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Biomedical subjects

Francesco Blasi

Publications and source records attributed to Francesco Blasi.

At least 19 recordsLinked to original sources
PubMed2006

Expression of Hoxa2 in rhombomere 4 is regulated by a conserved cross-regulatory mechanism dependent upon Hoxb1.

The Hoxa2 gene is an important component of regulatory events during hindbrain segmentation and head development in vertebrates. In this study we have used sequenced comparisons of the Hoxa2 locus from 12 vertebrate species in combination with detailed regulatory analyses in mouse and chicken embryos to characterize the mechanistic basis for the regulation of Hoxa2 in rhombomere (r) 4. A highly conserved region in the Hoxa2 intron functions as an r4 enhancer. In vitro binding studies demonstrate that within the conserved region three bipartite Hox/Pbx binding sites (PH1-PH3) in combination with a single binding site for Pbx-Prep/Meis (PM) heterodimers co-operate to regulate enhancer activity in r4. Mutational analysis reveals that these sites are required for activity of the enhancer, suggesting that the r4 enhancer from Hoxa2 functions in vivo as a Hox-response module in combination with the Hox cofactors, Pbx and Prep/Meis. Furthermore, this r4 enhancer is capable of mediating a response to ectopic HOXB1 expression in the hindbrain. These findings reveal that Hoxa2 is a target gene of Hoxb1 and permit us to develop a gene regulatory network for r4, whereby Hoxa2, along with Hoxb1, Hoxb2 and Hoxa1, is integrated into a series of auto- and cross-regulatory loops between Hox genes. These data highlight the important role played by direct cross-talk between Hox genes in regulating hindbrain patterning.

Animals↗
PubMed2006

Acute tonsillopharyngitis associated with atypical bacterial infection in children: natural history and impact of macrolide therapy.

This study evaluated the natural history of acute tonsillopharyngitis associated with atypical bacterial infections, showing that Mycoplasma pneumoniae and Chlamydia pneumoniae organisms are frequently found in children with acute tonsillopharyngitis. The study also demonstrated, for what we believe to be the first time, that, unless adequately treated, acute tonsillopharyngitis associated with infection with M. pneumoniae and C. pneumoniae may have a negative outcome with a high risk of recurrence of respiratory illness.

Acute Disease↗
PubMed2006

Requirement of the enzymatic and signaling activities of plasmin for phorbol-ester-induced scattering of colon cancer cells.

Colon cancer progression is associated with the activation of protein kinase C (PKC), the downregulation of functional E-cadherin and an increased expression of the serine protease urokinase (u-PA) and its receptor (u-PAR). HT29-M6 intestinal epithelial cells represent an in vitro model to study colon cancer progression. These cells are induced to scatter and to invade by phorbol esters. Using proteolytic and cell signaling inhibitors, we show that HT29-M6 cells require plasminogen for the acquisition of the scattering response to PMA. Our results indicate that, prior to inducing a state of competency for plasminogen-dependent scattering, PMA triggers an ordered succession of events where upregulation of the activity of u-PA precedes proteolysis of u-PAR and active degradation of the extracellular matrix (ECM). These events poise HT29-M6 cells to a scatter-competent state that allows the subsequent localized proteolytic activation of plasminogen to plasmin, required for the execution of scattering. Finally, we show that, in addition to its enzymatic activity directed at the degradation of ECM, plasmin generates an intracellular signal resulting in the phosphorylation of ERK 1/2. For a full motogenic activity, plasmin requires this signal since the use of a MEK inhibitor (PD98059) specifically blocks the plasmin-dependent phase of cell scattering. Our observations suggest that plasmin exerts a dual role in PMA-induced scattering of HT29-M6 cells, one directed extracellularly to promote proteolysis of the ECM and one directed to generate intracellular signaling.

Aminocaproic Acid↗
PubMed2006

The effect of telithromycin in acute exacerbations of asthma.

BACKGROUND: We conducted a double-blind, randomized, placebo-controlled study to evaluate the efficacy of telithromycin in patients with acute exacerbations of asthma. METHODS: A total of 278 adults with diagnosed asthma were enrolled within 24 hours after an acute exacerbation of asthma requiring short-term medical care. The patients were randomly assigned to receive 10 days of oral treatment with telithromycin (at a dose of 800 mg daily) or placebo in addition to usual care. Primary efficacy end points were a change from baseline over the treatment period in symptoms (as recorded by patients in a diary card) and in the peak expiratory flow in the morning at home. The presence of Chlamydophila pneumoniae or Mycoplasma pneumoniae was ascertained by serologic analysis, polymerase chain reaction, and culture. RESULTS: Of the two prespecified primary outcomes, only asthma symptoms showed a significantly greater reduction among patients receiving telithromycin than among those receiving placebo. Mean (+/-SD) scores on a test of asthma symptoms (on a 7-point scale, with 0 denoting no symptoms and 6 denoting severe symptoms) were 3.0+/-1.4 at baseline and 1.7+/-1.1 at the end of treatment for the telithromycin group and 2.8+/-1.3 at baseline and 2.0+/-1.0 at the end of treatment for the placebo group. The mean decrease in symptom scores during the treatment period was 1.3 for telithromycin and 1.0 for placebo (mean difference, -0.3; 95 percent confidence interval, -0.5 to -0.1; P=0.004). There was no significant treatment effect on the other primary outcome measure, a change in morning peak expiratory flow. Nausea was more common among patients in the telithromycin group than in the placebo group (P=0.01). Although 61 percent of patients had evidence of infection with C. pneumoniae, M. pneumoniae, or both, there was no relationship between bacteriologic status and the response to asthma treatment. CONCLUSIONS: This study provides evidence of the benefit of telithromycin in patients with acute exacerbations of asthma; the mechanisms of benefit remain unclear. (ClinicalTrials.gov number, NCT00273520.).

Acute Disease↗
PubMed2006

Anxiety and depression in COPD patients: The roles of gender and disease severity.

BACKGROUND: The aim of our study was to assess the prevalence of anxiety and depression in the whole chronic obstructive pulmonary disease (COPD) population and in subgroups according to sex and severity classification. A secondary objective was to evaluate the possible differences between patients with and without a significant high level of anxiety, depression, or both, and finally to find out a correlation between psychological aspects, symptoms, functional parameters, and quality of life (QoL). METHODS: Two hundred and two COPD patients were enrolled. Their levels of anxiety, depression, dyspnea, and QoL were assessed using specific questionnaires. One hundred and fourteen sex- and age-matched healthy subjects were used as the control population. RESULTS: The prevalences of anxiety and depression were high (28.2% and 18.8%) in COPD even when it was of mild degree, compared to the control group, in which the prevalence of anxiety and depression were 6.1% and 3.5%, respectively. Female patients had higher levels of anxiety and depression and worse symptom-related QoL. Female patients reported a higher level of dyspnea than males for the same level of ventilatory impairment. Dyspnea was more strongly correlated with depression in women than in men. CONCLUSIONS: Anxiety and depressive symptoms are common in patients affected by COPD, even when their disease is mild in terms of FEV1 and respiratory symptoms. Female patients appear to be more exposed to psychological impairment, which correlates well with some specific symptomatic aspects of the disease, such as dyspnea. Psychological aspects need to be carefully assessed in COPD patients, particularly in females.

Aged↗
PubMed2006

Pertussis toxin B-oligomer suppresses IL-6 induced HIV-1 and chemokine expression in chronically infected U1 cells via inhibition of activator protein 1.

Pertussis toxin B-oligomer (PTX-B) inhibits HIV replication in T lymphocytes and monocyte-derived macrophages by interfering with multiple steps of the HIV life cycle. PTX-B prevents CCR5-dependent (R5) virus entry in a noncompetitive manner, and it also exerts suppressive effects on both R5- and CXCR4-dependent HIV expression at a less-characterized postentry level. We demonstrate in this study that PTX-B profoundly inhibits HIV expression in chronically infected promonocytic U1 cells stimulated with several cytokines and, particularly, the IL-6-mediated effect, a cytokine that triggers viral production in these cells independently of NF-kappaB activation. From U1 cells we have subcloned a cell line, named U1-CR1, with increased responsiveness to IL-6. In these cells, PTX-B neither down-regulated the IL-6R nor prevented IL-6 induced signaling in terms of STAT3 phosphorylation and DNA binding. In contrast, PTX-B inhibited AP-1 binding to target DNA and modified its composition with a proportional increases in FosB, Fra2, and ATF2. PTX-B inhibited IL-6-induced HIV-1 long-terminal repeat-driven transcription from A, C, E, and F viral subtypes, which contain functional AP-1 binding sites, but failed to inhibit transcription from subtypes B and D LTR devoid of these sites. In addition, PTX-B inhibited the secretion of IL-6-induced, AP-1-dependent genes, including urokinase-type plasminogen activator, CXCL8/IL-8, and CCL2/monocyte chemotactic protein-1. Thus, PTX-B suppression of IL-6 induced expression of HIV and cellular genes in chronically infected promonocytic cells is strongly correlated to inhibition of AP-1.

Base Sequence↗
PubMed2006

Hypomorphic mutation of the TALE gene Prep1 (pKnox1) causes a major reduction of Pbx and Meis proteins and a pleiotropic embryonic phenotype.

The interaction of Prep1 and Pbx homeodomain transcription factors regulates their activity, nuclear localization, and likely, function in development. To understand the in vivo role of Prep1, we have analyzed an embryonic lethal hypomorphic mutant mouse (Prep1(i/i)). Prep1(i/i) embryos die at embryonic day 17.5 (E17.5) to birth with an overall organ hypoplasia, severe anemia, impaired angiogenesis, and eye anomalies, particularly in the lens and retina. The anemia correlates with delayed differentiation of erythroid progenitors and may be, at least in part, responsible for intrauterine death. At E14.5, Prep1 is present in fetal liver (FL) cMyb-positive cells, whose deficiency causes a marked hematopoietic phenotype. Prep1 is also localized to FL endothelial progenitors, consistent with the observed angiogenic phenotype. Likewise, at the same gestational day, Prep1 is present in the eye cells that bear Pax6, implicated in eye development. The levels of cMyb and Pax6 in FL and in the retina, respectively, are significantly decreased in Prep1(i/i) embryos, consistent with the hematopoietic and eye phenotypes. Concomitantly, Prep1 deficiency results in the overall decrease of protein levels of its related family member Meis1 and its partners Pbx1 and Pbx2. As both Prep1 and Meis interact with Pbx, the overall Prep1/Meis-Pbx DNA-binding activity is strongly reduced in whole Prep1(i/i) embryos and their organs. Our data indicate that Prep1 is an essential gene that acts upstream of and within a Pbx-Meis network that regulates multiple aspects of embryonic development.

Allantois↗
PubMed2005

Specific immunofluorimetric assay detecting the chemotactic epitope of the urokinase receptor (uPAR).

The urokinase plasminogen activator receptor (uPAR) fragments D1 and D2D3 are often found in biological fluids from normal individuals and patients of cancer and other diseases. The D2D3 fragment may possess chemotactic activity depending on its N-terminal sequence. We have developed a sensitive and specific immunoassay for the chemotactic form of D2D3 and show that its level can be measured with high specificity and sensitivity in human serum and urine. Synthetic peptides (residues 84-92) derived from the linker region between domains 1 and 2 of uPAR were used as immunogens to generate mouse monoclonal antibodies. Recombinant soluble uPAR (D1D2D3(1-277)) was used to immunize rabbits to obtain polyclonal antibodies. A sandwich-type immunofluorimetric assay was developed with these antibodies. The assay specifically measures D2D3 containing the 84-88 residues, has a detection limit of 0.25 ng/ml and shows no cross-reactivity with D2D3(93-274). The assay is linear at 0-30 ng/ml, with an intra-assay CV of 10% (n=20), inter-assay CV of 15% (n=9) and a recovery of D2D3(84-274) added to urine samples of between 94% and 105%. A statistically significant difference level of D2D3(84-274) was found in two groups of tumor patients versus healthy volunteers (p<or=0.009 in colorectal carcinomas and p<or=0.036 in prostatic carcinomas). For the first time, monoclonal antibodies, detecting the chemotactic form of uPAR, D2D3(84-274), have been produced. The immunofluorimetric assay will quantitate uPAR chemotactic fragments in biological samples, including serum and urine, and evaluate their diagnostic or prognostic potential in clinical studies.

Amino Acid Sequence↗
PubMed2005

Clast4, the murine homologue of human eIF4E-Transporter, is highly expressed in developing oocytes and post-translationally modified at meiotic maturation.

In metazoans, translational regulation of a set of maternal mRNAs directs oocyte maturation and early embryogenesis. These transcripts are often kept dormant until their products are spatially and temporally required in development. The interaction between general translation factors (i.e. eIF4E) and their specific interactors influences translation initiation. A search of the protein database for a mouse homologue of the Drosophila Cup protein, a translational repressor during female germ-line development, identified the product of the Clast4 gene. In this report, we show that Clast4 mRNA and protein are highly expressed within the cytoplasm of growing oocytes. The Clast4 protein is stable during this developmental window and post-translationally modified by phosphorylation upon oocyte meiotic maturation. Additionally, we show that Clast4 and eIF4E directly interact by means of a canonical and functional eIF4E-binding motif. Our results suggest that Clast4, similar to Drosophila Cup, may act at the translational level during murine female germ-line development.

3' Untranslated Regions↗
PubMed2005

Highlights on the appropriate use of fluoroquinolones in respiratory tract infections.

The impact of respiratory infections on public health is increasing, and lower respiratory tract infections are a major cause of morbidity and mortality. Moreover, most antibiotic prescriptions are related to respiratory infections and this is probably one of the main determinants of the increasing rate of bacterial resistance in both community and hospital settings. This has been the catalyst for the development of new drugs, such as the new fluoroquinolones. The new fluoroquinolones have an excellent spectrum providing cover for the most important respiratory pathogens, including atypical and "typical" pathogens. The pharmacokinetic and dynamic properties of the new fluoroquinolones have a significant impact on their clinical and bacteriological efficacy. They cause a concentration-dependent killing with a sustained post-antibiotic effect. Fluoroquinolones combine exceptional efficacy with cost-effectiveness. Not surprisingly, different guidelines have inserted these agents among the drugs of choice in the empirical therapy of LRTIs. This review discusses the most recent data on the bacteriological and clinical activity of the new fluoroquinolones and critically analyses the risks of a potential overuse of this valuable new class of drugs.

Anti-Infective Agents↗
PubMed2005

A review of guidelines for antibacterial use in acute exacerbations of chronic bronchitis.

Acute exacerbations of chronic bronchitis (AECB) affect a significant proportion of the adult population worldwide and are associated with a substantial socioeconomic burden. The majority of episodes of AECB are bacterial in aetiology and patients are generally treated empirically with orally administered antibacterial agents. Guidelines for the management of AECB have been developed by a number of national health authorities and international organisations, with the aim of promoting rational selection of antibacterial therapy to minimise the risk of treatment failure and subsequent hospitalisation while containing the development and spread of antibacterial resistance. This paper reviews a number of recently published or updated AECB treatment guidelines, focusing on patient stratification strategies, antibacterial treatment recommendations, and newer antibacterial treatment options, including respiratory fluoroquinolones and the ketolide telithromycin, which have recently been added to a number of national treatment guidelines.

Anti-Bacterial Agents↗
PubMed2005

An uncleavable uPAR mutant allows dissection of signaling pathways in uPA-dependent cell migration.

Urokinase-type plasminogen activator (uPA) binding to uPAR induces migration, adhesion, and proliferation through multiple interactions with G proteins-coupled receptor FPRL1, integrins, or the epidermal growth factor (EGF) receptor (EGFR). At least two forms of uPAR are present on the cell surface: full-length and cleaved uPAR, each specifically interacting with one or more transmembrane proteins. The connection between these interactions and the effects on the signaling pathways activation is not clear. We have exploited an uPAR mutant (hcr, human cleavage resistant) to dissect the pathways involved in uPA-induced cell migration. This mutant is not cleaved by proteases, is glycosylphosphatidylinositol anchored, and binds uPA with a normal K(d). Both wild-type (wt) and hcr-uPAR are able to mediate uPA-induced migration, are constitutively associated with the EGFR, and associate with alpha3beta1 integrin upon uPA binding. However, they engage different pathways in response to uPA. wt-uPAR requires both integrins and FPRL1 to mediate uPA-induced migration, and association of wt-uPAR to alpha3beta1 results in uPAR cleavage and extracellular signal-regulated kinase (ERK) activation. On the contrary, hcr-uPAR does not activate ERK and does not engage FPRL1 or any other G protein-coupled receptor, but it activates an alternative pathway initiated by the formation of a triple complex (uPAR-alpha3beta1-EGFR) and resulting in the autotyrosine phosphorylation of EGFR.

Amino Acid Sequence↗
PubMed2005

Domain 2 of the urokinase receptor contains an integrin-interacting epitope with intrinsic signaling activity: generation of a new integrin inhibitor.

We investigated the interaction between the urokinase receptor (uPAR) and the integrin alphavbeta3. Vitronectin (VN) induces cell migration by binding to alphavbeta3, but expression of the uPAR boosts its efficacy. Thus, uPAR may regulate VN-induced cell migration by interacting laterally with alphavbeta3. In contrast, cells expressing a uPAR mutant lacking domain 2 do not migrate in response to VN. This effect is overcome by D2A, a synthetic peptide derived from the sequence of domain 2. In addition, D2A has chemotactic activity that requires alphavbeta3 and activates alphavbeta3-dependent signaling pathways such as the Janus kinase/Stat pathway. Moreover, D2A disrupts uPAR-alphavbeta3 and uPAR-alpha5beta1 co-immunoprecipitation, indicating that it can bind both of these integrins. We also identify the chemotactically active epitope harbored by peptide D2A. Mutating two glutamic acids into two alanines generates peptide D2A-Ala, which lacks chemotactic activity but inhibits VN-, FN-, and collagen-dependent cell migration. In fact, the GEEG peptide has potent chemotactic activity, and the GAAG sequence has inhibitory capacities. In summary, we have identified an integrin-interacting sequence located in domain 2 of uPAR, which is also a new chemotactic epitope that can activate alphavbeta3-dependent signaling pathways and stimulate cell migration. This sequence thus plays a pivotal role in the regulation of uPAR-integrin interactions. Moreover, we describe a novel, very potent inhibitor of integrin-dependent cell migration.

Adenoviridae↗
PubMed2005

Recombinant protein-based ELISA and immuno-cytochemical assay for the diagnosis of SARS.

A new Coronavirus (SARS-CoV) is the aetiological agent of the severe acute respiratory syndrome (SARS). Because of the critical role played by serological assays for SARS diagnosis, an in-house ELISA based on SARS-CoV recombinant antigens was developed. The SARS-CoV nucleocapsid protein (N), three N fragments (N1, N2, and N3) and the intraviral domain of the membrane protein (M2) were cloned and expressed in Escherichia coli as histidine-tagged proteins. Six reference sera from SARS patients were used to detect virus-specific IgG in an ELISA using each recombinant protein as coating antigen. High-titre positive reactions were detected in all SARS positive sera. The specificity of the assay appears to be high as no positive reaction was detected in the sera of 20 healthy subjects and 73 patients with non-SARS, low-tract respiratory infections. Specific hyper-immune sera to SARS-CoV and the recombinant proteins, N, N1, N2, N3, and M2 were also generated in mice and rabbits. The specificity of these sera was confirmed by an immunocytochemical assay on biochips of SARS-CoV infected and uninfected cells.

Animals↗
PubMed2005

Value of short-course antimicrobial therapy in community-acquired pneumonia.

Community-acquired pneumonia (CAP) is a major cause of morbidity and mortality worldwide. Non-compliance with therapy may be associated with deterioration in the patient's condition, treatment failure, and increased use and cost of healthcare resources such as the requirement for additional drugs and hospital admission. Adherence to the prescribed regimen is affected by a number of variables including dosing interval, treatment duration, adverse effects, and palatability in pediatric patients. Accumulating evidence suggests that short-course antimicrobial therapy may be at least as effective as, and in some cases may be more effective than, traditional longer therapies (7-14 days) even in hospital-acquired pneumonia. Given the unique pharmacokinetic properties of azithromycin, attempts have been made to condense the traditional total dose over a 3-5-day period into single-dose therapy with the aim of improving treatment compliance. The results of two phase III CAP trials indicate that a single 2.0 g dose of azithromycin microspheres is a suitable alternative to 7 days of either clarithromycin XL or levofloxacin.

Anti-Bacterial Agents↗
PubMed2005

Chlamydia pneumoniae and Mycoplasma pneumoniae.

Mycoplasma pneumoniae infection occurs worldwide and is the most common cause of community-acquired pneumonia (CAP) in 5- to 20-year-olds. The most reliable diagnostic test is the enzyme immunoassay, which allows immunoglobulin (Ig)G and IgM titration and presents 92% sensitivity and 95% specificity on paired samples. Potentially active drugs are tetracyclines, macrolides, ketolides, lincosamides, streptogamines, chloramphenicol, and fluoroquinolones. Chlamydia pneumoniae accounts for 6 to 20% of CAP cases, depending on several factors such as setting of the studied population, age group examined, and diagnostic methods used. The current gold standard for serological diagnosis of acute infection is microimmunofluorescence testing. Tetracyclines and erythromycin show good in vitro activity and so far have been the most commonly employed drugs in the treatment of C. pneumoniae infection. New macrolides, ketolides, and new fluoroquinolones are other potentially effective drugs.

Anti-Bacterial Agents↗
PubMed2005

Role of atypical bacteria and azithromycin therapy for children with recurrent respiratory tract infections.

BACKGROUND: The aim of this study of 352 patients, 1-14 years of age, with acute respiratory infections and a history of recurrent respiratory tract infections (RRTIs), and 208 healthy subjects was to evaluate whether Mycoplasma pneumoniae and Chlamydia pneumoniae played a role in causing acute respiratory episodes among children with RRTIs and whether specific antibiotic treatment for these bacteria could improve the acute episodes and reduce recurrences. METHODS: The patients were blindly randomized to receive azithromycin (10 mg/kg/d for 3 days weekly, for 3 weeks) together with symptom-specific agents or symptom-specific agents alone. Acute M. pneumoniae and/or C. pneumoniae infection was diagnosed if the child had a significant antibody response in paired sera and/or if the DNA of the bacteria was detected in nasopharyngeal aspirates. RESULTS: Atypical bacterial infections were identified for 190 patients (54.0%) and 8 healthy control subjects (3.8%; P < 0.0001). Short term (1-month) clinical success was significantly more frequent among the patients who had received azithromycin together with symptom-specific agents than among those who had received symptom-specific agents alone, but the difference was significant only for the group of patients with atypical bacteria. In contrast, long term (6-month) clinical success was significantly more frequent among the patients who had received azithromycin in addition to symptom-specific agents, regardless of whether they experienced infections with atypical bacteria or other pathogens, although positive outcomes were significantly more frequent among those with atypical bacteria. CONCLUSIONS: Atypical bacteria seem to play a role among children with RRTIs, and prolonged azithromycin therapy can significantly improve the acute episodes and reduce the risk of recurrences.

Adolescent↗