Biomedical subjects

B Maggio

Publications and source records attributed to B Maggio.

95 records · Page 6Linked to original sources

PubMedDate not supplied

Control by ganglioside GD1a of phospholipase A2 activity through modulation of the lamellar-hexagonal (HII) phase transition.

Ganglioside GD1a has a dual effect on the formation of the HII phase in mixtures of dioleoylphosphatidyl choline (DOPC)-dioleoylphosphatidylethanolamine (DOPE) (1:5). Below 1 mol% ganglioside in the mixture the formation of the HII phase is facilitated as indicated by a decrease of the lamellar-HII phase transition temperature; above 1 mol% the presence of ganglioside GD1a opposes formation of the HII phase and causes an increase of the phase transition temperature; the latter is completely abolished at 3 mol% GD1a or above. The rate of activity of phospholipase A2 against these mixtures showed a temperature variation in coincidence with the establishment of the lamellar-hexagonal II phase transition. In the presence of GD1a at 0.5 and 1 mol% in the mixture, the maximum activity shifted in correspondence with the ganglioside-induced displacement of the lamellar-hexagonal II phase transition. The temperature variation of the enzymatic activity did not show any maximum for pure DOPC of for DOPC-DOPE (1:5) mixtures containing 3 mol% GD1a or above, in which no lamellar-hexagonal II phase transition occurs. The effects of GD1a are probably due to the geometrical features of the ganglioside molecule that allow a composition-dependent compensation of the structural defects required for the formation of the HII phase which are detected by phospholipase A2.

Calorimetry↗

PubMedDate not supplied

Mutual modulation of sphingomyelinase and phospholipase A2 activities against mixed lipid monolayers by their lipid intermediates and glycosphingolipids.

Sphingomyelinase activity against pure sphingomyelin monolayers is constant up to a surface pressure of 18 mN/m and falls above it. Sphingomyelinase- and phospholipase A2-mediated phosphohydrolytic pathways are mutually modulated by the presence of their respective substrates and products. At 15 mN/m non-substrate lipids such as ceramide at a mole fraction of 0.1 in mixed films with the pure substrate, inhibit the sphingomyelinase activity. Ganglioside GM1, another ceramide-containing complex sphingolipid, also inhibits sphingomyelinase activity, while a chemically related glycosphingolipid such as asialo-GM1 has no effect. The activity is unaltered by dipalmitoylphosphatidylcholine and by an equimolar mixture of its products of hydrolysis by phospholipase A2, fatty acid and lysoderivative, but it is inhibited by only one of them or by dilauroylphosphatidylcholine. Phospholipase A2 is inhibited by sphingomyelin, and activated by ceramide and by palmitic acid, one of the products of its own phosphohydrolytic reaction.

Animals↗

PubMedDate not supplied

Synthesis and antimicrobial evaluation of new phenoxyacetamide derivatives.

New N-(5-methylisoxazol-3-yl)-2 or 3 or 4-(phenoxyacetamido)benzamides 6a-t were synthesized and tested for their in vitro antimicrobial activity against gram positive (Staphylococcus aureus ATCC 25923) and gram negative (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) bacteria as well as fungi (Candida albicans ATCC 10231, Candida tropicalis ATCC 13803 and Cryptococcus neoformans ATCC 90112). Compounds 6 were devoid of antibacterial as well as antifungal activities at maximum tested concentrations of 50 micrograms/ml for bacteria and 100 micrograms/ml for yeast.

Acetamides↗

PubMedDate not supplied

3 alpha-hydroxysteroid dehydrogenase inhibitory activity of some N(3)-(1-R-4-carboxypyrazol-5-yl)-1,2,3-benzotriazin-4(3H)-one and quinazolin-4(3H)-one acids.

Some carboxylic acids of N(3)-pyrazole substituted 1,2,3-benzotriazin-4-(3H)-ones and- quinazolin-4-(3H)-ones were prepared and tested for the inhibitory property of 3 alpha-hydroxysteroid dehydrogenase of rat liver cytosol. The results indicated that the degree of inhibition can be used to predict the antiinflammatory potency of the compounds described.

3-Hydroxysteroid Dehydrogenases↗

PubMedDate not supplied

Synthesis and antineoplastic activity of new 4-diazopyrazole derivatives.

Several new 4-diazopyrazole derivatives were synthesized by reaction of 1-(R-substituted)phenyl-3-methyl-5-benzamidopyrazoles with a sevenfold excess of nitrous acid in acetic media. The compounds were tested at 20 microM concentration for their antineoplastic activity in vitro against Raji (human Burkitt lymphoma), K562 (human chronic myelogenous leukemia) and U937 (human histiocytic lymphoma) cell lines. They showed a percent of growth inhibition in the range 23.4-100%.

Antineoplastic Agents↗