Search PubMed⌕ Search

Biomedical subjects

P Cremonesi

Publications and source records attributed to P Cremonesi.

At least 37 records · Page 2Linked to original sources
PubMed1988

Tumorigenicity of 6-halogenated derivatives of benzo[a]pyrene in mouse skin and rat mammary gland.

Studies of the tumorigenicity of 6-halogenated derivatives of benzo[a]pyrene (BP) can provide evidence about the role of the 6 position in the carcinogenic activation of BP. Female Swiss and A-strain mice were treated on the skin with BP, 6-fluorobenzo[a]pyrene (6-FBP), 6-chlorobenzo[a]pyrene (6-C1BP), 6-bromobenzo[a]pyrene (6-BrBP) and 6-iodobenzo[a]pyrene (6-IBP) by repeated application, and in some cases by initiation-promotion. While BP was more potent than 6-FBP, only these two compounds exhibits tumor-initiating and carcinogenic activity in mouse skin. Female Sprague-Dawley rats were treated with BP, 6-FBP, 6-ClBP, and 6-BrBP by intramammillary injection. BP and 6-FBP induced high levels of mammary epithelial tumors and fibrosarcomas. 6-ClBP elicited only a high percentage of fibrosarcomas, whereas 6-BrBP induced a few adenocarcinomas. These results indicate that chloro or bromo substitution at C-6 in BP reduces or eliminates carcinogenic activity. Conversely, 6-FBP, from which the fluoro substituent has been chemically and metabolically removed by one-electron oxidation, displays a moderate carcinogenic activity which is consistent with activation by either one-electron oxidation or monooxygenation.

Animals↗
PubMed1988

Tumor-initiating activity in mouse skin and carcinogenicity in rat mammary gland of fluorinated derivatives of benzo[a]pyrene and 3-methylcholanthrene.

Comparative studies of tumor-initiating activity in mouse skin and carcinogenicity in rat mammary gland were conducted with benzo[a]pyrene (BP) and 3-methylcholanthrene (MC) derivatives. SENCAR mice were initiated with BP, 6-fluorobenzo[a]pyrene (6-FBP), 6-methylBP, 7-FBP, 8-FBP, 9-FBP, 10-FBP, or 10-azaBP and promoted with tetradecanoyl phorbol acetate. The same compounds plus BP 7,8-dihydrodiol were tested by intramammillary injection in female Sprague-Dawley rats. Tumor-initiating activity in mice and/or carcinogenicity in rats were observed for BP, 6-methylBP, 6-, 7-, 8-, and 10-FBP, whereas 9-FBP was inactive in both experiments and 10-azaBP was only marginally active in the mammary gland. BP 7,8-dihydrodiol was carcinogenic in rat mammary gland, although it was less potent than BP. MC, 8-FMC, 10-FMC, and 3-methylcholanthrylene were also tested in Sprague-Dawley rats by intramammillary injection. All compounds were carcinogenic, with MC displaying the most potent activity. The less potent carcinogenic activity of BP 7,8-dihydrodiol in the mammary gland, compared with BP, and the moderate-to-weak tumor-initiating and/or carcinogenic activity of 7-, 8-, and 10-FBP suggest that the bay-region diol-epoxide pathway does not play a significant role in the activation of BP in these two target tissues. Similarly, the carcinogenic activity of 8-FMC and 10-FMC, in which the bay-region diol-epoxide pathway is blocked, suggests that this mechanism of activation is not important in the carcinogenicity of MC in rat mammary gland.

Animals↗
PubMed1988

Comparative absorption kinetics of imidazole and salicylic acid in volunteers after administration of ITF 182 tablets and suppositories.

Comparative absorption kinetics in volunteers of a new antiinflammatory drug (Selezen), in the form of 750 mg tablets and suppositories, were studied. The two components of the drug, imidazole and salicylic acid were found in plasma. Pharmacokinetic parameters were calculated according to a first order absorption. Salicylic acid showed a maximum concentration 59.2 +/- 5 min and 75.4 +/- 7.6 min after the administration of the tablet and suppository respectively; and imidazole after 86.3 +/- 10.8 min and 75.2 +/- 5.4 min, respectively.

Adult↗
PubMed1987

Structure and properties of enzyme graft copolymers: effects of using dissolved agarose on horseradish peroxidase immobilization.

The immobilization of horseradish peroxidase (HRP) onto dissolved agarose by a photochemically initiated graft copolymerization reaction, carried out at room temperature, was studied. Enzyme immobilization parameters such as the catalyst (FeCl3) and the enzyme concentration were considered. Using hexhydro-1,3,5-triacryloyl-s-triazine (HTsT) as vinyl monomer, the agarose/HTsT ratio was the main reaction parameter controlling the copolymer characteristics. By increasing the polymer content of the sample better stability properties were obtained. For the samples with agarose/HTsT ratios of 20/40 and 40/20 (S 20-40, S 40-20) the residual activities after 240 min at 60 degrees C were respectively 47 and 18%. The residual activity in continuous working was 33% for S 40-20 (after 20 h) and 64% for S 20-40 (after 70 h). For both the synthesized copolymers no limitation to substrate diffusion was found but the flexibility of immobilized enzyme decreased with the increase of polymer content as indicated by the Km values that were 0.90 X 10(-4) mol/liter for the sample S 40-20, and 1.50 X 10(-4) mol/liter for the sample S 20-40. Other enzymes (glucose oxidase, alpha-chymotrypsin, and lipoxidase), besides HRP, were immobilized with good yields, showing the wide applicability of the proposed methodology for the preparation of a solid biocatalyst which can be conveniently stored in water suspension or as lyophilized material.

Chymotrypsin↗
PubMed1985

Drug modulation of superoxide anion production from human neutrophils.

The effects of drugs on the production of superoxide anion from neutrophils stimulated by N-formylmethionyl-leucyl-phenylalanine (FMLP) were examined. Drugs acting on specific receptors, such as beta-adrenergic agonists (e.g. fenoterol, salbutamol) inhibited FMLP-evoked superoxide in a dose-dependent fashion. The order of activity: isoprenaline greater than fenoterol greater than salbutamol is the same as that found by assaying their effects on lysosomal enzyme release. Superoxide production from human neutrophils can also be affected in different manners, such as by a scavenging mechanism. A new non-steroidal anti-inflammatory drug, imidazole 2-hydroxybenzoate, by forming complexes with copper, displayed a significant superoxide dismutase activity which would contribute to explain its anti-inflammatory effect in vivo.

Adrenergic beta-Agonists↗
PubMed1984

Continuous-flow automated assay of steroids with nylon-tube-immobilized hydroxysteroid dehydrogenases.

Several NAD(P)+-dependent hydroxysteroid dehydrogenases, namely 3 alpha-hydroxysteroid dehydrogenase, beta-hydroxysteroid dehydrogenase, 7 alpha-hydroxysteroid dehydrogenase, and 12 alpha-hydroxysteroid dehydrogenase were separately immobilized on nylon tubes for the continuous-flow automated assay of hydroxysteroids. 3 alpha-Hydroxysteroid dehydrogenase was also immobilized on pore glass. Spectrophotometric monitoring in the visible region, where blank values were markedly reduced, was achieved through the Meldola blue catalyzed transfer of hydrogen from NAD(P)H to a tetrazolium salt. Nylon-tube-immobilized enzymes maintained 45-55% of the original activity after 1 month of intermittent use. The operational range, using the "end point" approach, was 1-25 nmol of steroid and the assay speed 10-15 samples/h. Reliable results were obtained in the determination of 3 alpha-hydroxysteroids and 3 beta, 17 beta-hydroxysteroids in urine and total bile acids in serum.

Autoanalysis↗
PubMed1984

Iron derivatives of modified milk protein.

A product containing a high amount of iron and maintaining all the necessary characteristics of stability and solubility for a drug can be prepared by succinylating the proteins, in the specific case the milk proteins, before the reaction with the iron salt. For these derivatives a particular advantage can be achieved, the iron succinyl protein precipitates at the pH of the stomach further keeping the iron bonded and it re-solubilizes at pH higher than 7, the intestine pH level. Electrophoresis indicates that the iron succinyl protein is homogeneous and gel filtration shows an apparent high molecular weight that contributes to the stability of the complexed iron. The preliminary structure determined by analytical and physical-chemical methods indicates that iron, in the form of oligomeric complexes, is tightly bonded to the protein not in chelated structures with basic residues but involving several sites of the protein chain. The solubility of the iron complex is assured by the increased availability of carboxyl groups that follows the succinylation reaction.

Amino Acids↗
PubMed1984

Penetration of imidazole 2-hydroxybenzoate (ITF 182) into experimentally inflamed pleural and knee joint exudates.

The penetration of the two components of imidazole 2-hydroxybenzoate (ITF 182), imidazole and salicylate, into inflamed sites induced by intrapleural injection of carrageenin in the rat and by a urate-cotton pellet implantation in the knee joint of the rabbit is studied. The results obtained show that the two components of the salt penetrate rapidly the inflamed sites and display different kinetic profiles: imidazole diffuses throughout inflamed and non-inflamed fluids without any specific localization, salicylate shows preferential localization in inflamed fluids and remains longer than imidazole.

Animals↗
PubMed1979

Immobilized hydroxysteroid dehydrogenases for the transformation of steroids in water--organic solvent systems.

The hydroxysteroid dehydrogenases: beta-HSDH, 20 beta-HSDH, and 3 alpha-HSDH, were immobilized on CNBr-activated Sepharose. The effect of various immobilization conditions on the activity recovery and stability were examined. The presence of cofactor during the immobilization reaction increased the activity recovery (40--60% of the total) and also led to materials highly stable in the presence of organic solvents. For example, beta-HSDH maintained 60% of its original activity two months after continuous use in the water--ethyl-acetate system. Kinetic experiments showed that the increase of the apparent Km values is poor and demonstrated that the organic solvent behaves as a weak inhibitor (ki greater than 0.2M) for the substrate. The immobilized enzymes lyophilized in the presence of sucrose had full activity restored even after several months storage at room temperature. Immobilized hydroxysteroid dehydrogenases were shown to be suitable for preparative transformation of steroids in water--organic solvent systems.

Cortisone↗
PubMed1979

Patterns of transport and binding of sex steroids.

The seminal plasma-sex steroid binding kinetic was evaluated by measuring the amount of labeled hormone extractable after 5 sec to 100 min of incubation. For testosterone in normal subjects, a peak of binding was reached after 30 sec of incubation. In subjects with severe oligoasthenospermia the kinetic pattern for testosterone was different but similar to the binding kinetic between seminal plasma of normal men and estradiol. The phenomena did not occur with frozen plasma samples.

Estradiol↗
PubMed1975

Enzymatic preparation of 20 beta-hydroxysteroids in a two-phase system.

The behavior of 20 beta-hydroxysteroid dehydrogenase in a two-phase system consisting of an emulsion of water with an immiscible organic solvent was investigated. The effect of several organic solvents on the stability, activity, and kinetic profile of the enzyme was considered. The most suitable system for carrying out the enzymatic reaction proved to be water-butyl acetate. The production of high quantitied of 20 beta-hydroxysteroids in 100% yield using catalytic amount of cofactor was achieved by coupling the 20 beta-hydroxysteroid dehydrogenase-and the alcohol dehydrogenase-catalyzed reactions.

20-Hydroxysteroid Dehydrogenases↗