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Biomedical subjects

A Semplicini

Publications and source records attributed to A Semplicini.

At least 109 records · Page 6Linked to original sources
PubMed1985

[Dynamic evaluation of the renin-angiotensin system with captopril in screening for renovascular hypertension].

In 69 hypertensive with suspected renovascular hypertension the response of plasma renin and angiotensin I to a single oral dose of Captopril (Captopril test) was determined. In 15 of the 16 patients found to have renal artery stenosis at angiography and cured by either revascularization or nephrectomy, Captopril stimulated both plasma renin activity and plasma angiotensin I to a far greater extent than in the majority of the 53 classified as essential hypertensives. False positives were limited to 8. Sensitivity and specificity were 94% and 85%, respectively. In the same series sequential renal angiophotoscan showed 100% sensitivity but a lower specificity (75%). In comparison, both the sensitivity and the specificity of rapid-sequence intravenous pielography, isotopic renogram and recumbent plasma renin activity were far less satisfactory. It is concluded that this simple, safe and economical test should be preferred to the other diagnostic procedures in the screening of renovascular hypertension. Its use in combination with renal angiophotoscan improves diagnostic reliability.

Adult↗
PubMed1985

Evidence of reduced atherosclerotic lesions in broad breasted white turkeys treated with oxprenolol.

Male Broad Breasted White Turkeys (BBWT) are naturally hypertensive and prone to develop atherosclerosis. Hypertension is characterized by high levels of circulating and tissue catecholamines; atherosclerosis affects mainly the aorto-iliac tract. To evaluate the effect of a beta-blocker on both hypertension and atherosclerosis, 2 groups of BBWT were studied. First group: 12 BBWT treated from the 8th week of age with daily p.o. placebo; second group: 6BBWT treated from the 8th week with 2 mg/kg p.o. daily oxprenolol. Blood pressure (BP) and heart rate (HR) were periodically measured with an indirect method. Seven and 5 BBWT of the first group were sacrificed at 24 and 51 weeks respectively. The 6 animals of the second group were sacrificed at 51 weeks. No significant difference in mean BP and HR values was found between the two groups of animals. On the contrary the oxprenolol treated group displayed a significant reduction in extent and severity of the atherosclerotic lesions. These results seem to substantiate that oxprenolol might positively interfere with the setting of atherosclerosis in these animals independently of BP reduction. One possible explanation could be a direct effect of oxprenolol on the arterial wall.

Aging↗
PubMed1983

[Evaluation of the efficacy of various hypotensive drugs in broad-breasted white turkeys as an experimental model of arterial hypertension with high catecholamine levels].

Male Broad Breasted White Turkeys (BBWT) represent an experimental model of arterial hypertension characterized by high levels of circulating and tissue catecholamines. We thought interesting to evaluate the efficacy of the long term treatment with different antihypertensive drugs. 59 male BBWT were studied, divided in five groups. The first group (13 animals) was treated with placebo; the second (14 animals) with oxprenolol 4 mg/Kg/q.d.; the third (10 animals) with labetalol 25 mg/Kg/q.d.; the fourth (11 animals) with verapamil 15 mg/Kg/ q.d.; the fifth (11 animals) with captopril 8 mg/Kg/ q.d. and furosemide 2,5 mg/Kg/q.d. All drugs were given p.o, from the 8th to the 33rd week of age. Weekly or every two weeks Blood Pressure (BP) and Heart Rate (HR) were measured by an indirect method. In all animals BP progressively increased and HR progressively decreased with age. Only the labetalol-treated animals showed a significant reduction of BP and HR through the study period as compared with the placebo-treated animals. These results confirm the preminent role played by the high levels of circulating catecholamines in determining and maintaining the arterial hypertension.

Animals↗
PubMed1983

Alpha-adrenoceptor blockade by labetalol during long-term dosing.

The hypotensive effect of short-term labetalol, the alpha- and beta-adrenoceptor blocker, is greater in subjects in the orthostatic position, possibly because of the alpha-adrenoceptor blockade. During prolonged use the orthostatic blood pressure fall disappears. To verify whether or not this is due to reduction in alpha-blocking activity, phenylephrine-induced increase in blood pressure was studied in six subjects with mild essential hypertension before and after 3 and 6 days and 1 and 6 mo of continuous treatment with 200 mg labetalol three times a day by mouth. At the same intervals, isoproterenol-induced tachycardia was followed to assess beta-blockade. After 3 days on labetalol, the log dose-response curve of phenylephrine-induced increase in blood pressure shifted to the right and the dose of agonist required to elicit a 20% increase in systolic pressure was 1.7 times that before treatment. There was a progressive decline in the dose of agonist that induced the same increase in pressure so that after 6 mo of continuous labetalol it was the same as control. In contrast, the amount of isoproterenol needed to induce a 20% increase in heart rate was two to three times that before labetalol and did not change throughout 6 mo of therapy. These data indicate a decline in the alpha-adrenoceptor-blocking effect of oral labetalol without concomitant change in the degree of beta-adrenoceptor blockade. This might account for the disappearance of orthostatic hypotension early in the course of treatment and for some decrease in the antihypertensive efficacy of labetalol.

Adrenergic alpha-Antagonists↗
PubMed1983

[Hypotensive effect and changes of arterial pressure variability induced by treatment with labetalol in patients with slight and moderate arterial hypertension].

To evaluate the hypotensive efficacy of labetalol (600 mg/day) six mild to moderate hypertensive patients were studied by the indirect continuous blood pressure monitoring with the Del Mar Avionics Pressurometer 111 degrees. This technique gives a much larger number of blood pressure values in a greater variety of conditions than the conventional Riva-Rocci sphygmomanometer. After one month of continuous therapy there was a substantial reduction in systolic and diastolic pressure. The increased index of Kurtosis revealed a decreased blood pressure variability. The circadian changes of blood pressure were not significantly affected, but the morning peak was smoothed by labetalol.

Blood Pressure↗
PubMed1982

Effects of captopril on renal function in hypertensive patients.

The effects of captopril (SQ 14225) on renal function were studied in 10 hypertensive patients. After 7 weeks of treatment (75 to 500 mg/day) renal plasma flow was practically unchanged and glomerular filtration rate was only slightly decreased despite a significant decrease in blood pressure. All indexes of glomerular capillary permeability and of tubular anatomic integrity remained normal during the treatment period.

Adult↗
PubMed1982

Intravenous labetalol in severe hypertension.

1 Labetalol was administered by intravenous infusion or by the combination of intravenous bolus injection plus infusion to 15 patients with severe essential hypertension and to one with phaeochromocytoma. 2 With the infusion alone the reduction of arterial pressure was slow to develop and limited in degree, but with the combination of the bolus injection plus the infusion the reduction in pressure was more prompt, more pronounced and longer lasting. Apart from an uncomplicated syncopal attack in one patient, no serious side--effects were encountered. 3 Subsequent treatment with oral labetalol usually required the addition of a diuretic to control the blood pressure probably due to sodium and fluid retention during treatment with labetalol alone.

Administration, Oral↗
PubMed1982

[Use of labetalol in the treatment of hypertensive crises].

Labetalol, a combined alpha and beta adrenoceptor blocking drug, has been shown to be effective in the treatment of hypertensive crises when given intravenously. It also offers the advantage that treatment can be continued with the oral preparation. The purpose of our study was to evaluate if the administration of an intravenous bolus followed by an iv infusion and subsequently by the oral preparation might increase the efficacy of the drug without reducing its tolerance. Thirteen patients with severe essential hypertension and one with pheochromocytoma were treated during one or more hypertensive crises with Labetalol, 100 mg bolus i.v. injection in two minutes, followed by an intravenous infusion (2-4 mg/min for 60-90 minutes) and, one hour after the end of the infusion, by the oral preparation (200 mg t.i.d.). In 11 subjects with essential hypertension and in the patient with pheochromocytoma a 30% fall in systolic and diastolic blood pressure [from 240 +/- 10/155 +/- 6 mmHg (mean +/- 1 s.e.m.), to 162 +/- 8/111 +/- 6, p less than 0.01] was achieved within five minutes from the beginning of the treatment. Blood pressure remained well controlled thereafter, throughout the infusion period and during the first 24 hours of the oral administration. Heart rate fell simultaneously with the fall in blood pressure. Only in one patient blood pressure was not adequately controlled despite of the bolus and of an infusion at the rate of 4 mg/min for 20 minutes. In another case the fall in pressure caused near-fainting and the infusion was therefore not started. No other side effects were encountered except for transient orthostatic hypotension. We conclude that the administration of a bolus plus infusion of Labetalol is more effective than single or repeated boluses or graded infusions and it is equally well tolerated.

Ethanolamines↗
PubMed1981

Changes in ventricular myosin properties during broad breasted white turkey (BBWT) development.

This paper reports the following data with regard to the BBWT cardiovascular system: 1) Arterial Blood pressure progressively increases from 1 to 12 month of age, accompanied by marked left ventricular hypertrophy; 2) The myosin ATPase activity is enhanced about three times; 3) No differences in myosin light chain pattern is observed; 4) The peptide pattern obtained after chymotryptic digestion of the myosin molecule shows that some peptides, which are not evident or barely discernible, in 1 month old animal, are present in the adult one. These findings are surprising because it is well known that the ATPase activity decreases with age and hypertrophy. It is possible that other factors, as the levels of circulating cathecolamines or the thyroid hormones, are involved in the control of myosin synthesis and consequently in its ATPase activity.

Adenosine Triphosphatases↗
PubMed1981

Hypotensive and renal effects of captopril.

The effects of Captopril on blood pressure and renal function were evaluated in ten patients with different degrees of hypertension. In seven, blood pressure was reduced after 7 weeks of therapy; in three it remained practically unchanged. No correlation was found between the standing plasma renin activity before treatment and the hypotensive response. Plasma renin activity increased significantly from the median value of 5.4 (range 1-16.7) to 9.5 (range 2.6-19.8) ng ml-1 h-1 (P less than 0.05) and urine aldosterone significantly fell from 13 (range 2.3-52.5) to 7.4 (range 1.6-14) microgram 24 h-1 (P less than 0.01) during therapy. Renal plasma flow decreased from 534 (range 300-616) to 471 (range 333-606) ml min-1, but the difference was not significant, and glomerular filtration rate fell significantly form 122 (range 64-143) to 88 (range 71-116) ml min-1 (P less than 0.05). No urinary excretion of alpha 2-macroglobulin was observed during Captopril. 24 h proteinuria, albumin and transferrin clearance, alanine-amino transferase, gammaglutamyl transferase and alpha glucosidase excretion rate and malate-dehydrogenase clearance remained unaltered throughout the treatment. This indicates that neither glomerular permeability nor renal tubular function were affected by the drug.

Adult↗
PubMed1981

Orthostatic hypotension after the first administration of prazosin in hypertensive patients: role of the plasma volume.

1. Prazosin (2 mg, p.o.) was administered to nine patients with essential hypertension while intra-arterial pressure was recorded by an Oxford portable apparatus. In all patients, 30 min-3 h after the administration, systolic and diastolic pressure fell on assuming the upright posture and four patients fainted. No correlation was found between the degree of fall in pressure and the plasma concentration of the drug. Acute expansion of the plasma volume by means of 6% Dextran infusion reduced the orthostatic blood pressure fall in all cases and a significant inverse correlation was found between plasma volume and orthostatic fall of pressure. 2. After ten days of continuous treatment with prazosin, 2 mg daily, a significant decrease in blood pressure was observed while orthostatic hypotension disappeared, probably due to the plasma volume expansion induced by the drug.

Adolescent↗
PubMed1981

Computer analysis of continuous blood pressure recordings in essential hypertension.

Blood pressure signals recorded continuously in ambulatory patients were analyzed by an IBM 370 computer and the systolic and diastolic values of each pressure cycle presented in form of a histogram. The results of pressure recordings in patients with 'borderline or labile' and 'established' hypertension are presented and discussed.

Adolescent↗