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Biomedical subjects

C Fiorentini

Publications and source records attributed to C Fiorentini.

At least 19 recordsLinked to original sources
PubMed2006

A multinucleating Escherichia coli cytotoxin perturbs cell cycle in cultured epithelial cells.

Pathogenic Escherichia coli strains produce a number of virulence-associated factors, among which cytotoxic necrotizing factor 1 (CNF1). CNF1 is a chromosomally encoded toxin that permanently activates the small GTP-binding proteins of the Rho family (Rho, Rac and Cdc42) by catalizing their deamidation at a specific glutamine residue. This activation modulates a high number of cellular functions, including the reorganization of the actin cytoskeleton, the promotion of cell spreading and the multinucleation. Indeed, accumulating evidence indicates that, in addition to the well-characterized Ras GTPases, also Rho family proteins are crucial in different points of cell cycle regulation. Here, we report that CNF1 induces a block of the cell cycle at the G(2)/M transition in epithelial cell line HEp-2, and up-regulates cyclin B1 and p53 proteins confining them in the cytoplasm region. The ability of CNF1 to perturb cell cycle progression could play a role in E. coli pathogenicity.

Bacterial Toxins↗
PubMed2006

Potential of ultrasonography for epidemiological study of work-related wrist tenosynovitis.

OBJECTIVE: To explore the possible role of ultrasonography in case definitions for epidemiological studies of work-related wrist tenosynovitis. METHODS: Clinical and ultrasonography (7.5 MHz linear probe) data systematically collected from meat workers (n = 128) with biomechanical exposure characterisation were analysed. The diagnostic accuracy of different combinations of potentially relevant ultrasonography findings (nonhomogeneity, thickening and anechoic halo) was evaluated using symptomatology as a reference standard. The concordance between ultrasonography findings and symptoms was then analysed. RESULTS: Analysis of wrist biomechanical exposure was suggestive of increased prevalence of musculoskeletal disorders. Using symptoms as a reference standard, each of the three ultrasonography findings (and their combinations) showed good specificity (> or =85%) accompanied by low sensitivity (<60%); the positive likelihood ratio for at least two findings was 4.1. kappa Values (95% confidence intervals) between symptoms and different sets of ultrasonography findings were as follows: for non-homogeneity, kappa = 0.31 (0.19 to 0.43); at least one finding, kappa = 0.28 (0.16 to 0.40); at least two findings, kappa = 0.32 (0.20 to 0.44); all p<0.01. CONCLUSION: The use of ultrasonography in symptomatic subjects could contribute to a more specific epidemiological case definition of wrist tenosynovitis. The results of this study could help orient future research in this direction.

Adult↗
PubMed2006

Multinucleation and pro-inflammatory cytokine release promoted by fibrous fluoro-edenite in lung epithelial A549 cells.

An unusual cluster of malignant mesothelioma was evidenced in Biancavilla, a Sicily village where no inhabitant had been significantly and professionally exposed to asbestos. Mineralogical and environmental studies led to the identification of a new prismatic amphibole, named fluoro-edenite. We previously reported, by using the human lung epithelial A549 cells, that prismatic fluoro-edenite was unable to induce changes that could be somehow related to cellular transformation, and this was in accordance with studies carried out in vivo. More recently, a fibrous amphibole with a composition very similar to that of prismatic fluoro-edenite, was identified in Biancavilla. This fibrous fluoro-edenite was shown to induce mesothelioma in rats. In keeping with this effect in vivo, in the present work we observed multinucleation and spreading, common features of transformed cells, as well as pro-inflammatory cytokine release in A549 cells. Such cell changes occurred without interfering with the passage of the resulting multinucleated cells through the cell cycle and without condemning cells to death. Hence, in lung epithelial cells, fibrous fluoro-edenite behaved similarly to the unrelated asbestos type crocidolite, whose connection with severe inflammation and cancer of the lung is renowned.

Asbestos, Amphibole↗
PubMed2005

Prevalence and incidence of antibodies to Borrelia burgdorferi and to tick-borne encephalitis virus in agricultural and forestry workers from Tuscany, Italy.

The ticks Ixodes persulcatus and Ixodes ricinus are the main vectors of both Borrelia burgdorferi sensu lato and tick-borne encephalitis (TBE) virus in Eurasia. Borrelia burgdorferi is the cause of Lyme borreliosis, and TBE is a biphasic meningoencephalitis induced by an arbovirus belonging to the flavivirus family. The principal aims of the current investigation were (i) to determine the frequency of serological evidence of Borrelia burgdorferi sensu lato and TBE infections in healthy agricultural and forestry workers, (ii) to determine the incidence of seroconversion for antibodies against Borrelia burgdorferi sensu lato and TBE virus in Tuscan workers during a 1-year survey; and (iii) to assess the occupational risk for agricultural and forestry activities in a defined area (Tuscany, Italy). A total of 412 blood samples were taken from agricultural and forestry workers, and information on age, duration of employment, and history of tick bites was collected in a questionnaire to establish the risk factors for the diseases. Three hundred sixty-five blood donors from the same region served as controls. To estimate the rate of seroconversion, 176 of the agricultural and forestry workers were tested 1 year later. IgG and IgM antibodies against Borrelia burgdorferi sensu lato and TBE virus were detected in serum by an enzyme-linked immunosorbent assay and confirmed by Western blot analysis for Borrelia burgdorferi and by a test for inhibition of hemagglutination for TBE. Antibodies against Borrelia burgdorferi were more frequent among the workers than in the control group (7.8% vs. 4.9% in the IgG-IgM enzyme-linked immunosorbent assay and 7.03% vs. 3.56% in the confirmatory test). No seropositivity was observed for TBE virus. Eighteen of 176 subjects who underwent a second blood test developed specific antibodies against Borrelia burgdorferi within 1 year.

Adult↗
PubMed2005

Cytotoxic necrotizing factor 1 hinders skeletal muscle differentiation in vitro by perturbing the activation/deactivation balance of Rho GTPases.

The current knowledge assigns a crucial role to the Rho GTPases family (Rho, Rac, Cdc42) in the complex transductive pathway leading to skeletal muscle cell differentiation. Their exact function in myogenesis, however, remains largely undefined. The protein toxin CNF1 was herein employed as a tool to activate Rho, Rac and Cdc42 in the myogenic cell line C2C12. We demonstrated that CNF1 impaired myogenesis by affecting the muscle regulatory factors MyoD and myogenin and the structural protein MHC expressions. This was principally driven by Rac/Cdc42 activation whereas Rho apparently controlled only the fusion process. More importantly, we proved that a controlled balance between Rho and Rac/Cdc42 activation/deactivation state was crucial for the correct execution of the differentiation program, thus providing a novel view for the role of Rho GTPases in muscle cell differentiation. Also, the use of Rho hijacking toxins can represent a new strategy to pharmacologically influence the differentiative process.

Animals↗
PubMed2004

Oligomeric assembly of dopamine D1 and glutamate NMDA receptors: molecular mechanisms and functional implications.

In the striatum, dopamine D(1)R (D(1) receptor) activation potentiates NMDA (N-methyl-D-aspartate) transmission and is required for NMDA-mediated long-term potentiation at corticostriatal synapses. By using a combination of co-immunoprecipitation, pull-out with glutathione S-transferase-fusion proteins and bioluminescence resonance energy transfer, we have reported that the D(1)R forms a heteromeric complex with the NMDAR (NMDA receptor) and that this mechanism is crucial to recruit the D(1)R to the postsynaptic density. By using confocal and radioligand-binding assay, we also demonstrated that the interaction with NMDAR abolishes agonist-mediated D(1)R sequestration, indicating that oligomerization with NMDAR could represent a novel regulatory mechanism modulating D(1)R cellular trafficking and desensitization.

Animals↗
PubMed2004

The behaviour of the flow-mediated brachial artery vasodilatation during orthostatic stress in normal man.

AIMS: Flow-mediated brachial artery vasodilatation is an index of endothelial function. Published literature describes only supine data and no study has been performed during vertical displacement. This subject deserves investigation for two main reasons: humans spend the larger part of their life in the upright position; this position has significant effects on neural vascular regulation. METHODS: In 21 healthy men (25 +/- 2 years) the flow-dependent brachial artery vasodilating response to distal circulatory arrest was assessed by Doppler ultrasound imaging, while supine and during 20 degrees and 60 degrees head-up tilting (HUT). In 11 of these subjects the vasodilating response to nitroglycerine was also explored. RESULTS: Absolute and percentage increments in brachial calibre during hyperaemia after deflation of the occluding cuff became increasingly greater at 20 degrees (+0.44 mm) and 60 degrees (+0.92 mm) HUT (P < 0.01), compared with the horizontal position (+0.27 mm), and the arterial dilatation for an increase in flow (0.98 +/- 0.08 and 1.68 +/- 0.06 mm mL(-1) min(-1) x 1000, respectively) was larger (P < 0.01) than occurred while supine (0.41 +/- 0.05 mm mL(-1) min(-1) x 1000). Nitroglycerine-mediated vasodilatation at 60 degrees HUT was similar to that in the supine position. CONCLUSION: The orthostatic stimulus is associated with an increase of the flow-mediated brachial artery vasodilatation, which is proportional to the degree of displacement. The mechanism of this effect does not consist of changes in nitric oxide sensitivity.

Adult↗
PubMed2003

The Rac-activating toxin cytotoxic necrotizing factor 1 oversees NK cell-mediated activity by regulating the actin/microtubule interplay.

The cell cytoskeleton is widely acknowledged as a master for NK cell function. Specifically, actin filaments guide the NK cell binding to target cells, engendering the formation of the so-called immunological synapse, while microtubules direct the killer behavior. All these cytoskeleton-dependent activities are competently governed by the Rho GTPases, a family of regulatory molecules encompassing the three different subfamilies, Rho, Rac, and Cdc42. By using a Rac GTPase-activating bacterial protein toxin from Escherichia coli named cytotoxic necrotizing factor 1 (CNF1), we obtained results supporting the activation of Rac GTPase as a booster for effector cell-binding efficiency, recruitment ability, and, consequently, cytotoxicity. In particular, the augmented killer capacity of CNF1-treated NK cells was associated with the increased expression of certain cell adhesion or activation-associated molecules and the reshaping of the actin and microtubule networks. Importantly, CNF1 counteracted the activity exerted by toxins disrupting the cytoskeletal architecture. Hence, the activation of Rho GTPases, particularly Rac, induced by CNF1, appears to orchestrate a dynamic cross talk between microtubules and actin filaments, leading to a fruitful NK cell activity and polarization state. Our findings suggest that protein toxins might be viewed as modulators of NK cell cytotoxic activity and could possibly be regarded as useful pharmacological tools for certain Rho-linked immune diseases in the near future.

Actins↗
PubMed2003

Idebenone treatment in Friedreich patients: one-year-long randomized placebo-controlled trial.

The authors carried out a 1-year, randomized, placebo-controlled trial of idebenone in 29 patients with Friedreich ataxia. They found significant reductions of interventricular septal thickness and left ventricular mass in the idebenone group vs the placebo group, with no improvement in other heart ultrasound measures or neurologic condition. The absolute cardiac changes were modest, but the findings suggest that larger trials should assess whether idebenone reduces ventricular hypertrophy in patients with Friedreich ataxia.

Adolescent↗
PubMed2003

Hijacking Rho GTPases by protein toxins and apoptosis: molecular strategies of pathogenic bacteria.

Certain bacterial toxins and type-III-translocated virulence factors have a peculiar property: they exert part of their actions by modulating Rho GTPases. These toxins target the actin cytoskeleton of host cells and reorganize it to their own advantage, either to facilitate macropinocytosis, which is required for invasive bacteria to enter cells, or to block pathogen sequestration by macrophages. In addition, by acting on Rho GTPases, bacteria may also interfere with the fate of host cells, favoring survival or death depending on their needs. Rho GTPases control the activation of NF-kappaB, which is involved in the expression of antiapoptotic proteins and mediates immunological responses as well. Here, we give a perspective on how NF-kappaB may participate in linking Rho-acting toxins and apoptosis.

Animals↗
PubMed2002

Epithelial cells challenged with a Rac-activating E. coli cytotoxin acquire features of professional phagocytes.

Activation of Rho, Rac and Cdc42 GTPases by an Escherichia coli cytotoxin (CNF1) has been reported to induce a phagocytic-like activity by epithelial cells in terms of a ruffle-driven capture and ingestion of large material. More recently, it has been reported that treatment with CNF1 induces superoxide anion release by these cells following a phagocytic stimulus. We herein show that in epithelial cells both transfection with the dominant form of Rac (RacV12) and treatment with the Rac-activating epidermal growth factor (EGF) may increase the secretion of superoxide anions on challenge with latex beads. Moreover, exposure to CNF1 induces a significant augmentation of acidic vesicles where the internalized particles were detectable. Our results indicate that (i) Rac is a pivotal GTPase for inducing in epithelial cells superoxide anion generation and (ii) the internalized material travels trough acidic compartments in CNF1-treated epithelial cells. Altogether this suggests a novel role for epithelial cells that, following Rac activation, might share with professional phagocytes the task of eliminating unwanted pathogens.

Bacterial Toxins↗
PubMed2002

Epithelial cells and expression of the phagocytic marker CD68: scavenging of apoptotic bodies following Rho activation.

Macropinocytosis is a ruffling-driven process which drives the ingestion of large particles by both macrophages and epithelial cells. In this context, we have previously described a Rho-activating bacterial toxin from E. coli, the cytotoxic necrotizing factor 1 (CNF1), which allows epithelial cells to macropinocytose not only latex beads and bacteria, but also apoptotic cells in a fashion similar to that of professional phagocytes. We herein report that (i) epithelial cells express the typical phagocytic marker CD68, (ii) Rho activation by CNF1 varies the intracellular localization of CD68, which appears to be co-distributed, as in macrophages, with the homologous lysosomal protein Lamp-1. Together with the capability of digesting apoptotic cells following their internalization, our findings indicate that Rho-activated epithelial cells behave in most respects as professional phagocytes.

Acute-Phase Proteins↗
PubMed2002

Perioperative myocardial infarction in noncardiac surgery: the diagnostic and prognostic role of cardiac troponins.

Despite the number of technologies used, the diagnosis of perioperative myocardial infarction is still a challenge. Studies conducted in surgical series have demonstrated that cardiac troponins (cTns) have both a superior diagnostic sensitivity and specificity, compared with other traditional techniques, and an independent power to predict short- and long-term prognosis. Nevertheless, some points need to be clarified. They include the usefulness of cTns in patients with end-stage renal failure; the standardization of the cTns cut-off for the diagnosis of myocardial injury; the timing of postoperative blood samplings; the cost-effectiveness of a screening in asymptomatic patients; and the possible therapeutic strategies.

Cost-Benefit Analysis↗
PubMed2002

Myocardial injury revealed by plasma troponin I in breast cancer treated with high-dose chemotherapy.

BACKGROUND: High-dose chemotherapy (HDC) has been widely utilized in high-risk breast cancer, but it may induce cardiac toxicity. Cardiac dysfunction may become evident weeks or months after HDC and, to date, no early markers of myocardial injury that are able to predict late ventricular impairment are available. We investigated the role of plasma troponin I (TnI) in this setting. PATIENTS AND METHODS: We measured TnI plasma concentration after HDC in 211 high-risk breast cancer women (46 +/- 11 years, mean +/- SD). According to TnI value (< 0.5 or > or = 0.5 ng/ml), patients were allocated into a troponin positive (TnI+; n = 70) and a troponin negative (TnI-; n = 141) group. All patients underwent left ventricular ejection fraction (LVEF, Echo) examination during the following 12 months. RESULTS: LVEF progressively decreased in the TnI+ group but not in the TnI- group. In TnI+ patients a close relationship between the TnI increase, as well as the number of positive TnI assays, and the maximal LVEF decrement, was found (r = -0.92, P < 0.0001 and r = -0.93, P < 0.0001, respectively). CONCLUSIONS: In our population, the elevation of TnI soon after HDC accurately predicts the development of future LVEF depression. In this setting, TnI can be considered a sensitive and reliable marker of myocardial damage with relevant clinical and prognostic implications.

Adult↗
PubMed2001

Positive modulation by Ras of interleukin-1beta-mediated nitric oxide generation in insulin-secreting clonal beta (HIT-T15) cells.

In the present study, we have shown that exposure of insulin-secreting clonal beta (HIT-T15) cells to interleukin-1beta (IL-1beta) results in a time- and concentration-dependent increase in nitric oxide (NO) release. These effects by IL-1beta on NO release were mediated by induction of inducible nitric oxide synthase (iNOS) from the cells. Preincubation of HIT cells with Clostridium sordellii lethal toxin-82, which irreversibly glucosylates and inactivates small G-proteins, such as Ras, Rap, Ral, and Rac, but not Cdc42, completely abolished IL-1beta-induced NO release. Pre-exposure of HIT cells to C. sordellii lethal toxin-9048, which monoglucosylates and inhibits Ras, Cdc42, Rac, and Rap, but not Ral, also attenuated IL-1beta-mediated NO release. These data indicate that activation of Ras and/or Rac may be necessary for IL-1beta-mediated NO release. Preincubation of HIT cells with C. difficile toxin-B, which monoglucosylates Rac, Cdc42, and Rho, had no demonstrable effects on IL-mediated NO release, ruling out the possibility that Rac may be involved in this signaling step. Further, two structurally dissimilar inhibitors of Ras function, namely manumycin A and damnacanthal, inhibited, in a concentration-dependent manner, the IL-1beta-mediated NO release from these cells. Together, our data provide evidence, for the first time, that Ras activation is an obligatory step in IL-1beta-mediated NO release and, presumably, the subsequent dysfunction of the pancreatic beta cell. Our data also provide a basis for future investigations to understand the mechanism of cytokine-induced beta cell death leading to the onset of insulin-dependent diabetes mellitus.

Animals↗