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Biomedical subjects

C Benvenuti

Publications and source records attributed to C Benvenuti.

At least 19 recordsLinked to original sources
PubMed2006

A strain of Salmonella enterica serovar Virchow isolated in Turkey and carrying a CTX-M-3 extended-spectrum beta-lactamase.

A multiply resistant strain of Salmonella enterica subsp. enterica serovar Virchow was isolated in November 2002 from a catheterized patient admitted to the SSK Training Hospital in Ankara, Turkey. This isolate showed an antimicrobial susceptibility pattern compatible with the presence of a CTX-M-type ESBL, namely resistance to cefotaxime, aztreonam and cefepime, and intermediate susceptibility to ceftazidime. On checking for the presence of the bla(TEM), bla(SHV), and bla(CTX-M )resistance genes by PCR, negative results were obtained with the primers specific for SHV and TEM genes, while positive results were obtained with those specific for CTX-M-type genes. After sequencing, the beta-lactamase was identified as CTX-M-3. This is the first report of this enzyme in Salmonella Virchow and represents a further disquieting threat to the therapy of infections caused by Salmonella isolates.

Anti-Bacterial Agents↗
PubMed2006

Soy isoflavones, lactobacilli, Magnolia bark extract, vitamin D3 and calcium. Controlled clinical study in menopause.

AIM: Affective and behavioural disorders possibly concomitant to the vasomotor menopausal symptoms worsen quality of life. A rational formulation containing soy isoflavones (60 mg), lactobacilli (500 millions spores), calcium (141 mg) and vitamin D3 (5 microg) was added of Magnolia bark extract (60 mg) and magnesium (50 mg) (Estromineral serena, ES). The Magnolia extract active principles interact with GABA system and exhibit a sedative central action. Magnesium intervenes in enzymatic reactions of the energetic metabolism and protects the bone integrity. Aim of this controlled study was to compare the clinical activity and safety of ES versus calcium+vitamin D3 (Ca+D) in menopause. METHODS: A controlled, randomised, multicentre study was carried out in symptomatic menopausal women with sleep or mood alterations. Women received 1 tablet/day of ES or Ca+D for 24 weeks. Symptoms during the treatment and final judgements on efficacy and acceptability were evaluated. RESULTS: Eighty-nine women (44 ES and 45 Ca+D, mean age 53.8 years, in menopause since 56.6 months) participated to the study. Flushing, nocturnal sweating, palpitations, insomnia, asthenia, anxiety, mood depression, irritability, vaginal dryness, dyspareunia, and libido loss, significantly decreased in severity and frequency during ES versus Ca+D treatment even since the fourth week. Woman wellbeing (good/very good 66.7% vs 20%) judgement on efficacy (72.7% vs 17.1%) and acceptability (93.9% vs 31.4%) were significantly better for ES. CONCLUSIONS: The controlled study showed the efficacy of Magnolia extract and magnesium on psycho-affective and sleep disturbances in menopause, in addition to the effects of isoflavones on vasomotor symptoms. A global natural approach to menopause with ES evidenced its therapeutic usefulness and safety.

Calcium↗
PubMed2003

[Clinical significance of thyroid nodule calcification].

To confirm the predictive value of calcifications in thyroid nodules as a risk factor for malignancy and to detect specific aspects for tumours, in a set of 175 patients--30 papillary carcinoma (PC) and 145 multinodular goiters (MNG) with dominant nodule--calcifications were detected by ultrasound scan. Calcifications were significantly more frequent in PC than in MNG (40% vs 20.7% p < 0.05) but their considered characteristics (size, number, position, location in the gland, sonographic features of the nodule) did not show any particular difference between PC and MNG. The frequency of calcifications in our series was higher in older patients (mean age 58.7 +/- 13.3 vs 51.1 +/- 12.7 in patients without calcifications, p < 0.001) and this could imply that their onset is time-dependent. Calcifications can be a useful indicator of enhanced risk, to be considered in the overall process of surgical decision making.

Adult↗
PubMed2001

Binding affinity profile of betahistine and its metabolites for central histamine receptors of rodents.

In order to clarify the interaction of betahistine (BH) and its metabolites [aminoethylpyridine (AEP) and hydroxyethylpyridine (HEP)] for receptors that mediate the physio-pharmacological activities of histamine, we performed in vitro competition binding studies to obtain their binding affinity profile for H(1)-, H(2)- and H(3)-histamine receptors prepared from rodent brains. Crude synaptosomal membranes were incubated in the absence (total binding) or presence of the unlabelled ligands used to saturate the specific binding, or with different concentrations of BH, AEP or HEP. Receptor binding methods were validated by running known standard drugs together with the test compounds. Like histamine, only BH interacted with H(1)-histamine receptors with comparable affinity (around 10(-5)M). BH and its metabolite AEP both interacted with the H(3)-histamine receptors, with microM affinity. HEP still showed some affinity for the H(3)-receptors but with a K(i)only 1/50 that of the parent compound. Histamine showed 10(-8)M affinity for the H(3)-receptor sites and was the only ligand to interact with H(2)-histamine receptors, all the others giving affinities above the mM range. Hill coefficients (as slopes of the sigmoidal inhibition isotherms) were close to unity for BH against H(1)- and H(3)-binding sites and for AEP against H(3)-sites, indicating that these interactions take place in the absence of cooperativity. Histamine and HEP interacted with H(1)- and H(3)-receptors with a Hill coefficient less than unity for the former and higher than unity for the latter (presence of negative and positive cooperativity, respectively). The results suggest that BH and its metabolites may act as neurotransmitter modulators of the histaminergic system.

Animals↗
PubMed2001

Immunologic events and long-term survival after combined heart and kidney transplantation: a 12-year single-center experience.

BACKGROUND: In this study we compare the incidence of cardiac rejection and long-term survival after combined heart and kidney transplantation (HK) and single heart transplantation (H). Combined HK transplantation is a surgical option for patients with irreversible cardiac and renal failure. However, long-term results of combined HK transplantation on immunologic events and patient survival remain unknown. METHODS: Between 1988 and 1997, 12 consecutive patients underwent combined HK transplantation (HK group) at a single institution. A control group (H group) of 24 single heart transplant recipients operated on within the same period was matched for age, pre-operative pulmonary vascular resistance, hepatic insufficiency and gender mismatch. Recipients and donors were ABO compatible without HLA antigen matching. All patients received immediate triple immunosuppression that included cyclosporine. Because of early renal dysfunction, cyclosporine was switched to anti-thymocyte globulin in 5 patients from the HK group and in 1 patient from the H group (p = 0.01). RESULTS: Actuarial freedom from heart rejection at 6 months and at 1 year following transplantation averaged 90 +/- 9% and 70 +/- 14% in the HK group, and 65 +/- 10% and 49 +/- 11% in the H group, respectively (p = 0.023). Actuarial survival at 1, 5 and 12 years was not significantly different between groups, at 66%, 55% and 28% in the HK group, and 66%, 44% and 32% in the H group, respectively (p = 0.66). CONCLUSION: The incidence of cardiac rejection was significantly lower. Long-term survival in the HK group was similar to that in the H group. Putative mechanisms of decreased cardiac rejection in the HK group include allogeneic stimulation, donor-derived dendritic cells and induction by anti-thymocyte globulins. The need for long-term immunosuppression may be reduced after combined heart and kidney transplantation.

ABO Blood-Group System↗
PubMed2001

Betahistine produces post-synaptic inhibition of the excitability of the primary afferent neurons in the vestibular endorgans.

Betahistine has been used to treat several vestibular disorders of both central and peripheral origin. The objective of this work was to study the action of betahistine in the vestibular endorgans. Experiments were done in wild larval axolotl (Ambystoma tigrinum). Multiunit extracellular recordings were obtained from the semicircular canal nerve using a suction electrode. Betahistine (10 microM to 10 mM; n = 32) inhibited the basal spike discharge of the vestibular afferent neurons with an IC50 of 600 microM. To define the site of action of betahistine, its interactions with the nitric oxide synthase inhibitor NG-nitro-L-arginine (3 microM) and with the cholinergic antagonists atropine (10 microM; n = 3) and d-tubocurarine (10 microM; n = 3) were studied. The action of betahistine when co-administered with these drugs was the same as that in control experiments, indicating that its effects did not include nitric oxide production or the activation of cholinergic receptors. In contrast, 0.01-1 mM betahistine reduced the excitatory action of kainic acid (10 microM; n = 6) and quiscualic acid (1 microM; n = 13). These results indicate that the action of betahistine on the spike discharge of afferent neurons seems to be due to a post-synaptic inhibitory action on the primary afferent neuron response to the hair cell neurotransmitter.

Ambystoma↗
PubMed2001

Effects of betahistine and of its metabolites on vestibular sensory organs.

Betahistine is widely used in the treatment of peripheral and central vestibular disorders. Till now the anti-vertigo effect of the drug was though to be mainly due to an action of betahistine on inner ear or cerebral microcirculation or on some structures of the CNS, chiefly the vestibular nuclei. Vertigo, however is, in most cases, of peripheral origin but it remains unknown whether betahistine, or some of its metabolities, may directly affect the vestibular system at peripheral level. Pharmacokinetic studies have in fact demonstrated that betahistine is transformed, mainly at the hepatic level, in aminoethylpyridine (M1), hydroxyethylpyridine (M2) and, finally, in pyridylacetic acid (M3) which is excreted with the urine. All these substances are therefore present in the body fluids of subjects treated with betahistine, and thus might have pharmacological effects. The goal of the present study was to investigate whether betahistine or some of its metabolites could exert any effect on vestibular receptors. To this end, the effects of the drugs (10(-7)-10(-2) M) have been examined on frog semicircular canals, an animal model well suited for this purpose. The effects of betahistine and of its metabolites have been evaluated by recording ampullar receptor activity both at rest and during mechanical stimulation of the sensory organ. The results demonstrated that both betahistine and one of its metabolites, the aminoethylpyridine (M1), exert effects quite similar on ampullar receptors; both these substances in fact could reduce greatly ampullar receptor resting discharge but had scanty effects on mechanically-evoked responses. This observation might justify betahistine and possibly M1 anti-vertigo effects. In fact vertigo is normally due to uncontrolled changes in vestibular receptor resting discharge. It is therefore probable that any factor able to reduce vestibular receptor resting firing rate and, in consequence, its variations, may have, as final effect, an anti-vertigo action. The observation that betahistine and M1 have similar effects might be of some clinical interest. In fact, on the basis of our data, the hypothesis may be put forward that the anti-vertigo action of betahistine is at first achieved by betahistine itself and then sustained and prolonged in time by M1.

Animals↗
PubMed2001

Action mechanism of betahistine in the vestibular end organs.

Betahistine has been used to treat several vestibular disorders of both central and peripheral origin. The objective of this work was to study the betahistine action mechanism at the vestibular end organs. Experiments were carried out in wild larval axolotl (Ambystoma tigrinum). Multiunit extracellular recordings were obtained from the semicircular canal nerve using a suction electrode. Betahistine (10 microM to 10 mM, n = 32) inhibited the basal spike discharge of the vestibular afferent neurons with an IC50 of 600 microM. To define the site of action of betahistine, its interactions with antagonists of nitric oxide sintethizing enzyme, cholinergic drugs, and excitatory amino acids were studied. Betahistine 1 mM (n = 5) was coadministered with NG-nitro-L-arginine 3 microM. The action of betahistine remained as in control experiments. Betahistine 1 mM reduced the excitatory action of carbachol (200 microM, n = 5) in a 30 +/- 3.4%. Cholinergic antagonists atropine (10 microM, n = 3) and d-tubocurarine (10 microM, n = 3) did not modify betahistine actions. Betahistine 1 mM also reduced kainic acid (10 microM, n = 4) excitatory action in 45.5 +/- 9.8%. These results corroborate that betahistine has a peripheral inhibitory action in the spike discharge of the afferent neurons in the vestibule. This action seems to involve neither NO production nor modifications in the release of acetylcholine from the efferent fibers. The inhibitory action of betahistine seems to be due to a postsynaptic binding site on the afferent neurons.

Ambystoma↗
PubMed2000

Effects of bradykinin on coronary blood flow and vasomotion in transplant patients.

OBJECTIVES: To evaluate the effects of exogenous bradykinin on coronary epicardial and microcirculatory tone in transplant patients (HTXs), and to compare them with the effects of acetylcholine. BACKGROUND: Coronary endothelial dysfunction has been reported to occur early after heart transplantation, most notably when acetylcholine was the endothelium-function marker used. The effects of bradykinin on coronary vasomotion are unknown in HTXs. METHODS: Sixteen HTXs were compared 3.6 +/- 1.7 months after transplantation to seven control subjects. Coronary flow velocity was measured using guide-wire Doppler. Diameters (D) of three segments of the left coronary artery and coronary blood flow (CBF) were assessed at baseline, after 3-min infusions of increasing bradykinin doses (50, 150 and 250 ng/min) then of increasing acetylcholine doses (estimated blood concentrations of 10(-8), 10(-7) and 10(-6) M). RESULTS: Bradykinin induced similar dose-dependent increases in D and CBF in both groups: D was 11 +/- 12%, 19 +/- 14% and 22 +/- 16% (all p < 0.0001), and CBF was 50 +/- 40%, 130 +/- 68% and 186 +/- 77% (all p < 0.0001). Acetylcholine induced significant epicardial vasodilation in control subjects and vasoconstriction in HTX, as well as a marked increase in CBF in both groups. Acute allograft rejection, present in 8 of the 16 HTXs, did not modify responses to bradykinin, but was associated with a smaller CBF increase in response to acetylcholine (p < 0.05). CONCLUSIONS: The coronary vasodilating effects of bradykinin are preserved early after heart transplantation, even in the presence of acute allograft rejection. Although there is an abnormal vasoconstricting response to acetylcholine reflecting endothelium dysfunction, the endothelium remains a functionally active organ in heart transplant recipients.

Acetylcholine↗
PubMed2000

Effects of betahistine metabolites on frog ampullar receptors.

Previous studies have demonstrated that betahistine, an histamine-like substance used widely as an anti-vertigo drug, can decrease ampullar receptor resting discharge without affecting their mechanically evoked responses. Pharmacokinetic studies have shown that this drug is transformed, mainly at the hepatic level, into aminoethylpyridine (M1), hydroxyethylpyridine (M2), then excreted with the urine as pyridylacetic acid (M3). The goal of the present study was to investigate whether betahistine metabolites are also able to affect vestibular receptor activity. Results demonstrated that, in the range tested (10(-7)-10(-2) M), M2 and M3 exerted no effect, whereas M1, at concentrations higher than 10(-6) M, was able to reduce the resting discharge of ampullar receptors without affecting the evoked responses. M1 therefore exerts effects similar to those of betahistine on ampullar receptors. This might be of some clinical interest. On the basis of our data, the hypothesis may be put forward that the anti-vertigo action of betahistine is at first achieved by betahistine itself and then sustained by M1.

Animals↗
PubMed1999

Pharmacodynamics and pharmacokinetics of pinacidil in normotensive volunteers after repeated doses of a new slow-release tablet formulation.

Pinacidil (CAS 85371-64-8) is an antihypertensive drug of the class of agents called "potassium channel openers". The pharmacokinetics of were studied after repeated oral administration of a new slow release tablet formulation (Pindac) as compared with the standard slow release capsule formulation in healthy volunteers. Eighteen healthy volunteers (3 males and 15 females), aged from 22 to 48 years, and 49 to 95 kg in weight, were given a 12.5 mg dose of each formulation every 12 h for 7 days on two occasions, in a randomized, cross-over trial with at least two weeks interval between trials. Blood samples were drawn immediately before drug administration on the morning of days 1, 2, 3, 4, 5, 6, and 7 and 0.5, 1, 2, 3, 4, 6, 8, 12, 24 and 36 h after the last drug administration. Blood pressure, heart rate, and respiratory function were assessed at admission and on the morning of day 0 (baseline), 2 and 7, before drug administration, and at 4, 24 and 36 h after the final administration. Pinacidil plasma levels were determined by an HPLC method. Both formulations elicited similar reductions of systolic and diastolic pressures from 4 h after administration, but did not change heart rate. The main model-independent pharmacokinetic parameters of pinacidil (Cmax, Tmax, AUC, MRT), as well as the absorption and elimination half-lives were similar with the two formulations. During the study there were no complaints of side-effects with either of the formulations. One advantage of the new formulation as compared to the capsules is that the tablets can be cut easily and the dosage adapted to a patient's needs.

Adult↗
PubMed1999

Prognostic value of MIBG imaging in idiopathic dilated cardiomyopathy.

UNLABELLED: Alterations of cardiac sympathetic innervation are likely to contribute to fatal outcomes in patients with heart failure. These alterations can be evaluated noninvasively by 123I-metaiodoben-zylguanidine (MIBG) imaging. METHODS: The hypothesis that impaired cardiac sympathetic innervation, as assessed using MIBG imaging, is related to adverse outcomes was tested in 112 patients with heart failure resulting from idiopathic cardiomyopathy. Main inclusion criteria were New York Heart Association classes II-IV and radionuclide left ventricular ejection fraction (LVEF) < 40%. Patients were assessed for cardiac MIBG uptake, circulating norepinephrine concentration, LVEF, peak Vo2, x-ray cardiothoracic ratio, M-mode echographic end-diastolic diameter and right-sided heart catheterization parameters. RESULTS: During a mean follow-up of 27 +/- 20 mo, 19 patients had transplants, 25 died of cardiac death (8 sudden deaths), 2 died of noncardiac death and 66 survived without transplantation. The only independent predictors for mortality were low MIBG uptake (P < 0.001) and LVEF (P = 0.02) when using multivariate discriminant analysis. Moreover, MIBG uptake (P < 0.001) and circulating norepinephrine concentration (P = 0.001) were the only independent predictors for life duration when using multivariate life table analysis. CONCLUSION: Impaired cardiac adrenergic innervation as assessed by MIBG imaging is strongly related to mortality. MIBG imaging may help risk stratify patients with heart failure resulting from idiopathic dilated cardiomyopathy.

3-Iodobenzylguanidine↗
PubMed1998

Complete androgen blockade versus chemical castration in advanced prostatic cancer: analysis of an Italian multicentre study. Italian Leuprorelin Group.

OBJECTIVES: In spite of a great amount of data, the hormonal treatment of advanced prostatic carcinoma (CaP) still remains controversial. As a relevant amount of dihydrotestosterone is present within the prostate tissue after castration, complete androgen blockade (CAB), with inhibition of the activity of both testicular and adrenal androgens, has been advocated as up-front treatment of advanced CaP. However, many controlled studies have failed to demonstrate a benefit for CAB in comparison with simple surgical or chemical castration. The present study was performed to bring additional data for a worldwide meta-analysis of all phase III trials comparing castration and CAB. METHODS: This is a centrally controlled phase III study in which chemical castration with leuprorelin acetate depot was compared with leuprorelin plus flutamide in stage C and D CaP. Two hundred and forty-one eligible and evaluable patients with histologically proven CaP were recruited for the study (120 treated with castration and 121 with CAB). The diagnostic and staging workup consisted of blood chemistry, general condition assessment, prostate-specific antigen (PSA), abdominal sonography and computed tomography scan, and whole-body isotopic bone scan. End points of the study were survival, time to treatment failure, and time to progression. The patients were followed every 6 months with PSA and sonography. RESULTS: At a cut-off analysis performed in December 1996, when the mean follow-up period was 43.7 +/- (SD) 24.1 months, no statistical differences in terms of time to treatment failure, time to progression, and death rate could be detected. Also considering the common risk factors, such as basal PSA, haemoglobin, alkaline phosphatase, and Gleason score, the outcome did not show any clear advantage for CAB. CONCLUSIONS: This study appears to confirm that the advantages of first-line CAB in CaP are at best marginal. The final analysis will be performed when the follow-up period has reached 5-years, but it seems unlikely that the present results will change.

Aged↗
PubMed1998

Pretransplantation risk factors for death after heart transplantation: the Henri Mondor experience.

BACKGROUND AND METHODS: Risk factors for death after primary heart transplantation were identified by analyzing our total experience with 234 patients who underwent transplantation at our institution from May 28, 1979, to May 27, 1996. RESULTS: There were 205 male and 29 female patients. Mean recipient age was 48.5+/-10.9 years (standard deviation). Recipient diagnosis included ischemic cardiomyopathy in 103 (44%), idiopathic cardiomyopathy in 98 (42%), valvular heart disease in 17 (7%), congenital heart disease in 4 (2%), and other diagnoses in 12 (5%) patients. Donor age was 32+/-10.2 years. Graft ischemic time was 138.1+/-51.8 minutes. The operative mortality rate was 23.5%. Actuarial survival estimates for all patients at 1, 5, and 10 years were 62%, 50%, and 44%, respectively. The three most common causes of death (both early and late) after primary heart transplantation were infection (27.4%), acute rejection (18.9%), and early graft failure (17.9%). Multivariate logistic regression analysis identified older recipient age (p = 0.007), higher preoperative pulmonary vascular resistance (p = 0.01), recipient preoperative hepatic insufficiency (p = 0.001), and gender mismatch (p = 0.02) as independent predictors of early death (within 3 months of the procedure). Multivariate proportional hazard regression analysis revealed that recipient idiopathic cardiomyopathy (p = 0.02) and recipient preoperative liver failure (p = 0.01) were independent risk factors for late death (after 3 months). CONCLUSION: These results underscore the importance of adequate recipient selection and recipient/donor matching for short- and long-term survival after primary heart transplantation.

Adolescent↗
PubMed1998

Pharmacodynamics and pharmacokinetics of pinacidil after a single dose of a new slow release tablet in healthy volunteers.

Pinacidil (CAS 85371-64-8) is a recently developed antihypertensive drug of the class called "potassium channel openers". It produces vasodilatation and a fall of arterial blood pressure. The pharmacokinetics and the pharmacodynamics of pinacidil were studied after single oral administration of a new slow-release tablet formulation (Pindac) in comparison to the standard slow-release capsule formulation in healthy volunteers. Eighteen healthy subjects (3 men and 15 women), with a mean age of 31.1 years were given a single 12.5 mg dose of each formulation in an open, cross-over study, with randomised sequences and a 7-day wash-out period between doses. Blood samples were collected before and several times up to 36 h after drug administration. Blood pressure, heart rate and respiratory functions were assessed before and 1, 4, 24 and 36 h-after drug administration. Pinacidil plasma levels were determined by HPLC. Both formulations produced a similar significant reduction (10 +/- 4 mmHg) of systolic blood pressure 4 h after administration but no changes of diastolic pressure and heart rate. Both the maximal effect (Emax) and the area under the effect-time curve (AUE0-36) were similar for the two formulations. The main model-independent pharmacokinetic parameters of Pinacidil (Cmax, Tmax, AUC, MRT) as well as the absorption and the elimination half-lives were similar after the two formulations. The main advantage of the tablet formulation compared to the capsules is that tablets can be easily cut and therefore the dosage can be adapted to an individual patient's needs.

Adolescent↗
PubMed1997

[Indication of mechanical circulatory assistance].

Over the last decade, we have seen considerable progress both in medical treatment of acute and chronic heart failure and in circulatory assist systems, including the first used aorta counter-pulse system. More sophisticated systems have been developed with specific indications recognized by specialized teams. However, in the treatment of chronic heart failure, whether caused by idiopathic dilated cardiomyopathies or ischemic heart disease (frequently improved with coronary revascularization), the nature of the disease in patients hospitalized in intensive care units has greatly changed. There is a net tendency towards hospitalizing older patients who may no longer be reasonable candidates for transplantation. The option of circulatory assist is thus undoubtedly reasonable for these patients due to the lack of a sufficient number of donor organs.

Acute Disease↗