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P Marconi

Publications and source records attributed to P Marconi.

At least 19 recordsLinked to original sources
PubMed1992

In vivo modulation of lymphokine-activated killer cell activity by cell wall components of Candida albicans.

We have previously reported that inoculating CD2F1 mice intraperitoneally with five doses of 2 x 10(7) inactivated Candida albicans (CA) cells was associated with the induction of lymphokine-activated killer (LAK)-like effectors. In this study we investigated the ability of some purified cell wall components of CA (CA-CW) to induce LAK-like cells in vivo. Multiple administrations of glucan ghost (GG), a mannoprotein mixture (MP) and a low-protein mannan fraction (M) at variance with whole CA did not induce LAK-like cells in the peritoneal cavity. However, the broad-spectrum antitumor cytotoxicity induced by CA could be recalled to a high level by a booster dose of MP and M, but not GG, given up to 70 days after the multiple CA-treatment. This induced cytotoxicity was maximum when the booster was given on Day +14 after CA-treatment and minimum on Day +70. In CA-treated mice, inoculated on Day +30 with CA or MP, LAK-like cytotoxicity was already significantly increased 4 hr after the booster, but the maximum value was reached at 24 hr. Anti-mannan antibodies did not interfere with LAK-like cells induction by CA because splenectomy before CA-treatment or passive administration of anti-mannan antibodies had no effect on the rapid activation of cytotoxicity by CA or a booster dose of MP. Administration of recombinant human interleukin-2 (rhIL-2) to CA-treated mice induced a higher level of NK activity than that induced by the same dose in untreated control mice, but did not activate LAK-like effectors. The results indicate that LAK-like effectors are easily generated in the peritoneal cavity by a booster with a defined antigenic constituent of CA cell wall for a long period in CA-sensitized mice.

Animals↗
PubMed1991

In-vitro effects of teicoplanin, teicoplanin derivative MDL 62211 and vancomycin on human polymorphonuclear cell function.

The in-vitro effects on human neutrophil (PMN) functions of three structurally related glycopeptide antibiotics, vancomycin, teicoplanin and the teicoplanin derivative MDL 62211 were investigated. Teicoplanin and MDL 62211 significantly inhibited adherence, chemotaxis, phagocytosis and killing of Candida albicans by PMN's at a concentration of 500 mg/l, whereas PMN viability was only affected at drug concentrations of 2000 mg/l. Vancomycin interfered with PMN adherence and phagocytosis only at a concentration of 2000 mg/l without affecting PMN viability. Chemotaxis and killing of C. albicans were also not affected by this concentration. Teicoplanin and the teicoplanin-derivative MDL 62211 was found to have adverse effects on selected indices of PMN function in vitro only at concentrations higher than those employed in therapy, while vancomycin interfered only at very high concentrations.

Anti-Bacterial Agents↗
PubMed1991

Fungicidal activity of Candida albicans-induced murine lymphokine-activated killer cells against C. albicans hyphae in vitro.

Multiple intraperitoneal injections of inactivated Candida albicans cells resulted in the generation of cytotoxic peritoneal cells with phenotypical and functional properties similar to in vitro-generated lymphokine-activated killer (LAK) cells. Using an in vitro [3H]glucose uptake assay, C. albicans-induced LAK-like (CA-LAK) cells exhibited high levels of anti-hyphal activity, the effects being effector to target cell (E:T) ratio- and time-dependent. Maximal levels of anti-C. albicans activity (approximately 60%) were observed after 4 h and at E:T greater than or equal to 300:1. Similar patterns of anti-C. albicans activity were exerted by in vivo-activated natural killer (NK) cells, in vitro interleukin-2- (IL-2) generated LAK cells and polymorphonuclear cells. The anti-hyphal activity of CA-LAK cells was enriched by separation on a Percoll gradient, F2 and F3 fractions retaining most of the activity. Experiments using immunodepressed animals demonstrated that the in vivo lethality of the C. albicans hyphal form is significantly affected by in vitro pre-exposure to CA-LAK cells. While control mice receiving C. albicans alone had a median survival time of 2 d, mice receiving C. albicans pre-exposed to CA-LAK cells (E:T = 300:1) had a median survival time of 15 d. Overall, the susceptibility of the C. albicans hyphal form to CA-LAK cells suggests that C. albicans-induced effectors might play a significant role as a second-line defence mechanism against the C. albicans hyphal form.

Animals↗
PubMed1991

[A "signal averaging" analysis of the P wave in patients with a history of isolated paroxysmal atrial fibrillation].

The aim of this study was to verify the utility of the signal averaged electrocardiogram for the analysis of the P wave in patients with paroxysmal lone atrial fibrillation. We studied 22 patients with documented paroxysmal atrial fibrillation without cardiovascular or endocrine diseases. The results were compared with 24 normal subjects. Signal averaged electrocardiogram was recorded from bipolar orthogonal leads X, Y, Z using ART equipment mod. 1200 EPX, with 50-250 Hz filter and effective time-base resolution of 100 mm/sec and voltage of 1 mm/microV. Signal averaging of at least 300 beats was performed to reduce noise level under 0.3 microV. In patients with atrial fibrillation the duration of the P wave was significantly longer (135.0 +/- 13.0 msec) than in the normal subjects (109.4 +/- 11.4 msec) (p less than 0.000001). These results were steady in successive recordings (2-30 days after the first recording). The analysis of the P wave signal averaging seems useful in identifying patients with lone paroxysmal atrial fibrillation.

Adult↗
PubMed1990

A rapid objective immunofluorescence microassay. Application for detection of surface and intracellular antigens.

An indirect immunofluorescence microassay, which permits automated reading, has been employed for simple, rapid and objective detection of surface and intracellular antigens. Initially, the cells, spun in microplates, are fixed with glutaraldehyde (0.25% v/v in PBS). Following fixation, the cells can be stored at 4 degrees C for up to 2 weeks before being used in the immunofluorescence microassay. The fixed cells are then stained according to standard procedures using appropriate first and fluorescein-conjugated second antibodies. An automated and quantitative evaluation of the fluorescence intensity of the cell samples was achieved using the Titertek Fluoroskan II automatic reader. This microassay was shown to be suitable for the detection of the surface MAC1 antigen and intracellular v-myc protein in the GG2EE macrophage cell line.

Animals↗
PubMed1990

Induction of LAK-like cells in the peritoneal cavity of mice by inactivated Candida albicans.

We have investigated the effect of multiple administrations of inactivated Candida albicans (CA) cells on induction of non-MHC-restricted antitumor cytotoxic responses both in normal and congenitally athymic (nude) mice. Intraperitoneal inoculation of CD2F1 mice with five doses of 2 x 10(7) CA cells over a 2-week interval was associated with the induction of peritoneal exudate cells (PEC) that mediated natural killer cell activity. These cells, in contrast to those elicited by a single dose of CA, killed both NK-sensitive and NK-resistant tumor target cells in vitro. This broad-spectrum, antitumor cytotoxicity peaked 1 day after the last injection of CA, and decreased to control values within 6 (NK-resistant) or 14 (NK-sensitive target cells) days. Cytotoxicity could be recalled to a high level by a boosting injection of CA or a major mannoprotein-soluble antigen (MP) from the Candida cell wall, given 30 days after multiple CA treatment. Upon a 24-hr in vitro incubation, CA-induced peritoneal immunoeffectors lost their killing activity unless human recombinant interleukin-2 (rIL-2) was added to cultures. The non-MHC-restricted cytotoxic PEC activity induced by CA was mainly associated with nonadherent, nonphagocytic large granular lymphocytes (LGL) which exhibited the following phenotypes: (i) asialo GM1+, Lyt 2.2-, and partially Thy 1.2+ (effectors active against NK-sensitive targets) and (ii) asialo GM1+, Lyt 2.2-, and Thy 1.2+ (effectors active against NK-resistant targets). Nude mice also responded to multiple CA inoculations by displaying high cytotoxic activity against NK-sensitive targets and significant cytotoxicity against NK-resistant targets. This cytotoxicity could be recalled on Day +30, and the cytotoxic effectors involved were highly sensitive to anti-asialo GM1 plus complement treatment. Overall, the results add further experimental evidence to the wide range of immunomodulatory properties possessed by C. albicans, and demonstrate that the majority of antitumor cytotoxic activity induced by fungal cells was due to lymphokine-activated killer (LAK)-like effectors.

Animals↗
PubMed1990

Gamma interferon-induced specific binding of tetanus toxin on the GG2EE macrophage cell line.

We have recently demonstrated that tetanus toxin (TT) selectively inhibited gamma interferon-(IFN-gamma)-induced, but not basal, lysozyme activity in the GG2EE macrophage cell line. By an indirect immunofluorescence technique, we show that tetanus toxin, as well as the BIIb tetanus toxin-derived fragment, selectively binds to IFN-gamma-treated cells but fails to bind to control cells. Moreover, BIIb fragment and TT share the same binding sites, as demonstrated by competition/displacement experiments. These data indicate that IFN-gamma pretreatment results in the acquisition of tetanus toxin binding sites on GG2EE cells by a mechanism(s) yet to be identified.

Animals↗
PubMed1990

Experimental model of type IV Streptococcus agalactiae (group B streptococcus) infection in mice with early development of septic arthritis.

We have established an experimental murine model to gain insight into the pathogenicity and clinical features of type IV group B streptococcus (GBS) infections. Adult CD-1 mice were challenged intravenously with 10(7) type IV GBS cells, inducing systemic invasion. Most of the animals were able to clear the infection from the blood, brain, and lungs within 2 weeks and from the spleen and liver within 1 month. However, the animals were unable to clear the microorganism from the joints and kidneys during the 60-day observation period. About 80% of the mice challenged intravenously with type IV GBS manifested early septic arthritis, which evolved from an acute exudative synovitis to permanent lesions characterized by irreversible joint damage and ankylosis. Induction of persistent septic arthritis was dependent on the number and viability of microorganisms inoculated and was unrelated to the strain of type IV GBS and the growth phase of the inoculum. Type-specific antibodies of both immunoglobulin M and G classes could be detected by agglutination and enzyme-linked immunosorbent assay from days 7 and 14, respectively; immunoglobulin G antibodies persisted for more than 40 days. Complexes of antibodies and group- and type-specific antigens were detected in mouse sera 24 h after infection and persisted up to day 22. These results were obtained an experimental model of type IV GBS chronic infection with early development of septic arthritis, which could be useful in future studies of pathogenicity and immune mechanisms involved in the host resistance to this microorganism.

Animals↗
PubMed1990

Presence of a plant-like glyoxalase II in Candida albicans.

Glyoxalase II from Candida albicans was purified by affinity chromatography on S-carbobenzoxyglutathione-Affi Gel 10. The enzyme was characterized and compared with the glyoxalases II from animal and plant sources. The relative molecular mass is 29 kDa, and the isoelectric point (pI) is 6.0. The acidic pI value appears to be typical for plant glyoxalase II, in contrast to the uniformly basic glyoxalase II pI values from animals. S-D-Lactoylglutathione and S-acetoacetylglutathione are the best substrates, and S-carbobenzoxyglutathione is the best inhibitor of the yeast enzyme. Glutathione derivatives with a thioether bond are not inhibitory. Glyoxalase II from Candida albicans is compared either with animal and plant enzymes.

Animals↗
PubMed1989

Identification of a trypanocidal factor against Trypanosoma equiperdum in normal human serum.

Normal human serum (HS) contains trypanolytic activity and agglutinins to Trypanosoma equiperdum, while such activities are not found in sera from a range of animals susceptible to infection. HS given to T. equiperdum-infected mice caused a rapid decrease in the number of circulating trypanosomes and protection from lethal infection. Trypanolytic activity of human serum was found to be associated, after DEAE chromatography and Sephadex G-200 gel filtration, with the fraction containing 19S antibodies. Immunofluorescence assays confirmed a binding of human IgM and C1q complement component onto the surface of T. equiperdum. Anti-T. equiperdum activity of HS was specifically directed to T. equiperdum surface components and not to some mouse serum components adsorbed on parasites during the growth in the host, because HS adsorbed in vivo in CD-1 mice retained full protective and agglutinating properties. Trypanocidal activity appears in human serum about the 7th month after birth and persists until late in life. On the contrary, human purified high-density lipoprotein had no significant in vitro or in vivo trypanocidal activity. In conclusion, strong natural anti-T. equiperdum activity in human serum was mainly mediated by natural antibodies of the IgM class. The presence of natural IgM active against T. equiperdum in HS could represent one of the natural mechanisms of resistance of refractory hosts against trypanosome infections. This phenomenon provides further evidence that host specificity of trypanosomes may be partly conditioned by the presence of natural antibodies.

Agglutination Tests↗
PubMed1989

Immunosuppressive effect of cyclosporin A on resistance to systemic infection with Candida albicans.

We studied the influence of cyclosporin-A (Cy-A) on resistance of mice to systemic infection with Candida albicans. Cy-A clearly inhibited resistance to C. albicans. The effect was dose-dependent and time and route of administration of the drug were important. This immunodepressive effect was due, at least in part, to an impairment of polymorphonuclear leucocyte (PMNL) candidacidal activity, as demonstrated in vitro by a reduction of phagocytic and cytotoxic activity and in vivo by protection when PMNL from untreated mice were transferred into cyclophosphamide-treated hosts challenged with C. albicans. The decreased activity of PMNL could be partly restored by adoptive transfer of normal T-lymphocytes into Cy-A-treated mice, as well as by exposure of PMNL to gamma-interferon (IFN-gamma) in vitro.

Animals↗
PubMed1989

Selective inhibition of cytokine-induced lysozyme activity by tetanus toxin in the GG2EE macrophage cell line.

This study was designed to evaluate the effects of tetanus toxin (TT) on lysozyme (LZM) activity by the GG2EE macrophage cell line. GG2EE cells spontaneously produced low amounts of LZM, which were mostly secreted into the culture medium. Upon treatment with various cytokines, GG2EE cells exhibited altered LZM activity. In particular, exposure of GG2EE cells to alpha/beta interferon (IFN-alpha/beta) reduced LZM activity, as opposed to treatment with gamma interferon (IFN-gamma) or colony-stimulating factor 1, which potentiated LZM activity. Spontaneous LZM activity of GG2EE cells was not susceptible to TT action; in contrast, when IFN-gamma- or colony-stimulating factor 1-susceptible cells were treated with TT, a significant reduction on LZM activity was observed. The TT inhibitory effect was dose dependent and manifested only after a 6-h incubation of GG2EE cells with TT. Treatment of GG2EE cells with heat-inactivated TT as well as Ibc- and B-IIb-TT-derived fragments was found to be ineffective, while pretreatment with B-IIb- but not with Ibc-TT-derived fragment abrogated the TT effect. Overall, these data indicate the existence of a specific TT-GG2EE cell interaction, leading to selective inhibition of cytokine-induced LZM activity.

Animals↗
PubMed1988

Immunomodulation by a low-virulence, agerminative variant of Candida albicans. Further evidence for macrophage activation as one of the effector mechanisms of nonspecific anti-infectious protection.

Systemic infection of mice with a Candida albicans strain (PCA-2) incapable of yeast-mycelial conversion is known to activate host macrophages and confer protection against subsequent challenge with highly pathogenic cells of the same species or by other micro-organisms. In an attempt to define the relative contributions of different immune components to the protection mediated by PCA-2, we evaluated the effect of manipulations known to selectively deplete immune functions. By means of cytostatic drug or silica induced toxicity, it was possible to demonstrate that no crucial role in protection is played by cytotoxic T lymphocytes or B cells, nor by PCA-2 induced granulocytosis alone. The cells responsible for this effect were dacarbazine-resistant silica-sensitive macrophages whose activity in vivo paralleled the in vitro expression of splenic candidacidal activity. Macrophage activation by PCA-2 and increased anti-Candida resistance did not result from an immunological response mediated by T-dependent effectors, as these effects could be reproduced in athymic mice.

Adjuvants, Immunologic↗
PubMed1988

Cell wall components of Candida albicans as immunomodulators: induction of natural killer and macrophage-mediated peritoneal cell cytotoxicity in mice by mannoprotein and glucan fractions.

Cell wall components from Candida albicans were compared to intact cells for their ability to induce natural cytotoxic immunoeffectors in the peritoneal cavity of mice. A soluble mannoprotein extract (MP) and an insoluble glucan fraction (GG) strongly stimulated the generation of peritoneal effectors capable of lysing YAC-1 and P-815 tumour cell lines in vitro. The anti-YAC-1 effectors were characterized as natural killer (NK) lymphocytes while the anti-P-815 effectors appeared to be activated macrophages. The activity of each fraction was typically dose-dependent and both fractions differed from whole cells in the kinetics of induction of cytotoxicity. However, the NK and macrophage effectors generated by these materials had similar functional and phenotypic properties, irrespective of the material used as inducer. No mannoprotein was detected in the insoluble glucan fraction GG. Hence, the immunoenhancing activity of GG could not be attributed to the presence of some MP or MP-like component. Mannan-rich fractions with low (less than 3%) protein content (M) or extracted by hot alkaline reagent (M-alk) were inactive as NK and macrophage inducers. Thus, the cell wall of C. albicans contains at least two distinct macromolecular complexes which mediate the induction in murine peritoneal exudates of cytotoxic effectors active against tumour cell lines.

Animals↗
PubMed1988

Comparative in vitro activity of imipenem against gram-positive and gram-negative aerobic bacteria from clinical isolates.

Imipenem is a member of a new class of beta-lactam antibiotics, carbapenems, with a very broad antibacterial spectrum. In this work we evaluated the in vitro activity of imipenem against a variety of bacterial strains isolated from clinical specimens as well as the activity of other beta-lactam antibiotics. The results obtained with 501 bacterial strains show that imipenem is active on both gram-negative and gram-positive microorganisms isolated from different infections. The in vitro inhibitory activity is greater than that of aztreonam, cefotaxime, ceftriaxone, piperacillin, amikacin, and netilmicin, against the majority of strains tested.

Anti-Bacterial Agents↗
PubMed1987

Cell wall of Candida albicans and host response.

Modulation in chemistry and organization of cell wall macromolecules play decisive roles in the morphogenic processes and virulence of Candida albicans. Cell wall components also have a diversified range of effects on the host's immune system, including immunopotentiating or immunodepressing activities. Mannan, mannan-protein, and glucan fractions have been especially studied in this context. In in vitro cultured human peripheral blood mononuclear cells, a mannan-protein fraction (GMP) from the cell wall of the yeast form acted as a strong antigenic activator by stimulating lymphokine production and lymphocyte proliferation. Cytolytic effectors active against several tumor targets were also generated. In the mouse, GMP was a strong inducer of natural killer lymphocytes. Other cell wall components, mostly the insoluble beta-glucan, modulated the activity of macrophages and monocyte precursors. Some of the immunomodulating properties of artificially extracted components were shared, even with greater potency, by antigens which were released from C. albicans during its growth and hyphal morphogenesis. Altogether, the range of the immunoresponses elicited and the intensity of the observed effects are such as to individuate in this human indigenous fungus a microorganism capable of profoundly affecting the host's immune system.

Animals↗