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Biomedical subjects

P Conti

Publications and source records attributed to P Conti.

At least 37 records · Page 2Linked to original sources
PubMed2001

Elevated circulating levels of monocyte chemoattractant protein-1 in patients with restenosis after coronary angioplasty.

Inflammation plays a pathogenic role in the development of restenosis after percutaneous transluminal coronary angioplasty (PTCA). Monocyte chemoattractant protein-1 (MCP-1) is a potent chemoattractant of monocytes; however, its role in the pathophysiology of restenosis is still unclear. We set out to investigate the role of MCP-1 in restenosis after PTCA. In addition, we tested the hypothesis that MCP-1 exerts its effect, at least in part, by inducing O(2)(-) generation in circulating monocytes. Plasma levels of MCP-1 were measured before and 1, 5, 15, and 180 days after PTCA in 50 patients (30 males and 20 females, aged 62+/-5 years) who underwent PTCA and who had repeated angiograms at 6-month follow-up. Restenosis occurred in 14 (28%) patients. The MCP-1 level was no different at baseline between patients with or without restenosis. However, after the procedure, restenotic patients, compared with nonrestenotic patients, had statistically significant (P<0.0001) elevated levels of MCP-1. In contrast, plasma levels of other chemokines, such as RANTES and interleukin-8, did not differ between the 2 groups after PTCA. Higher MCP-1 throughout the study was correlated with restenosis. Moreover, increased MCP-1 was significantly correlated with increased monocyte activity, as reflected by enhanced O(2)(-) generation. Finally, multivariate regression analysis showed that the MCP-1 plasma level measured 15 days after PTCA was the only statistically significant independent predictor of restenosis (beta=0.688, P<0.0001). This study suggests that MCP-1 production and macrophage accumulation in the balloon-injured vessel may play a pivotal role in restenosis after PTCA. MCP-1 may induce luminal renarrowing, at least in part, by inducing O(2)(-) release in monocytes. Further understanding of the mechanism(s) by which MCP-1 is produced and acts after arterial injury may provide insight into therapies to limit the progression of atherosclerosis and restenosis after balloon angioplasty.

Aged↗
PubMed2001

Expression and secretion of RANTES by human peripheral blood CD4+ cells are dependent on the presence of monocytes.

The cDNA for RANTES (an acronym for "Regulated upon Activation, Normal T cell Expressed and Secreted") was initially discovered by subtractive hybridization as a T cell-specific sequence. Consistent with it being a C-C (beta) chemokine, RANTES is a monocyte chemoattractant. In addition, RANTES can chemoattract unstimulated CD4+/CD45RO+ memory T cells and stimulated CD4+ and CD8+ T cells with the naive and memory phenotypes in immunologically active sites. It has been shown that CD8+ cells are dominant sources of RANTES. Here we attempted to determine if CD4+ cells express and secrete RANTES alone, or if other accessory cells (activated monocytes) are needed to activate them. We found that when autologous monocytes are added to CD4+ cells and then stimulated with phytohaemagglutinin (PHA), the quantity of RANTES, in terms of transcription and translation of the protein, is significantly higher than the amount produced by the PHA-activated monocytes alone; isolated CD4+ cells stimulated with PHA do not produce any appreciable quantity of RANTES. When CD4+ cells are primed overnight with monocytes and then stimulated with PHA, they produce more RANTES compared to PHA-stimulated CD4+ cells alone. The influence that monocytes have on CD4+ cells to produce RANTES was confirmed when the physiological activator, tumor necrosis factor-alpha (TNF-alpha), was used. These data show that CD4+ cells need monocytes to express and secrete appreciable amounts of RANTES.

Blotting, Northern↗
PubMed2001

Endothelial nitric oxide synthase (eNOS) expression and localization in healthy and diabetic rat hearts.

Several studies suggest that nitric oxide (NO) production is reduced in diabetes and that the decrease of NO may be related to the pathogenesis of diabetic endothelial damage. NO synthase (NOS) catalyses the conversion of L-arginine to L-citrulline in the presence of oxygen and NADPH-diaphorase (NADPH-d). In this study, we evaluated the expression of endothelial NOS (eNOS) enzyme and its co-enzyme in diabetic rat hearts. Male Wistar rats (n = 20, 4 mo old) and 20 male Bio Breeding Wistar (BB/W) rats of the same age were used; the Wistar rats represent the control non-diabetic rats while the BB/W rats represent the diabetic group. After the hearts were excised, the NADPH-d co-enzyme was visualized by a histochemical method and the endothelial isoform of NOS was localized by immunohistochemistry. In addition, eNOS gene expression was estimated by rt-PCR, and eNOS protein level was detected by Western blot analysis. The eNOS visualization, which involved immunoprecipitation, and the NADPH-d visualization, which involved histochemical staining, were both diminished in endothelial cells of the vascular wall of diabetic hearts, compared to non-diabetic hearts. The eNOS protein level, evaluated by Western blotting, was evident as an intense band in cardiac homogenates of non-diabetic and diabetic rats. The expression of mRNA for eNOS did not differ significantly between the two groups. These findings indicate that, in this rat heart model, diabetes does not influence the overall eNOS protein level or its mRNA level. However, there a diminution in the deposition of eNOS in cardiac endothelial cells of diabetic rats, versus non-diabetic controls, suggesting a relation between eNOS and the loss of vasodilatory response that is observed in diabetes.

Animals↗
PubMed2001

MCP-1 and MIP-2 levels during Echinococcus granulosus infections in mice.

Ten BALB/c mice were infected with the cestode Echinococcus granulosus. After the infection, serum was collected at different periods of time and monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) were determined. The level of MCP-1 increased from at day 20 post infection (p.i.), to a maximum of on day 60 p.i., then decreased to on day 130 p.i. A second peak was observed at day 150 p.i. In addition, MIP-2 was detectable in serum as late as day 100 p.i. The highest level was observed on day 130 p.i., and decreased thereafter. Serum from noninfected animals (controls) contained no detectable levels of either MCP-1 or MIP-2. However, MCP-1 and MIP-2 appear to be implicated in E. granulosus infections, but their exact role during the disease is under determination.

Animals↗
PubMed2000

Endothelial NOS expression and ischemia-reperfusion in isolated working rat heart from hypoxic and hyperoxic conditions.

Induction of endothelial nitric oxide synthase (eNOS) contributes to the mechanism of heart protection against ischemia-reperfusion damage. We analyzed the effects of hypoxia and hyperoxia on eNOS expression in isolated working rat hearts after ischemia-reperfusion damage. Adult male Wistar rats were submitted to chronic hypoxia (2 weeks) and hyperoxia (72 h). The hearts were submitted to 15 min of ischemia and reperfused for 60 min, then we evaluated hemodynamic parameters and creatine phosphokinase (CPK) release. eNOS expression was estimated by RT-PCR; enzyme localization was evaluated by immunohistochemistry and the eNOS protein levels were detected by Western blot. All hemodynamic parameters in hypoxic conditions were better with respect to other groups. The CPK release was lower in hypoxic (P<0.01) than in normoxic and hyperoxic conditions. The eNOS deposition was significantly higher in the hypoxic group versus the normoxic or hyperoxic groups. The eNOS protein and mRNA levels were increased by hypoxia versus both other groups. Chronic hypoxic exposure may decrease injury and increase eNOS protein and mRNA levels in heart subjected to ischemia-reperfusion.

Animals↗
PubMed2000

Localization of the e-NOS enzyme in endothelial cells and odontoblasts of healthy human dental pulp.

Nitric oxide synthases (NOS) are important enzymes present in different cells such as endothelial cells, macrophages, etc. Recently, it has been found that nitric oxide (NO) is responsible for vasodilation, blood pressure regulation, platelet aggregation, cardiac contractility, and the mediation of immunity during bacterial infections and inflammation. However, the production and role of NO in various structures of the oral cavity have not been investigated extensively. The aim of this study was to evaluate the presence of e-NOS in healthy human odontoblasts and endothelial cells of the dental pulp. Twenty healthy human dental pulps were collected and frozen and pulp slices were obtained using a cryostat. The e-NOS enzyme was revealed by immunohistochemical analysis and the enzyme level was detected by Western blotting and mRNA expression by RT-PCR. The immunohistochemical results demonstrated, for the first time, the presence of e-NOS in odontoblasts and in endothelial cells. The presence of e-NOS m-RNA was confirmed by RT-PCR and the expression of the protein by Western blotting. These results clearly show that the e-NOS enzyme is present in both odontoblasts and endothelial cells of healthy human pulp. The presence of e-NOS in the odontoblast and endothelial cells of the dental pulp may mediate local vasodilation and cell proliferation.

Blotting, Western↗
PubMed2000

RANTES production and expression is reduced in relapsing-remitting multiple sclerosis patients treated with interferon-beta-1b.

RANTES (regulated upon activation, normal T-cell expressed and secreted), a CC chemokine, appears to play a role in the pathogenesis of relapsing-remitting multiple sclerosis (RR-MS), enhancing the inflammatory response within the nervous system. We have demonstrated that RANTES production is increased in RR-MS compared to controls. Interferon-beta-1b (IFN-beta-1b) treatment reduces RANTES production in sera and peripheral blood adherent mononuclear cell (PBAM) supernatants both in relapse and remission. IFN-beta-1b also reduces RANTES expression in PBAM. Our results suggest that RANTES modulation might represent one of the mechanisms of action of IFN-beta-1b in RR-MS.

Adjuvants, Immunologic↗
PubMed2000

In situ X-ray absorption spectroelectrochemical study of hydroxocobalamin.

An in situ X-ray absorption spectroscopy (XAS) spectroelectrochemical study of aquocobalamin (system B12a-B12r-B12s) has been carried out in aqueous solutions buffered at different pH values. To the best of our knowledge, this is the first structural study of aquocobalamin at room temperature under controlled oxidation conditions. Most of the previous work was in fact performed using frozen samples chemically treated to produce the species. The spectroelectrochemical approach offers several advantages: (1) the reduction products may be studied without poisoning the system with chemical reductive reagents and (2) any possible variation of the oxidation state owing to the electrons produced by the incident beam is avoided as the electrode, under potentiostatic control, acts as a scavenger. The spectroelectrochemical approach, together with more careful data analysis, has led to an improved interpretation of the XAS data. These conditions were not met in previous works where the oxidation state was not controlled and multiple scattering contributions were not taken into account. The general shape of the XAS spectra of the different species is not greatly affected by pH. A signature for the base-off square-planar coordination has been evidenced for the Co(II) compound at basic pH. A new signature for Co(I), indicating square-planar coordination, has been identified on the experimental spectra and simulated in theoretical X-ray absorption near-edge structure (XANES) studies. The flexibility of the electrochemical approach, that permits to unambiguously establish the formal oxidation state, has led to very reliable values for energy shift and peak intensity variations. The experimental XANES and extended X-ray absorption fine structure (EXAFS) spectra with a very good signal-to-noise ratio have been processed using the GNXAS package that takes into account multiple scattering contributions. EXAFS and XANES independent analysis result in the same structural model. The reduction from Co(III) to Co(II) produces the most significant structural changes: the cobalt coordination number decreases from six to five, and the edge position shifts by 2.4 +/- 0.3 eV. In addition, the XANES spectra are strongly modified. The reduction from Co(II) to Co(I) produces mainly electronic effects with no apparent change of the coordination number. A discussion of the limits and potentialities of EXAFS in this type of study has also been included.

Absorptiometry, Photon↗
PubMed2000

Design of new analogues of glutamic acid with a conformationally restricted structure.

Regioisomeric 3-carboxyisoxazolinyl prolines (CIP-A and CIP-B) and 3-hydroxyisoxazolinyl prolines [(+/-)-8 and (+/-)-9] were synthesized and assayed for glutamate receptor activity. CIP-A [(+/-)-6] showed a convulsant activity evaluated in vivo on DBA/2 mice, higher than AMPA and similar to kainic acid. The eutomer of CIP-A [CIP-AS, (-)-6], obtained from (S)-3,4-didehydroproline, evidenced common stereochemical requirements with AMPA and kainic acid.

Animals↗
PubMed2000

Lymphocyte subpopulations, cytokines and trace elements in asymptomatic atopic women exposed to an urban environment.

This study evaluates the immune response to exposure to an urban environment from 30 non-atopic and 30 non-symptomatic women with history of respiratory and/or cutaneous allergies. Blood lymphocyte subsets and serum interleukin (IL) 4 and interferon gamma (INF-gamma) of the two groups were similar, while serum IgE and "in vitro" production of IL-4 and INF-gamma by mononuclear blood cells of the atopic women were higher spontaneously or in the presence of PHA, respectively. Blood lead of the nonatopic women (mean 55 microg/l) was positively correlated with CD4+-CD45RO-, CD3+-CD8+ and CD3--HLA-DR+ lymphocyte subsets, while urinary trans-trans muconic acid (a metabolite of benzene) of both groups of women (mean about 50 microg/l) was significantly correlated with NK CD16+CD56+ lymphocytes. Urine chromium of the non-atopic subjects was significantly correlated with activated T, B and NK HLA-DR+ cells. Urine nickel of both groups of women was correlated with CD4+-CD45RO+ "memory" lymphocytes and their ratio with CD4+-CD45RO- "virgin" lymphocytes suggesting that the metal enhances maturation of "virgin" into "memory" lymphocytes. On the whole, this study demonstrates that exposure to low levels of toxic agents, produced by vehicular traffic in an urban environment, exerts effects on immune functions of women.

Adult↗
PubMed2000

Increase in CD45RO+ cells and activated eosinophils in chronic allergic conjunctivitis.

We assessed the infiltration of CD45RO+ cells in conjunctival biopsies of fifteen subjects affected by seasonal allergic conjunctivitis by means of immunohistochemistry. Correlations between infiltration of CD45RO+ cells and serum and mucosal indices of eosinophilic activation were investigated. The study was performed in autumn and all selected patients showed < > also in absence of sensitising pollens. Fifteen healthy subjects were used as controls. The semi-quantitative count of CD45RO+ cells in biopsy specimens demonstrated that positive cells were higher in allergic patients than in controls (p < 0.001) and EG2+ eosinophils were present only in biopsies of allergic patients. Furthermore, a statistically significant positive correlation (r = 0.73; p < 0.001) between CD45RO+ lymphocytes and EG2 positive eosinophils, was observed in the biopsies of allergic patients. Total serum IgE significantly correlated with CD45RO+ cells (r = 0.61; p < 0.02) and EG2+ eosinophils (r = 0.67; p < 0.01) in the conjunctiva. On the other hand serum ECP did not correlate with any histological and immunohistochemical parameters in the conjunctival biopsies. The present study shows that mild symptoms in SCA patients out of pollen season are associated with inflammation of the conjunctiva as shown by an increased number of CD45RO and EG2 positive cells.

Adolescent↗
PubMed2000

Lymphocyte subset changes in blood and gastrointestinal mucosa after oral nickel challenge in nickel-sensitized women.

This study investigates lymphocyte subsets in both the gastrointestinal mucosa and blood, in patients with nickel allergic contact dermatitis, after 10 mg oral nickel challenge (double-blind, placebo-controlled). 6 such patients with cutaneous symptoms induced only by skin contact with nickel (group A), 6 with a flare-up of cutaneous symptoms after food nickel ingestion (group B) and 6 healthy controls (group C) were enrolled. Blood lymphocyte subsets (CD4, CD45RO, CD8) were analyzed before and after 4 and 24 h from the challenge (test 1, 2, and 3), and intestinal biopsies were performed 2 days later. Challenges were positive in group B and negative in group A and controls. Serum and urine nickel levels significantly increased after nickel ingestion, with no differences between the 3 groups. At test 3, a significant decrease of the all CDs studied was found in group B. Biopsies of this group showed higher levels of CD45RO+ cells in the lamina propria and in the epithelium and lower levels of epithelial CD8+ lymphocytes. This study confirms that ingested nickel may induce flare-up of cutaneous reactions in some nickel-allergic patients, independently of the degree of sensitization and the intake of metal. In these patients, oral nickel stimulates the immune system, inducing maturation of T lymphocytes from virgin into memory cells; these latter cells seem to accumulate in the intestinal mucosa. The immunoreaction also involves CD8+ cells, whose role is not yet clear.

Administration, Oral↗
PubMed1999

Synthesis and enantiopharmacology of new AMPA-kainate receptor agonists.

Regioisomeric 3-carboxyisoxazolinyl prolines [CIP-A (+/-)-6 and CIP-B (+/-)-7] and 3-hydroxyisoxazolinyl prolines [(+/-)-8 and (+/-)-9] were synthesized and assayed for glutamate receptor activity. The tests were carried out in vitro by means of receptor binding techniques, second messenger assays, and the rat cortical wedge preparation. CIP-A showed a good affinity for both 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) and kainic acid (KAIN) receptors. These results were confirmed in the cortical slice model where CIP-A displayed an EC(50) value very close to that of AMPA. The convulsant properties of all the compounds were evaluated in vivo on DBA/2 mice after icv injection. CIP-A showed a convulsant activity, measured as tonus and clonus seizures, 18-65 times higher than that produced by AMPA. It was also quite active after ip administration, since it induced seizures in mice at doses as low as 3.2 nmol/mouse. On the basis of the above-reported results we prepared and tested the enantiomers of CIP-A and CIP-B, obtained by reacting (S)-3,4-didehydroproline and (R)-3,4-didehydroproline, respectively, with ethoxycarbonylformonitrile oxide. In all the tests the S-form, CIP-AS [(-)-6], emerged as the eutomer evidencing common stereochemical requirements with the reference compounds AMPA and KAIN. Through modeling studies, carried out on CIP-A, AMPA, and KAIN, active conformations for CIP-AS and AMPA at AMPA receptors as well as for CIP-AS and KAIN at KAIN receptors are suggested.

Animals↗
PubMed1999

Monocyte chemotactic protein-1 gene expression and translation in formed granulomatous calcified tissue in vivo.

Monocyte chemotactic protein-1 (MCP-1) and related molecules constitute the C-C class of the beta chemokine supergene family with inflammatory properties. However, the exact role, function, and implication in inflammatory diseases remain to be determined. Here we report that subcutaneous injections (0.2 ml) of a saturated water solution (1:40) of potassium permanganate crystals induces the generation of granuloma tissue at the site of injection in the rat, and reaches its peak of formation after 1 week. The size and weight of the granulomas were increased by i.p. lipopolysaccharide (LPS) (6 microgram/200 microliter) and inhibited by intraperitoneal (i.p.) dexamethasone (Dxs) 300 microgram/200 microliter) treatments in rats, injected 18 hours before sacrifice. Moreover, steady-state levels of MCP-1 mRNA in the granuloma tissue (control), were strongly generated. Rats treated i.p. with LPS produced an increase of MCP-1 mRNA in the granuloma tissue compared with controls (i.p. PBS-treated) whereas in animals treated with Dxs, there was a decrease in (P < 0.05) in formation of mRNA protein. When the granuloma tissues were homogenized the generation of MCP-1 was found in the supernatants. The level of MCP-1 was higher (P < 0.05) in the LPS-treated animals and lower (P < 0.05) in the Dxs group compared with the controls (treated with PBS). Similar results were obtained in the serum and in minced granuloma tissue where samples were further incubated in vitro with LPS (100 ng/ml) overnight. A Strong increase (P < 0.01) in MCP-1 in all samples was detected, but not in the minced granuloma tissue from Dxs-treated animals. Our data demonstrate that calcified tissue from chronic inflammation induced by KMnO4 generates MCP-1 gene expression and translation, an effect increased by LPS and decreased by Dxs.

Animals↗
PubMed1999

Expression of lymphocyte subpopulations, cytokine serum levels, and blood and urinary trace elements in asymptomatic atopic men exposed to an urban environment.

The objective of this study was to analyze the role of some trace metals in the immune system of nonallergic or atopic men. One of these elements (Zn) is essential for immune function, whereas others, present in the urban environment, are known to be allergenic (Ni and Cr) or toxic (Pb). Serum levels of interleukin (IL) 2, 4, 5, and 13 and of interferon-y and immunoglobulins, blood lymphocyte subsets, blood concentrations of Pb and Zn, serum levels of Zn, and urinary Cr and Ni concentrations were determined in 17 nonallergic men (mean age 34 years) and 17 healthy nonsymptomatic atopic men living in urban areas. The mean blood concentration of Pb (a marker of exposure to toxic agents) was 11 microg/dl in both groups, which showed similar levels of blood Zn and of urinary Ni and Cr, whereas the serum Zn concentration was lower in the atopic group. Serum IgE levels were much higher in atopic men than in nonallergics, whereas serum IL-2, IL-5, and IL-13 concentrations were lower, possibly due to binding to tissue receptors and cells. Moreover, in atopic subjects, numbers of blood CD4+-CD45RO-"virgin" lymphocytes were significantly lower and the CD4+ -CD45RO+/CD4+ -CD45RO- ratio was more elevated, indicating an activation of the immune system. Serum IgE levels of atopic men, in contrast to those of nonallergic subjects, were correlated with CD19+ and CD5--CD19+ B lymphocytes. Blood Pb levels of both groups of men were correlated with CD4+, CD4+-CD45RO+, and HLA-DR+ [activated T-, B-, CO4+ -C. and natural killer (NK) cells] lymphocytes; in particular, blood Pb levels of the nonallergic men were also significantly correlated with CD25+ cells activated by IL-2, whereas those of the atopic men were also correlated with CD3--HLA-DR+ (B- and NK-cells) and CD5--CD19+ lymphocytes. Besides serum Zn levels, urinary Ni and Cr of nonallergic men were correlated with several immune parameters; in particular, urinary Cr was correlated with serum IL-5 and IgE and urinary Ni was correlated with CD4+ -CD45RO+ and CD3+ -CD25+ lymphocytes. This correlation of Ni and Cr, also found in previous studies in nonallergic subjects, confirms the hypothesis that these metals are involved in mechanisms of immune response regulation and that allergy to Ni or Cr represents an alteration of physiological mechanisms. Previous experimental studies have demonstrated that Pb exerts immunomodulatory effects on CD4+ and B- lymphocytes, enhancing the production of Th2-like cytokines and IgE. These experimental results confirm those of this study, showing in atopic men the correlation of B-lymphocytes with both blood Pb and serum IgE levels. This suggests that Pb may enhance the incidence of atopy in populations exposed to an urban environment.

Case-Control Studies↗
PubMed1999

Systemic effects of ingested nickel on the immune system of nickel sensitised women.

This study evaluates the immune response to ingestion of 10 mg of nickel (Ni) (as Ni sulphate) in 19 young non-atopic Ni-sensitised or 9 non-allergic women (group A). After Ni ingestion at 8 a.m, non-allergic and 12 Ni-sensitised women (group B) were non-symptomatic, while 7 Ni-sensitised women (group C) showed a flare up of urticaria and/or eczema. Serum and urine Ni were greatly lower before Ni administration than after 4 and 24 hours, without difference among the 3 groups. Before treatment, group B and C showed higher values of blood CD19+ and CD5--CD19+ cells than group A, while group C showed higher serum interleukin (IL) 2 and lower serum IL-5. Four hours after Ni ingestion, group C showed significant increase in serum IL-5. Twenty-four hours after treatment, group A showed a significant reduction in blood CD4+-CD45RO- "virgin" cells and an increase of CD8+ lymphocytes, while group C showed a marked decrease in total blood lymphocytes and CD3+, CD4+-CD45RO-, CD4+-CD45RO+, CD8+, CD19+ and CD5--CD19+ cell subsets. These data may be explained with migration of lymphocytes in tissues with a Th0-like immune response, as shown by the elevated serum IL-2 and the increase of serum IL-5 during the test.

Adolescent↗