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Biomedical subjects

G Donà

Publications and source records attributed to G Donà.

8 recordsLinked to original sources
PubMed2004

Mini-TEPCs for radiation therapy.

A mini-tissue-equivalent proportional-counter (TEPC) has been constructed to study the possibility to manufacture mini-counters without field-shaping tubes for radiation therapy. The mini-TEPC can be assembled with and without field-shaping tubes. It can be equipped with a mini-alpha source for a precise lineal energy calibration. After the positive conclusions of this study, a slim TEPC has been designed and constructed. The slim TEPC has an external diameter of only 2.7 mm. It has been tested with therapeutic proton beams and gamma ray sources.

Equipment Design↗
PubMed1997

Treatment of chronic hepatitis C with interferon-alpha by monitoring the response according to viraemia.

In chronic hepatitis C (HCV) infection, treatment with interferon is associated with a rather low rate of sustained response and many treated patients do not achieve significant benefit. Efforts have therefore been made to identify non-responders as early as possible to avoid unjustified costs and side-effects. We treated 106 cases of HCV with an algorithm based on the results of sequential alanine aminotransferase (ALT) and HCV RNA determinations, using an initial dose of 6 MU thrice weekly for 4 months, and modified the subsequent treatment according to the biochemical and virological profile. Thirty-three out of 48 patients (68.7%) who were HCV RNA negative with normal ALT at 4 months after initiation of treatment were sustained responders when treated for an additional 4-month period with a reduced 3 MU dose, while sustained response was achieved in 12.5% of HCV RNA positive patients treated with a higher dosage and for a more prolonged period of time. Our findings indicate that HCV RNA monitoring during interferon therapy may be useful in modifying of the treatment schedule for the individual patient.

Adolescent↗
PubMed1995

New antianginal nitro esters with reduced hypotensive activity. Synthesis and pharmacological evaluation of 3-[(nitrooxy)alkyl]-2H-1,3-benzoxazin-4(3H)-ones.

New nitro ester 3-[(nitrooxy)alkyl]-2H-1,3-benzoxazin-4(3H)-ones show marked inhibitory activity against ischemia-induced electrocardiographic changes, with only limited systemic hemodynamic effects, and are reported in the present study. These new nitro vasodilators are potent inhibitors of the electrocardiographic T-wave and S-T segment elevation induced by intravenous or intracoronary administration of Arg-vasopressin or methacholine in the anesthetized rat. The most active compounds are up to 300- and 600-fold more potent than glyceryl trinitrate or Nicorandil, respectively. These nitro esters relax in a concentration-dependent manner the isolated rabbit aorta, at higher concentrations (2-40-fold) than glyceryl trinitrate, and reduce the mean arterial blood pressure at doses 7-300-fold higher than those required by glyceryl trinitrate to exert a similar hypotensive effect. Remarkably, these compounds retain their anti-ischemic and hemodynamic profile after oral (po) administration. These new nitro ester derivatives, endowed with a marked antianginal activity, which is not associated with concurrent and pronounced falls in systemic blood pressure, represent the leads of a new class of selective nitrovasodilators having a preferential action on large coronary vessels, which could be clinically relevant in the treatment of coronary artery diseases.

Angina Pectoris↗
PubMed1995

Mechanism of ITF 296-induced vasorelaxation compared to nitroglycerin and isosorbide dinitrate: relationship between relaxation of rabbit aorta and tissue cGMP.

The vasorelaxant properties of ITF 296, a new mononitrate ester, were studied in endothelium-denuded rabbit aortic rings and were compared to nitroglycerin (NTG) and isosorbide dinitrate (ISDN). In norepinephrine-contracted arteries, ITF 296, NTG, and ISDN elicited maximal and concentration-dependent vasodilation with pD2 values of 7.07, 7.95, and 7.2, respectively. The concentration-relaxation curves of ITF 296 were shifted markedly to the right (p < 0.01) in the presence of 10 microM methylene blue (MB) and 3 microM oxyhemoglobin (HbO2), whereas a significant shift to the left (p < 0.01) was observed in the presence of 10 microM M&B-22948 (a specific cGMP phosphodiesterase inhibitor). When KCl (60 mM) was used as contracting agent, a weak relaxation was observed with ITF 296, suggesting the absence of activity on the voltage-dependent Ca2+ channels. A time-dependent increase in cGMP content and a positive correlation between cGMP and vasodilation were observed in norepinephrine-contracted arteries after exposure to a single submaximal concentration of ITF 296 (1 microM). Similar results were obtained with NTG and ISDN, although NTG was found to be more active than ITF 296 or ISDN. The presence of either MB or HbO2 almost completely abolished the increase in cGMP induced by ITF 296, whereas a further increase in cGMP was observed in the presence of isobutylmethylxanthine. No changes in cAMP levels were observed after exposure of the tissues to a concentration of ITF 296 that induced significant elevation in the cGMP content. In the presence of L-cysteine, ITF 296 stimulated semipurified rat lung guanylate cyclase at higher concentrations than those of NTG or ISDN, probably because of its lower rate of nitric oxide (NO) release. These results suggest that, in common with the reference compounds NTG and ISDN, ITF 296-induced vasorelaxation in rabbit aortic rings is mediated by an NO-cGMP mechanism.

Animals↗
PubMed1991

Diuretic agents related to indapamide. IV--Synthesis and pharmacological activity of N-(4-chloro-3-sulfamoylbenzamido)-methyl-phenyl-pyrrolidines and N1-(4-chloro-3-sulfamoylbenzoyl)-N2-aryl- or aralkyl-alkyl-hydrazines.

A series of N(4-chloro-3-sulfamoylbenzamido) derivatives (6 a-c, 10, 11, 12), structurally related to indapamide and isoindapamide, were synthesized and tested for their diuretic and saluretic activity. In addition, the antihypertensive activity of the most interesting term trans 6a was studied on spontaneously hypertensive rats. All tested compounds with the exception of 10 showed diuretic activity comparable to or higher (trans 6 a) than that of indapamide, taken as reference drug. The antihypertensive activity of trans 6 a was comparable to that of indapamide in potency, but its onset of action was slower.

Animals↗
PubMed1989

[Liver cirrhosis. Survival of a homogeneous population].

The aim of the study was the evaluation of survival of 140 cirrhotic patients who had a liver biopsy between 1970 and 1987. It is interesting to point out that all the patients with cirrhosis were included in the study and that they were all coming from a limited geographic area. This justifies the limited drop-out (7/147 patients). The high survival rate could be due to the fact that only patients suitable to receive a liver biopsy were elected for the study. We found that factors critical for prognosis in the short term (6-12 months) are biochemical values such as prothrombin index, serum albumin, serum bilirubin, alkaline phosphatase, while the factors affecting long-term prognosis are age, sex, etiology of cirrhosis, high alcohol intake after biopsy, ascites and untreated portal hypertension.

Adult↗