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Biomedical subjects

G Grassi

Publications and source records attributed to G Grassi.

At least 217 records · Page 12Linked to original sources
PubMed1984

Role of cardiopulmonary receptors in reflex control of renin release in man.

Animal studies have shown that renin release is reflexly modulated by cardiopulmonary and arterial baroreceptors, and that during changes in posture the former receptors play a major role. This role has been challenged in man, however, by reflex modulation of renin secretion which has been claimed to take place only if arterial and cardiopulmonary receptor areas are engaged together. We studied 19 normotensive and essential hypertensive subjects in which plasma renin activity was assessed by radioimmunoassay during a mild 20 min increase and a mild 20 min reduction in central venous pressure (+1.1 +/- 0.2 mmHg and -2.6 +/- 0.4 mmHg). The increase and reduction in central venous pressure were accompanied by no change in systolic blood pressure, diastolic blood pressure and heart rate which indicated that the increased and reduced stimulus had involved only cardiopulmonary receptors and not arterial baroreceptors as well. During the increase in central venous pressure plasma renin activity showed a significant (P less than 0.01) reduction (-18 +/- 3%) whereas during the reduction in central venous pressure it showed a significant (P less than 0.01) and more marked increased (+64 +/- 17%). The plasma renin activity increase observed during lower body suction was not significantly different from that observed during a 20 min tilting, a manoeuvre that reduced central venous pressure to an extent similar to that observed during lower body suction, but that also deactivated carotid baroreceptors by positioning the carotid sinuses above the heart and reducing their transmural pressure. Thus in normotensive and hypertensive humans renin release can be reflexly modulated by selective engagement of cardiopulmonary receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Alterations in plasma noradrenaline in response to reflex modulation of sympathetic vasoconstrictor tone to skeletal muscles.

In man, stimulation and deactivation of carotid baroreceptors are accompanied by sympathetically-induced reduction and increase in total peripheral resistance, but not by alterations in plasma noradrenaline. This has been explained by the inability of arterial baroreflexes to sustainedly modulate sympathetic tone to skeletal muscle vessels on which plasma noradrenaline has been assumed largely to depend. In the present study nine subjects were submitted to procedures that cause a sustained alteration in muscle sympathetic vasoconstrictor tone, i.e. deactivation and stimulation of cardiopulmonary receptors. Cardiopulmonary receptor deactivation was achieved by a 20-min reduction in central venous pressure via application of subatmospheric pressure to the lower body, and the cardiopulmonary receptor stimulation by a 20-min increase in central venous pressure via passive leg raising. Plasma noradrenaline was measured radioenzymatically on blood sampled from an antecubital vein or the right atrium before, and at the 2nd, 5th, 10th and 20th min of each manoeuvre. The noradrenaline measurements were coupled with measurements of arterial blood pressure, heart rate and forearm blood flow and resistance (plethysmographic method). During reduction and increase in central venous pressure, blood pressure and heart rate did not change, whereas forearm vascular resistance markedly rose and fell with a peak response at 5 min and a subsequent plateau. These changes were accompanied by a marked rise and fall in plasma noradrenaline which also peaked within 5 min and were then sustained. Changes in forearm vascular resistance and noradrenaline showed a close qualitative parallelism, each increase in the former being accompanied by an increase in the latter, and vice-versa.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Effects of blood-pressure measurement by the doctor on patient's blood pressure and heart rate.

Changes in blood pressure in 10 or 15 min periods during which a doctor repeatedly measured blood pressure by the cuff method were monitored by a continuous intra-arterial recorder. In almost all the 48 normotensive and hypertensive subjects tested the doctor's arrival at the bedside induced immediate rises in systolic and diastolic blood pressures peaking within 1 to 4 min (mean 26.7 +/- 2.3 mm Hg and 14.9 +/- 1.6 mm Hg above pre-visit values). There were large differences between individuals in the peak response (range, 4--75 mm Hg systolic and 1--36 mm Hg diastolic) unrelated to age, sex, baseline blood pressure, or blood-pressure variability. There was concomitant tachycardia (average peak response 15.9 +/- 1.5 beats/min, range 4--45 beats/min) which was only slightly correlated with the blood-pressure rise. After the peak response blood pressure declined and at the end of the visit was only slightly above the pre-visit level. A second visit by the same doctor did not change the average size of the early pressor response or the slope of its subsequent decline.

Adolescent↗
PubMed1983

Unwanted symptoms in depressed patients treated with viloxazine: an algorithm for identification of illness-related symptoms.

Ninety-six depressed outpatients from 5 centres were given viloxazine 200-400 mg/day. The treatment produced significant clinical improvement as evaluated by the Hamilton Rating Scale for Depression. Thirteen patients dropped-out because of possible side effects. Many untoward symptoms were described by all the patients. To distinguish between illness-related symptoms (IRSs) and potential side effect symptoms (SESs) a new approach was taken, using an algorithm that provides a decision strategy based on the time course both of the symptom and the illness. By this procedure, 90 of the 187 claimed untoward symptoms were identified as IRSs. Of the 97 potential SESs, only 36 were spontaneously volunteered, and the remaining 61 symptoms were elicited on specific questioning. Whenever possible, volunteered potential SESs were assessed to determine the relationship between the drug treatment and the adverse reaction. It was found that only a few instances of gastric disturbance and exacerbation of anxiety were probably viloxazine-related.

Adult↗
PubMed1983

Transesophageal pacing for prognostic evaluation of preexcitation syndrome and assessment of protective therapy.

An esophageal lead was used to perform decremental atrial pacing and elective induction of atrial fibrillation (AF) in 5 patients with the Wolff-Parkinson-White (W-P-W) syndrome before and after amiodarone therapy. In the control state, 1:1 atrioventricular (AV) conduction over the accessory pathway ranged from 220 to 260 ms (mean 232). The shortest R-R interval during AF ranged from 190 to 210 ms (mean 198). The ventricular rate ranged from 175 to 212 beats/min (mean 196). After amiodarone therapy, the shortest cycle length with 1:1 AV conduction increased in all patients, ranging from 290 to 540 ms (mean 370); during AF, no preexcited beat was present in 2 patients, whereas the minimal preexcited R-R interval in the remaining 3 was 290, 240, and 370 ms, respectively. The ventricular response during AF decreased in all patients. Thus, esophageal pacing is a useful method for identifying patients at risk with the W-P-W syndrome and for assessing appropriate management in individual patients. Amiodarone provides protection against life-threatening arrhythmias in these patients.

Adolescent↗
PubMed1983

Mechanisms of antihypertensive action of beta-adrenergic blocking drugs: evidence against potentiation of baroreflexes.

A possibility that can be advanced to explain the antihypertensive effect of beta-blocking drugs is that they act through the baroreflex control of the cardiovascular system. In 38 essential hypertensive patients we measured 1) The lengthening and shortening in R-R interval caused by stimulation or deactivation of arterial baroreceptors (vasoactive drug technique); 2) The fall and rise in blood pressure caused by stimulation and deactivation of carotid baroreceptors (neck chamber); 3) The rise in forearm vascular resistance caused by deactivation of cardiopulmonary receptors (lower body suction). The study was made before and after 6-10 days' administration of nadolol (80-360 mg once a day) or acebutolol (200-600 mg t.i.d.). Nadolol and acebutolol similarly reduced blood pressure and heart rate. Either drug increased heart rate responses to arterial baroreceptor manipulation but the increase fell short of statistical significance. Blood pressure and vasomotor responses to carotid baroreceptor and cardiopulmonary receptor manipulation were also not significantly modified by beta blockade. The baroreceptor control of heart rate and blood pressure showed a modification, however, insofar as a resetting towards the lower blood pressure values occurred. These findings demonstrate that arterial baroreceptor and cardiopulmonary receptor control of circulation is not potentiated by beta-blocking drugs, and that therefore this mechanism cannot account for their antihypertensive effect. The resetting of the baroreflex that occurs during beta blockade may, however, contribute to maintain the hypotension obtained.

Adrenergic beta-Antagonists↗
PubMed1983

Long term results in traumatic dislocation of the hip in children.

The long term results of 14 cases of traumatic dislocation of the hip in children are reviewed. The follow-up period was from 10 to 30 years, which in all but 2 cases involved attaining skeletal maturity. The following observations are recorded. The lesion can be produced by comparatively minor trauma; the prognosis is more benign than in adults; prolonged restriction of weight bearing does not play any significant role in the development of complications, particularly in children under the age of 6. Late complications are essentially related to the severity of the initial trauma than to early or late weight bearing.

Adolescent↗
PubMed1982

Modification of arterial baroreflexes by captopril in essential hypertension.

Captopril lowers blood pressure without increasing heart rate and plasma norepinephrine, which suggests that this drug may potentiate arterial baroreflexes. In eight subjects with untreated essential hypertension, blood pressure was monitored intraarterially and the effects of baroreceptor stimulation or deactivation were assessed by measuring (1) the slopes of the relations between increase or reduction in systolic pressure (intravenous phenylephrine or nitroglycerin) and the resulting lengthening or shortening in R-R interval, and (2) the increase or decrease in mean arterial pressure induced by increasing and decreasing carotid transmural pressure (neck chamber). The measurements were made before and after a hypotensive oral dose of captopril (50 mg). Before captopril, the slopes of the R-R interval changes with increase and reduction in systolic pressure were 8 and 4 ms/mm Hg, respectively. The slopes of the mean arterial pressure changes with increase and reduction in carotid transmural pressure were 0.51 and 0.40 mm Hg, respectively. After captopril, the responses to baroreceptor stimulation were unaltered but those to baroreceptor deactivation were augmented. The pressor and heart rate responses to hand-grip and cold exposure were unchanged by captopril. Administration of captopril is accompanied by a baroreflex potentiation which involves the lower portion of the stimulus-response curve of the reflex. This phenomenon (which may originate at the afferent baroreceptor fibers or centrally) may avoid a reduction in the tonic baroreflex influence during captopril-induced hypotension, thus contributing to the hemodynamic effects of the drug.

Adult↗
PubMed1982

Blood pressure response to labetalol in twice and three times daily administration during a 24-hour period.

1 The anti-hypertensive effect of labetalol given twice or three times daily was evaluated in ambulant subjects with essential hypertension by recording blood pressure directly for 24 h before and after 15 d of labetalol administration (daily dose 600-1800 mg). 2 Labetalol reduced 24 h systolic and diastolic blood pressures by about 20%. The reduction was evident throughout the whole 24 h period, although it was less marked during sleep. The hypotensive effect was similar when the drug was given twice or three times daily. 3 The 24 h heart rate was reduced during labetalol treatment. However, this effect was less marked than the hypotensive effect and was not present in all subjects. 4 There was a reduction in the standard deviations of blood pressure and heart rate values. However, in neither case was the coefficient of variation altered, indicating that labetalol did not have any significant effect on the shape of the 24 h blood pressure measurements.

Adult↗
PubMed1981

[Does the number of treated rejection episodes in the first transplantation influence the survival of the patient with kidney re-transplantation?].

The records of 77 patients who received a second kidney transplant at the Surgery Department of Addenbrooke's Hospital, Cambridge, have been re-examined to assess the influence of the number of rejection episodes treated during the first transplant on the survival of the second. 61 of the 77 retransplanted patients lost their first kidney for immunological reasons. 6 did not present any treated episode of rejection, 45 one episode only and in 10 greater than 1 episode was treated during the first transplant. P less than 0.05 from 1 to 5 years as regards survival of the second transplants in patients whose first kidney did not present treated rejection episodes by comparison with those presenting 1 or greater than 1. No significant difference was noted in patient survival in the various groups under examination. On the basis of the results obtained, it is concluded that, in addition to the cause of failure and duration of the first transplant, the number of treated rejection episodes during the first transplant should be considered as a critical parameter for better selection of the most suitable candidates for receiving a second transplant.

Graft Rejection↗