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Biomedical subjects

L Bianconi

Publications and source records attributed to L Bianconi.

68 records · Page 4Linked to original sources
PubMed1989

Arginine vasopressin secretion in non-obese women with polycystic ovary syndrome.

Arginine vasopressin responses to osmotic (0.1 ml.kg-1.min-1 NaCl), orthostatic (standing upright and maintenance of orthostatic position for 20 min), and hypoglycemic (0.15 IU/kg insulin) stimuli were evaluated in women with polycystic ovaries and in normal subjects. Blood dehydroepiandrosterone, dehydroepiandrosterone sulphate, androstenedione, testosterone, cortisol, and endogenous insulin levels were significantly higher in women with polycystic ovaries than in controls, whereas estrone, estradiol-17 beta, progesterone and 17OH-progesterone concentrations were normal in all subjects. Arginine vasopressin basal levels (mean +/- SEM of 3 test days; women with polycystic ovaries: 2.8 +/- 0.2 pmol/l; controls: 2.7 +/- 0.2 pmol/l) and secretory responses to orthostatic (mean peaks 100% higher than baseline values) and to hypertonic (130% increments) stimuli were similar in the two groups. Arginine vasopressin responses to hypoglycemia were lower in women with polycystic ovaries (50% increment) than in controls (150% increment), although comparable blood glucose decrements and GH or cortisol increments were found in the two groups. Arginine vasopressin peak responses to hypoglycemia were negatively correlated to testosterone, androstenedione, and endogenous insulin levels, but did not correlate with basal and hypoglycemia-induced peak cortisol concentrations or with circulating levels of other steroids. These data indicate a hypothalamic posterior pituitary disorder affecting arginine vasopressin response to insulin-induced hypoglycemia in women with polycystic ovaries syndrome associated with elevated blood androgen and insulin concentrations.

Adult↗
PubMed1988

Metergoline, naloxone, and sodium valproate did not modify arginine vasopressin response to insulin-induced hypoglycemia in man.

The present study was carried out in order to determine whether insulin-induced hypoglycemia exerts its stimulatory effect on plasma concentrations of arginine vasopressin (AVP) by interacting with a serotonergic, a GABA-ergic or an opioid pathway. For this purpose, the effect of the serotonergic antagonist metergoline (10 mg/day for 4 days po), the GABA-ergic agonist sodium valproate (600 mg in three divided doses po) and the opioid-receptor blocker naloxone (10 mg in a iv bolus) on the AVP response during an insulin (0.15 IU/kg bw) tolerance test (ITT) was evaluated in three groups of 6 normal men each. In all men, control ITTs were performed without drug treatments. Basal and ITT-stimulated AVP secretion was not modified by drug administration, suggesting that serotonergic, GABAergic and naloxone-sensitive opioid receptors are not involved in the regulation of AVP secretion in response to insulin-induced hypoglycemia.

Adrenocorticotropic Hormone↗
PubMed1988

Dopaminergic control of TSH secretion in endogenous depression.

To evaluate whether the inhibitory control exerted by endogenous dopamine on thyroid-stimulating hormone (TSH) secretion is altered in patients with major depressive disorder, 11 depressed patients and 9 normal controls were tested with the dopaminergic receptor antagonist domperidone (10 or 20 mg i.v.). The administration of domperidone induced a significant increase in circulating TSH levels in the normal controls, but not in the depressed patients. These data excluded the possibility that the dopaminergic inhibition of TSH secretion is enhanced in depression. To establish whether domperidone failure was due to a reduced dopaminergic tone, domperidone was administered before stimulation of TSH secretion with thyrotropin-releasing hormone (TRH) (200 micrograms i.v.). The TSH response to TRH was significantly lower in the depressed than in the control subjects, regardless of domperidone priming. However, in both groups domperidone enhanced the TRH-induced TSH release by 50%. These data suggest that the dopaminergic control of TSH secretion is not altered in patients with endogenous depression and that a reduced capacity of the pituitary to secrete TSH might be responsible for the reduced TSH responsiveness to TRH and domperidone.

Adult↗
PubMed1988

Oxytocin reduces exercise-induced ACTH and cortisol rise in man.

The effect of oxytocin on the ACTH, cortisol, GH and PRL response to physical exercise was investigated in 6 normal men. In addition, the possible involvement of endogenous opioids in the mediation of oxytocin action was evaluated. After fasting overnight, each subject was tested on four mornings at least 1 week apart. Exercise was performed on a bicycle ergometer. The workload was gradually increased at 3-min intervals until exhaustion and lasted about 20 min in all subjects. Tests were carried out under administration of oxytocin (2000 mIU as an iv bolus injection plus 32 mIU/min per 30 min) or naloxone (10 mg as an iv bolus injection) alone; furthermore, the effect of oxytocin together with naloxone (10 mg as an iv bolus injection) was evaluated. In the remaining test, normal saline was given instead of drugs. Plasma ACTH, cortisol, PRL and GH concentrations were significantly increased by physical exercise. Administration of oxytocin, naloxone or their combination was without effect on the PRL and GH rise elicited by exercise. In contrast, the exercise-induced ACTH and cortisol response was significantly raised by naloxone and reduced by oxytocin. When oxytocin was preceded by administration of naloxone, the ACTH and cortisol response to exercise was not reduced by oxytocin. These data show that oxytocin is capable of inhibiting the rise in ACTH and cortisol, but not in GH and PRL induced by physical exercise. Since naloxone abolished the inhibitory effect of oxytocin, oxytocin action on ACTH and cortisol secretion might be supposed to be mediated by an opioid pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1988

Effect of bromocriptine on neurophysin secretion in pregnant women in labour.

In order to determine whether dopamine plays a role in the control of neuropituitary function in pregnant women during labour, blood levels of nicotine (NSN)- and estrogen (ESN)-stimulated neurophysins were measured in 119 women treated orally with placebo (n = 59, control group) or 5 mg bromocriptine, a potent dopaminergic receptor agonist (n = 60, experimental group). Serum samples were taken before drug ingestion (basal sample) and at delivery. The serum basal concentrations of NSN and ESN were similar in both groups of pregnant women in labour. At delivery, serum ESN levels were similar in all women regardless of the treatment, whereas NSN concentrations were significantly lower in the bromocriptine-treated women than in those who were given placebo. In additional experiments the effect of 5 mg bromocriptine on the serum concentrations of NSN and ESN was tested for 6 hours after drug ingestion in 10 healthy, non-pregnant women and in 8 women in the 3rd trimester of pregnancy. Bromocriptine did not modify the circulating levels of NSN and ESN in either of these 2 groups of women. Since NSN and ESN are thought to be associated with vasopressin and oxytocin, respectively, these results indicate that in non-pregnant women and in pregnant women during late pregnancy dopaminergic stimulation with a dopaminergic receptor agonist does not inhibit the release of either vasopressin or oxytocin during rest. In contrast, dopaminergic receptor stimulation appears to play an inhibitory role in the regulation of vasopressin, but not oxytocin secretion in pregnant women in labour.

Adult↗
PubMed1987

[Fibrillation and atrial flutter. Immediate control and conversion to sinus rhythm with intravenous propafenone].

The safety and efficacy of intravenous Propafenone, in the treatment of atrial fibrillation (a.f.) or flutter (A.F.) of recent onset (15 days), were assessed. Propafenone (2 mg/kg) was administered to 36 consecutive patients (mean age 60.8 years), 28 with a.f. and 8 with A.F. Nineteen patients (52.7%) reverted to sinus rhythm within 85 min (mean 27.2 min): 17 of 28 (60.7%) with a.f. and 2 of 8 (25%) with A.F. The efficacy of the drug was significantly influenced by the time elapsed from the onset of the arrhythmia: 14/21 (66.6%) patients with the arrhythmia lasting less then 48 hours and only 5/15 (33.3%) of those with the arrhythmia lasting more than 48 hours or of unknown onset, were converted (p less than 0.05). 18 patients underwent echocardiographic control: mean left atrial dimensions were 41.4 +/- 11.4 mm in converters and 47.4 +/- 11.2 mm in non converters (p = NS). Mean QRS lengthening observed was 16% (from 89 +/- 35.1 to 103.5 +/- 48.8 msec) (p = NS); QTc interval increased from 390 +/- 64.3 to 403 +/- 36.2 msec (p = NS). Arterial blood pressure showed significant changes only in two patients in whom a serious hypotension developed, needing infusion of adrenergic drugs. Non converters showed a reduction of the ventricular rate from 141.8 +/- 29.4/min to 101.8 +/- 18/min (p less than 0.01) meanwhile the shortest RR interval increased from 359.5 +/- 60.8 to 450 +/- 81.5 msec (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[Anterior ST segment depression during the exercise test in patients with previous inferior myocardial infarct. Scintigraphic and coronary arteriographic correlations].

Left ventriculography and coronary arteriography were performed in 49 patients: agreement on location of infarcted area was present between ventriculography and ECG in 22 cases and between ventriculography and myocardial scintigraphy in 34 cases (p less than 0.00125). Consequently on the basis of the scintigraphic redistribution image, all our patients were divided in 2 Groups: Group A, with inferior infraction (120 cases), and Group B, with infero-posterior or posterior infarction (68 cases). Exercise test showed anterior ST segment depression in 97 patients (59 from Group A and 38 from Group B). In these cases myocardial scintigraphy showed anterior ischemia in 48 (81%) patients of Group A and only in 17 (45%) of Group B (p less than 0.005). In patients with negative exercise test, myocardial scintigraphy detected anterior ischemia with similar incidence in both groups (about 40%). Out of the 49 patients studied by coronary arteriography, 33 had left anterior descending coronary artery disease: exercise test induced anterior ST depression in 25 of them (sensitivity 77%), while myocardial scintigraphy showed anterior ischemia in 29 (sensitivity 87%). Normal coronary arteries or isolated right or circumflex artery disease were found in 16 patients: 9 of them had anterior ST depression (specificity 56%) and none showed scintigraphic evidence of anterior ischemia (specificity 100%). In conclusion, in patients with previous infarction of inferior and/or posterior wall, ST-segment depression induced by exercise in anterior leads can be a false positive result, without a corresponding anterior myocardial ischemia. This finding is more often observed in patients with infarction of the posterior wall, in whom anterior ST depression on exercise might be due to ischemia or dyssynergy of the infarcted area. Myocardial scintigraphy allows a more precise identification of the scar location, and above all it is provided with good sensitivity and specificity in identifying residual ischemia due to left anterior descending coronary disease.

Adult↗
PubMed1981

[Echocardiographic evaluation of myocardial infarct patients undergoing rehabilitation].

29 patients with a recent myocardial infarction underwent a M-mode echocardiographic study before and after an ergometric training in order to study the training effects on the left ventricular function and on the cardiac chambers dimensions. 25 patients in the same clinical conditions and no trained acted as a control group and were evaluated with the same procedure. Our results show, in the trained group, a significant reduction of the diastolic (-5.6%) and systolic (-6.5%) diameters of the left ventricle and of the diameter of the left atrium (-7.5%). Moreover we observed an improvement of the left ventricular kinesis, as showed by the increased systolic movement of left posterior wall and of the interventricular septum and by the increased ventricular performance, as it results from increased systolic movement of the aortic root. In the control group no significant variation of the examined data was observed. The reduction of the diameters and the improvement of the kinesis and of ventricular performance could be explained by the reduced after-load and it shows the presence of direct beneficial effects of the exercise training on the heart, consisting both of improved cardiac mechanics and of a reduced MVO2.

Adult↗
PubMed1981

[Comparison between holter dynamic ECG and exercise stress test in the evaluation of ventricular arrhythmias in patients with ischaemic heart disease (author's transl)].

The Authors have examined the possibility for diagnostic and prognostic value of exercise stress test and of dynamic ecg in the identification of ventricular ectopic activity which represent a factor risk of sudden death. 41 male patients with IHD and Myocardial Infarction were given exercise stress test and Holter monitoring according to the usual methods. Both methods were useful to identify Pts with arrhythmias. The total incidence of ventricular ectopic beats was 78% with Holter and 46% with exercise test. Holter monitoring showed a major possibility to detect high degree arrhythmias (39%) against 9% of exercise test. Two methods are not comparable, not it was possible to demonstrate statistically significant incidence of ventricular ectopics with respect to the localization of M.I. 90% of Pts with positive exercise test (angina and/or ecg alterations) showed ventricular ectopic beats against 45% of Pts with negative exercise test. The association of ventricular ectopic beats in Holter and positive response to exercise test is highly predictable of sudden death. The results of investigation suggest the opportunity to evaluate Pts with MI by both methods, dynamic ecg and exercise stress test.

Adult↗
PubMed1980

[Exercise test in women with abnormal ecg (author's transl)].

114 women with abnormal resting electrocardiograms underwent exercise test on bicycle ergometry; they were grouped as follows: --group I: 40 asymptomatic females; --group II: 67 cases with atypical chest pain; --group III: 7 cases with typical angina. The exercise test was always maximal or submaximal SL. The only criteria used for positive stress was a 1 mm or more ischemic ST segment depression below the resting level, for at least 0.08 sec. The test was positive in 11 subjects (10.7%): 5 women of group II (7.5%) and 6 of group III (85.7%). Our results suggest that repolarisation abnormalities, not caused by hypertrophy, conduction disturbances and drugs, do not modify the outcomes of stress test. Ischemic patterns during exercise test are more frequently seen when flat or diphasic T waves are present in control ECG. In the majority of patients in all groups the T wave either does not change or becomes more positive or less negative after exercise. A greater prevalence of resting hypertension and arrhythmias is present in patients with positive tests.

Adult↗
PubMedDate not supplied

Selenium administration does not cause thyroid insufficiency in subjects with mild iodine deficiency and sufficient selenium intake.

Selenium is a trace element essential for the activity of type I 5'-deiodinase which converts thyroxine (T4) to 3,5,3'-triiodothyronine (T3). In iodine deficient hypothyroid children at low selenium dietary intake the supplementation of selenium induced a significant decrement of serum FT4 and T4 concentrations and an increase of serum TSH concentrations. Since in western countries selenium tablets begin to be largely consumed as a diet integrator, we have administered 100 micrograms/day of selenium as selenium methionine to 8 euthyroid female subjects with a positive iodine-perchlorate discharge test who had a previous episode of subacute or postpartum thyroiditis. We have studied subjects with positive iodine-perchlorate discharge test since the test indicates the existence of a subtle defect of thyroid hormone synthesis and therefore these subjects are prone to develop thyroid dysfunction. In contrast to previous findings in hypothyroid children at low iodine and selenium dietary intake, the supplementation of selenium did not decompensate thyroid hormone synthesis of euthyroid subjects with reduced thyroid iodine organification. The lack of any effect of selenium on thyroid hormone synthesis even in subjects with subtle thyroid hormone synthesis defect may be due to the fact that these subjects had a sufficient selenium dietary intake before selenium supplementation and an only marginally reduced dietary iodine intake.

Adult↗
PubMedDate not supplied

Effect of lysine vasopressin on basal and TRH stimulated TSH and PRL release in normal men.

In order to test the possible effects of lysine vasopressin (LVP) on basal and TRH stimulated TSH and PRL release, an iv bolus of LVP (0.06 IU/kg bw) was injected alone or just before TRH (20 or 400 micrograms iv) in 18 normal male subjects. The administration of LVP modified neither the basal secretion of TSH and PRL nor the TSH and PRL release induced by 20 or 400 micrograms TRH. These data suggest that in humans, vasopressin is not involved in the control of TSH and PRL release at the anterior pituitary level.

Adult↗
PubMedDate not supplied

Electrophysiological characteristics of the human atria after cardioversion of persistent atrial fibrillation.

BACKGROUND: In animal models, induced atrial fibrillation shortens the atrial effective refractory period (ERP) and reverses its physiological adaptation to rate. It is not clear whether this process, known as "electrical remodeling," occurs in humans. METHODS AND RESULTS: We determined the ERPs, at 5 pacing cycle lengths (300 to 700 ms) and in 5 right atrial sites, after internal cardioversion of chronic atrial fibrillation in 25 patients (14 in pharmacological washout and 11 on amiodarone). The ERPs were 195.5+/-18.8 ms in the washout and 206.3+/-17.9 ms in the amiodarone patients (P<0.0001). ERPs were closely correlated with the stimulation rates (r=0.95 in the washout and r=0.94 in the amiodarone group), and slope values indicating a normal (>/=0.07) or nearly normal (0.05 to 0.06) adaptation of ERP to rate were found in 77% of the 84 paced sites. The mean ERP was shorter in the lateral wall (198.1+/-17.9 ms) than in the atrial roof (203.3+/-21.5 ms) and in the septum (210.5+/-20.0 ms) (P<0.03). After 4 weeks of sinus rhythm, the mean ERP, determined again in 8 patients (4 in wash-out and 4 on amiodarone), was significantly increased compared with the basal study (221. 4+/-21.4 versus 197.8+/-18.3 ms, P<0.0001). CONCLUSIONS: After cardioversion of chronic atrial fibrillation, (1) atrial ERP adaptation to rate was normal or nearly normal in the majority of the cases, (2) a significant dispersion of refractoriness between different right atrial sites was present, and (3) ERPs were significantly increased after 4 weeks of sinus rhythm in both washout and amiodarone patients.

Adaptation, Physiological↗