PubMed Health⌕ Search

Biomedical subjects

M Bevilacqua

Publications and source records attributed to M Bevilacqua.

At least 55 records · Page 3Linked to original sources

Gastric Peristalsis Control by Mono Situ Electrical Stimulation: a Preliminary Study.

BACKGROUND: This study was initiated 3 years ago when antral gastric stimulation was first used successfully to reduce free feeding in swine. METHODS: Three swine weighing 45 kg each were implanted with one subserosal bipolar electrode, positioned in the antrum, close to the pylorus, at the anterior side of the lesser gastric curvature. RESULTS: During 4 hours of kethamine anesthesia we paced the stomach by various patterns of electrical stimulation and obtained both forward and backward peristalsis, as well as gastric peresis. CONCLUSION: Variations in antral electrical stimulation produce characteristic patterns of forward and reverse peristalsis.

Journal Article↗

Pharmacologic data reveal the heterogeneity of angiotensin-converting enzyme according to its source (lung versus heart).

Angiotensin-converting enzyme (ACE) has 2 different active sites: a C-site (in the carboxy terminal region) and an N-site (in the amino terminal part). Some ACE inhibitors have a relatively greater affinity for the C-sites, whereas others bind to the 2 sites with equal affinity. The different ontogenesis of lung and heart endothelial cells can be related to binding differences to the C- and N-sites. We labeled Ro31-8472, a clizapril derivative, which has the same affinity for the 2 ACE sites. Binding of 125I-Ro31-8472 to human left ventricle and lung plasma membranes was saturable, inhibited by ethylene diaminetetraacetic acid and displayed affinities of 360 +/- 41 pM in heart and 320 +/- 51 pM in lung. For captopril the Hill slope was 0.57 +/- 0.03 for heart and 0.48 +/- 0.05 for lung; for delaprilat, a nonsulfhydryl analogue of captopril, the slope was 0.43 +/- 0.05 for heart and 0.55 +/- 0.05 for lung. These drugs were characterized by biphasic competition isotherms. The Hill slope of enalaprilat was 1.01 +/- 0.06 for heart and 0.93 +/- 0.06 for lung, and Ro31-8472 had a slope of 0.97 +/- 0.04 for heart and 0.93 +/- 0.03 for lung. The affinity of ACE inhibitors with Hill slope different from unity varied according to the source of ACE; in fact, delaprilat had greater affinity for the high-affinity sites of heart than lung (pKi, 9.89 and 9.47, respectively), whereas captopril had greater affinity for the high-affinity sites of lung than heart (9.40 and 8.85, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Pure Autonomic Failure: complex abnormalities in the neural mechanisms regulating the cardiovascular system.

The aim of this study was to evaluate the sympatho-vagal interaction modulating cardiovascular function and the possible impairment of baroreceptor sensitivity in patients affected by Pure Autonomic Failure (PAF). We studied 4 patients affected by PAF and 7 controls at rest and during different levels (45 degrees, 60 degrees, 90 degrees) of head-up tilt. On a different day all subjects underwent i.v. administration of phenylephrine at dosages adequate to enhance systolic blood pressure by about 20 mmHg both at rest and during 45 degrees head-up tilt. Finally, 1.5 mg atropine was infused intravenously only in the patients. Spectral analysis of RR interval and systolic arterial pressure (SAP) variabilities provided markers of sympathetic (low-frequency oscillations, about 0.1 Hz, LFRR) and vagal (high-frequency oscillations, about 0.25 Hz, HFRR) modulations of heart period and of sympathetic vasomotor activity (low-frequency oscillations of SAP variability, LFSAP). Baroreceptor mechanisms were quantified by means of the index alpha (calculated from the square root of the ratio between the powers of HF components of RR interval and SAP variabilities) and of the phenylephrine RR-SAP slope. Patients affected by PAF were characterized by a drastic decrease in total power of RR variability and by the absence of LFRR and LFSAP components. Moreover, HFRR, although largely predominant in its relative value, was also markedly reduced in its absolute value. Finally, the baroreceptive mechanisms appeared to be heavily impaired. In conclusion, PAF patients seem to be characterized by a complex alteration of neural mechanisms, which in addition to the signs of a sympathetic denervation include an impairment, at least functional, of the vagal modulation of heart rate.

Atropine↗

Sulphonamides as anti-inflammatory agents: old drugs for new therapeutic strategies in neutrophilic inflammation?

1. It is well known that neutrophils act as mediators of tissue injury in a variety of inflammatory diseases. Their histotoxic activity is presently thought to involve proteinases and oxidants, primarily hypochlorous acid (HOCl). This oxidant is also capable of inactivating the specific inhibitor of neutrophil elastase (alpha 1-antitrypsin), thereby favouring digestion of the connective matrix. 2. In the present work, we found that sulphanilamide and some sulphanilamide-related anti-inflammatory drugs such as dapsone, nimesulide and sulphapyridine reduce the availability of HOCl in the extracellular microenvironment of activated neutrophils and prevent the inactivation of alpha 1-antitrypsin by these cells in a dose-dependent manner. The ability of each drug to prevent alpha 1-antitrypsin from inactivation by neutrophils correlates significantly with its capacity to reduce the recovery of HOCl from neutrophils. Five other non-steroidal anti-inflammatory drugs were completely ineffective. 3. Therefore, sulphanilamide-related drugs, i.e. dapsone, nimesulide and sulphapyridine, have the potential to reduce the bioavailability of neutrophil-derived HOCl and, in turn, to favour the alpha 1-antitrypsin-dependent control of neutrophil elastolytic activity. These drugs appear as a well-defined group of agents which are particularly prone to attenuate neutrophil histotoxicity. They can also be viewed as a previously unrecognized starting point for the development of new compounds in order to plan rational therapeutic strategies for controlling tissue injury during neutrophilic inflammation.

Anti-Inflammatory Agents↗

[Echographic and sonographic study of ovaries in girls with precocious puberty].

The aim of this study is the biometrical and morphological evaluation of the ovaries by sonography and the study of the haemodynamics of the ovarian artery flow by doppler ultrasound in 14 girls with precocious puberty and in 33 control subjects. All people ranged in age from 5 to 7 years. The gonadian mean volume and the mean pulsatility index have been evaluated. A significant difference in the ovarian volume has been found between patients and controls. No index between the two groups. We conclude that the doppler ultrasound needs a larger number of cases to evaluate its validity in girls with precocious puberty.

Adolescent↗

Effect of nimesulide action time dependence on selectivity towards prostaglandin G/H synthase/cyclooxygenase activity.

PGHS (cyclooxygenase, prostaglandin endoperoxide synthase, 8.11,14-icosatrienoate hydrogen donor oxygen oxidoreductase, EC 1.14.99.1) is a bifunctional, membrane-bound hemoprotein that catalyzes both the bisoxygenation of arachidonic acid to form PGG2 and the peroxidative reduction of PGG2 to form PGH2. Recently two forms of cyclooxygenase have been isolated, one (COX-1) being "constitutive", the other (COX-2) being mitogen-inducible. Nimesulide (CAS 51803-78-2) has been shown to inhibit with high selectivity COX-2 without affecting COX-1 activity, so explaining the previous observations about the selectivity of the anti-prostaglandin effect of the drug. The potency of the effect, however, seems to be different according to these works. The time dependence of COX-2 inhibitors might afford some clues to a better understanding of the mechanism of COX-2 selective inhibition, on the discrepancy between some authors about the potency of the drug and on the relationship between COX-2 inhibition and inhibition of superoxide anion production, an event also characterized by a time dependence. So we evaluated the time dependency of the effect of nimesulide on COX-1 and COX-2. COX-1 was isolated from ram seminal vesicles, and COX-2 was from sheep placenta. Nimesulide inhibited COX-2 activity in a concentration-dependent manner. The inhibition of COX-2 was characterized by the time dependence, so the IC50 varied according to the time of pre-incubation (from 70 +/- 35 mumol/l to 0.07 +/- 0.05 mumol/l). Nimesulide did not affect COX-1 activity until 1 mumol/l and with an IC50 > 100 mumol/l. In conclusion nimesulide's selective inhibitory effect on COX-2 is time-dependent whereas its weak effect on COX-1 is not time-dependent. This observation agrees with the time dependence effect of COX-2 reported by other workers with NS-398 (N-(2-cyclohexyl-oxy-4-nitrophenyl)methane sulphonamide) and with flosulide and explains the different values of IC50 reported by other workers. Nimesulide shares with other sulfanilide-like drugs the time dependence of its selective effect on COX-2.

Animals↗

Possible modes of action of nimesulide in controlling neutrophilic inflammation.

Even in recent years the development of new non-steroidal anti-inflammatory drugs (NSAIDs) appears to be essentially driven by the archaic idea to protect humans from pain and other symptoms of inflammation. Very few attempts have been made to understand if any of these drugs can limit the tissue injury during one or several forms of inflammatory reaction. In studying the events underlying the development of the tissue injury during neutrophilic inflammation, it was found that at least a NSAID, i.e. nimesulide (CAS 51803-78-2), has high potential to interfere efficiently with the major pathway responsible for neutrophil-dependent histotoxicity. Other chemically related drugs, not classified as NSAIDs but used in disease conditions characterized by neutrophilic inflammation, i.e. dapsone and sulfapyridine, have similar activities. Therefore, it is suggested that derivates from sulfanilamide (nimesulide, dapsone and sulfapyridine) are the major candidates for developing rational therapeutic anti-inflammatory strategies for controlling the development of tissue injury during neutrophilic inflammation. Also, these molecules might serve to drive the synthesis of new histoprotective antiinflammatory drugs.

Animals↗

Nimesulide decreases superoxide production by inhibiting phosphodiesterase type IV.

Nimesulide, the prototype of a new class of anti-inflammatory drugs, dose-dependently decreases the production of the superoxide anion (O2-.) in N-formyl-methionyl-leucyl-phenylalanine (fMLP)- and in phorbol myristate acetate (PMA)-stimulated polymorphonuclear leukocytes. The inhibition of O2-. is possibly related to its inhibitory effect on polymorphonuclear leukocyte cytosolic phosphodiesterase type IV (IC50 = 39 +/- 2 microM), to the related increase in cAMP (P < 0.01 at 1 microM) and the subsequent increase in protein kinase A activity. In fact H-89, a specific protein kinase A inhibitor, counteracts the inhibitory effect of nimesulide on O2-. production by fMLP and PMA. The activation of protein kinase A may prompt the phosphorylation of a number of substrates, thus inhibiting the assembly of NADPH-oxidase in the plasma membrane. Accordingly, nimesulide decreases PMA-induced assembly of NADPH-oxidase in polymorphonuclear leukocytes plasma membranes by about 35%. Protein kinase A activation may also interfere with chemotaxis. Nimesulide inhibits stimulated chemotaxis and the effect is decreased by H-89. Inhibition of phosphodiesterase type IV may explain many of nimesulide's effects.

Adenylyl Cyclases↗

Hyponatraemia in AIDS.

Hyponatraemia is very common in AIDS patients. It is observed in about 40-50% of hospitalized patients. It may contribute to overall mortality in advanced disease. Vasopressin measurements in these patients basically present two distinct syndromes: hyponatraemia and 'normal' vasopressin levels (i.e. measurable vasopressin) and hyponatraemia with suppressed vasopressin. Hyponatraemia with suppressed vasopressin is very rare and has only been observed in AIDS patients with dementia and primary polydipsia. Hyponatraemia and measurable vasopressin can be also divided into two syndromes. In some patients vasopressin is 'appropriately' elevated, i.e. in those with body fluid losses (diarrhoea) or chronic hypovolaemia (adrenal failure); these patients also present with hyperuricaemia and other signs of low blood volume. In other patients vasopressin is 'inappropriately' elevated in those with no clinical evidence of hypovolaemia (typically characterized by low serum uric acid levels) such as in Pneumocystis carinii pneumonia and other opportunistic infections leading to SIADH. CSWS is a relatively frequent complication in some patients with cerebral infection or tumour. High-dose trimethoprim (for Pneumocystis carinii prevention) acts as an amiloride-like drug and induces a clinical state characterized by hyponatraemia and hyperkalaemia which is indistinguishable from hyporeninaemic hypoaldosteronism. The mechanism of the hyponatraemia caused by other drugs (miconazole, pentamidine, amphotericin, vidarabine) is not as yet known.

Acquired Immunodeficiency Syndrome↗

Effects of naftifine and terbinafine, two allylamine antifungal drugs, on selected functions of human polymorphonuclear leukocytes.

Many antimycotic agents negatively affect the natural immune response. Typically, these drugs impair polymorphonuclear leukocyte (PMN) production of superoxide anion, chemotaxis, or the killing of pathogens. Allylamines are a new class of antimycotic compounds with a new mechanism of antifungal action, i.e., inhibition of the fungal squalene epoxidase. The trial that we describe aimed to evaluate the effects of two allylamines, terbinafine and naftifine, on selected functions of PMNs, i.e., superoxide anion production, chemotaxis, and killing of Candida albicans blastospores. Terbinafine and naftifine on their own did not affect superoxide anion production when they were added to PMNs. When PMNs were preincubated with allylamines and were then stimulated by N-formyl-Met-Leu-Phe or phorbol 12-myristate 13-acetate, superoxide anion production was increased (priming effect). Since intracellular free calcium (Ca2+i) is involved in the control of superoxide anion production, we evaluated the effects of the allylamines on the Ca2+i concentration ([Ca2+]i). In the presence of terbinafine or naftifine, the [Ca2+]i increased in a dose-dependent manner; the source of Ca2+i was not extracellular since it was not affected by extracellular calcium chelation with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. In the presence of terbinafine or naftifine, chemotaxis of PMNs was not impaired. Terbinafine and naftifine slightly but significantly increased the killing of C. albicans blastospores (P < 0.05 at 10 and 100 microM). In conclusion, in contrast to imidazole-like drugs, the allylamine antimycotic compounds terbinafine and naftifine enhance selected functions of PMNs.

Allylamine↗

Loss of osmotic thirst in multiple system atrophy: association with sinoaortic baroreceptor deafferentation.

We evaluated plasma osmolality (pOsm), thirst, and vasopressin response to hypertonic saline infusion in 14 patients with multiple system atrophy (MSA). This disease is characterized by the degeneration of noradrenergic neurons in the central nervous system and severe orthostatic hypotension. Seven patients were also characterized by the lack of vasopressin response to hypotension (group B) and seven by a preserved response (group A). In group A pOsm rose from 290 +/- 2 to 312 +/- 6 mosmol/kgH2O, vasopressin from 0.9 +/- 0.3 to 5.7 +/- 0.5 pmol/l, and thirst from 1.1 +/- 0.1 to 8.7 +/- 1.1 cm on the visual analog scale. After saline, patients drank 1,215 +/- 150 ml of water (no different from healthy controls). In group B patients' pOsm rose from 296 +/- 3 to 325 +/- 6 mosmol/kgH2O and vasopressin from 1.2 +/- 0.1 to 19.6 +/- 0.4 pmol/l (P < 0.01 vs. group A and controls). Group B patients had no thirst during saline and drank little after the challenge (175 +/- 50 ml; P < 0.01 vs. group A and control). Forced drinking decreased vasopressin in patients before changes in pOsm, showing that inhibitory afferents from oropharyngeal mucosa were intact. In MSA patients with altered afferent control of vasopressin there is a dissociation between the osmotic control of thirst and the osmotic control of vasopressin.

Afferent Pathways↗

Long-term nasal intermittent positive pressure ventilation in advanced Duchenne's muscular dystrophy.

The aim of our study was to evaluate the long-term effect of nasal ventilation in patients with advanced Duchenne's muscular dystrophy (DMD). To this end, we compared the clinical and pulmonary function course of five subjects affected with chronic ventilatory failure due to DMD and treated with nasal intermittent positive pressure ventilation (NIPPV) with that of an unventilated comparison group; the latter consisted of another five patients with DMD, with a similar degree of clinical and respiratory functional impairment, who refused long-term mechanical ventilation. The duration of the follow-up was 24 months. At the conclusion of the trial, all patients treated with NIPPV were still alive; in contrast, four of five patients who underwent simple conservative treatment had already died (mean survival, 9.7 +/- 5.8 months). After 6 months of follow-up, mean loss of FVC and maximal voluntary ventilation was considerably higher in nonventilated subjects (respectively: -0.23 L vs +0.03 L and -5 L/min vs -1.5 L/min). These are the first comparative results confirming that long-term NIPPV helps to stabilize pulmonary function and to prolong the expectancy of life of patients with DMD.

Adolescent↗

[Cardiac retransplantation: is it justified in childhood?].

A 7-year-old boy had undergone heart transplantation (HT) at 1 year of age. The immunosuppressive regimen consisted of cyclosporine and azathioprine (Cy+Aza). During the follow-up there were 7 episodes of moderate rejection: 4 of them occurred during the first 3 months. He had cytomegalovirus (CMV) seroconversion 4 years after HT. After 5 years since he underwent primary HT, cardiac catheterization and selective coronary angiography, performed on a yearly basis, showed triple vessel occlusive disease. The treadmill test was positive. During the following year, the patient's clinical condition deteriorated: in May '92 he underwent retransplantation. Cross-match was negative and there were no common HLA-DR antigens between the first and the second donor heart. Only 1 rejection episode occurred during the first 18 months of follow-up. Despite the shortage of donor hearts we feel that retransplantation is justified as an elective procedure in pediatric patients with cardiac allograft vasculopathy (CAV).

Biopsy↗

Seroepidemiology, morbidity and vaccination strategies against rubella infection. Eight years experience in Oltrepò Pavese.

Selective rubella vaccination of schoolgirls in Italy started 14 years ago following the United Kingdom strategy that was adopted in 1970. The aims of this program were to eliminate the risk of rubella among women of childbearing age, encourage the acquisition of immunity by natural infection during early childhood and allow the vaccine-induced antibody production by the circulating virus. On the basis of this program, between 1982 to 1990, a prospective serosurvey for rubella antibody in the province of Pavia was performed. The results showed a decline in the overall seropositivity rate for rubella antibodies from 57.7% in 1982 to 41.9% in 1984 followed by a remarkable increase in 1985 (53.3%) and in 1987 (56.5%). This trend was confirmed by the number of cases reported to the local Public Health Service. The results of this study provide further evidence of the need to change the current selective immunization policy in order to obtain a significant reduction of risk of the infection in the population.

Adolescent↗

Myopathy and hypertrophic cardiomyopathy with selective lysis of thick filaments.

We present a undescribed condition in a girl who died at 8 years of hypertrophic cardiomyopathy. Muscle and endomyocardial biopsies disclosed a selective loss of thick filaments ultrastructurally. In muscle biopsy histochemical abnormalities of myofibrillar AT-Pase were confined to type 1 fibres. Gel electrophoresis of muscle homogenate showed no qualitative abnormalities of slow and fast myosin heavy chains (MHC) and light chains, and the amount of the different myosin isozymes was in agreement with histochemical myofibrillar ATPase findings. The pathogenetic mechanisms have not been elucidated in this case but we suspect an abnormality of the beta-cardiac MHC gene, the only gene expressed in the heart and in type 1 skeletal muscle fibres.

Calmodulin-Binding Proteins↗

An electrophysiological method to assess the distribution of the sensory propagation velocity of the digital nerve in normal and diabetic subjects.

We report a new computer-assisted collision method to evaluate sensory conduction velocity (SCV) distribution in the digital nerve of the middle finger in normal subjects and in insulin-dependent diabetic subjects without any neurological impairment. Distribution curves were monomodally shaped in controls, indicating a greater proportion of fibers with relatively slow conduction velocity and a lesser proportion of fibers with faster velocity. In most diabetic nerves, a monomodal trend of the SCV distribution indicated a definite reduction in high and intermediate SCV. In a small proportion of nerves, the SCV distribution tended to be bimodal, with an absolute maximum corresponding to lower velocities and a relative maximum to intermediate-fast velocities. Slowing of the intermediate velocity, or loss of fibers of intermediate velocity, can be hypothesized to represent the early electrical evidence of a subclinical polyneuropathy in insulin-dependent diabetic subjects.

Action Potentials↗

Recent contributions to knowledge of the mechanism of action of nimesulide.

Nimesulide is a nonsteroidal anti-inflammatory drug (NSAID) of the sulfonanilide class. Its anti-inflammatory, analgesic and antipyretic activities have been demonstrated in several widely used animal experimental models and in numerous clinical trials. Nimesulide only weakly inhibits prostaglandin synthesis and appears to exert its effects through various mechanisms. It inhibits the release of oxidants from activated neutrophils and has a scavenging effect on hypochlorous acid without affecting neutrophil function. Nimesulide also decreases histamine release from tissue mast cells and inhibits the production of platelet-activating factor by human basophils. Furthermore, when added in vitro to cultures of human articular chondrocytes, nimesulide inhibits the release of stromelysin and blocks metalloproteinase activity.

Animals↗