at least two different antihypertensive agents, diastolic pressures fell below 96 mmHg in approximately 60% of the patients and below 90 mmHg in only a small fraction. Thus it appears that it is not easy for physicians in private practice to optimally reduce blood pressure levels in hypertensive patients despite the availability of numerous antihypertensive drugs. The tendency of practitioners to approximate blood pressure levels to multiples of 5 or even 10 mmHg may be partially responsible for the unsatisfactory results.

Antihypertensive Agents↗
PubMed1984

Highly sensitive microassay for aldosterone in unextracted plasma: comparison with two other methods.

A direct radioimmunoassay for aldosterone in unextracted plasma was developed using a highly sensitive and specific antiserum and 125I-labeled aldosterone. This new method was compared with the previously used assay based on methylene chloride extraction and column chromatography and with a micromethod utilizing methylene chloride extraction alone. Concentrations of 2 pg/ml aldosterone can be measured in 25 microliter plasma. The within-assay coefficient of variation ranged between 4.0% and 5.3% over a sixfold range of aldosterone concentrations, and the between-assay coefficient of variation ranged between 5.0% and 9.4% over a tenfold range. The correlation coefficients among the three methods varied between 0.97 and 0.99, and results were virtually identical between the new direct and the standard chromatography methods. Normal values on unrestricted salt intake were 68 +/- 28 pg/ml (n = 30, mean +/- SD) in seated humans. In conclusion, this is an extremely simple, truly direct microradioimmunoassay for plasma aldosterone that is accurate over a wide range of plasma concentrations, is exquisitely sensitive, and provides results identical to those obtained with established methods.

Aldosterone↗
PubMed1983

[Treatment of hypertensive crisis with captopril].

The usefulness of captopril in managing hypertensive emergencies was evaluated in 9 untreated patients. During the 30 minutes following oral administration of 25 mg of this angiotensin converting enzyme inhibitor, blood pressure decreased from 239/134 to 204/118 mm Hg (p less than 0.05). At that time, furosemide (20 mg i.v. or 40 mg orally) had to be added in 5 patients to further decrease pressure levels. Ninety to 120 minutes after starting therapy, an additional dose of captopril (100 mg orally) was given to all patients. 12 and 24 hours after admission respectively, blood pressure averaged 140/93 and 139/86 mm Hg in the patients treated with captopril alone and 166/107 and 153/91 mm Hg in those treated with both captopril and furosemide. The blood pressure fall was well tolerated and no adverse effect was induced by captopril. These results show that captopril given alone or in association with a diuretic makes it possible to deal quickly and effectively with hypertensive crises without necessarily requiring monitoring in an intensive care unit.

Administration, Oral↗
PubMed1983

[Usefulness of the Remler device in avoiding overtreatment of the so-called hypertensive population].

To assess the reliability of the Remler system, a semi-automatic pressure recording device, several blood pressures were measured simultaneously by the conventional auscultatory method and by the Remler in 12 normotensive volunteers. In all situations tested both the Remler and auscultatory blood pressures were very close, thus demonstrating the reliability of this new technique. Ambulatory blood pressure recordings were then obtained with the Remler in 245 untreated patients referred for hypertension by their private physicians. Surprisingly, in close to 60% of them the average of all blood pressures recorded during usual activities was within the normal range. Since cardiovascular complications seem to correlate better with ambulatory than with office blood pressure levels, the Remler system appears particularly useful in recognizing those patients who, although hypertensive in the physician's office, remain normotensive during the day and therefore may not require antihypertensive treatment.

Activities of Daily Living↗
PubMed1983

Blood pressure and heart rate effect of a vasopressin antagonist in conscious normotensive rats pretreated with exogenous vasopressin.

The blood pressure and heart rate effects of the specific pressor antagonist of vasopressin d(CH2)5Tyr(Me)AVP, 5 micrograms i.v. was evaluated in conscious normotensive rats. Our results suggest that a baroreceptor reflex mediated decrease in sympathetic nerve activity, as reflected by a slowing in heart rate, returns blood pressure to baseline levels shortly after injections of exogenous vasopressin. This has to be taken into account when interpreting the hemodynamic response to vasopressin antagonists in rats pretreated with this vasopressive hormone.

Animals↗
PubMed1983

[Use of ambulatory recording of arterial pressure].

It is often difficult for the physician to decide the need for antihypertensive therapy on the basis of office blood pressure readings. This decision is important for the individual patient since lifelong treatment may be started in some instances though blood pressure is elevated only when taken at the physician's office. For this reason the Remler, a portable and patient-activated blood pressure recorder, appears to be very useful in evaluating ambulatory blood pressure profiles during normal daily activities.

Ambulatory Care↗
PubMed1983

[Profiles and variations of ambulatory arterial pressure in treated and untreated hypertensive patients].

It is now possible to record numerous ambulatory blood pressures by a noninvasive method using the Remler, a portable semi-automatic device. The blood pressure profiles obtained with this recorder in hypertensive patients during customary daily activities have revealed the existence of a circadian blood pressure variation. Thus, blood pressure is highest in the morning, lowest early in the afternoon and tends to increase again late in the afternoon. This circadian variation is not modified by treatment with diuretics and/or betablockers. These blood pressure recordings also made it possible to establish that antihypertensive therapy with these agents does not modify blood pressure variability over the day.

Adrenergic beta-Antagonists↗
PubMed1983

[Evaluation by practicing physicians of the antihypertensive efficacy of debrisoquin, methyldopa and propranolol].

The antihypertensive effect of debrisoquine (20 mg/day), methyldopa (100 mg/day) and propranolol (160 mg/day) was compared to that obtained with a placebo in a controlled trial carried out by a group of 14 internists. Forty-eight patients with uncomplicated essential hypertension were included. Mefruside (25 mg/day) was first given alone for 6 weeks ("open phase" of the trial) and to this diuretic was then added in double-blind fashion and randomized sequence a placebo or an active drug. Each of the 4 blind phases lasted 4 weeks. At the end of the "open phase", blood pressure in seated position averaged 168/111 +/- 19.6/13.5 mm Hg (mean +/- SD). A significant blood pressure decrease was observed after 4 weeks of treatment with the placebo as well as with the investigated compounds. With the placebo blood pressure was reduced to 158/102 +/- 19.6/13.5 mm Hg (p less than 0.001). The magnitude of the additional blood pressure decrease induced by the active drugs was relatively small and varied from 4 (debrisoquine) to 10 mm Hg (methyldopa, p less than 0.01) for the systolic and from 3 (debrisoquine, p less than 0.05) to 5 mm Hg (propranolol, p less than 0.05) for the diastolic. The percentage of patients with systolic pressure of less than or equal to 140 mm Hg and with diastolic pressure of less than 90 mm Hg during administration of either drug was not greater than 40 to 20% respectively. Propranolol appeared to be better tolerated than the other antihypertensive agents. These rather disappointing blood pressure results suggest that the efficacy of antihypertensive agents in private practice cannot be extrapolated from studies carried out in specialized hypertension clinics.

Adult↗
PubMed1983

Hypertensive crisis treated with orally administered captopril.

The value of the orally active converting enzyme inhibitor captopril in managing hypertensive crisis was tested in 9 untreated patients admitted to the emergency room, who were in need of rapid blood pressure reduction because of signs and symptoms of neurological and/or cardiac complications. During the 30 min following administration of captopril 25 mg the blood pressure decreased from 239/134 +/- 12/4 mmHg (mean +/- SEM) to 204/118 +/- 8/4 mmHg (p less than 0.05). From that time on, captopril 200 to 300 mg/day was continued for 2 to 5 days. In 5 patients furosemide in a total dose of 40 to 160 mg i.v. or p.o. had also to be given in order to control the blood pressure. 12 and 24 h after admission blood pressure averaged 140/93 and 139/86 mmHg respectively, in the patients treated with captopril alone, and 166/107 and 153/91 mmHg in those treated both with captopril and furosemide. The pronounced fall in blood pressure produced by blockade of the renin system was well tolerated and did not cause tachycardia. It appears, therefore, that captopril given alone or in association with a diuretic makes it possible to treat the hypertensive crisis without the need for monitoring in an intensive care unit.

Administration, Oral↗
PubMed1983

The renin-angiotensin system in refractory heart failure: clinical, hemodynamic and hormonal effects of captopril and enalapril.

Studies using a competitive inhibitor of angiotensin II (saralasin) or converting enzyme inhibitors (teprotide, captopril, enalapril) have established that the renin-angiotensin system participates in the control of vascular tone in congestive heart failure both in experimental settings and in patients. In man, the marked decrease in left ventricular filling pressure and the variable increase in stroke volume induced by renin-angiotensin blockade suggests that angiotensin II actively constricts venous as well as arteriolar vascular beds. Captopril, in doses of 25 to 150 mg p.o. TID, maintains its efficacy during chronic administration with persistent clinical and hemodynamic improvement as well as increased exercise tolerance. In our experience, enalapril, 10 mg p.o., improves cardiac function within 4 to 6 h as reflected by a 30% decrease in left ventricular filling pressure, a 28% increase in stroke volume in the face of unchanged heart rate. Clinical improvement, enhanced exercise tolerance and characteristic hormonal responses suggest that enalapril also maintains its efficacy during long-term treatment. Chronic angiotensin II converting enzyme inhibition appears to be a major advance in the treatment of patients with severe congestive heart failure, refractory to digitalis and diuretics.

Aldosterone↗
PubMed1983

The clinical application of converting enzyme inhibitors.

Chronic blockade of the renin angiotensin system became possible when orally active inhibitors of angiotensin converting enzyme, the enzyme which catalyzes the transformation of angiotensin I into angiotensin II, were synthetized. Two compounds, captopril and enalapril, have been investigated in clinical studies. The decrease of the pressor response to exogenous angiotensin I and of the circulating levels of angiotensin II following administration of these inhibitors has been demonstrated to be directly related to the degree of suppression of plasma angiotensin converting enzyme activity. These inhibitors have been shown to normalize blood pressure alone in some hypertensive patients whereas in many others, satisfactory blood pressure control can be achieved only after the addition of a diuretic. Captopril and enalapril also markedly improve cardiac function of patients with chronic congestive heart failure. Chronic blockade of the renin angiotensin system has therefore provided an interesting new approach to the treatment of clinical hypertension and heart failure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1983

Long-term clinical experience with enalapril in essential hypertension.

This study was undertaken to evaluate whether, after long-term enalapril administration tachyphylaxis to the blockade of angiotensin II (Ang II) generation occurs. After a mean follow-up of 24 months, six patients taking enalapril once daily with or without an associated diuretic were studied for 7 h in hospital. Blood pressure, heart rate, plasma converting enzyme activity, angiotension I (Ang I), Ang II and aldosterone were measured before and 2, 4 and 6 h after the morning dose of enalapril. While blood pressure remained unchanged after drug administration, Ang II and aldosterone levels fell following enalapril to very low levels, similar to those observed during the initial study, at the time of peak effect of enalapril. After enalapril administration, there was no correlation between plasma Ang I and Ang II suggesting that blockade of Ang II generation was complete, excluding the possibility of Ang I related interference with the Ang II measurements. These results indicate that virtually complete angiotension converting enzyme inhibition can still be achieved after prolonged use of enalapril.

Adult↗
PubMed1983

Blood pressure dependency on vasopressin and angiotensin II in prazosin-treated conscious normotensive rats.

The role of the sympathetic nervous system, angiotensin II and vasopressin in limiting the hypotensive effect of prazosin (0.25 mg i.v.) was investigated in conscious normotensive rats. Within 45 min, mean blood pressure fell from 120 +/- 1 to 98 +/- 1 mm Hg (mean +/- S.E.M., P less than .001) while pulse rate rose from 463 +/- 9 to 500 +/- 9 beats/min (P less than .01). The blood pressure response to prazosin tended to be most pronounced in the rats with the smallest increase in heart rate (r = 0.58, P less than .001). Plasma norepinephrine and epinephrine levels were higher in prazosin-treated rats than in the controls (P less than .001). In the animals receiving prazosin, plasma renin activity was 4 times (P less than .001) and plasma vasopressin 7 times (P less than .01) higher than in the controls. Blockade of angiotensin II with saralasin (10 micrograms/min) further decreased blood pressure of the prazosin-treated rats by 22 +/- 4 mm Hg (P less than .001). In contrast, dPVDAVP (25 micrograms), a vasopressin antagonist, had no effect. Prazosin decreased the pressor response to methoxamine (10 micrograms) by 80% (P less than .001) but not to angiotensin II (60 ng). However, prazosin enhanced the reflex bradycardia induced by angiotensin II (P less than .001). These data demonstrate that both the sympathetic and the renin angiotensin system are markedly stimulated by prazosin; they both appear to limit its acute hypotensive action. In contrast, although plasma vasopressin is also increased, its pressor action is effectively buffered, probably due to enhanced baroreflex sensitivity.

Angiotensin II↗