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M Pretolani

Publications and source records attributed to M Pretolani.

At least 55 records · Page 3Linked to original sources
PubMed1994

Role of eosinophil activation in the bronchial reactivity of allergic guinea pigs.

Ovalbumin inhalation by sensitized guinea pigs induced a marked increase in the number of eosinophils (0.89 +/- 0.18 to 5.45 +/- 0.77 x 10(5)/ml, n = 10, p < 0.05) and elevations in the amounts of protein and eosinophil-derived major basic protein (MBP) (1,010.7 +/- 184.9 to 4,116.6 +/- 973.0 ng/ml, n = 10, p < 0.05) recovered by bronchoalveolar lavage (BAL). In contrast, no changes in the levels of eosinophil peroxidase (EPO) or in the sensitivity of the airways to bronchoconstriction induced by methacholine were detected. However, when ovalbumin-exposed guinea pigs received an intratracheal instillation of 1 microgram leukotriene (LT)B4 30 min prior to methacholine provocation, elevated levels of EPO and MBP in the BAL fluid and a marked bronchial hyperreactivity to methacholine were noted when compared with saline-challenged LTB4-injected animals (p < 0.05). In contrast, the intratracheal instillation of 1 or 3 micrograms platelet-activating factor (PAF) did not significantly modify the bronchial reactivity to methacholine or the levels of EPO and MBP. PAF and LTB4 induced similar enhancements in the amount of protein in BAL fluids from antigen-exposed guinea pigs, suggesting that increased endothelial/epithelial permeability does not account for hyperreactivity. A significant correlation between the levels of EPO or MBP and the intensity of the bronchial responsiveness to methacholine were shown in ovalbumin-challenged guinea pigs, irrespective of their subsequent treatment, i.e., either with PAF or with LTB4 or with their vehicle (r = 0.579, p = 0.0002 and r = 0.330, p = 0.049, n = 36 for EPO and MBP, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Emergence of T-lymphocytes, eosinophils and dendritic cells in the bronchi of actively sensitized guinea pigs after antigenic challenge.

Bronchi from guinea pigs actively sensitized to ovalbumin and boosted two weeks later display increased numbers of CD4+ T-lymphocytes and eosinophils. We have further investigated immunopathological changes in sensitized guinea pigs 2 or 24 h after antigenic challenge with ovalbumin. Lungs were resected, frozen and cryostat sections stained with monoclonal antibodies that recognize relevant guinea pig epitopes. Cyanide-resistant peroxidase activity was used to stain eosinophils. No further increase in T-lymphocytes or eosinophils was observed 2 h after challenge. At 24 h, a marked increase in EPO+ eosinophils was found, and this was accompanied by severe mucosal damage characterized by epithelial shedding and ulceration. The numbers of T-lymphocytes remained stable but a novel population of cells with the appearance of dendritic cells was seen in the bronchial wall. They were negative for macrophage markers but were strongly Class II positive. These findings suggest that antigenic challenge results in further recruitment of eosinophils, their activation and release of toxic substances to the epithelium. Furthermore, other cell types, possibly dendritic cells, are attracted to the bronchi and could play a role in maintaining allergic inflammation via antigen presentation.

Animals↗
PubMed1993

Lung responsiveness to antigen in sensitised mice of different strains.

A new model of the isolated perfused lung from different strains of mice was developed. Lungs from Swiss, Balb/C and CBA mice actively sensitised to ovalbumin were challenged intratracheally (i.t.) by antigen on day 14. In Swiss mice instillation of ovalbumin led to the release of leukotriene (LT) C4 significantly above basal values. Conversely, lungs from Balb/C and CBA mice were unresponsive to ovalbumin in terms of production of LTC4. All strains failed to release histamine when challenged with antigen. Intratracheal instillation of platelet-activating factor (PAF), to lungs from non-sensitised animals, induced the release of comparable amounts of LTC4, irrespective of the strain. In contrast, i.t. administration of fMLP to lungs from Swiss mice elicited release of significantly higher amounts of LTC4 as compared to Balb/C and CBA mice. In separate experiments, ovalbumin was injected into the paws and anaphylactic oedema was evaluated. Balb/C and CBA required 1 microgram to show an oedema formation, whereas the dose of ovalbumin for Swiss mice to develop a similar response was at least 30-fold lower. In conclusion, antigen provocation induced release of LTC4 from lungs from Swiss mice but not from Balb/C or CBA. This difference may be accounted for by strain-dependent factors, such as antibody production and requires further investigation.

Animals↗
PubMed1993

Inhibition by nedocromil sodium of recombinant human interleukin-5-induced lung hyperresponsiveness to platelet-activating factor in actively sensitized guinea pigs.

BACKGROUND: The intratracheal instillation of recombinant human interleukin-5 (rhIL-5) into isolated lungs from sensitized and antigen-boosted guinea pigs is followed by enhanced responses to platelet-activating factor (PAF). METHODS: Modulation by nedocromil sodium of rhIL-5-dependent hyperresponsiveness to PAF was investigated. Perfused lungs from guinea pigs actively sensitized to ovalbumin were injected intratracheally with 300 ng rhIL-5 followed by PAF (10 and 100 ng intraarterially). RESULTS: No inhibition of rhIL-5-induced increased bronchoconstriction and release of thromboxane (TX)B2 and histamine by PAF was observed when nedocromil sodium (10 mumol/L) was perfused into the lungs. In contrast, when guinea pigs were treated for 2 days (30 mg/kg twice a day), eosinophil recruitment into the bronchoalveolar lavage fluid and hyperresponsiveness to PAF were markedly reduced (100% [p < 0.001]; around 70% [p < 0.05] and around 90% [p < 0.001] inhibition for bronchoconstriction, TXB2 and histamine release, respectively). CONCLUSION: Our results indicate that nedocromil sodium prevents the rhIL-5-induced lung hyperresponsiveness to PAF and the eosinophil migration into the airways only when it is administered in vivo. It is thus suggested that nedocromil sodium interferes with the development of airway inflammation by inhibiting the recruitment in the lung of a target on which PAF and IL-5 interact.

Animals↗
PubMed1993

Characterization and pharmacological modulation of antigen-induced peritonitis in actively sensitized mice.

1. The intraperitoneal (i.p.) injection of 1 or 10 micrograms ovalbumin to sensitized Balb/c mice led to an acute histamine release, firstly evidenced 1 min after the challenge and returning to basal levels 30 min thereafter. This phenomenon was unaccompanied by protein extravasation. A dose-dependent increase in the amounts of immunoreactive leukotriene (LT) C4 and LTB4 was observed in the peritoneal washing from sensitized mice 6 h after 1 or 10 micrograms ovalbumin administration. In separate experiments, the i.p. administration of 1 mg activated zymosan to non-immunized mice was followed by a marked protein extravasation, and by immunoreactive LTC4 and LTB4, but not histamine, release in mouse peritoneum 1 h after its injection. 2. Mediator release in the mice peritoneal cavity was concomitant with a transient neutrophil infiltration, which peaked at 6 h and returned to basal levels therefore. An intense eosinophil accumulation starting at 24 h, peaking at 48 h and returning to basal values at 164 h, was also observed. 3. Ovalbumin (1 microgram)-induced eosinophilia, observed at 24 h, was reduced by the pretreatment of the animals with dexamethasone (1 mg kg-1, s.c.) or with the 5-lipoxygenase inhibitor, BWA4C (20 mg kg-1, s.c.), whereas indomethacin (2 mg kg-1, s.c.) and the platelet-activating factor (PAF)-antagonist SR 27417 (10 mg kg-1, s.c.) were ineffective. These results indicate that metabolites of arachidonic acid of lipoxygenase pathway, but not cyclo-oxygenase derivatives or PAF, mediate antigen-induced eosinophil accumulation in the mouse peritoneum. 4. The histamine HI receptor antagonist drug, cetirizine (15-30 mg kg-1, s.c.) markedly reduced ovalbumin-induced eosinophil accumulation under conditions where terfenadine was ineffective, suggesting that the effect of cetirizine was not related to the inhibition of the H1 receptor effects of histamine.5. The immunosuppressive agent, FK-506 (1-2 mg kg-1, s.c.) and the protein synthesis inhibitor,cylcoheximide, when administered either in situ (0.06 ng/cavity) or systemically (5 mg kg-1, s.c.),prevented antigen-induced eosinophil accumulation in the mouse peritoneum, contributing to the concept that substances (probably cytokines) originating from lymphocytes may be involved in the modulation of the eosinophilotactic response in this model.6. The results of the present study indicate that the i.p. administration of ovalbumin to actively sensitized mice induced late eosinophil accumulation in the peritoneal cavity. This phenomenon, which may be in part mediated by the release of lipoxygenase metabolites and/or by newly generated factors,such as T-lymphocytes-derived eosinophilotactic cytokines, offers an interesting tool to investigate the mechanism of action of anti-allergic and anti-inflammatory drugs.

Animals↗
PubMed1993

Immunopathologic alterations in the bronchi of immunized guinea pigs.

Isolated lungs from guinea pigs actively sensitized to ovalbumin and boosted 2 wk later display an enhanced bronchoconstriction and release larger amounts of secondary mediators as compared with lungs from nonimmunized animals when stimulated by platelet-activating factor or other agonists. We have investigated changes in T lymphocytes and eosinophils found in the bronchial wall of immunized and nonimmunized guinea pigs. The animals received two injections of 10 micrograms ovalbumin in Al(OH)3, at a 2-wk interval. Two studies were performed: (1) the animals were killed 7 days after the booster injection of antigen, (2) they were challenged with ovalbumin at this same day and killed after 2 or 24 h. Lungs were resected and frozen, and cryostat sections stained using monoclonal antibodies that recognize T cells, T cell subsets, or other relevant epitopes. Cyanide-resistant peroxidase activity was used to identify eosinophils. A large number of T cells, mainly of the CD4+ subset, and eosinophils were recruited into the bronchi 7 days after the booster injection of the antigen, compared with nonimmunized or nonboosted animals. In antigen-challenged animals, the numbers of T cells did not change but eosinophils were further increased in number at the 24 h time point. Also at this time point, a population of cells with a dendritic appearance was seen in the bronchial wall, which did not express macrophage markers but was strongly class II positive. Class II positivity was also noted in the bronchial epithelium and on many cells infiltrating the mucosa. These findings suggest that activated T cells and/or their products play an important role in the bronchopulmonary immunopathology associated with this model and possibly with the development of bronchial hyperreactivity.

Animals↗
PubMed1993

Effect of active sensitization on the bronchopulmonary responses to tachykinins in the guinea pig. Modulation by peptidase inhibitors.

The i.v. administration of substance P (SP, 0.25-16 micrograms/kg) or of the selective metabolic stable NK-1 agonist, [Glp6,Pro9]SP-(6-11) (septide, 0.03-0.25 microgram) to atropine-treated guinea pigs or to isolated perfused lungs triggered a dose-dependent bronchoconstriction, which was enhanced in animals actively sensitized to ovalbumin. In vivo, bronchial hyper-responsiveness was restricted to SP and to septide, inasmuch as neurokinin A (0.06-1 microgram/kg)- or capsaicin (0.5-32 micrograms/kg)-induced bronchoconstriction were not modified. In contrast, isolated lungs from sensitized guinea pigs exhibited an increased bronchoconstriction also in response to capsaicin (0.01-10 micrograms), which was inhibited by atropine in the medium. Pretreatment of actively sensitized guinea pigs either with indomethacin plus mepyramine, the lipoxygenase inhibitor BW A4C or with the platelet-activating factor antagonist SR 27417, did not modify bronchial hyper-reactivity to SP. Captopril (5 mg/kg i.v.), but not thiorphan (0.8 mg/kg i.v.), increased the SP-induced bronchoconstriction in actively sensitized animals, whereas both inhibitors were equally effective in nonsensitized guinea pigs. Thiorphan, however, did not modify the in vivo response to septide. Our results demonstrate that guinea pigs sensitized to ovalbumin exhibit bronchial hyperreactivity to SP, but not to neurokinin A, as compared to nonsensitized animals, suggesting a decrease in the neutral endopeptidase activity in the airways brought by the immunization. However, the results obtained by using septide indicate that other mechanisms may be involved in the bronchial hyper-reactivity to SP.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Inhibition by azelastine of the effects of platelet-activating factor in lungs from actively sensitised guinea-pigs.

The effect of azelastine on platelet-activating factor (PAF)-induced bronchoconstriction and mediator release in isolated lungs from actively sensitised guinea-pigs was investigated. Guinea-pigs were actively sensitised with two s.c. injections of 10 micrograms ovalbumin in 1 mg Al (OH)3 at a 2-week interval. One week after the second injection, the lungs were removed and challenged intra-arterially with PAF or arachidonic acid. In some experiments lungs from non-immunised guinea-pigs were injected with PAF or histamine. Bronchoconstriction, the release of thromboxane (TX)B2 or leukotriene (LT)-like material and the histamine content of the effluent were evaluated. Azelastine was given s.c. at 10 or 100 micrograms/kg, 4 h before lung removal. Azelastine (100 micrograms/kg) did not inhibit PAF-induced bronchoconstriction and mediator release from lungs from non-immunised guinea-pigs. In contrast, the hyperresponsiveness to 1 ng PAF observed in lungs from actively sensitised animals was dose dependently inhibited by azelastine. Azelastine did not reduce the histamine-induced bronchoconstriction and consequent TXB2 release from lungs from immunised guinea-pigs, indicating that the protective effect exerted against hyperresponsiveness to PAF was not due to histamine antagonism. Azelastine also reduced arachidonic acid-induced bronchoconstriction and LT-like material release from sensitised lungs, regardless of the presence of indomethacin. These results suggest that inhibition of lung hyperresponsiveness to PAF by azelastine may result from an interference with leukotriene synthesis.

Animals↗
PubMed1992

Effect of human recombinant interleukin-5 on in vitro responsiveness to PAF of lung from actively sensitized guinea-pigs.

1. The intra-tracheal (i.t.) administration of human recombinant interleukin-5 (rhIL-5; 100 or 300 ng) to isolated perfused lungs from guinea-pigs actively sensitized to ovalbumin induced an increased bronchoconstriction and release of thromboxane A2 (TXA2) and histamine into the lung effluent following the subsequent (10 min) intra-arterial injection of platelet-activating factor (PAF). Lung responses to 5-hydroxytryptamine were unaffected by rhIL-5. 2. Hyperresponsiveness to PAF was observed when the lungs were obtained from guinea-pigs used 2 or 7 days after a booster injection of the antigen and, to a lower extent, when they were from animals sensitized by a single antigen administration. By contrast, rhIL-5 did not modify the responses to PAF of lungs from passively sensitized or from adjuvant-treated guinea-pigs, suggesting that immunological stimulation is required to allow the expression of synergism between rhIL-5 and PAF. 3. Guinea-pigs killed 2 and 7 days after the booster injection of the antigen exhibited a marked increase in the number of eosinophils in the bronchoalveolar lavage fluid (BAL), as compared to non-sensitized animals. 4. Our results demonstrate that rhIL-5 and PAF act synergistically to induce enhanced bronchoconstriction and mediator release exclusively when lungs are obtained from guinea-pigs sensitized once to ovalbumin and then boosted. Since recruitment of eosinophils into the airways and the development of hyperresponsiveness to PAF are concomitant, it is suggested that eosinophils are the target cells for interaction between rhIL-5 and PAF.

Animals↗
PubMed1991

[The inhibitory effect of magnesium on mitochondrial calcium uptake in ischemic and reperfused rat hearts].

Several studies suggest that the protection exerted by Mg2+ on the reperfused myocardium may be mostly due to its competitive effect with respect to Ca2+. The aim of this research was to evaluate the inhibitory action of Mg2+ on mitochondrial Ca2+ uptake in the reperfused myocardium. Hearts of male Wistar rats (250-300 g) were isolated and perfused by the Langendorff technique. Aerobic control hearts (n = 6) were perfused with a constant flow of 10 ml/min/g for 65 min. In a second group (n = 6) the hearts were aerobically equilibrated for 20 min, then subjected to 30 min of ischemia (98% reduction of coronary flow) and subsequently reperfused for 15 min at the same preischemic flow. The hearts of both groups were electrically stimulated at 300 b/min. Then, the hearts were pooled in groups of 2 each and homogenized for the isolation of mitochondria. One part of mitochondrial suspension was used to evaluate the respiratory function by a polarographic technique. The remaining part was incubated with fura-2/AM for 10 min at 30 degrees C in order to determine the kinetics of Ca2+ transport within mitochondria in the presence of succinate as substrate. Ca2+ uptake was reduced in the mitochondria of reperfused hearts with respect to control, particularly in the presence of elevated extramitochondrial Ca2+ concentrations (greater than 10 nM). On the contrary the initial rate of Ca2+ uptake was increased in the reperfused mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[The blood rheological and microcirculatory changes in the hypertensive patient].

The authors examined the microcirculatory system alterations which are present in case of arterial hypertension. These alterations consist of an increase in capillary peripheral resistances and in total blood viscosity, of a reduction in red cell deformability and of a vasomotion alteration. The authors evaluated the opportunities of a therapeutic intervention with hypotensive treatments also affecting the microcirculatory system in hypertensive patients with or without associated diabetes mellitus.

Blood Viscosity↗
PubMed1990

An alternative point of view on experimental lung hyperreactivity.

The booster injection of antigen to pre-sensitized guinea-pigs induces lung modifications leading to hyperresponsiveness and to shifts in the profile of the effective drugs. The introduction of the concept of lung inflammation offers new targets for drug discovery.

Animals↗
PubMed1990

Antigen induces leucopenia in non-immunised guinea-pigs injected with platelets from actively sensitized animals.

1. Ovalbumin administration to animals injected with 0.5-5 x 10(6) washed platelets microliter-1 from actively sensitized animals induced a marked decrease (maximum of around 50% at 60 min) in the number of circulating leucocytes, whereas platelet counts were unaffected. The intensity of the decrease in leucocyte counts was dependent upon the concentration of the injected platelets. 2. No drop in leucocyte counts was measured upon antigen challenge of guinea-pigs injected with platelets from non-sensitized animals. 3. This phenomenon was unaffected by pretreatment of the recipient animals with a platelet-activating factor (PAF) antagonist WEB 2086 (3 mg kg-1 i.v.) but was markedly reduced (around 50% inhibition) by the anti-allergic drug nedocromil sodium (100 mg kg-1 i.v.). By contrast, indomethacin (5 mg kg-1 i.v.) caused a significant (P less than 0.01) enhancement of the antigen-induced leucopenia, whereas the mixed cyclooxygenase and lipoxygenase inhibitor, BW 755C (10 mg kg-1 i.v.) suppressed the drop in leucocyte counts evoked by ovalbumin administration. 4. These results indicate that platelets from actively sensitized guinea-pigs transferred to normal animals still responds to the specific antigen with the activation of circulating leucocytes. This phenomenon appears to be independent of the production of PAF and of cyclo-oxygenase metabolites. By contrast, the production of the metabolites of the lipoxygenase pathway by platelets could account for the marked leucopenia observed following the immunological stimulation.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1990

Protection by nedocromil sodium of active immunization-induced bronchopulmonary alterations in the guinea pig.

The effect of nedocromil sodium on PAF-acether- and antigen-induced bronchoconstriction (BC) and mediator release in lungs from actively sensitized guinea pigs and on the eosinophil content of bronchoalveolar lavage (BAL) was investigated. Guinea pigs were actively sensitized by two subcutaneous injections of 10 micrograms ovalbumin in 1 mg AI(OH)3 at 2-wk intervals. One week after the second (booster) injection, the lungs were removed, perfused in the absence or presence of indomethacin, and challenged at 10-min intervals with PAF-acether (1 and 100 ng) and with ovalbumin (1 micrograms). No inhibition of PAF-acether- and antigen-induced BC or mediator release from sensitized lungs was observed when nedocromil sodium (10 microM) was added directly to the buffer solution. By contrast, when guinea pigs were treated for 1 wk before the experiment with nedocromil sodium (30 mg/kg per day), BC and the release of leukotrienelike material (but not of thromboxane B2) to 1 ng PAF-acether were reduced by around 50% (p less than 0.05) and 62% (p less than 0.05), respectively. No inhibition was observed for 100 ng PAF-acether and 1 micrograms ovalbumin. Furthermore, nedocromil sodium markedly impaired histamine secretion induced by both PAF-acether and antigen administration. Nedocromil sodium did not affect the titers of circulating ovalbumin-specific immunoglobulin G, as detected by an enzyme-linked immunosorbent assay. The 1-wk treatment with nedocromil sodium also reduced markedly the proportion of eosinophils in the BAL of sensitized guinea pigs, whereas it was ineffective when injected once subcutaneously at the dose of 30 mg/kg 2 h before the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗