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Biomedical subjects

F Baggi

Publications and source records attributed to F Baggi.

At least 19 recordsLinked to original sources
PubMed2006

Species identification of non-tuberculous mycobacteria from humans and cattle of Chad.

In Chad, during a study on tuberculosis in humans and cattle, 52 non-tuberculous mycobacteria (NTM) strains were isolated. By means of INNO-LiPA, PRA-hsp65 amplification and sequencing of 16S rDNA, NTM species of 25/52 isolates were identified. M. fortuitum complex (8) was the most frequent species, followed by M. nonchromogenicum (4) and M. avium complex (4). PRA method could identify M. fortuitum 3rd variant among isolates derived from cattle specimens. This finding could confirm the existence of farcy in the Chadian cattle population as M. fortuitum 3rd variant and putitative pathogen M. farcinogenes can't be distinguished by the methods used in this study. Half of the NTM isolates could not be specified and we considered them as contaminants from the environment.

Animals↗
PubMed2006

Dendritic cells pulsed with glioma lysates induce immunity against syngeneic intracranial gliomas and increase survival of tumor-bearing mice.

In recent years, the use of dendritic cells (DC), the most powerful antigen presenting cells, has been proposed for the creation of vaccines against gliomas. This approach has been demonstrated to be safe and non-toxic in phase I or I-II trials (2, 3). Immunotherapy plays a central role in the search for new treatments for glioblastoma multiforme (GBM). In particular, several phase I studies have been performed using DC pulsed by GBM proteins as a vaccine for patients with relapsing GBM. The studies demonstrated that DC vaccination is safe and may produce a significant increase in overall survival. As the first step in the preparation of appropriate conditions for a clinical evaluation in Italy, we have performed pre-clinical experiments on immune-competent mice injected intra-cerebrally with syngeneic GL261GBM cells and treated subcutaneously and intra-tumorally with DC loaded with a GL261 homogenate. These results show that vaccination with DC pulsed with a tumor lysate increases considerably survival in mice bearing intracranial glioblastomas and supports the development of DC-based clinical trials for patients with glioblastomas that do not respond to standard therapies.

Animals↗
PubMed2005

Rapid detection of diarrheagenic E. coli by real-time PCR.

Enterovirulent Escherichia coli are among the most important causes of acute diarrhea in developing as well as in developed countries. We have adapted classical PCR to detect these organisms in stool specimens to real-time PCR using the LightCycler (LC) SYBR Green format followed by melting curve analysis. With only two different cycling protocols we could detect enteropathogenic E. coli (EPEC) and verocytotoxin-producing E. coli (VTEC) (duplex assay for both Verotoxin 1 (VT1) and Verotoxin 2 (VT2)) in one run and enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC) and enterotoxigenic E. coli (ETEC) (duplex assay detecting both heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT)) in another run. Using serial dilutions of control strains, the LC proved to be clearly more sensitive than conventional PCR for five out of seven investigated targets: VTEC (VT1 and VT2), ETEC (ST and LT) and EIEC. For EPEC and EAEC, LC and conventional PCR had identical sensitivities. With stool samples, we found an optimal agreement between LC-PCR and the conventional PCR when samples were tested in a 1:10 dilution. Only one specimen was discrepant, being repetitively positive for VT by LightCycler but not by conventional PCR. Given the significantly higher sensitivity of the LC-PCR for the VT target (up to a 10(-4) dilution factor by melting curve analysis and up to a 10(-6) dilution factor following gel electrophoresis), this is probably a false negative result by conventional PCR. We conclude that LightCycler PCR is more rapid, easier than and at least as sensitive as our conventional PCR for the detection of enterovirulent E. coli in stool specimens after culture on MacConkey.

Bacterial Toxins↗
PubMed2004

[First isolation of tuberculous mycobacteria in man and animals in Chad].

This report describes the first successful isolation and identification of mycobacterial infection in humans and animals of Chad. All mycobacterial strains from human specimens were M. tuberculosis and strains from animal specimens (cattle) were M. bovis. None of the 10 of M. tuberculosis strains tested for antibiotic resistance were multidrug resistant. Due to the intrinsic resistance of M. bovis to pyrazinamide and the growing number of tuberculosis cases in HIV-infected people in Africa and elsewhere, more information on the potential of M. bovis for human infection is needed to guide disease control policy.

Animals↗
PubMed2001

Persistence of viral pathogens and bacteriophages during sewage treatment: lack of correlation with indicator bacteria.

The effects of different sewage treatments on the viral contamination in rivers which receive water from treatment plants without a final sand filtration step were investigated. They were all heavily contaminated with bacteriophages and human enteric viruses (detected by single step reverse transcription amplification followed by a nested polymerase chain reaction). Bacteriophages, but not faecal indicator organisms, were correlated with viral contamination.

Bacteria↗
PubMed2000

Cytokines and chemokines are both expressed by human myoblasts: possible relevance for the immune pathogenesis of muscle inflammation.

The idiopathic inflammatory myopathies are characterized by antibody- or cell-mediated immune response against unknown muscle tissue antigens. In these diseases a cellular infiltrate, composed of T and B lymphocytes, macrophages and NK cells, may invade muscle tissue with a gradient from the perivascular space to the endomysial compartment. Muscle cells may be actively involved in the processes of mononuclear cell recruitment and activation from the blood stream to the areas of inflammation. In order to verify this hypothesis, cultured human myoblasts were tested for their capacity to express different pro-inflammatory cytokines [IL-1alpha, IL-1beta, IL-6 and tumor necrosis factor (TNF)-alpha] and chemokines (IL-8, MCP-1 and RANTES) at the mRNA level and protein secretion, in the presence of the pro-inflammatory cytokines IFN-gamma and TNF-alpha alone or in combination. We confirmed that human myoblasts expressed IL-1alpha and IL-6 constitutively, while IL-1beta and TNF-alpha are detected only after treatment with pro-inflammatory cytokines; moreover, we observed that TNF-alpha was expressed on an autocrine fashion by myoblasts. IL-8 and RANTES were expressed constitutively while MCP-1 after proper induction. These molecular data were further confirmed by specific ELISA in the supernatant from cultured myoblasts. Our results underline the importance of human myoblasts in the recruitment of leukocytes from the blood stream and, most probably, in the cross-talk between infiltrating inflammatory cells and muscle cells, creating the conditions for a chronic inflammation. Moreover, the capacity of muscle cells to behave as cells of the immune system has to be kept in mind, also in view of i.m. vaccination and use of molecular engineered myoblasts as vehicles in gene therapy.

Cells, Cultured↗
PubMed2000

Genotyping of rotaviruses in environmental water and stool samples in Southern Switzerland by nucleotide sequence analysis of 189 base pairs at the 5' end of the VP7 gene.

Stool specimens from children (<4 years old) with diarrhea were collected over a 1-year period in Ticino (southern region of Switzerland). During the same period, environmental samples were collected from surface waters in the proximity of major water treatment plants. From treatment plants, samples were collected from the raw sewage and before the release of the treated water. From rivers, samples were collected before and after receiving the treated waters. A single-step reverse transcription (RT)-PCR amplification of the entire VP7 gene from extracted double-stranded RNA was developed. For the water samples, a further nested PCR was necessary to increase sensitivity. All amplified viral products were sequenced, and the sequence profile was compared to that of the VP7 genes of human and animal rotaviruses from GenBank. Rotavirus strains are characterized by outer capsid proteins G (glycoprotein) and P (protease-cleaved protein). Correct G genotyping of viral sequences from stool and water samples was possible by analyzing only 189 bp at the 5' end of the VP7 gene. In the Ticino region, the most predominant G genotype among clinical and water samples was G1. Genotypes G2 and G4 were found only among clinical samples. We also detected rotavirus G1-type sequences in feces from a healthy adult. This finding corroborates the hypothesis that healthy adults act as potential reservoirs for the spread of rotavirus in the environment. In our experiments, this RT-PCR-based method for rotavirus genotyping has proven to be a useful tool for epidemiological investigations.

5' Untranslated Regions↗
PubMed1999

Oral administration of an immunodominant T-cell epitope downregulates Th1/Th2 cytokines and prevents experimental myasthenia gravis.

The mucosal administration of the native antigen or peptide fragments corresponding to immunodominant regions is effective in preventing or treating several T cell-dependent models of autoimmune disease. No data are yet available on oral tolerance with immunodominant T-cell peptides in experimental autoimmune myasthenia gravis (EAMG), an animal model of B cell-dependent disease. We report that oral administration of the T-cell epitope alpha146-162 of the Torpedo californica acetylcholine receptor (TAChR) alpha-subunit suppressed T-cell responses to AChR and ameliorated the disease in C57Bl/6 (B6) mice. Protection from EAMG was associated with reduced serum Ab's to mouse AChR and reduced AChR loss in muscle. The effect of Talpha146-162 feeding was specific; treatment with a control peptide did not affect EAMG manifestations. The protective effect induced by peptide Talpha146-162 was mediated by reduced production of IFN-gamma, IL-2, and IL-10 by TAChR-reactive cells, suggesting T-cell anergy. TGF-beta-secreting Th3 cells did not seem to be involved in tolerance induction. We therefore demonstrate that feeding a single immunodominant epitope can prevent an Ab-mediated experimental model of autoimmune disease.

Administration, Oral↗
PubMed1998

The expression of co-stimulatory and accessory molecules on cultured human muscle cells is not dependent on stimulus by pro-inflammatory cytokines: relevance for the pathogenesis of inflammatory myopathy.

Specific activation of naive T cells requires TCR engagement plus interaction of CD28 on T cells with co-stimulatory B7-1/B7-2 on APCs. Since muscle cells may be directly involved in activating muscle-infiltrating T lymphocytes in polymyositis and inclusion body myositis, we analyzed B7 expression on myoblasts before and after treatment with pro-inflammatory cytokines. We found no expression of B7-1/B7-2, either constitutively or after stimulus with cytokines. Furthermore, myoblasts failed to stimulate alloreactive peripheral blood lymphocytes in mixed lymphocyte reactions. Lack of B7 expression was confirmed by immunostaining of polymyositis patients' muscle: only T and the few B lymphocytes present in inflammation areas expressed B7-1.

Antigens, CD↗
PubMed1997

Acetylcholine receptor alpha-subunit isoforms are differentially expressed in thymuses from myasthenic patients.

A central role of the thymus in autosensitization to the acetylcholine receptor has been proposed to explain the immunopathogenetic processes in myasthenia gravis (MG). Two isoforms of the alpha-subunit of the acetylcholine receptor are known; they differ by a 25-amino-acid insertion coded by the P3A exon. We investigated the expression of the P3A exon by RNA polymerase chain reaction in fetal and adult human myoblasts and TE671 cells; both isoforms were expressed. Muscle biopsies from patients with MG, Duchenne muscular dystrophy, and polymyositis were also studied and it was again found that both isoforms were expressed, indicating that the P3A exon is not associated with autoimmune, degenerative, and inflammatory muscle diseases. When P3A expression was studied in thymus samples from normal subjects and from thymectomized MG patients, the P3A+ subunit was absent in 75% of patients with involuted thymus and in all patients with thymomas but was present in normal thymuses and in patients with hyperplasia. Differential expression of the alpha-subunit isoforms of the acetylcholine receptor within the thymus may play a role in the immune pathogenesis of MG.

Acetylcholine↗
PubMed1996

Major histocompatibility complex class II molecule expression on muscle cells is regulated by differentiation: implications for the immunopathogenesis of muscle autoimmune diseases.

Major histocompatibility complex (MHC) class II molecules are expressed on myoblasts after interferon-gamma (IFN-gamma) treatment, suggesting a muscle cell involvement in antigen presentation in inflammatory myopathies. However, they were not observed on normal or pathological myofibers. This discrepancy might be related to different responsiveness of developmentally differentiated muscle cells to IFN-gamma. Myoblasts expressed class II transcripts and proteins after IFN-gamma, while myotubes and innervated contracting muscle cells did not show staining for class II molecules. At all cell stages no loss of IFN-gamma receptor was detected indicating that myofiber maturation blocks their capacity to express MHC class II molecules. This suggests that completely differentiated myofibers cannot participate in class II restricted immunological reactions.

Actins↗
PubMed1995

Use of amplified fragment length polymorphism in molecular typing of Legionella pneumophila and application to epidemiological studies.

A novel method for molecular typing of organisms, amplified fragment length polymorphism analysis, was tested for its suitability in epidemiological studies in medical microbiology. Amplified fragment length polymorphism analysis, originally developed for typing crop plants, consists of a simple restriction-ligation reaction and a subsequent PCR amplification. In a single-step reaction, the genomic DNA is digested and the restriction fragments are ligated to specially constructed adapters. PCR amplification of such tagged restriction fragments with primers complementary to the adapters allows the detection of restriction fragment length polymorphisms upon resolution on agarose gels. The method is fast, efficient, and reproducible for typing strains of Legionella pneumophila isolated from both humans and the environment. The accuracy of the method was tested by comparison with standard restriction fragment length polymorphism typing performed with both a ribosomal and a genomic probe.

Bacterial Typing Techniques↗