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Biomedical subjects

G Roma

Publications and source records attributed to G Roma.

At least 19 recordsLinked to original sources
PubMed2001

Oxygen self-diffusion in alpha-quartz.

We have studied the formation energy of the simplest oxygen defects in alpha-quartz, the oxygen vacancy and interstitial, by an ab initio approach based on density functional theory in the local density approximation. We have determined the formation energies and entropies and the migration paths and energies. From our results we can conclude that oxygen diffuses in quartz by an interstitial mechanism: the interstitial has a dumbbell structure; one of the constitutive atoms jumps towards a neighboring oxygen site. The activation energy amounts to 4.7 eV in the intrinsic regime and 2.8 eV in the extrinsic regime.

Journal Article↗
PubMed2001

1,5-Benzodiazepine tricyclic derivatives exerting anti-inflammatory effects in mice by inhibiting interleukin-6 and prostaglandinE(2)production.

The 1,4- and the 1,5-benzodiazepines (BDZ) are commonly used as anxiolytic and anticonvulsive drugs. It has been suggested that they influence, particularly through stimulation of peripheral BDZ receptors, some immune cell properties such as pro-inflammatory cytokine production. The availability of a new class of [1,2,4]triazolo[4,3-a][1,5]benzodiazepine derivatives (compounds IV), endowed with anti-inflammatory and/or analgesic properties but no anti-pentylenetetrazole activity, prompted us to investigate in more detail the anti-inflammatory properties of three selected compounds IV (N,N-dimethyl-1-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benz- odiazepin-5-amine; N,N-dibutyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine; 1-methyl-N,N-dimethyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine) and one structurally related compound (1-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5(6H)-one). These BDZ derivatives have lost their affinity for the central and peripheral BDZ receptors. The in vivo effect on leukocyte migration of these compounds was investigated by using the mouse air-pouch model of local inflammation. Compounds A and B, significantly inhibited the carrageenan-induced leukocyte recruitment in a dose-dependent manner starting from the dose of 50 mgkg(-1), whereas compound C was effective only at the higher dose of 100 mgkg(-1). Compound D did not exert such effects at any of the doses considered. The effect of compounds A, B and C on leukocyte recruitment was paralleled by a significant inhibition of interleukin-6 and prostaglandin E(2)production in the exudate, similarly to indomethacin, and by a partial reduction of vascular permeability. These features may be relevant for the design and development of innovative anti-inflammatory molecules among the 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine derivatives.

Analgesics↗
PubMed2000

1,8-Naphthyridines IV. 9-substituted N,N-dialkyl-5-(alkylamino or cycloalkylamino) [1,2,4]triazolo[4,3-a][1, 8]naphthyridine-6-carboxamides, new compounds with anti-aggressive and potent anti-inflammatory activities.

The title compounds (8) were synthesized through the cyclocondensation of the corresponding N-substituted 4-amino-2-chloro-1,8-naphthyridine-3-carboxamides (4) with the proper hydrazides, in order to evaluate their anti-inflammatory and anti-aggressive properties. Several compounds 8 exhibited high anti-inflammatory activity (carrageenin-induced paw edema assay in the rat) along with appreciable anti-aggressive properties (isolation-induced aggressiveness test in mice). With respect to anti-inflammatory activity, the most active compounds (8n and 8c) produced a 61% edema inhibition at the 25 mg/kg dose, and 50 or 35% inhibition, respectively, at the 12.5 mg/kg dose. The structure-activity relationships are discussed.

Aggression↗
PubMed2000

Synthesis, antiplatelet activity and comparative molecular field analysis of substituted 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones, their congeners and isosteric analogues.

2-(1-Piperazinyl)-4H-pyrido[1,2-a]pyrimidin-4-one (5a) is a recently described in vitro inhibitor of human platelet aggregation which specifically inhibits the activity of high affinity cAMP phosphodiesterase. A number of substitution derivatives, isosteres, and analogues of 5a were now synthesized and tested in vitro for their inhibitory activity on human platelet aggregation induced in platelet-rich plasma by ADP, collagen, or the Ca2+ ionophore A23187. Among the most effective compounds, the 6-methyl, 8-methyl and 6,8-dimethyl derivatives of 5a resulted nearly as active as the lead when platelet aggregation was induced by ADP or A23187, but less active when collagen was the inducer. On the basis of present results and those previously obtained by us in this and 2-aminochromone structural fields, we have developed a statistically significant 3-D QSAR model, using comparative molecular field analysis (CoMFA), describing the variation of the antiplatelet activity in terms of molecular steric and electrostatic potential changes.

Humans↗
PubMed1998

Pyran derivatives. XX. 2-Aminochromone benzo-fused derivatives with antiproliferative properties.

The N-substituted 2-aminochromones 1 and their benzo-fused derivatives 2-4 described herein were mostly prepared by treating the corresponding (methylthio) derivatives 10-13 with an excess of the proper amines. Only the morpholino derivatives 3d and 4c were obtained from the reaction of the ethyl 3-morpholino-3-oxopropanoate/POCl3 reagent with 1-naphthol or 1-methyl-2-naphthol, respectively. The amino derivatives 1-4, as well as their methylthio analogues 10-13, were tested in vitro for their inhibitory activity on the infectivity of T2 bacteriophage, on the macromolecular synthesis in Ehrlich cells and on the clonal growth capacity of HeLa cells. Several of the angular or linear aminonaphthopyranones 2 and 3 or 4, respectively, and the (methylthio) derivatives 10, 11 and 13 induced a significant inhibition of DNA synthesis, but usually a clearly lower inhibition of clonal growth. Only the linear 2-amino-10-methyl-4H-naphtho[2,3-b]pyran-4-ones 4a and 4b significantly inhibited the clonal growth in HeLa cells and T2 bacteriophage infectivity, respectively.

Animals↗
PubMed1998

Acid-catalysed hydrolysis and benzodiazepine-like properties of 5-(dialkylamino)- and 5-(alkylthio)-substituted 8-chloro-6-phenyl-6H-[1,2,4]triazolol[4,3-a][1,5]benzodiazepines in mice.

The in-vitro and in-vivo hydrolysis of two benzodiazepine compounds has been studied to evaluate their in-vivo activity in mice. Compounds RL 218 and RL 236, selected as representative examples of N,N-dialkyl-8-chloro-6-phenyl-6H-[1,2,4]triazolo[4,3-a][1,5]benzodiaz epin-5-amines (1) and of their 5-(alkylthio) substituted analogues (2), were rapidly hydrolysed to the corresponding 8-chloro-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5(6H )-one 3 (RL 214) in aqueous acidic solution at pH 1.5. This reaction also occurred extensively in mice when compounds RL 218 and RL 236 were given orally but not intraperitoneally. Both compounds were active against pentylenetetrazole-induced lethal convulsions in mice only when administered orally. After administration of pharmacologically effective oral doses (ED50, the dose protecting 50% of mice), at the time of assessment of the anti-pentylenetetrazole activity, mean brain concentrations of RL 218 and RL 236 were below the limits of sensitivity of the analytical procedure whereas brain concentrations of their metabolite RL 214 were comparable with that present after an oral equiactive dose of this compound itself. RL 214 but not RL 218 or RL 236 had in-vitro affinity for brain benzodiazepine receptors. These results indicate that the anticonvulsant activity of RL 218 and RL 236 in mice depends essentially on their in-vivo transformation into the common active metabolite RL 214 which most probably arises as a result of acid catalysed hydrolysis in the gastric juice.

Administration, Oral↗
PubMed1997

Effect of 2-(1-piperazinyl)-4H-pyrido[1,2-a]pyrimidin-4-one (AP155) on human platelets in vitro.

The effect on human platelets of 2-(1-piperazinyl)-4H-pyrido[1,2-a]pyrimi din-4-one (AP155) was tested in vitro by measuring cyclic adenosine monophosphate (cAMP) level, cytosolic Ca++, [(125I)]fibrinogen binding as well as aggregation induced by several agonists. AP155 dose-dependently inhibited aggregation both in platelet rich plasma (PRP) and in washed platelets (WP), exerting its maximal power in the presence of collagen, ADP and platelet activating factor (PAF). It specifically inhibited the activity of cAMP high affinity phosphodiesterase (PDE), resulting in a sufficient increase in cAMP levels to activate cAMP-dependent protein kinase. AP155 was able to inhibit aggregation, the increase in cytosolic Ca++ induced by thrombin, and fibrinogen binding to ADP or thrombin-stimulated platelets. Thus, this new pyridopyrimidine derivative exerts its antiplatelet activity by increasing cAMP intracellular concentration.

Blood Platelets↗
PubMed1997

1,8-Naphthyridines. III. N,N-dialkyl-5-chloro[1,2,4]-triazolo[4,3-a][1,8]naphthyridine-6-carboxa mides with anti-inflammatory activity.

Fifteen N,N-dialkyl-5-chloro[1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxami des (7a-o) were synthesized through the cyclocondensation of the corresponding N,N-dialkyl-2,4-dichloro-1,8-naphthyridine-3-carboxamides with proper hydrazides, in order to evaluate their anti-inflammatory, antiaggressive, and analgesic properties. Four of the compounds tested showed a statistically significant and dose-dependent anti-inflammatory activity.

Aggression↗
PubMed1996

Solid and cystic tumor of the pancreas--case report.

Pancreatic tumors are rarely present in childhood. The authors present a case of papillary-cystic tumor in a 13-year-old girl, treated by partial pancreatoduodenectomy, with preservation of the pylorus. The histologic pattern was of a papillary cystic tumor without evident atypical nuclei. One year after operation, the girl is well without any finding of disease.

Adolescent↗
PubMed1995

Pyran derivatives XIX. (Dialkylamino) substituted 1-benzopyranones and naphthopyranones with platelet antiaggregating activity.

2-(Dialkylamino)chromones 4 and 4-(1-piperazinyl)coumarins 11, as well as their angular benzo-fused derivatives 1, 2 and 12, 13, respectively, were synthesized and tested in vitro for their inhibitory activity on human platelet aggregation induced in platelet-rich plasma by ADP (5.0 microM), collagen (10.0 micrograms/ml), and A 23187 (calcimycin) (20.0 microM). Among the dialkylamino substituents used, and the ring systems examined, 1-piperazinyl and 1-benzopyran or naphtho[2,1-b]pyran, respectively, resulted the most effective ones for antiplatelet activity, both in the chromone and coumarin fields. 7-Ethoxy-4-(1-piperazinyl)coumarin 11b showed the highest activity, and higher than those of all reference compounds (ASA, trifluoperazine, propranolol, and dipyridamole) towards all platelet aggregation inducers.

Coumarins↗
PubMed1994

1,8-naphthyridines II. 2,4-disubstituted N,N-dialkyl-1,8-naphthyridine-3-carboxamides with anti-inflammatory and/or antiaggressive activities.

The preparation of the novel N,N-dialkyl-2,4-dichloro-1,8-naphthyridine-3-carboxamides 1c, e and N,N-dialkyl-2-(alkylamino or cycloalkylamino)-4-chloro-1,8-naphthyridine-3- carboxamides 2b, d-g, j-p is described. These compounds and the previously obtained analogs 1a, b, d, f and 2a, c, h, i have been tested for their anti-inflammatory and antiaggressive activities, as well as for their gross behavioral effects and acute toxicity. Nine of the twenty-two tested compounds exhibited a statistically significant anti-inflammatory activity in the carrageenin-induced edema assay in the rat (1e, f and 2h, o were the most active compounds). On the other hand, an interesting antiaggressive activity was displayed by ten compounds in the isolation-induced aggressiveness test in mice (compounds 2d, i, k showed the highest activity). Structure-activity relationships are briefly discussed.

Aggression↗
PubMed1993

1,2-fused pyrimidines. VI. Substituted 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones with antiplatelet activity.

The N-substituted 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 2 d,g-i,l-p,r,s and derivatives 4,5 b,6 a,b, 7 a,b were prepared. Both these novel compounds (except the insoluble 7a) and compounds 2 a-c,e,f,j,k,q, 5a, previously prepared by us, were tested in vitro for their inhibitory activity on human platelet aggregation induced by ADP, collagen, or A23187. On the whole, the compounds tested proved to be more active towards collagen than towards ADP and A23187. The 2-(4-methyl-1-piperazinyl)derivative 2 g was the most active compound both towards ADP and collagen, whereas the 2-(diethylamino)derivative 2 b proved to be the most active one towards A23187.

Adenosine Diphosphate↗
PubMed1992

1,5-Benzodiazepines. X. Dialkylamino substituted 1,5-benzodiazepine and [1,2,4]triazolo [4,3-a][1,5] benzodiazepine derivatives with inhibitory activity on PAF-induced platelet aggregation.

Novel 4-(dialkylamino) substituted (4, 5 c, 8) and 2,4-bis(dialkylamino) substituted (6) 1,5-benzodiazepine derivatives were synthesized. Both these new compounds and the substituted 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepine-5-amines 2 a-h, recently described by us, were tested in vitro for their inhibitory activity on the PAF-induced aggregation of human platelets. Actually, bicyclic compounds 4 d, 5 c and tricyclic compounds 2 g, h showed a significant activity: in all them the dialkylamino substituent was the 4-(ethoxycarbonyl)-1-piperazinyl group. On the contrary, compounds 4 d, 5 c, 2 g,h showed practically no inhibitory activity when platelet aggregation was induced by ADP, A23187, or collagen.

Benzodiazepines↗
PubMed1989

[Synthesis and preliminary pharmacological screening of 2,4-disubstituted N,N-dialkyl-1,8-naphthyridine-3-carboxamides].

By treating at 100 degrees C 2-aminonicotinic acid with ethyl N,N-dialkylmalonamate (I) and phosphorus oxychloride N,N-dialkyl-4-chloro-1,2-dihydro-2-oxo-1,8-naphthyridine- 3-carboxamides (II) were obtained. The reaction of compounds (II) with an excess of refluxing phosphorus oxychloride afforded N,N-dialkyl-2,4-dichloro-1,8-naphthyridine-3-carboxamides (III), which in turn were treated at room temperature with excess primary amines to give a mixture of isomeric N,N-dialkyl-2-(alkylamino or cycloalkylamino)-4-chloro-1,8-naphthyridine-3-carboxamides (IV) and N,N-dialkyl-4-(alkylamino or cycloalkylamino)-2-chloro-1,8-naphthyridine-3-carboxamides (V). When this last reaction was performed at 160 degrees C, only N,N-dialkyl-2,4-bis(alkylamino or cycloalkylamino)-1,8-naphthyridine-3-carboxamides (VI) were obtained; under the same conditions (IV c) or (V c) reacted with methylamine to give isomeric 2,4-bis(alkylamino)derivatives (VII) or (VIII), respectively. Compounds (II b), (III b), (IV a,c,d), (V a,c,d) were submitted to a wide preliminary pharmacological screening. Some of them, depending on the structure, showed antihypertensive [(IV c)], anti-inflammatory [(IV c) greater than (III b)], or, in the behavioral test, anti-aggressive [(IV d) greater than (III b)] activity. Furthermore compound (III b) caused moderate inhibition of the 5-HT induced contraction of the guinea-pig ileum.

Aggression↗
PubMed1989

HPLC analysis of the nitrosation products of chlordiazepoxide.

Products originated from Chlordiazepoxide (I) hydrochloride/sodium nitrite interaction were analyzed by HPLC. The studied reactions were carried out in diluted hydrochloric acid solutions at pH values ranging between 0.5-5.0. Depending on the reaction pH values and molar ratios it was possible to find and assess variable amounts of the N-nitrosochlordiazepoxide (II), the dihydroquinazoline (III) and the lactam (IV). The highest degree of N-nitrosation was found at pH 3.5. At this pH value the yields of (II) were respectively 54.8% and 18.3% when the drug (I)/nitrite molar ratios were correspondingly 0.41 and 0.25. When the reaction was performed in concentrations which is possible to find in the gastric juice of patients taking (I) together with nitrite-rich foods the yield of (II) at pH 3.5 was 2.5%. Since in the meantime the genotoxicity of (II) was proved, "in vivo" formation of N-nitrosochlordiazepoxide (II) represents a potential risk not to be underestimated.

Chlordiazepoxide↗
PubMed1989

[Chemistry and pharmacology of pyrane derivatives. XVII. Synthesis of substituted 2-(dialkylamino)-3-formylchromones and their tricyclic derivatives].

Substituted 2-(dialkylamino)-3-formylchromones (II) were obtained from the reaction of substituted 2-(dialkylamino)chromones (I) either with the N,N-dimethylformamide-POCl3 reagent [compounds (IIa-e)] or with dichloromethylmethylether in the presence of TiCl4 [compounds (IIf-i)]. By treating (IIa,f) with hydroxylamine the oximes (IIIa,f) were prepared, which in turn were converted into the nitriles (IVa,f) by treatment with acetic anhydride. Compound (IIa), selected for the smallest steric hindrance of the 2-dialkylamino substituent, by reaction with hydrazines afforded [1]benzopyrano [2,3-c]pyrazole derivatives (VI), whereas reaction of (IIa) with guanidine, benzamidine or S-methylisothiourea gave rise to the formation of 5H-[1]benzopyrano[2,3-d]pyrimidine derivatives (IX). Among the compounds tested for their antiallergic properties, (IIf) showed an appreciable activity, but also high toxicity.

Amines↗
PubMed1988

Formation of 2,6-dimethoxy-1,4-benzoquinone, a highly genotoxic compound, from the reaction of sodium nitrite with the sympathomimetic drug dimethophrine in acidic aqueous solution.

Because of the genotoxic effects shown by Dimethophrine (DMP) nitrosation mixtures, the interaction between DMP hydrochloride and sodium nitrite in acidic aqueous solution at 37 degrees was investigated in a wide range of reagent concentrations and molar ratios, reaction times and pH values. Actually, depending on the operating conditions, it was possible to detect variable amounts of 2,6-dimethoxy-1,4-benzoquinone (DMBQ), a highly genotoxic compound, but no N-nitrosoderivative. The highest conversion of DMP into DMBQ was obtained when concentrated acidic solutions of DMP and NaNO2 (molar ratio 1:1.9) reacted at pH 3.0-4.0 (50-60% after 1 hour, depending on the pH conditions). When DMP hydrochloride and NaNO2 (molar ratio 1:0.95) were allowed to react at pH 3.5 in a more diluted solution, to mimic gastric conditions, the conversion of DMP into DMBQ after 20 min was about 3%. The breakdown of DMP can be prevented by adding suitable amounts of ascorbic acid to the reagents.

Benzoquinones↗