Biomedical subjects

M C Liberto

Publications and source records attributed to M C Liberto.

At least 19 recordsLinked to original sources

PubMed2006

Applications of LightCycler Staphylococcus M-GRADE assay to detect Staphylococcus aureus and coagulase-negative staphylococci in clinical blood samples and in blood culture bottles.

We evaluated the applicability of the LightCycler Staphylococcus M(GRADE0 assay on artificially infected blood samples from healthy donors and on clinical specimens of 31 hospitalized patients. The sensitivity and specificity of the assay for detecting Staphylococcus aureus was 100% in blood samples, and 100% in blood culture bottles, when data from the BACTEC 9120 blood culture system were taken as gold standard. The same specificity and sensitivity was found during the search for CoNS (Coagulase Negative Staphylococci) in blood culture bottles, whereas a 93.33% sensitivity and 100% specificity was observed for detecting CoNS directly in blood clinical specimens.

Bacteremia↗

PubMed2004

Fourteen-year experience with imported malaria.

Geographical position, an increasing flow of immigrants and refugees coming from regions where malaria is endemic might further increase those cases of malaria imported to Calabria due to travel on military missions, visiting relatives, business and leisure. However, few reports have been published regarding malaria imported into the southern Italian region of Calabria. Based on data from our laboratory, official reports received from the Italian Ministry of Health and Regional Health Offices, an epidemiological analysis of malaria cases registered in Calabria from January 1988 to December 2001 is reported. The epidemiological and clinical features concerning the cases are discussed. A total of 34 slide-confirmed malaria cases were observed in Calabria during the period in question. Infections were mostly acquired in Africa (84.8%), while remaining infections came from Asia (9.1%) and South America and Europe (6.0%). Length of stay in the endemic area did not increase the infection risk. Etiological diagnosis indicated Plasmodium falciparum as the species most often involved (60.6%), followed by Plasmodium vivax (36.3%) and P. vivax/Plasmodium malariae mixed infection (3.0%). The mortality rate was about 3.0%. The number of cases during the second seven-year period of this study was almost double that of the first seven-year period. Correct chemoprophylaxis was performed by only 27.3% of our studied subjects. Delay of malaria diagnosis ranged between 4 days and 1 month. In conclusion, increases in malaria cases, mostly due to P. falciparum, delay in diagnosis and reporting to the Regional Health Office, as well as the increasing arrival of refugees from endemic areas, are epidemiological concerns in Calabria, the southernmost region of continental Italy.

Adult↗

PubMed2000

Early detection of Leishmania promastigotes in dog bone marrow cultures by acridine orange stain.

An acridine orange staining technique was evaluated in comparison with other well-known methods for the laboratory diagnosis of leishmaniasis. A higher number of promastigotes was found in Novy-MacNeal-Nicolle (NNN) cultures inoculated with canine bone marrow, when culture samples were stained with acridine orange vital stain, compared with those detected using either Giemsa staining or unstained wet mount examination. Based on our data the acridine orange stain is a useful and timely technique in reflecting the true numbers of microorganisms present in a culture and also enhances the visualization of the parasites. The present results warrant further studies with human samples from suspected leishmaniasis patients.

Acridine Orange↗

PubMed2000

Evidence favouring the gastro-oral route in the transmission of Helicobacter pylori infection in children.

OBJECTIVE: Several studies support the view that Helicobacter pylori is acquired in early life and within families. However, the exact route of transmission remains unknown. Given that H. pylori colonizes only the human gastric mucosa, the hypothesis that history of vomiting in siblings may be a relevant risk factor was tested in a paediatric setting. METHODS: One hundred urban children (age range 0.8-16.6 years, median 9), 44% with evidence of active H. pylori infection, were recruited. A structured questionnaire dealing with socio-economic issues was completed. Vomiting siblings and siblings of vomiting index children were screened for H. pylori by means of (13)C-urea breath test. Serum samples from index children were assayed for immunoglobulin G to hepatitis A (HAV) and Epstein-Barr virus (EBV) in order to check for faecal-oral and oral-oral exposure, respectively. RESULTS: Vomiting siblings of H. pylori-infected index children and siblings of H. pylori-infected vomiting index children had a high rate of active H. pylori infection (60 and 67%, respectively). History of vomiting in siblings was positively associated with active H. pylori infection in the index children (multivariate odds ratio 2.4, 95% confidence interval 1.3-4.3). Seropositivity for HAV and EBV was found in 1 and 68 index children, respectively. The agreement between active H. pylori infection and EBV seropositivity was not significant (kappa = 0.26). CONCLUSIONS: History of vomiting in siblings is an independent risk factor for H. pylori. Nowadays, transmission of H. pylori in urban children may involve the gastro-oral route more than the faecal-oral or oral-oral pathways.

Adolescent↗

PubMed2000

Pathogenic mechanisms of Bartonella quintana.

Bartonella quintana is an epi- and intracellular gram-negative rod responsible for both acute and chronic clinical manifestations. We review the literature about pathogenic mechanisms of B. quintana and discuss our data. Our efforts to clarify Bartonella quintana pathogenesis run on two parallel tracks. The first one concerns interactions between Bartonella quintana and endothelial cells by evaluation and modulation of apoptosis, signal transduction pathways and inflammation. The second one concerns some biological activities of Bartonella quintana endotoxin on human whole blood and endothelium. The elucidation of the mechanisms regulating the inflammatory/proliferative pattern of chronic clinical manifestations of Bartonella quintana infections may offer a contribution for addressing the pathogenesis of intracellular bacterial persistence.

Apoptosis↗

PubMed1999

Altered cytokine production after human herpes virus type 6 infection.

Several strategies allow viruses to elude the surveillance of the immune system and to establish persistent infection in the host. One of such mechanisms is the immunosuppression caused by the direct infection and functional impairment of immune cells. Human Herpes virus type 6 (HHV-6) is a typical immunosuppressive agent, as suggested by its tropism for both CD4+ and CD8+ T cells, B cells, monocytes/macrophages, megakaryocytes and NK cells. In this study the production of IL-10 and IL-12 by peripheral blood mononuclear cells (PBMC) was evaluated during HHV-6 infection "in vitro". Our results demonstrate that HHV-6 up-regulates IL-10 production by PBMC. Furthermore, our data suggest that rhIFN gamma addition counteracts the effect of HHV-6 in promoting IL-10 release. To gain more insight into the role of IFN gamma, anti-IFN gamma monoclonal antibodies were added to PBMC stimulated with LPS. Neutralization of endogenous IFN gamma upregulated IL-10 release. Furthermore, HHV-6 infection inhibited IFN gamma release induced by LPS in PBMC. No basal production of IL-12 was found in PBMC. Moreover, HHV-6 infection did not induce IL-12 release by PBMC. On the contrary, IL-12 was detected in the supernatants of PBMC treated with LPS with or without rhIFN gamma. In these experimental conditions the further addition of HHV-6 markedly impaired IL-12 production. Moreover, the neutralization of IL-10 resulted in a significant up-regulation of IL-12. Finally our data suggest that the immunodysregulation induced by HHV-6 could be accounted for by a shift from a Th-1 to a Th-2 type cytokine profile.

Cells, Cultured↗

PubMed1998

Kinetics of IL-8, MIP-1 alpha, TNF alpha, IL-1 beta, IL-1ra and IL-10 in human whole blood samples triggered by smooth and rough LPS.

An in vitro model for the study of sepsis mediators was used to investigate the effects of two different lipopolysaccharides (LPS), a smooth (LPS-S) and a rough (LPS-R) type, on the release of chemokines (IL-8 and MIP-1 alpha) and cytokines (TNF alpha, IL-1 beta, IL-1ra and IL-10) from human whole blood samples. TNF alpha level increased significantly vs. control, at 4 h and 8 h after the challenge with smooth and rough type of LPS respectively. Concentrations of the two chemokines studied, IL-8 and MIP-1 alpha, were significantly elevated following stimulation by both LPS, and reached concentrations significantly different from controls at 4, 8 and 24 h. After 24 h of incubation both LPS produced a significant IL-10 increase, although such change was more substantial with the rough type. Present data suggest an early and maintained release of chemokines regardless of the type of LPS used and often in absence of a significant increase in primary pro-inflammatory cytokines.

Chemokine CCL4↗

PubMed1997

Productive HHV-6 infection in differentiated U937 cells: role of TNF alpha in regulation of HHV-6.

This study characterizes the effect of differentiation on the resistance of the human monocytic cell line U937 to human herpes virus type 6 (HHV-6). The use of monocytic cell line has the advantage of avoiding genetic variations among different donors. The HHV-6 infection was compared in undifferentiated U937 cells and U937 cells differentiated with a combination of vitamin D3 and retinoic acid. Undifferentiated U937 cells were highly resistant to HHV-6 infection. Differentiation of U937 cells was accompanied by an increase in permissiveness for HHV-6 demonstrated in terms of extracellular virus production and viral antigen positive immunofluorescent cells. Tumor necrosis factor alpha (TNF alpha) appears to be an essential mediator during the first line defences of the host against viruses, even though its role during viral infection remains controversial. For this reason we examined the behaviour of TNF alpha in differentiated U937 upon HHV-6 infection. No basal production of TNF alpha was found in culture supernatants, while HHV-6 infection up-regulated TNF alpha release. The addition of human recombinant-TNF alpha to HHV-6 infected cells induced a marked cytotoxic effect accompanied by an increased release of extracellular virus, whereas it did not affect viral replication, as shown by the unmodified percentage of antigen positive cells. In conclusion, TNF alpha acts as a soluble mediator of cytotoxicity against HHV-6 infected U937 cells, but it fails to induce an antiviral state.

Antibodies, Blocking↗

PubMed1996

Impairment of immunological functions in genetically epilepsy-prone rats.

1. In genetically epilepsy-prone rats (GEPR-9s), which represent a natural genetic model of epilepsy, we observed that the number of peritoneal macrophages was significantly lower with respect to normal rats, and that some functional parameters (i.e. phagocytosis and intracellular killing) of these macrophages were impaired. 2. The count of lymphocyte populations showed a predominance of T-helper over T-cytotoxic/suppressor both in the spleen and lymph nodes. Moreover, an increased T-cell/B-cell ratio was observed in GEPR-9s. Flow cytometry revealed that GEPR-9s spleens possessed a large percentage of T-helper cells in comparison to normal rats. 3. By using concanavalin A-induced proliferation of GEPR-9s cultured lymphocytes, we have shown increased functional activation. 4. We suggest that the alterations in T-cell functions in GEPR-9s could be due to the involvement of the neuroendocrine system in the modulation of immunity, in the shift between Th1 and Th2, and in the activation of stress response.

Animals↗

PubMed1992

Teicoplanin reduces in-vitro reactivity and murine lethality of Salmonella minnesota R595 lipopolysaccharide.

Three different tests were performed to investigate the effect of teicoplanin on lipopolysaccharide (LPS). After incubation for 3 h with teicoplanin, LPS from Salmonella minnesota R595 showed reduced reactivity in the metachromatic dimethyl-methylene blue assay and the limulus amoebocyte lysate test. In addition, galactosamine-sensitized mice had an increased survival rate, from 29% to 72%, when teicoplanin was pre-incubated for 3 h with the LPS to be injected intraperitoneally. The results suggest that teicoplanin may have a neutralizing effect on LPS.

Animals↗

PubMed1991

Serum TNF alpha in mouse typhoid and enhancement of a Salmonella infection by anti-TNF alpha antibodies.

Tumour necrosis factor alpha (TNF alpha) was detected by the L929 cell assay in the sera of mice 1 h after large i.v. inocula of virulent Salmonella typhimurium C5. TNF alpha was not detectable in sera from innately susceptible BALB/c mice during the course of a lethal infection commencing from a low inoculum, or from resistant A/J mice during the course of a lethal or sublethal infection, but only 1 h after i.v. challenge with large numbers of organisms. Administration of a single dose of rabbit polyclonal anti-TNF alpha antiserum on day 1 had no effect on the early course of a lethal infection in A/J mice. However, the same treatment exacerbated a sublethal infection in A/J mice. Anti-TNF alpha treatment did not accelerate the early bacterial net growth rate in the RES. Instead, the cfu count in treated mice continued to increase past the point at which the host response suppressed a further increase in bacterial numbers (the plateau phase) in normal controls. A second dose of anti-TNF alpha antiserum on day 4 together with a higher but still sublethal challenge caused a lethal infection in A/J mice. The results indicate that TNF alpha is important in mediating the plateau phase in a salmonella infection, and its effect may be local.

Animals↗

PubMed1991

Aminoglycosides modify the in vitro metachromatic reaction and murine generalized Shwartzman phenomenon induced by Salmonella minnesota R595 lipopolysaccharide.

Endotoxin-neutralizing activity may be an important property for antibiotics to be used in severe sepsis. Several antibiotics, belonging to different classes, were evaluated as to their endotoxin-neutralizing ability, using the inhibition of an in vitro metachromatic assay for lipopolysaccharides and a murine generalized Shwartzman reaction model. Gentamicin, amikacin, and sisomicin have been found to share significant in vitro antiendotoxin activity at an antibiotic/endotoxin ratio as low as 1.0/5 (by weight) and to reduce the murine generalized Shwartzman reaction at an antibiotic/endotoxin ratio of 3.3/5.

Aminoglycosides↗

PubMed1991

Cefixime does not affect polymorphonuclear cell and monocyte functions from chronic lymphoid leukemia patients and from healthy donors.

It is well documented that to evaluate the efficacy of an antibiotic treatment it is important to know the relationships between the drug and the cells belonging to the immune system, by studying the possible effects on some cellular functions, particularly in immunosuppressed and immunodeficient patients. We describe the influence of cefixime, a new orally administered cephalosporin, on some polymorphonuclear cell (PMN) and monocyte functions from healthy donors and from patients affected by chronic lymphoid leukemia (CLL).

Administration, Oral↗

PubMed1991

Cefixime shows good effects on group A and group B beta-haemolytic streptococci.

There is continued interest in the development of oral beta-lactam compounds, which can be used clinically to treat various bacterial infections, particularly those caused by beta-haemolytic streptococci. Cefixime is a new orally active cephalosporin, with a broad spectrum of antibacterial activity, including Enterobacteriaceae, Haemophilus influenzae, Branhamella catarrhalis, Streptococcus pneumoniae and Streptococcus pyogenes. Cefixime is highly resistant to hydrolysis by most beta-lactamases. In this study the authors examined the effects of this molecule on Group A and Group B beta-haemolytic streptococci, recently isolated from clinical specimens in the authors' laboratory. MICs and the growth curves of 36 strains of Group A streptococci and the effects of sub-MICs on buccal cell adhesion were evaluated. The results show that concerning the sub-MIC cefixime effect on streptococci adherence, the treatment led to a decrease in adherence to the cells of the strains studied. Moreover cefixime showed good activity with 86.1% of the strains with MIC less than or equal to 0.5 microgram/ml, and the growth curves demonstrated that the molecule possesses a bactericidal effect after 3 h. Concerning Group B streptococci, 70.3% of the strains showed a MIC less than or equal to 2 micrograms/ml. In conclusion cefixime demonstrates good activity on beta-haemolytic streptococci, particularly those of Group A.

Anti-Infective Agents, Urinary↗

PubMed1991

Biological effects of Veillonella parvula and Bacteroides intermedius lipopolysaccharides.

A comparative study on the endotoxic effects of lipopolysaccharide (LPS) from Veillonella parvula ATCC 10790 and from Bacteroides intermedius BMH was performed using an in vivo approach in the C57BL/6 mouse. Phenol-water extracted LPS of such anaerobes was purified by ultracentrifugation and DNase/RNase digestion, and characterized by a metachromatic assay for endotoxins and by electrophoresis on SDS-polyacrylamide gel and silver staining. Mouse LD50 for V. parvula LPS was 1.479 mg and for B. intermedius greater than 3.160 mg. Sublethal amounts of the LPS from anaerobes as well as from facultative aerobes decreased daily water intake and body weight in the mouse. Endotoxin from Salmonella typhimurium SL1102, Escherichia coli 0128:B12 and V. parvula had a strong effect on water intake and body weight, whereas Bacteroides intermedius LPS activity was very weak. The results of the present report suggest that V. parvula LPS has a toxic in vivo activity on mouse, which is comparable to LPS from classic enteric organisms and stronger than B. intermedius LPS.

Animals↗

PubMed1990

Role of exogenous interferons on intrinsic antiviral activity of macrophages from patients affected by neoplasia.

Macrophages derived from in vitro cultured monocytes were infected with herpes simplex virus type 2. A marked impairment in the intrinsic antiviral activity was found in macrophages obtained from patients with breast cancer or melanoma. Moreover, the antiviral activity of macrophages from healthy donors, differentiated in serum from patients with neoplasia, was also impaired. The aim of this work was the evaluation of alpha, beta, gamma exogenous interferon in restoring the intrinsic antiviral activity of macrophages from patients affected by breast cancer or melanoma under different conditions. Pretreatment of macrophages with alpha, beta interferons, but not gamma interferon, restored their impaired intrinsic antiviral activity.

Aged↗

PubMed1990

In vitro activity of cefixime: correlation index between MIC and disc diffusion test.

In this study the in vitro antibacterial effects of cefixime are presented. Its activity was studied by evaluation of MICs, MBCs and the disc diffusion susceptibility method on Enterobacteriaceae, Staphylococcus aureus and Streptococcus pneumoniae. Moreover, the coefficient of correlation between MIC values and the disc diffusion susceptibility test was evaluated. The results support the wide antimicrobial activity of cefixime, which appears to be particularly effective against enterobacteria.

Anti-Infective Agents, Urinary↗

PubMed1988

Influence of sera from patients affected by neoplasia on some human macrophage functions.

It has been repeatedly reported that several functions of mononuclear cells are impaired in patients affected by neoplasia. Moreover, inhibitory activity of serum and tumor extracts on macrophages have been described. In a previous study, we found a marked impairment of the intrinsic antiviral activity of macrophages derived from monocytes isolated from peripheral blood of patients with breast carcinoma or melanoma compared with that from blood of normal subjects. The aim of the present work was to study whether this impairment was due to circulating inhibitory factors. Macrophages were differentiated in vitro in sera from patients with neoplasia and in sera from healthy donors and then challenged with herpes simplex virus type 2 (HSV-2). Macrophages from normal subjects, incubated with sera from patients, were significantly impaired in their intrinsic antiviral activity. These results support the possibility that circulating inhibitory factors influence the functionality of mononuclear phagocytes in the tumor-bearing host.

Adult↗