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Biomedical subjects

N Simonetti

Publications and source records attributed to N Simonetti.

At least 19 recordsLinked to original sources
PubMed2001

Contact imidazole activity against resistant bacteria and fungi.

The activities of miconazole and miconazole sulphosalicylate were evaluated by a contact test using strains of Enterococcus faecalis and Escherichia coli and Candida spp selected for their resistance. The results showed that killing of the organisms occurred within a few minutes. Imidazole activity required a medium of low electrical conductivity and a pH of 5.6. Greater sensitivity could be obtained with pretreatment of the microbial suspensions with sodium dioctylsulphosuccinate. Microorganisms tested in culture media with low electrical conductivity and at pH 5.6 showed enhanced sensitivity to azoles with MIC values about 20-30 times lower than those obtained using control media. Practical implications of the use of topical drugs are discussed.

Antifungal Agents↗
PubMed2001

In vitro activity of propyl gallate-azole drug combination against fluconazole- and itraconazole-resistant Candida albicans strains.

AIMS: The influence of an antioxidant, propyl gallate (PG), on the in vitro antifungal activity of itraconazole and fluconazole, was investigated to determine whether PG could increase the antifungal activity and reduce strain resistance. METHODS AND RESULTS: Susceptibility tests were performed against azole-resistant isolates of Candida albicans by the microbroth dilution method in the presence of PG at 400 microg ml-1. PG-triazole combination brought about a marked reduction of inhibitory azole concentration. In particular, the MIC90 for itraconazole and fluconazole dropped from 1 microg ml-1 to 0.125 microg ml-1 and from > 64 microg ml-1-8 microg ml-1, respectively. CONCLUSION: It is likely that more than one mechanism is involved in the above synergistic interaction, including effects of PG on ATP synthesis, thus reducing the ABC transporters activity, or an effect on the target of azole, i.e. the P-450 cytochrome. SIGNIFICANCE AND IMPACT OF THE STUDY: The PG-triazole combination may have a role in future topical antifungal strategies but other studies are warranted.

Antifungal Agents↗
PubMed2000

Anticandidal activity of SPA-S-843, a new polyenic drug.

The activity of a new, soluble and stable polyene (SPA-S-843) against Candida albicans was assessed by contact and culture tests and by inhibition of germ-tube formation. The drug demonstrated a higher contact activity and lower MICs than amphotericin B. This antimicrobial activity was more evident under acid pH and low ionic strength. In addition, the ability of SPA-S-843 to inhibit Candida sp. conversion from yeast to mycelial form was evident at low drug concentrations (0.25-0.62 mg/L).

Amphotericin B↗
PubMed1997

Emergency medical services in mass gatherings: the experience of the Formula 1 Grand Prix 'San Marino' in Imola.

Mass gatherings are special situations for which mass medical care must be preplanned. Acute emergencies occur at public gatherings and medical coverage on site has proven benefit. Responsibility of general plan, management of specific problems, transport planning, communications system, guidelines and protocols, special situations management, ancillary supports, sources of extra help for unforeseen needs are the most important items to consider. In mass gatherings the whole emergency medical service (EMS) planning and management has to depend on the emergency department direction, with its authority on all aspects of patient care in the EMS system. This report concerns the planning of EMS and of medical care in a situation at risk for mass casualties at the Formula I Grand Prix-Championship Racing 'San Marino' of Imola.

Automobiles↗
PubMed1997

Overcoming Streptococcus agalactiae in vitro resistance to imidazoles.

The increased diffusion of Streptococcus agalactiae in the urinary tract and vagina has affected the strain's resistance to antimicrobial agents, so we decided to study the possibility of overcoming its resistance to imidazoles. Our data suggest that overcoming S. agalactiae resistance to imidazoles in contact and growth culture tests depends partly on the electrical conductivity of the culture medium. Although imidazole contact activity and culture activity have different targets in cell structures, we have demonstrated that imidazole resistance in S. agalactiae cells in both types of tests can be affected by the same conditions regulating membrane permeability.

Anti-Bacterial Agents↗
PubMed1996

Identification of a glucan-associated enolase as a main cell wall protein of Candida albicans and an indirect target of lipopeptide antimycotics.

Growth-subinhibitory nonlytic doses of cilofungin (lipopeptide antibiotic affecting (1,3)-beta-D-glucan synthesis) inhibited the incorporation of 46- to 48-kDa glucan-associated (46K) protein into the growing cell wall of Candida albicans. The purified 46K protein constituent strongly reacted with a monoclonal antibody against enolase, a major cytoplasmic enzyme of the fungus. In addition, two internal fragments of 12- and 15-amino acid residues from a tryptic digest of 46K protein showed 100% identity with amino acids in positions 34-45 and 66-80 of enolase. By immunoelectron microscopy with polyclonal and monoclonal anti-enolase antibodies, the 46K protein was clearly detected in the inner layers of the fungal cell wall. Thus, consistent with the proposed immunogenic and diagnostic roles of enolase in candidiasis, biochemical, immunochemical, and ultrastructural evidence strongly suggest that the cilofungin-susceptible 46K protein is a cell wall-associated form of this enzyme.

Amino Acid Sequence↗
PubMed1996

Study of interaction effects of polyacrylic acid polymers (carbopol 940) on antimicrobial activity of methyl parahydroxybenzoate against some gram-negative, gram-positive bacteria and yeast.

Cosmetic or pharmaceutical formulations containing hydrophilic polymers of natural or synthetic origin, may be more exposed to successful microbial contamination because of a polymer-preservative interaction. The experimental data reported in this paper relate to the possible interference of Carbopol 940 with methyl parahydroxybenzoate. Results show that this hydrophilic polymer, widely employed in many formulations, exerts, on the contrary, an interesting synergism on microbicidal activity of the preserving agent against E. coli and P. Aeruginosa. A reduction in microbicidal activity against S. aureus and C. albicans is observed for a polymer concentration higher than that needed for anti-Gram-negative synergy.

Acrylic Resins↗
PubMed1996

Antimicrobial activity of electrochemical silver ions in nonionic surfactant solutions and in model dispersions.

The microbicidal effectiveness against Gram-positive and Gram-negative bacteria and Candida albicans of electrochemical silver ions in aqueous solutions containing nonionic surfactants was investigated. From the perspective of the possible use of anodic silver as a preservative in cosmetic or pharmaceutical preparations, microbicidal efficacy was also studied in oil/water model dispersions. Surfactants and botanical extracts partially inhibited the microbicidal effectiveness of anodic silver. Nevertheless in all the experimental conditions, silver ions reduced the microbial concentration up to 4 log units of the starting inoculum in less than 6 h. The wide microbicidal spectrum and the high rate of kill of silver ions appear, therefore, attractive enough to suggest a possible utilization of anodic silver as a preserving agent.

Candida albicans↗
PubMed1996

Overcoming imidazole resistance in Escherichia coli.

We have demonstrated that the high resistance to imidazoles in 60 Escherichia coli strains is overcome by lowering the minimum inhibitory concentration (MIC) in culture from > 3200 to < 0.39 micrograms ml(-1) and, by determining, in contact tests, the disappearance of 10(4) CFU with 25 micrograms ml(-1) of imidazoles after 3 min. Although the contact activity was not the same as growth inhibition due to the different target of the drug in the cell structures, we annulled E. coli imidazole resistance in cultural and direct tests by means of the same non-antimicrobial conditions related to outer membrane functions.

Cell Membrane Permeability↗
PubMed1996

Synthesis and microbiological evaluations of (N-heteroaryl) arylmethanamines and their Schiff bases.

The synthesis as well as the antimicrobial and antiviral activities of new (N-heteroaryl)arylmethanamines and their Schiff bases are reported. None of the tested compounds shown activity against Herpes simplex virus type 2 and against Gram positive and Gram negative bacteria. Weak or moderate activity on poliovirus Sabin type 1, on reverse transcriptase and against Cryptococcus neoformans was shown by some of the tested compounds. Viceversa several synthesized compounds exhibited a moderate or good activity against strains of Candida albicans, while only some of the tested compounds were found moderately active against strains of Candida sp. Instead numerous new compounds 3 or 4 were active as control against isolates of plant pathogenic fungi. The obtained results are discussed on the basis of structure-activity relationships.

Amines↗
PubMed1995

Antifungal agents, Part 11. Biphenyl analogues of naftifine: synthesis and antifungal activities.

A series of naftifine analogues having the biphenyl instead of the naphthyl moiety have been synthesized in a search devoted to study bioanalogues of clinically efficacious antifungal agents. The new derivatives were tested against Candida albicans by the direct contact method. They were also assayed against Gram-positive and Gram-negative bacteria and against some isolates of plant pathogenic fungi. Derivatives 8a, 8c, and 9a were found to be active against Candida albicans, derivative 5a was active against E. coli, a very resistant species to antimycotic agents, and derivatives 8a and 8b inhibited the plant pathogenic Rhizoctonia solani.

Allylamine↗
PubMed1995

The activity of cilofungin on the incorporation of glucan associated proteins into hyphal cells of Candida albicans.

The effect of the cilofungin, a beta 1-3 glucan synthase inhibitor, on the incorporation of the glucan associated proteins (GAP) into the mycelial wall of Candida albicans was investigated. For this study sub-inhibitory (< 2 micrograms/ml) doses of cilofungin were employed during the yeast to mycelial transition in a defined chemical medium, at 37 degrees C for 24 hours. Under these conditions, and particularly at the dose of 0.50 micrograms/ml cilofungin exerted a marked effect on GAP incorporation into the mycelial cell wall. The changes were essentially the absence of the two prominent bands of 46 and 31 kDa of the untreated cell wall coupled with an apparent increase in the amount of 55-56 kDa constituent, as well as of a minor constituent of 27-28 kDa. Radiolabel incorporation experiments demonstrated increased synthesis of a 34 kDa GAP, in addition to confirming the absence of the 46 kDa constituent, in mycelial cells under cilofunging treatment. Thus, sub-inhibitory doses of cilofungin may greatly alter the pattern of essential cell wall constituents such as the glucan-associated proteins, suggesting that this drug also has important effects on cell wall structure and fine organization, independent of, or prior to, its principal lytic effect on the fungal organism.

Blotting, Western↗
PubMed1995

Study of the Mannich reaction: beta-amino-methylation of N-aryl and N-azaheteroaryl-substituted 2,5-dimethylpyrroles, compounds with potential biological activity.

Owing to the increasing need of drugs for the treatment of a variety of fungal and bacterial opportunistic infections, a study has been started with the aim of synthesizing structures amenable to a number of easily-to-perform structural modifications in order to meet the requirement of bypassing resistance phenomena. This paper reports on the synthesis of several N-(alpha-azaheteroaryl)-substituted 2,5-dimethyl-pyrroles bearing in one beta-position (or in both beta-positions) aminomethyl groups, introduced via a Mannich reaction. Electronic and steric effects by the N-(azaheteroaryl) substituents and the 2- and 5-methyl groups on the course of the Mannich reaction are discussed along with the results of in vitro tests against many Candida species, some bacteria, and several pathogenic plant fungi.

Anti-Bacterial Agents↗
PubMed1994

The lipopeptide antimycotic, cilofungin modulates the incorporation of glucan-associated proteins into the cell wall of Candida albicans.

The effect of the beta 1-3 glucan synthase inhibitor, cilofungin, on the incorporation of 35S-methionine-labelled glucan associated proteins (GAP) in the cell wall of Candida albicans was investigated in a susceptible strain C. albicans 3153 and resistant strain C. albicans CA-2. Cilofungin exerted a marked effect on the GAP composition of the cell wall at 0.25 mg/L, a concentration which reduced beta 1-3 glucan synthesis by approximately 50% and also inhibited the growth of the susceptible strain C. albicans 3153. A 46 kDa protein was present in large amounts in C. albicans 3153 but not in strain CA-2. This protein was probably not mannosylated and its incorporation was greatly reduced by cilofungin. In addition, a well defined 34 kDa protein was identified together with a distinct band of high molecular mass polydisperse material of between 65 and 96 kDa and another of > 200 kDa. These proteins were strongly reactive to concanavalin A indicating that they were mannosylated, and treatment with cilofungin caused an increase in their production which was also confirmed by immunoblotting with rabbit anti-Candida serum. In contrast, exposure of the drug-resistant strain CA-2 to cilofungin did not result in changes in the composition of the GAP constituents. Only the mannosylated proteins of 34 kDa and the high molecular mass polydisperse material 65-96 kDa were present in the cell wall. The pulse-chase labelling experiments showed that the 46 kDa protein was the first of the GAPs to be incorporated into the cell wall, and that this was suppressed in the presence of cilofungin whereas there was a concomitant increase in the incorporation of the 34 kDa and the high-molecular weight polydisperse material. Thus, cilofungin causes a profound imbalance in GAP incorporation into the growing cell wall which is possibly related to changes in the amount and type of glucan being synthesized at sub-inhibitory concentrations of the antimycotic.

Antifungal Agents↗
PubMed1993

Antifungal agents, II: Synthesis and antifungal activities of aryl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methane derivatives with unsaturated chains.

The synthesis and antifungal activities of aryl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methanes having allyl, crotyl, and acrylate chains linked to the N-pyrrole atom and substituted at phenyl ring by Cl, F, CH3, and NO2 groups are reported. In vitro tests against Candida albicans and Candida spp. showed 2,4-dichlorophenyl-1-allyl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methane to be the most potent derivative with activities comparable to those of ketoconazole and slightly inferior to those of bifonazole and miconazole. Some structure-activity relationships are discussed.

Antifungal Agents↗
PubMed1993

Variations in the antigenic effects of tunicamycin on Candida albicans.

We report on the effect of subinhibitory doses of tunicamycin on Candida albicans cells (BP strain high responder NCYC 1466) in a defined medium favourable for expression of the mycelial phase. Tunicamycin inhibited the synthesis of some protein fractions ranging from 40 to 65 kDa, where the immunodominant antigens of C. albicans responsible for the antibody response to systemic mycosis were inhibited. By two-dimensional immunoelectrophoresis, antigen extracts from the cell cultures grown with tunicamycin showed a migration modification and a lower number of precipitation arcs with variation in their height and range.

Antigens, Fungal↗
PubMed1993

Antifungal agents. VI. In vitro antifungal activities of halobenzoyl esters of cis- and trans-[2-(1,1'-biphenyl-4-yl)-2-(1H-imidazol-1-ylmethyl)-1,3- dioxolan-4-yl]carbinols.

The synthesis and the in vitro antifungal activities against Candida albicans and Candida spp of a number of halobenzoyl esters of cis- and trans- [2-(1,1'-biphenyl-4-yl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan -4- yl]carbinols is reported. Some new imidazoles were found more active than ketoconazole and sometimes as potent as bifonazole against Candida albicans. All derivatives were found scarcely active against Candida spp.

Antifungal Agents↗