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Biomedical subjects

E Baldi

Publications and source records attributed to E Baldi.

At least 109 records · Page 6Linked to original sources
PubMed1989

Renal hemodynamic and natriuretic effects of human atrial natriuretic factor infusion in cirrhosis with ascites.

We investigated the effect of a continuous infusion (50 micrograms as an initial bolus followed by a maintenance infusion at a rate of 0.1 micrograms/min.kg body wt for 45 min) of synthetic human atrial natriuretic factor (hANF) on renal hemodynamics and the renin-angiotensin-aldosterone system in 15 cirrhotic patients with ascites. Basal hANF levels were higher in cirrhotic patients when compared with normal values. Human atrial natriuretic factor infusion induced a significant decrease in mean blood pressure (from 77.8 +/- 1.1 to 68.6 +/- 1.5 mmHg, p less than 0.001) and a significant increase in heart rate (from 76.4 +/- 2.7 to 89.8 +/- 2.4 beats/min, p less than 0.001) in the patients studied. A remarkable increase in natriuresis (i.e., greater than or equal to 200 muEq/min) was observed in 5 patients (responders), whereas the infusion did not modify sodium excretion (i.e., less than or equal to 20 muEq/min) in 6 patients (nonresponders) and induced an intermediate response in 4 patients. Human atrial natriuretic factor-induced natriuresis was related to changes in renal hemodynamics that occurred during hANF infusion. In responders, the extent of the natriuretic response paralleled the increase of effective renal plasma flow and glomerular filtration rate; in non-responders the absent natriuretic response was associated with an evident reduction of these parameters. The reduction of blood pressure was similar in responders and nonresponders, but in the latter group it was followed by a marked increase of plasma renin activity and heart rate. It is likely that in nonresponders the natriuretic effect of hANF was blunted by the hemodynamic and hormonal changes triggered by the concomitant hANF-induced hypotension. This probably occurs in the presence of a greater reduction of effective arterial blood volume, as suggested by the higher baseline levels of plasma renin activity and the inability to increase free water excretion after a water load observed in nonresponders.

Adult↗
PubMed1989

Calcitonin gene-related peptide in the rat kidney: occurrence, sensitivity to capsaicin, and stimulation of adenylate cyclase.

The occurrence, effects and sensitivity to capsaicin and stimulation of adenylate cyclase of calcitonin gene-related peptide (CGRP) in the rat kidney have been investigated. CGRP-like immunoreactivity was higher in the medulla than in the papilla and the cortex. Capsaicin pretreatment significantly reduced CGRP-like immunoreactivity in the medulla and papilla while a small reduction was found in the cortex. CGRP-immunoreactive nerve fibres were observed surrounding blood vessels and occasionally in the vicinity of renal tubules and between the collecting ducts in the papilla. Some CGRP-immunoreactive fibres were also seen in kidneys from capsaicin-pretreated rats. Infusion of capsaicin (1 microM) through the renal artery of isolated and perfused rat kidney increased the CGRP-like immunoreactivity outflow from the venous effluent. This effect exhibited desensitization at the second challenge with the drug. Infusion of either capsaicin (1 microM) or CGRP (1 microM) reduced the increase of perfusion pressure induced by norepinephrine in isolated perfused rat kidney. Plasma protein extravasation was studied in the various regions of the rat kidney following infusion of capsaicin. No significant change was observed in the medulla, papilla or cortex after capsaicin administration. Adenylate cyclase activity was studied in membrane preparations from cortex, medulla and papilla of rat kidney. Cortical and medullary adenylate cyclase was stimulated in a concentration-dependent manner by salmon calcitonin, rat calcitonin and rat CGRP. Salmon calcitonin in these two areas showed half-maximal effective concentration approximately 1000 times lower and maximal stimulation only slightly higher than those of rat calcitonin and rat CGRP. However, in the papilla, only rat CGRP was able to induce a 60% increase of enzyme activity (half-maximal effective concentration, 19 +/- 1.6 nM). It is concluded that CGRP contained in capsaicin-sensitive sensory nerve may exert a local function in discrete areas of the rat kidney.

Adenylyl Cyclases↗
PubMed1989

Regional differences of adenylate cyclase stimulation by calcitonin and calcitonin gene-related peptide in the human kidney.

Calcitonin (CT) gene-related peptide (CGRP)-like immunoreactivity was detected in both the cortex and medullo-papillary portion of human kidneys. The two forms of human CGRP as well as rat CGRP were capable of stimulating renal cortical adenylate cyclase activity in a concentration-related manner, with a half-maximally effective concentration (EC50) similar to that of human CT and approximately 100-1000 times higher than that of salmon CT. However, in the medullo-papillary portion, in which both salmon CT and human CT were inactive, the two forms of human and rat CGRP increased adenylate cyclase activity by 100%, with EC50 values ranging from 36 nmol/L to 1 mumol/L. In cortical membrane preparations the effect of CGRP was additive to that of salmon CT. We concluded that regional differences exist in the effect of CT and CGRP in human renal tissue and that in the medullo-papillary portion and possibly in the cortex, CGRP stimulates adenylate cyclase activity through a CT-independent mechanism.

Adenylyl Cyclases↗
PubMed1988

Presence of dopamine-dependent adenylate cyclase activity in human renal cortex.

The effects of dopamine (DA) and of two selective DA DA1 agonists (SKF 38393 and SKF 82526) on adenylate cyclase activity were studied with human kidney cortex membrane preparations. DA elicited a dose-related stimulation of adenylate cyclase activity with an EC50 of 60 microM. The selective DA DA1 antagonist SCH 23390 behaved as a competitive antagonist, shifting the dose-response curve to the right. The non-selective beta-adrenoceptor antagonist (-)-propranolol did not affect the EC50 of the dose-response curve to DA but attenuated the maximal stimulatory effect of DA at concentrations higher than 100 microM. (+)-Sulpiride inhibited DA-induced adenylate cyclase stimulation in a dose-dependent manner with an IC50 of 4.6 X 10(-8) M but (-)-sulpiride was without effect. Both SKF 38393 and SKF 82526 stimulated the adenylate cyclase activity of human kidney cortex; this effect was completely antagonized by SCH 23390. Our results, demonstrating the presence of DA-sensitive adenylate cyclase activity, strongly suggest the presence of a DA receptor of the DA1 subtype in human kidney cortex.

Adenylyl Cyclases↗
PubMed1988

Measurement of catecholamines, met-enkephalin, somatostatin and substance P-like immunoreactivities in 12 human pheochromocytomas.

The present study was designed to evaluate the simultaneous presence of epinephrine (E), norepinephrine (NE), met-enkephalin (ME)-, somatostatin (SRIF)- and substance P (SP)- like immunoreactivities (LI) in extracts of 12 pheochromocytomas obtained at the time of surgery from 10 patients. Moreover, catecholamines and ME-LI levels were measured in peripheral plasma of each patient. Each pheochromocytoma was characterized by a high variability of ME-LI, SRIF-LI, SP-LI, E and NE levels. The highest E concentrations were found in tumors from patients with Multiple Endocrine Adenomatosis (MEA) IIa syndrome, whereas in sporadic pheochromocytomas NE was the main catecholamine. Among the neuropeptides ME-LI showed the highest intratumoral concentration, and SP-LI the lowest. No correlations were found between intratumoral levels of catecholamines and any of the neuropeptides or between any of the different neuropeptides measured. Plasma catecholamine levels were not correlated with intratumoral catecholamine levels. Plasma ME-LI was higher than normal in only one patient. No correlation was observed between tumoral CA or peptide content and the clinical picture. Our study confirms that human pheochromocytoma cells can synthetize different neuropeptides. The variability of the clinical picture very likely depends on the biochemical and biological heterogeneity of this chromaffin tumor.

Adrenal Gland Neoplasms↗
PubMed1988

Regional differences in the motor response to capsaicin in the guinea-pig urinary bladder: relative role of pre- and postjunctional factors related to neuropeptide-containing sensory nerves.

Capsaicin induced a contraction of isolated strips from the guinea-pig urinary bladder which was more evident in the dome than in the neck and inhibited contractions induced by field stimulation, particularly in the neck. Both responses exhibited prompt desensitization and were tetrodotoxin-resistant, suggesting a specific action on transmitter release from sensory nerve terminals. Indeed, the contractile response in the dome was prevented by a substance P antagonist while the inhibitory response in the neck was prevented by immunoblockade with anticalcitonin gene-related peptide (CGRP) serum. Substance P produced a contraction of the guinea-pig bladder, being about 5 times more potent in the dome than in the neck, while CGRP inhibited the evoked contractions, being about 8 times more potent in the neck than in the dome. Further, the maximal effect of CGRP in the neck was almost double that in the dome. Substance P- and CGRP-like immunoreactivity were detected in both the dome and the neck with no regional differences for each peptide. CGRP-like immunoreactivity was 6.3 and 7.9 times higher than substance P-like immunoreactivity in the dome and the neck, respectively. Exposure to capsaicin evoked release of both substance P- and CGRP-like immunoreactivity from the dome and the neck. Peak CGRP-like immunoreactivity released by capsaicin was 12.3 and 8 times greater than substance P-like immunoreactivity in the dome and the neck, respectively. For each peptide, no difference was found in peak release in the dome vs neck. Total substance P-like immunoreactivity released from the neck was 25% lower than that released from the dome. The ability of CGRP to stimulate accumulation of 3',5' cyclic adenosine monophosphate in membranes prepared from the bladder muscle was greater in preparations from the neck than from the dome. These findings indicate that postjunctional mechanisms (type and number of receptors for sensory neuropeptides, coupling with second messengers) are a major determinant of the type of motor responses consequent of the release of sensory neuropeptides from capsaicin-sensitive nerves.

Animals↗
PubMed1988

Vasopressin and oxytocin receptors in vagina, myometrium, and oviduct of rabbits.

In view of the presence of distinct oxytocin (OT) and vasopressin (VP) receptors in the male genital tract (porcine) we have reexamined the receptors for OT and AVP in the classical OT target tissue, female genital tract (rabbit). Neurohypophysial hormone receptors have been investigated in vagina, myometrium, and oviduct using quantitative ligand binding, adenylate cyclase, and contractility studies. Our results clearly indicate the presence of distinct OT and V1 VP receptors in the myometrium, while only the latter was detected in vagina and oviduct. In myometrium, estrogen treatment increases the density of OT and AVP receptors, while progesterone administration inhibits the estrogen effect. At the time of spontaneous delivery a dramatic (17-fold) increase was observed for the OT sites, while the AVP sites were unchanged. AVP receptors in vagina were sensitive to sex steroid administration and were reduced during pregnancy and delivery. Isometric contractility studies suggest that not just OT, but AVP can stimulate uterine strips, an effect that is partially reversible by the V1 antagonist d(CH2)5TyrMeAVP. In vagina only AVP is effective in inducing contractions at nanomolar concentrations. These results suggest a role for AVP as well as OT in regulation of the motility of female genital tract.

Adenylyl Cyclases↗
PubMed1987

[Hormonal, beta-endorphin and renin activity changes in man during partial immersion, as a therapeutic method, in water at 38 degrees C].

This research was carried out to define the effects on men of head-out water immersion in a bath at 38.41 +/- 0.04 degrees C (mean +/- S.E.) with a method similar to that used for therapeutical rehabilitation and time of immersion of 30 minutes. Beta-endorphin, renin activity, aldosterone, cortisol, HGH, FSH, LH, TSH, T3, T4 and prolactin haematic levels were analysed. Seventeen healthy subjects (fourteen males and three females), aged 21-65 years (mean age 29.8 +/- 2.6) were studied. Water immersion caused a decrease in FSH and LH haematic concentrations; no significant changes occurred in beta-endorphin, renin activity, aldosterone, prolactin, cortisol, HGH, TSH, T3, T4 and FTI values. Thirty minutes after the end of immersion, FSH and LH levels returned to pre-immersion values. The probable pathogenesis of these observations is suggested.

Adult↗
PubMed1987

Usefulness of basal catecholamine plasma levels and clonidine suppression test in the diagnosis of pheochromocytoma.

In the present paper we report our experience on the utility of basal plasma catecholamine (CA) measurement and of the clonidine-suppression test in the diagnosis of pheochromocytoma. Basal noradrenaline (NA) and adrenaline (A) were assayed in plasma samples of 27 subjects affected by pheochromocytoma. When compared to basal values obtained in hypertensive patients without pheochromocytoma, one or both the CA resulted pathologically elevated in all patients except one. The response to the clonidine-suppression test was evaluated in 41 hypertensive patients suspected of having a pheochromocytoma measuring plasma NA and A in basal conditions and 2 and 3 h after oral administration of 300 micrograms clonidine. Extensive laboratory and instrumental findings confirmed the presence of pheochromocytoma only in 12 patients. Among the other 29 patients basal plasma CA resulted higher than normal in 4 patients. In patients without pheochromocytoma clonidine induced a significant fall in both NA and A plasma levels. The decrease in NA was observed in each patient. The 12 patients with pheochromocytoma showed a pathological elevation of one or both the CA. In this group clonidine did not significantly suppress plasma CA. The individual responses were extremely variable. Our data confirm the validity of plasma CA measurement as a diagnostic tool for the diagnosis of pheochromocytoma. The results of the clonidine-suppression test were generally confirmatory of the basal CA plasma values but in the 4 hypertensive patients without pheochromocytoma who showed basal plasma CA higher than normal clonidine resulted a useful tool in excluding the presence of pheochromocytoma.

Adolescent↗
PubMed1986

[Plasma beta endorphin in man during partial immersion in water using the therapeutic method].

The following study was designed to evaluate plasma beta-endorphin (beta-EP) variations in healthy volunteers during thermoneutral head-out water immersion while prevalently in the standing position. The type of immersion was similar to that currently adopted for therapeutic rehabilitation. Plasma beta-EP was evaluated by RIA previous beta-lipotropin stripping and Sep-Pack cartridge methanol extraction. Plasma beta-EP levels significantly decreased during water immersion from a value of 12.71 +/- 2.04 pmol/l to 7.46 +/- 1.09 pmol/l at 15 min (P less than 0.05) and to 6.08 +/- 1.87 pmol/l at 30 min (P less than 0.01). Thirty min after the end of immersion, plasma beta-EP levels showed a slight increase to 6.98 +/- 1.88 pmol/l but were still significantly below the basal level (P less than 0.05). These results are consistent with the previously demonstrated decrease of ACTH and prolactin and the increase of plasma dopamine and decrease of norepinephrine, suggesting that thermoneutral head-out water immersion is not a stressful condition in healthy subjects. Further studies are necessary in order to clarify the mechanism involved in beta-EP decrease in normal subjects during thermoneutral head-out water immersion.

Adrenocorticotropic Hormone↗
PubMed1986

Opioid modulation of normal and pathological human chromaffin tissue.

To evaluate whether opioid receptor blockade might modulate sympathetic-adrenal activity, we studied the effects of placebo or naloxone administration on plasma catecholamine (CA) levels in a group of 13 normal subjects and 15 hypertensive patients suspected to have a pheochromocytoma. Diagnostic evaluation confirmed the presence of pheochromocytoma in 9 patients. Among these, 4 had a unilateral epinephrine (E)-secreting tumor, 3 had bilateral E-secreting tumors due to multiple endocrine adenomatosis type IIa, and 2 had a unilateral norepinephrine (NE)-secreting tumor. In each subject studied, CA secretion was evaluated by calculating the area (0-30 min) under the plasma hormone curves after placebo or naloxone administration. In normal subjects naloxone caused a significant increase (P less than 0.005) of E secretion, whereas NE did not change. Similarly, in the group of hypertensive patients, E secretion increased after naloxone (P less than 0.01). In pheochromocytoma patients naloxone caused a significant increase in E (P less than 0.05) and NE (P less than 0.01) secretion from E-producing tumors but no increase in the patients with NE-secreting pheochromocytomas. The study suggests that CA secretion from normal and pathological chromaffin tissue is modulated by endogenous opioids; this modulation seems particularly evident in patients with E-secreting pheochromocytoma.

Adolescent↗
PubMed1986

Hypernociceptive syndromes and pharmacological inhibition of endogenous opioid degradation.

Endogenous opioid peptides, by modulating the release of sympathetic transmitters, may play a role in the pathogenesis of migraine and related headaches which are considered hypernociceptive syndromes. Hypoendorphinaemia has been demonstrated in migraine attack. Captopril, a drug able to potentiate morphine analgesia in rats and inhibit enkephalinase in animals and in man, improves the clinical course of migraine. In the present research the cerebrospinal fluid and plasma beta-endorphin (beta-EP) levels have been evaluated following a single oral dose of captopril. The drug increased plasma beta-EP levels in migraine sufferers, and these data may be relevant in the mechanism of action of this drug in migraine and related headaches.

Captopril↗
PubMed1986

Met-enkephalin-like immunoreactivity (MELI) and enkephalinase activity (EKA) in cord blood and newborns in the first hours of life.

Recently, the presence and the concomitant release with catecholamines of metenkephalin and other pro-enkephalin A deriving peptides have been demonstrated in the adrenal medulla of various mammals and man. As high amounts of catecholamines are released in the newborn at delivery, probably following the stress of parturition, a similar release of met-enkephalin and other pro-enkephalin A deriving peptides from the newborn chromaffin tissue may be hypothesized. In the present study we investigate the occurrence of met-enkephalin-like immunoreactivity and enkephalinase (quite a specific enkephalin degrading enzyme) in cord and newborn plasma at different hours after birth. Our results show the presence of high met-enkephalin-like immunoreactivity levels in cord and newborn plasma with respect to normal adult values. On the contrary, cord blood enkephalinase activity was lower than in adult subjects and further decreased during the first hours of life. A positive correlation was found between the two parameters. These data seem to indicate a release of met-enkephalin-like peptides from the newborns' sympathoadrenal tissue following the stress of delivery and in the first hours of life.

Chromatography, High Pressure Liquid↗
PubMed1986

Measurement of transferrin in human seminal plasma by a chemiluminescent method.

We describe a luminescence immunoassay for measuring transferrin in human seminal plasma. Human transferrin conjugated with 7-[(N-4-aminobutyl)-N-ethylamino]naphthalene-1,2-dicarboxylic acid hydrazide was used to monitor the immunological reaction. The conjugate was stable for at least one year. The sensitivity (2 ng per tube) of the assay allows measurement of this protein in diluted seminal plasma. Results by this method (y) correlated well (r = .9681) with those by a conventional RIA method (x): y = 1.000x + 1.646 micrograms per ejaculate. Seminal transferrin concentrations are reported for normal control subjects, vasectomized subjects, and infertile patients. The method described appears suitable for measurement of seminal transferrin as an index of Sertoli cell function in male infertility.

Humans↗
PubMed1982

Intermittent hypoendorphinaemia in migraine attack.

Beta-endorphin (RIA method, previous chromatographic extraction) was evaluated in plasma of migraine sufferers in free periods and during attacks. Decreased levels of the endogenous opioid peptide were found in plasma sampled during the attacks but not in free periods. Even chronic headache sufferers exhibited significantly lowered levels of beta-endorphin, when compared with control subjects with a negative personal and family history of head pains. The mechanism of the hypoendorphinaemia is unknown: lowered levels of the neuropeptide, which controls nociception, vegetative functions and hedonia, could be important in a syndrome such as migraine, characterized by pain, dysautonomia and anhedonia. The impairment of monoaminergic synapses ("empty neuron" condition) constantly present in sufferers from serious headaches, could be due to the fact that opioid neuropeptides, because of a receptoral or metabolic impairment, poorly modulate the respective monoaminergic neurons, resulting in imbalance of synaptic neurotransmission.

Adult↗