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Biomedical subjects

M Valassina

Publications and source records attributed to M Valassina.

At least 19 recordsLinked to original sources
PubMed2005

Increased phospholipase activity in Helicobacter pylori strains isolated from patients with gastric carcinoma.

PURPOSE: Phospholipase activity, one of Helicobacter pylori pathogenicity factors, has not been investigated enough, so far, although it may induce a remarkable damage to the gastric mucosa. In the present work, we have compared the whole phospholipase activity of H. pylori strains isolated from patients with gastric carcinoma with that of strains isolated from dyspeptic patients without gastric carcinoma. METHODS: We measured the phospholipase activity of one distinct H. pylori colony isolated from each of 10 patients with gastric carcinoma and 10 controls, dyspeptic patients without endoscopic and histological signs of gastric carcinoma. We also determined the phospholipase activity of 20 additional strains isolated from different areas of neoplastic and non-neoplastic tissue of two patients with gastric carcinoma, the cagA and vacA positive G27 and 328 wild strains and their respective vacA and cagA negative isogenic mutants. The whole phospholipase activity of strains was determined by measuring the release of (14)C-labeled palmitic acid from the radioactive l-3-phosphatidylcholine, 1,2-di[1-(14)C]palmiloyl substrate; results were expressed in pmol of palmitic acid per mg of protein. RESULTS: H. pylori strains isolated from patients with gastric carcinoma had levels of phospholipase activity significantly higher than those of strains isolated from controls (99.37 [S.D. 40.45] versus 34.46 [S.D. 16.46], P<0.001). In patients with gastric carcinoma, the mean phospholipase activity of strains isolated from neoplastic tissue was similar to that of strains isolated from non-neoplastic tissues (123.02 [S.D. 44.36] and 115.77 [S.D. 81.48], respectively. Interruption of cagA gene caused a ca. 20% reduction of phospholipase activity (36.38 versus 45.22 of the wild strain); that of vacA caused no reduction of phospholipase activity (26.53 and 25.37 of the wild strain). CONCLUSIONS: The infection by H. pylori strains that produce high levels of phospholipase may increase the risk of developing gastric carcinoma. We hypothesise that indirect products of phospholipase activity, such as prostaglandins, leukotrienes and lysophospholipids, may mediate carcinogenesis.

Antigens, Bacterial↗
PubMed2004

A syndrome of bilateral hemorrhage of the thalamus and myocarditis with fatal course.

We report the case of a 41-year-old patient with bilateral hemorrhage of the thalamus, leading to death. Post-mortem examination showed acute myocarditis. Neuropathological study showed perivascular infiltrates in affected thalamic regions. Laboratory investigation failed to find any causal agent. We hypothesize an infective agent, affecting the heart and thalamus, as the cause of this syndrome. Diaschisis due to the strategic anatomical position of the thalamus may have been responsible for coma state and death.

Adult↗
PubMed2002

Influenza virosomes are an efficient delivery system for respiratory syncytial virus-F antigen inducing humoral and cell-mediated immunity.

In the present study we investigated the efficacy of a new potential vaccine constituted of the respiratory syncytial virus (RSV)-F protein associated with influenza virosomes (RSV-F/IRIV) in combination with the mucosal adjuvant Escheriagen (Escherichia coli heat-labile toxin), administered intranasally (i.n.) to BALB/c mice. After an intramuscular "priming" with influenza virus vaccine, group A of mice was i.n. immunized with of RSV-F/IRIV+heat-labile toxin (HLT), groups B and C were inoculated i.n. with F-RSV+HLT and IRIV+HLT, respectively. The results showed that the virosomal delivery system greatly potentiate immune responses in animals. All mice immunized with the RSV-F/IRIV+HLT developed a mucosal IgA response and a high level of serum IgG. A balanced Th1/Th2 cytokine profile was observed in mice immunized with RSV-F/IRIV+HLT, while a Th2 response was observed in mice immunized with RSV-F+HLT. Histological analysis of lung tissue of RSV challenged mice did not reveal a vaccine-enhanced pulmonary eosinophilia. These results show that i.n. immunization of BALB/c mice with RSV-F/IRIV in combination with HLT can be considered a promising approach for the development of an efficacious human vaccine.

Adjuvants, Immunologic↗
PubMed2001

Encephalitis without meningitis due to sandfly fever virus serotype toscana.

The role of Toscana (TOS) virus in producing encephalitis without meningitis is uncertain. We studied 2 cases of TOS virus encephalitis without meningitis by means of nested polymerase chain reaction assay and DNA sequencing. Findings confirm that TOS virus may directly cause encephalitis and suggest the usefulness of DNA sequencing in investigating relationships between TOS virus molecular patterns and the spectrum of neurological involvement.

Adult↗
PubMed2001

Comparative study of the immune response in mice immunized with four live attenuated strains of mumps virus by intranasal or intramuscular route.

The observation of many cases of mumps and mumps-associated CNS complications in vaccinees prompted us to perform an evaluation of the efficacy of four attenuated mumps virus (Urabe, Jeryl Lynn, Rubini and S12) vaccines. Two doses of vaccine were necessary to induce a good immunity in animals. The humoral and cell-mediated response induced in mice immunized intramuscularly or intranasally with these vaccines has been evaluated. Although the Urabe and Jeryl Lynn strains appear more immunogenic than the other strains and induce higher levels of IgG when administered intramuscularly, the S-12 strain administered intranasally induces a good IgG response. A marked specific CTL activity against mumps virus was observed in mice immunized intranasally with all the strains and, particularly, with the S12 strain. Thus, the intranasal immunization could be considered a possible alternative and efficient route of vaccination against mumps.

Administration, Intranasal↗
PubMed2001

Localization of a new neutralizing epitope on the mumps virus hemagglutinin-neuraminidase protein.

Four protein fragments which span the entire hemagglutinin-neuraminidase protein (HN) of mumps virus were expressed in HeLa cells and cell extracts were tested for their capability to induce neutralizing antibodies in mice. Fragment HN3 (aa 213-372) was able to induce the production of hemagglutination-inhibiting and neutralizing antibodies. When a subfragment of HN3, the synthetic peptide NSTLGVKSAREF (aa 329-340 of HN) was used for immunization, hemagglutination-inhibiting and neutralizing antibodies against mumps wild type virus but not against the Urabe Am9 vaccine virus were raised. The peptide could, therefore, contain a new epitope, which may be critical for protective host humoral immune response.

Animals↗
PubMed2001

Mycoplasma pneumoniae non-pulmonary infection presenting with pharyngitis, polyarthritis and localized exanthem.

We report a case of pharyngitis, polyarthritis and localized exanthem in acute Mycoplasma pneumoniae infection not involving the lower respiratory tract. Diagnosis was made by means of a particle agglutination test and IgM/IgG indirect immunofluorescence assay. This case describes a clinical complex never reported before and suggests the need for a high index of suspicion in cases of atypical presentation of M. pneumoniae infection.

Adolescent↗
PubMed2001

Neutralization of Toscana virus is partially mediated by antibodies to the nucleocapsid protein.

The envelope glycoproteins G1/G2 of Toscana virus (TOSV) seem to have the most important protective role in stimulating antibodies against the disease in humans, as well as antibodies against the Nucleoprotein (N), a partial neutralizing activity. Mice immunized with TOSV recombinant Nucleoprotein developed a strong humoral response to the TOSV that revealed the presence of neutralizing antibody than in vitro assay. The neutralizing antibody titre of mice immunized with the whole TOSV was analyzed before and after absorption of the sera with the recombinant N protein. A decrease of the neutralizing activity was observed in the treated sera. Similar results were obtained absorbing human anti-TOSV positive sera with the recombinant N protein. This study was designed to identify the nature of antibodies produced against the N protein of TOSV in mice and to establish correlation with antibodies produced in humans by natural infection.

Animals↗
PubMed2000

Intranasal immunization with mumps virus DNA vaccine delivered by influenza virosomes elicits mucosal and systemic immunity.

To improve the efficiency of liposome-mediated DNA transfer as a tool for gene therapy or vaccinology, we have further developed a new delivery system based on the modified immunopotentiating reconstituted influenza virus (IRIV). In this study, we engineered a plasmid DNA vector expressing the mumps virus hemagglutinin or the fusion protein. The administration of this DNA vaccine delivered by influenza virosomes, in combination with the mucosal adjuvant Escheriagen via the intranasal route, was efficient for inducing an immune response, both mucosally and systemically, in mice. The production of IgG2a mumps virus-specific antibodies and the secretion of interleukin 10 (IL-10) by antigen-specific T cells indicated that not only Th1 but also Th2 responses were induced by this DNA vaccine formulation. These results suggest that cationic virosomes in combination with Escheriagen may have great potential as an efficient delivery system for intranasal DNA immunization and provide an immune barrier at the mucosal sites.

Administration, Intranasal↗
PubMed2000

Immunopotentiating of mucosal and systemic antibody responses in mice by intranasal immunization with HLT-combined influenza virosomal vaccine.

The mucosal vaccination strategy against influenza has been investigated by using influenza virosomal vaccine (IRIV) combined with two different adjuvants: the procholeragenoid (PCG) and the Escherichia coli heat labile toxin (HLT). A comparative study has been carried out on mice administered intranasally with these different formulations of influenza vaccine. PCG appears less effective than HLT in inducing an IgG response, but both the adjuvants elicit mucosal adjuvant activity inducing s-IgA in the upper respiratory tract. On the contrary, only HLT when administered intranasally to mice with influenza virosomes stimulates the production of s-IgA in the lower respiratory tract thereby providing a better protection against primary infection of the respiratory system. Both HLT and PCG enhance the production of IFN-gamma in the respiratory tract, nevertheless HLT appears more efficacious as a mucosal adjuvant.

Adjuvants, Immunologic↗
PubMed2000

Detection of neurotropic viruses circulating in Tuscany: the incisive role of Toscana virus.

Acute meningitis is perhaps the most frequent among central nervous system infections. We report a study considering 277 cases of meningitis hospitalized in the southern Tuscany area (Italy) during the period from 1995 to 1998 investigated by tissue culture and polymerase chain reaction (PCR) methods. The cytochemical analysis of the cerebrospinal fluid samples suggested the diagnosis of aseptic meningitis, recognized as viral meningitis in 104 cases by detection of viral DNA or RNA. The results collected by tissue culture technique, available for 95 clinical samples, reported a positive isolation for only 12 cases. The viruses identified in the neurological infection were Toscana virus (81%), enterovirus (12%), mumps virus (3%), measles virus (1%), and herpes virus type 1 (3%). These data demonstrate the incisive role of the RNA viruses as the cause of meningitis, and overall the relevance of Toscana virus.

Adolescent↗
PubMed1999

Multiplex PCR for rapid and differential diagnosis of Mycoplasma pneumoniae and Chlamydia pneumoniae in respiratory infections.

A duplex polymerase chain reaction (PCR) was developed for the simultaneous detection of Chlamydia pneumoniae and Mycoplasma pneumoniae. A study of 163 respiratory specimens from in-patients of the "Centre Hospitalier et Universitaire de Nancy" showed the good sensitivity of this duplex PCR allowing the detection of C. pneumoniae and M. pneumoniae from 8 and 13 patients, respectively, whereas the culture was negative for C. pneumoniae for all the samples and positive for M. pneumoniae only in 9 cases. The value of these results has been confirmed by running on the same samples specific nested PCRs for these two microorganisms that gave the same results. Thus, the proposed duplex amplification technique may facilitate the diagnosis of infection by these two agents that are difficult to isolate.

Adolescent↗
PubMed1999

Encephalitis caused directly by Mycoplasma pneumoniae.

A case of non-fatal encephalitis in a 21-y-old immunocompetent woman is described. High titre serum antibodies against Mycoplasma pneumoniae were found. In addition, Mycoplasma pneumoniae DNA was detected in the cerebrospinal fluid by polymerase chain reaction. Neuroimaging findings by magnetic resonance and computed tomographic scanning of the brain, and laboratory investigations, including a search for serum antibodies to gangliosides, did not support an immune-mediated mechanism. No other pathogens were found. These results strongly suggest that the encephalitis was caused directly by Mycoplasma pneumoniae invasion of the central nervous system. They also indicate that such pathogenetic mechanism may sometimes be sufficient to explain neurological manifestations occurring during the course of Mycoplasma pneumoniae infection. The consequences for therapy are discussed.

Adult↗
PubMed1999

Intracellular life.

Intracellular parasites and endosymbionts are present in almost all forms of life, including bacteria. Some eukaryotic organelles are believed to be derived from ancestral endosymbionts. Parasites and symbionts show several adaptations to intracellular life. A comparative analysis of their biology suggests some general considerations involved in adapting to intracellular life and reveals a number of independently achieved strategies for the exploitation of an intracellular habitat. Symbioses mainly based on a form of syntrophy may have led to the establishment of unique physiological systems. Generally, a symbiont can be considered to be an attenuated pathogen. The combination of morphological studies, molecular phylogenetic analyses, and palaeobiological data has led to considerable improvement in the understanding of intracellular life evolution. Comparing host and symbiont phylogenies could lead to an explanation of the evolutionary history of symbiosis. These studies also provide strong evidences for the endosymbiogenesis of the eukaryotic cell. Indeed, an eubacterial origin for mitochondria and plastids is well accepted and is suggested for other organelles. The expansion of intracellular living associations is presented, with a particular emphasis on peculiar aspects and/or recent data, providing a global evaluation.

Animals↗
PubMed1999

Laboratory diagnosis of Toscana virus infection by enzyme immunoassay with recombinant viral nucleoprotein.

A recombinant enzyme immunoassay (rEIA) to detect serum immunoglobulin M (IgM) and IgG to Toscana virus (TOSV) was developed with the aim of establishing a simple and easily available assay for diagnosing acute and/or previous infections. The rEIA, based on the recombinant nucleoprotein of TOSV expressed in Escherichia coli, was evaluated with 97 serum samples collected in an area where TOSV is endemic and compared to an analogous assay based on cell-derived TOSV. Discordant results were resolved by immunoblotting (IB). Twenty-two of these samples, obtained from subjects hospitalized during the summer season with meningitis of suspected TOSV etiology, were further characterized by indirect immunofluorescence and IB, and detection of specific TOSV RNA sequences in the cerebrospinal fluid of these patients was attempted by nested PCR. The results indicated that rEIA was able to diagnose acute TOSV infection by detection of specific serum IgM in all of the subjects with TOSV meningitis confirmed by nested PCR or serology. The overall sensitivity and specificity of rEIA were both 100% for IgM detection and 100 and 96.6%, respectively, for IgG detection. Thus, rEIA appears to be a simple and reliable laboratory test for the diagnosis of acute TOSV infection and for the assessment of immune status.

Animals↗