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Biomedical subjects

L Pagani

Publications and source records attributed to L Pagani.

17 recordsLinked to original sources
PubMed1992

Assisted evaluation of antibiotic resistance development in Pseudomonas aeruginosa from intensive care units.

421 strains of Pseudomonas aeruginosa were isolated from patients admitted to intensive care units and tested with automated systems for sensitivity to 21 antimicrobial agents. Data were collected in a database for evaluation and monitoring of resistance development. Results showed that assisted monitoring of antimicrobial resistance gives continuously updated information, with particular attention to the different local therapeutical schedules. It is therefore advisable that clinicians constantly exchange information with the microbiology laboratory through a hospital information system in which data from different laboratories are pooled in real time.

Cross Infection↗
PubMed1992

Antibiotic susceptibility patterns surveillance and clinical distribution of Enterobacteriaceae.

3700 strains of Enterobacteriaceae clinical isolates were tested by automated devices for susceptibility to several antimicrobial agents widely used in clinical practice. Amikacin demonstrated the greatest in vitro activity whereas ampicillin and mezlocillin were the least active. Finally gentamicin and nalidixic acid had a similar activity to recently introduced cephalosporins. The bacterial species widely isolated were grouped in three clusters according to the clinical body site of isolates: several discrepancies emerged from the study of antibiotic susceptibilities of strains obtained from different body site sources. Source could be correlated with bacterial pattern of resistance.

Anti-Bacterial Agents↗
PubMed1992

[The use of systemic phosphocreatine in heart surgery].

Phosphocreatine (PC) has been widely used in cardiac surgery as a component of cardioplegic solutions because of its positive effects in preventing ischemic heart damage; we have researched the efficacy of PC in cardiac surgery when infused through the intravenous route before and after cardiac arrest. Two groups of patients who had undergone aortocoronary by-pass grafts were matched: group A (20 patients) did not receive any particular treatment; PC was administered intravenously to patients in group B after the induction of anaesthesia, immediately prior to cardiac arrest and after the release of aortic cross-clamp. To test the efficacy of the drug, the following parameters were evaluated: the recovery as the incidence of low cardiac output and/or need of inotropic drugs; dysrhythmias; electrocardiographic signs of myocardial ischemia or infarction; release of cardiac necrosis enzymes. Treated patients were found to have a better recovery, a lower incidence of dysrhythmias, an easier resumption of normal sinus rhythm with a lower number of electric defibrillations and a significantly lower release of cardiac enzymes. It can be therefore said that PC has a marked protective effect on myocardial anoxia in cardiac surgery, even when administered intravenously.

Cardiopulmonary Bypass↗
PubMed1991

Physico-chemical properties of amphoteric, isoelectric, macroreticulate buffers.

We report here the properties of a new family of resins possessing an amphoteric character and able to strongly buffer at their pI values. They have been adopted as carriers for growth of cells in tissue culture and for hydroponics (Righetti et al. 1991; J. Biotechnol. 17, 169-176) but it is to be expected that such resins could have interesting chromatographic applications. It has been found that such beads [made by incorporating a pK 6.2 weak acrylamido base and a pK 4.6 weak acrylamido acid in a 2:1 ratio (thus with a pI of 6.2) into a neutral polyacrylamide backbone], independently from their initial conditioning (acid- or base-washed), spontaneously seek their equilibrium position (pI value) upon washing off excess titrant. Thus, upon potentiometric titration, they are seen to buffer in both directions of the pH scale (contrary to the behaviour of a pure carboxyl or a pure amino surface, which will exhibit only unidirectional buffering power). From the behaviour of these amphoteric beads when polymerized in the absence or in the presence of salts (0.2 M NaCl), it is hypothesized that, for exerting buffering power, both the buffering ion and its counterion must be incorporated non-randomly in the chain, but as a couple or in close proximity. Upon random incorporation of the two ions, buffering power is lost.

Buffers↗
PubMed1990

Morphometric evaluation of CD16-positive cells with respect to CD2 antigen coexpression.

We examined morphometric as well as functional characteristics of CD16-positive human peripheral blood lymphocytes on the basis of the coexpression of the CD2 antigen. For morphometric analyses, nuclear area and cellular area were determined by counting line cross-points of a superimposed quadratic lattice test system overlying nuclei and the whole cell, respectively. Moreover, to evaluate the cellular villousity degree, the maximum inscrible circle and an irregular polygon were inscribed within cell profiles. The cytoplasm fraction included between the plasmalemma and the traced irregular polygon was considered as the villous portion of the cell. Finally, the NK capability was measured in a 6-hr 51Cr-release assay with human K-562 myeloid cells as targets. Within the CD16-positive cell population, the CD16-positive/CD2-negative cells seem to represent the most efficient NK cell subset. To the higher NK capability correspond a higher villousity degree and a lower nuclear area/cellular area ratio of the CD2-negative/CD16-positive subset, when compared with CD2-positive/CD16-positive cells.

Antibodies, Monoclonal↗
PubMed1990

Effects of propolis flavonoids on virus infectivity and replication.

The effect of five propolis flavonoids on the infectivity and replication of some herpesvirus, adenovirus, coronavirus and rotavirus strains has been studied. Experiments were performed in vitro in cell cultures using the viral plaque reduction technique. The cytotoxicity of flavonoids, including chrysine, kaempferol, acacetin, galangin and quercetin, was evaluated on uninfected monolayers to determine their effect on cell growth and viability. Chrysine and kaempferol caused a concentration-dependent reduction of intracellular replication of herpes-virus strains when monolayers were infected and subsequently cultured in a drug-containing medium. However, virus infectivity was not significantly affected. Acacetin and galangin had no effect on either the infectivity or replication of any of the viruses studied. Quercetin reduced infectivity and intracellular replication, but only at the highest concentrations tested.

Animals↗
PubMed1990

Emergence of cross-resistance to imipenem and other beta-lactam antibiotics in Pseudomonas aeruginosa during therapy.

The emergence of resistance to imipenem and other beta-lactams by Pseudomonas aeruginosa was investigated with two pairs of isolates. Two of these isolates were susceptible to imipenem and other beta-lactam antibiotics, such as moxalactam, ceftriaxone and cefotaxime, while the other two had developed resistance to those antibiotics during imipenem therapy. So far imipenem-resistant isolates have not demonstrated cross-resistance to other beta-lactam agents. We examined in these clinical isolates the possible mechanisms of resistance due to permeability modifications, either in outer membrane proteins (porins) or to LPS (lipopolysaccharides) complex. Particularly we analysed possible modification of physico-chemical properties of outer membrane proteins, such as changes in their hydrophobicity and electrical charge. beta-lactamase production was also studied. Results showed that resistance to imipenem may be related to loss or modifications in hydrophobicity of an outer membrane protein of about 46 Kdal; other modifications concerned hydrophobicity of the porin OMP F and, in one strain, the LPS complex appears to be responsible for resistance to other beta-lactam antibiotics together in combination with the production of beta-lactamases.

Anti-Bacterial Agents↗
PubMed1989

Modification of norfloxacin inhibition of DNA gyrase induced by a 28 KDal DNA binding protein.

We have previously studied a clinical isolate of Providencia stuartii which showed high levels of resistance to 4-quinolones, aminoglycoside and beta-lactam antibiotics (Landini et al., 1987). DNA gyrase from this isolate was inhibited for 50% of activity at a concentration of 15 microM of norfloxacin, which is about 5-fold higher compared to the 50% inhibitory concentration for a standard DNA gyrase. It has been described that 4-quinolone inhibition of DNA gyrase is caused by their binding to DNA and by the distortion induced in DNA tertiary structure, and that affinity binding of 4-quinolones is different for DNAs in different structures. In order to detect whether the interaction between pAT 153 and a protein able to modify DNA tertiary structure could affect norfloxacin inhibitory concentrations for DNA gyrase we purified from the clinical isolate of Providencia stuartii a DNA binding protein of about 28 KDal which induces changes in supercoiling degree of DNA. Assays of DNA gyrase activity were performed on the complex pAT 153-DNA binding protein-norfloxacin. Results showed an increase from 15 microM to 20 microM of 50% norfloxacin inhibitory concentration for DNA gyrase when pAT 153 was complexed with the 28 KDal protein.

DNA Helicases↗
PubMed1988

Beta-lactam resistant Pseudomonas aeruginosa strains emerging during therapy: synergistic resistance mechanisms.

The emergence of beta-lactam resistant strains of Pseudomonas aeruginosa during treatment was studied. Three different strains present before treatment persisted with changes in their beta-lactam resistance during treatment. The isolates before and after therapy were studied for beta-lactamase production and permeability barrier. The increased beta-lactam resistance was correlated with an increased permeability barrier. In order to verify if the permeability barrier was correlated with changes in outer membrane proteins, outer membrane preparations were analyzed by SDS-PAGE. Several differences were observed between the OMP profiles of the post therapy and the pre therapy isolates. Furthermore, an analysis of PBPs pattern of strains studied was carried out and alterations in target proteins were observed.

Anti-Bacterial Agents↗
PubMed1988

Antiviral activity of Chamaecyparis lawsoniana extract: study with herpes simplex virus type 2.

Ethanolic extract of the green part of Chamaecyparis Lawsoniana was tested for antiviral activity and toxicity in tissue culture. All experiments were carried out in confluent human embryo lung fibroblasts. Treatment of fibroblast cells with extracts after viral inoculation was effective in inhibiting the replication of herpes simplex virus type 2 (HSV-2). The critical time for virus inhibition was 4 to 5 h after virus absorption. The antiviral activity was assayed employing the techniques of viral plaque and yield reduction. Toxicity of Chamaecyparis Lawsoniana in uninfected cells was studied as alteration of cell morphology, cellular viability and inhibition of host cell DNA synthesis. Herpes simplex virus inhibition occurred in presence of extract concentration of 0.5 micrograms/ml, whereas concentrations exceeding 5 micrograms/ml and 140 micrograms/ml were found to be cytotoxic when evaluated with inhibition of host DNA synthesis and cellular viability respectively. Results suggest that further investigations concerning the isolation of substances responsible for antiviral activity and an effort to define the mechanisms of action are warranted.

Antiviral Agents↗
PubMed1987

Modifications of DNA-gyrase and of permeability in a norfloxacin-resistant clinical isolate of Providencia stuartii.

We obtained a clinical isolate of Providencia stuartii showing a high level of resistance to norfloxacin and to other 4-quinolones, whose target is the enzyme DNA-gyrase. This strain showed resistance also to beta-lactam and aminoglycoside antibiotics. In order to detect modification of DNA-gyrase, we performed supercoiling assays in vitro in presence of norfloxacin and ciprofloxacin. Furthermore, outer membrane proteins, which are involved in permeability mechanisms, were analyzed on SDS-polyacrylamide gels. Results showed that both modifications in DNA-gyrase and changes in outer membrane proteins can be held responsible for resistance to 4-quinolones; moreover, these modification are probably supported by a third mechanism of resistance.

Bacterial Outer Membrane Proteins↗
PubMed1986

Characterization of two morphologically distinct Leu-7+ cell subsets with respect to Leu-15 antigen. Evaluation of Leu-15 determinant distribution on both E rosetting and non-adherent non-E rosetting cell populations.

In the present study the fine structures of Leu-7+-Leu-15+ and Leu-7+-Leu-15- cell subpopulations were characterized by using an immunogold-immunoperoxidase double labelling in electron microscopy. The densities of Leu-15 antigenic sites on both E rosetting (Er) and non-adherent/non-E rosetting (non-A/non-Er) Leu-15 positive cell surfaces were also evaluated by using an immunogold analysis in electron microscopy. A majority of Leu-7+ cells co-expressed the Leu-15 antigen and showed an ultrastructural pattern specific for mature natural killer (NK) cells, i.e. abundant cytoplasm with many organelles, numerous electron dense granules, and irregular outline. On the other hand, a minority of Leu-7+ cells did not express the Leu-15 antigen and showed a clearly different ultrastructural feature in comparison to Leu-7+-Leu-15+ cells. Thus, the presence of the Leu-15 antigen on Leu-7+ cell surface corresponds to ultrastructural features specific to differentiated NK cells and may represent an expression of Leu-7+ cell differentiation. An alternative hypothesis may be that Leu-7+-Leu-15+ and Leu-7+-Leu-15- cells represent distinct cell lineages within non-A/non-Er Leu-7+ cells. Finally, the results of the present study provide proof that Leu-15 antigen is more frequently represented on non-A/non-Er Leu-15+ cells than on Er Leu-15+ cells.

Aged↗
PubMed1978

R factors from Enterobacter group.

Twenty-six R factors transmissible to E. coli K12 were derived from 79 strains of Enterobacter species isolated in various clinical specimens (urine, sputum, blood, pus); 71 of 79 strains were Enterobacter cloacae. Fifteen R factors were fi+: 14 belonged to group FII, 1 to group FI. Eleven R factors were fi-: 5 belonged to group M, of the others 6 (all controlling the cloramphenicol-resistance) 1 was recognized of group K, 1 was incompatible with standard plasmids of both groups S and W, and 4 belonged to group S.

Anti-Bacterial Agents↗
PubMedDate not supplied

Synthesis of an hydrophilic, pK 8.05 buffer for isoelectric focusing in immobilized pH gradients.

The synthesis of a new, pK 8.05 acrylamido weak base for isoelectric focusing in immobilized pH gradients (IPG) is here reported. This compound N,N-bis(2-hydroxyethyl)-N'-acryloyl-1,3-diaminopropane is strongly hydrophilic, and thus inhibits any potential hydrophobic interaction among proteins and the grafted basic groups in an IPG matrix. In addition, this novel buffer represents a step ahead towards the goal of closing the 'gap' between the commercially available Immobilines, pK 7.0 and 8.5. Owing to the large distance between these two neighboring pK values, it is difficult to arrange for linear narrow pH gradients in this region. IPG compositions obtained with this new buffer give highly linear pH gradients and protein profiles identical to those obtained with commercial Immobilines.

Acrylates↗