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Biomedical subjects

P Valenti

Publications and source records attributed to P Valenti.

At least 73 records · Page 4Linked to original sources
PubMed1997

Modulation of pharmacological profile of diphenylethane (lefetamine-type) derivatives.

With the aim to split the pharmacological properties of lefetamine (CAS 14148-99-3), some structural modifications of this compound have been studied. The basic group of lefetamine has been shifted from the alkyl chain to the vicinal phenyl ring and the N-substitution has been changed. The dimethylaminomethyl derivatives and chiefly the o-morpholinometyhl exhibited a strong anti-visceral chemical antinociception activity stripped of thermal antinociception properties and physical dependence liability. Furthermore, through the introduction of a diethylaminomethyl group in the lefetamine structure some derivatives were selected exhibiting besided a significant increase in the anti-visceral chemical antinociception activity, remarkable local anesthetic properties.

Analgesics, Non-Narcotic↗
PubMed1997

Synthesis, cytotoxicity and SAR of simple geiparvarin analogues.

Some simple geiparvarin analogues, in which the coumarin moiety has been replaced with an X-substituted benzene ring, are described. The compounds were tested on LoVo cells (human colon carcinoma cell line) and some of them show a cytotoxicity comparable with that of the prototype. A QSAR analysis was also attempted, but it did not provide satisfactory results, mainly because of the limited range of variation of the biological activity.

Antineoplastic Agents, Phytogenic↗
PubMed1996

Lactoferrin inhibits herpes simplex virus type 1 adsorption to Vero cells.

This paper describes the ability of human and bovine lactoferrins (HLf; BLf), iron-binding proteins belonging to the non-immune defense system, to interfere with herpes simplex virus type 1 (HSV-1) infection. Since lactoferrins are known to bind to heparan sulphate proteoglycans and to low density lipoprotein receptor, which in turn act as binding sites for the initial interaction of HSV-1 with host cells, we tested the effect of these proteins on HSV-1 multiplication in Vero cells. Both HLf and BLf are found to be potent inhibitors of HSV-1 infection, the concentrations required to inhibit the vital cytopathic effect in Vero cells by 50% being 1.41 microM and 0.12 microM, respectively. HLf and BLf exerted their activity through the inhibition of adsorption of virions to the cells independently of their iron withholding property showing similar activity in the apo- and iron-saturated form. The binding of [35S]methionine-labelled HSV-1 particles to Vero cells was strongly inhibited when BLf was added during the attachment step. BLf interacts with both Vero cell surfaces and HSV-1 particles, suggesting that the hindrance of cellular receptors and/or of viral attachment proteins may be involved in its antiviral mechanism.

Animals↗
PubMed1996

1,4-Dihydropyridines bearing a pharmacophoric fragment of lidoflazine.

A series of 1,4-dihydropyridines bearing a pharmacophoric fragment of lidoflazine was synthesized. The compounds were evaluated for inotropic, chronotropic, and calcium antagonist activities. All compounds behave as inotropic and chronotropic agents, except for compounds 4b, 5a, and 5b, which exhibit a rather weak calcium antagonism in vascular smooth muscle (like aorta). Compound 5b is about twofold more potent in decreasing both chronotropy and inotropy, while compound 5c is about fivefold more potent in decreasing inotropy than nifedipine. Moreover, compound 5b is the most potent calcium antagonist derivative of the series.

Animals↗
PubMed1996

The effects of inhibitors of vacuolar acidification on the release of Listeria monocytogenes from phagosomes of Caco-2 cells.

To evaluate the role of the acidic pH of phagosomes on the invasive ability and fate of Listeria monocytogenes within host cells, entry and replication of this gram-positive bacterium in a human enterocyte-like cell line (Caco-2) were investigated by a combination of biochemical and ultrastructural approaches. The effects of inhibitors of vacuolar acidification--the lipophilic weak base ammonium chloride, the carboxylic ionophore monensin and the vacuolar proton ATPase inhibitor bafilomycin A1--on the bacterial invasion pathway were analysed. These agents, which raise the intracellular vesicle acidic pH of living cells by different mechanisms, affected L. monocytogenes replication in Caco-2 cells. Bacteria internalised by bafilomycin-treated cells were unable to escape from phagosomes, as demonstrated by electronmicroscopy. The results provide evidence that low pH is required for efficient intracellular growth of L. monocytogenes.

Ammonium Chloride↗
PubMed1996

Iron availability affects entry of Listeria monocytogenes into the enterocytelike cell line Caco-2.

The influence of iron on the entry of Listeria monocytogenes into Caco-2 cells was studied. Iron availability was found to modify the surface hydrophobicity and protein profile of L. monocytogenes, with the result that cell invasion strongly increased upon bacterial growth in iron-rich medium. The enhanced invasive capability of iron-overloaded L. monocytogenes cells correlates to the higher-level expression of the inlAB virulence genes, which were positively iron regulated at the transcriptional level.

Bacterial Adhesion↗
PubMed1996

Interaction of geiparvarin and related compounds with purified microtubular protein.

Geiparvarin is an antiproliferative compound whose mechanism of action has not yet been identified. We have investigated the biochemical action on purified microtubular protein, as well as on tubulin, of geiparvarin and of some derivatives resulting from its conjugation with two synthetic oestrogens, diethylstilboestrol and meso-hexoestrol, in comparison with the antimicrotubular action of the reference oestrogens. Geiparvarin and derivatives did not inhibit colchicine binding to tubulin nor did they significantly influence GTP-induced polymerization. On the contrary, they effectively counteracted the stimulating effect of taxol on microtubule formation, both in the presence and in the absence of microtubule-associated proteins. A competitive inhibition mechanism at the taxol binding site of tubulin may thus be proposed to explain the antimicrotubular action of geiparvarin.

Animals↗
PubMed1996

Synthesis and antitumor activity of some analogues of flavone acetic acid.

Some coumarin-, flavonol- and flavanon-acetic acids are described. The cytotoxicity of the synthesized compounds was determined on a human colon carcinoma cell line (LoVo) through evaluation of neutral red uptake, performed by the Riddel method. All tested derivatives were able to induce a statistically significant reduction of lysosomal neutral red uptake at 5 x 10(-5) M concentration. Some compounds were more active than the reference compound flavon-8-acetic acid.

Acetates↗
PubMed1995

Invasion of cultured human cells by Streptococcus pyogenes.

The invasive capacity of streptococcal strains belonging to groups A and B was evaluated by infecting human epithelial and endothelial cells and monitoring the number of viable intracellular bacteria at different times postinfection. All strains tested entered eukaryotic cells (HeLa, HEp2 and HUVE), with Streptococcus pyogenes exhibiting a higher invasion efficiency than group B streptococci (GBS). No intracellular multiplication was observed, and GBS remained viable 24 h postinfection, whereas S. pyogenes were gradually killed. We found that cytochalasin D almost completely inhibited internalization of all bacterial strains, whereas colchicine had no effect, indicating that host microfilaments play a major role in bacterial internalization. Moreover, the use of the lysosomotropic agent ammonium chloride enabled us to demonstrate that a pH increase in the intracellular vesicles did not affect streptococcal entry. These results were documented by electron microscopic observations which revealed the different steps in the invasion pathway, including a fusion event between phagosomes containing S. pyogenes and lysosomes.

Ammonium Chloride↗
PubMed1995

Synthesis and pharmacological characterization of some benzazepinone derivatives.

A series of some benzazepinone derivatives were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonist properties. For the compounds bearing well-known alpha-blocking fragments, the antagonist potency at postsynaptic alpha-adrenoceptors was assessed. The new compounds were less effective as bradycardic agents and calcium antagonists but show remarkable negative inotropic activity.

Adrenergic alpha-Antagonists↗
PubMed1994

Effect of lactoferricin B, a pepsin-generated peptide of bovine lactoferrin, on Escherichia coli HB101 (pRI203) entry into HeLa cells.

Bovine lactoferrin and a pepsin-generated peptide of bovine lactoferrin, known as lactoferricin B, were tested for an ability to influence the cell-invasive properties of an Escherichia coli HB101 strain carrying the plasmid pRI203, which encodes the Yersinia pseudotuberculosis inv gene. At non-cytotoxic and non-bactericidal concentration (0.5 mg/ml) lactoferricin B lowered by about tenfold the cell invasion capability of E. coli HB101 (pRI203), whereas no effect was observed when bovine lactoferrin was added during the infection of HeLa cell monolayers. The step of the invasion process affected by lactoferrin B was the internalization since the adhesion of bacteria to HeLa cells was unaltered in the presence of the peptide. Latex beads coated with lactoferrin B bound to HeLa cell monolayers and induced the agglutination of bacterial cells, indicating that this highly cationic peptide interacts directly with both eukaryotic and bacterial surfaces. Moreover, we demonstrated that the anti-invasive effect induced by lactoferrin B was reversed when the medium was supplemented with Ca2+, Mg2+ and Fe2+ ions which diminished its affinity binding. Our findings suggest that lactoferrin B effectiveness towards E. coli HB101 (pRI203) invasion is correlated to its binding capability on the eukaryotic and bacterial cell surfaces.

Animals↗
PubMed1994

The effect of iron on the invasiveness of Escherichia coli carrying the inv gene of Yersinia pseudotuberculosis.

The effect of growth in iron-excess or iron-limitation conditions on the invasiveness for HeLa cells of Escherichia coli HB101 carrying plasmid pRI203 which bears the invasion gene of Yersinia pseudotuberculosis was examined. Iron-limitation reduced adhesion and the number of organisms internalised by HeLa cells by about 100-fold. The reduced adhesion of iron-starved bacteria correlated with reduced hydrophobicity and the reduced invasiveness appeared to depend on the plasmid copy number, which was 3.5-fold less than in bacteria grown in iron excess.

Bacterial Adhesion↗
PubMed1994

[Dorsocommissural flaps. Apropos of a clinical case].

Dorsocommissural flaps are pedicled flaps with retrograde flow, anastomosed to the dorsolateral vessels of the proximal phalanx of one of the two fingers adjacent to the site of the commissure flap. The authors describe the anatomical basis and operating technique. A clinical case illustrates the simplicity and reliability of the technique. The indications for these flaps are digital skin defects either palmar involving the proximal phalanx and metacarpophalangeal joint, or dorsal involving the middle phalanx and the distal interphalangeal joint.

Adult↗
PubMed1993

Influence of lactoferrin on the entry process of Escherichia coli HB101 (pRI203) in HeLa cells.

Lactoferrin (Lf) is an iron-binding protein which plays an important role in the host defense systems of different mucosal surfaces including the intestinal mucosa. In the present research the role of apo-Lf and iron-saturated Lf in the invasion process of enteroinvasive bacteria, grown in iron stress or excess, was investigated. As enteroinvasive bacterium, Escherichia coli HB101 strain harboring a plasmid which contains the chromosomal inv gene from Yersinia pseudotuberculosis was utilized. The product of this gene (invasin) enables this microorganism to invade human epithelial cultured cells (HeLa). The results obtained showed that apo-Lf and iron-saturated Lf added at physiological concentration during the infection exerted a significant inhibition of adhesion (3.2 x 10(5) instead 3.4 x 10(6) adherent bacteria grown in iron excess; 1.6 x 10(3) instead of 2.3 x 10(4) adherent bacteria grown in iron-limited medium) and internalization (4.0 x 10(5) instead of 3.7 x 10(6) internalized bacteria grown in iron excess; 2.1 x 10(3) instead 2.8 x 10(4) internalized bacteria grown in iron-limited medium). It has also been demonstrated that in these experimental conditions Lf binds to HeLa cell membrane as well as to bacterial outer membrane. It is likely that this binding interfere with the early events of interaction between bacteria and eukaryotic cells. This inhibiting effect of Lf on the invasion efficiency of E. coli HB101 (pRI203) could be related to the cationic nature of the molecule, although other mechanisms cannot be ruled out.

Adhesins, Bacterial↗
PubMed1993

Sociocultural aspects of AIDS in an urban peripheral area of Abidjan (Côte d'Ivoire).

This study aimed to gain a better understanding of the social dynamics--migration, urbanization, the status of women, education--related to AIDS in an urban peripheral area of Abidjan. Structured interviews were administered to 420 people, selected through cluster random sampling. Focus groups and semi-structured interviews were performed with key-informants. The results show that 26.9% of the interviewees are foreigners and 40% of all people interviewed participate in ethnic associations. Knowledge of AIDS is associated with age, gender, educational level and purchasing power. Those who are generally better informed about AIDS are: younger people; people with a higher education; and wealthier people. Men respond correctly to questions more frequently than women. French, the chosen language of the education campaigns, is not understood by 18% of the immigrants, and when considering only immigrant women, the figure increases to 38%. Particular attention should be paid to the design of health education messages and strategies for specific groups, such as non-educated people, women and immigrants. Care must also be taken to match the language used to the target population. Ethnic associations constitute an important starting point, particularly in relation to their use by immigrants, and these should be involved in educational programmes.

Acquired Immunodeficiency Syndrome↗