The lateral supramalleolar flap has proved to be versatile for managing a variety of skin defects of the foot, ankle and lower third of the leg. An anatomical study has shown the reliability of a subcutaneous vascular network, supplied by terminal branches of the perforating branch of the peroneal artery. Our technical refinement consists in designing the skin flap more proximally on the lateral aspect of the leg, and mobilising it on its vascular fascio-subcutaneous pedicle. The flap provides considerable possibilities for covering more distal skin defects of the lower extremity.

Adult↗

PubMedDate not supplied

Listeria monocytogenes infection of Caco-2 cells: role of growth temperature.

The aim of the present study was to evaluate the role of temperature in the virulence of Listeria monocytogenes, a Gram-positive facultative intracellular food-borne pathogen. The capacity of bacteria grown at 37, 25 and 4 degrees C to develop haemolytic activity, to enter the Caco-2 enterocyte-like cell line and to multiply intracellularly was investigated. We demonstrated that L. monocytogenes penetration was not significantly influenced by the growth temperature of cultures and that bacteria grown at low temperature were capable of synthesizing internalin and, during the infection process, of restoring the haemolytic phenotype which is normally lacking in the extracellular environment at 4 and 25 degrees C. It can be concluded that L. monocytogenes, frequently present in numerous environmental sources and also in refrigerated food products, produces at low temperature, the virulence factors necessary to invade intestinal cells.

Colonic Neoplasms↗

PubMedDate not supplied

Involvement of reactive oxygen species in bacterial killing within epithelial cells.

Several non-phagocytic cells can actively generate the superoxide anion by NAD(P)H oxidases resembling the enzymatic complex typical of phagocytes. Overexpression of periplasmic Cu,ZnSOD rescues invasive E. coli strains from killing within epithelial cells, suggesting that superoxide generation by such cells can oxidatively damage invading bacteria. Pre-treatment of HeLa cells with diphenyl iodonium or 4'-hydroxy-3'-methoxyacetophenone, two inhibitors of NAD(P)H oxidase, significantly enhances intracellular survival of wild type invasive E. coli cells. On the contrary, these inhibitors have no effect on the intracellular survival of an invasive E. coli strain engineered to overexpress Cu,ZnSOD. These results support the hypothesis that superoxide generation by a NAD(P)H oxidase-like complex can limit bacterial survival within epithelial cells and suggest that the role of periplasmic Cu,ZnSOD in bacterial infections is not simply that of conferring protection against the phagocytic oxidative burst.

Enzyme Inhibitors↗

PubMedDate not supplied

Apoptotic death of Listeria monocytogenes-infected human macrophages induced by lactoferricin B, a bovine lactoferrin-derived peptide.

Listeria monocytogenes, an intracellular facultative food-borne pathogen, was reported to induce apoptosis in vitro and in vivo in a variety of cell types with the exception of murine macrophages. These cells represent the predominant compartment of bacterial multiplication and die as a result of necrosis. In this study we showed that human non-activated and IFN-gamma-activated macrophagic-like (THP-1) cells infected with L. monocytogenes, mainly die by necrosis rather than by an apoptotic process. Two natural products derived from bovine milk, lactoferrin and its derivative peptide lactoferricin B, are capable of regulating the fate of infected human macrophages. Bovine lactoferrin treatment of macrophages protects them from L. monocytogenes-induced death whereas lactoferricin B, its derivative peptide, determines a shifting of the equilibrium from necrosis to apoptosis.

Animals↗

PubMedDate not supplied

Iron availability influences aggregation, biofilm, adhesion and invasion of Pseudomonas aeruginosa and Burkholderia cenocepacia.

Pseudomonas aeruginosa and Burkholderia cenocepacia are predominant opportunistic pathogens in cystic fibrosis (CF) patients. In healthy humans the lower respiratory tract as well as all mucosa, contains a very low free iron concentration (10(-18) M), while in CF patients sputum iron concentration is very high, showing a median value of 63x10(-6) M. Accumulation of catalytic reactive iron heavily contributes to subsequent clinical complications in the lung disorders by the production of reactive oxygen species and increases bacterial growth and virulence. The data reported in this study indicate that low iron concentration (Fe3+ 1 microM)induced free-living forms and motility both in P. aeruginosa and B. cenocepacia, while high iron concentrations (Fe3+ 10 and 100 microM) stimulated aggregation and biofilm formation already in the fluid phases, so demonstrating that aggregation and biofilm formation are positively iron-modulated in these bacteria. Moreover, the different morphological forms (free-living, aggregates and biofilm) showed different capabilities of adhering and invading the bronchial cell line A549. P. aeruginosa PAO1 aggregates, and mostly biofilm, exerted the highest adhesion efficiency, while B. cenocepacia PV1 aggregates or biofilm the lowest. A significant reduction in invasion efficiency by P. aeruginosa biofilm and a significant increase in cell internalization by B. cenocepacia biofilm has been reported. Therefore, the iron availability is an important signal to which P. aeruginosa and B. cenocepacia counteract by leaving the motile free-living forms and entering into a new lifestyle, i.e. biofilm. These data could contribute to explain that the iron-overload of the sputum of CF patients, inducing nonmotile forms, aggregates and biofilm, may facilitate penetration of host epithelial barriers contributing to the establishment of infection, colonization, persistence and systemic spread of these opportunistic pathogens.

Biofilms↗

PubMedDate not supplied

[Selection in Polyporus versicolor of mutants producing laccase].

Following preceeding research on the production of laccase in Polyporus versicolor the A. has studied the various cultural conditions which are favourable to a good production of the enzyme. By selecting U.V. induced mutants it has been possible to isolate strains with a high production of the enzyme, in which the enzyme is either constitutive or inducible.

Aniline Compounds↗

PubMedDate not supplied

Involvement of bovine lactoferrin moieties in the inhibition of herpes simplex virus type 1 infection.

Bovine lactoferrin (BLf) is an iron binding protein folded in two lobes, N- and C-lobes. In this study we have reported the inhibitory activity towards herpes simplex virus type 1 (HSV-1) in vitro infection of BLf tryptic digested N- and C-lobes in comparison with the whole protein. The N-lobe and C-lobe exerted an anti-herpesvirus activity 50- and 10-fold lower than native BLf, respectively. In order to assess the phase of viral replication affected, lactoferrin-derived lobes were added to the cells at different non cytotoxic concentrations, during the whole cycle of viral infection or during viral attachment step, demonstrating that both lobes interfered with the early phases of infection. Among the BLf tryptic digested fragments, two negatively-charged small peptides deriving from N-lobe, previously shown effective towards HSV-1, have been further studied. We assessed that the net negative charge of these peptides was not responsible for the antiviral activity since their activity was not modified when the aspartic and glutamic acidic residues of these peptides were replaced with asparagine and glutamine, respectively. The experiments here reported confirm a pivotal role of N-lobe in inhibiting viral infection. However, the residual inhibiting activity of C-lobe and the similar efficacy shown by negatively or positively charged peptides strongly support the idea that the antiviral activity of bovine lactoferrin cannot be fully explained simply on the basis of competition between the protein and viral recognition sites for binding to glycosaminoglycans.

Journal Article↗

PubMedDate not supplied

Invasion of human cultured cells by Prevotella nigrescens.

Invasion of gingival and junctional epithelial cells has been recently proposed as a potentially relevant mechanism in the pathogenesis and recurrence of periodontal disease. The gram negative anaerobe Prevotella nigrescens was shown to be involved in the development of periodontal lesions in man, suggesting a possible involvement of invasivity as a mean to circumvent the host immune surveillance and other hostile factors. Appropriately designed invasion assays demonstrated that P. nigrescens efficiently invades human epithelial cells, through a mechanism whose efficiency is influenced by the phase of growth, by the multiplicity of infection, and by the cell line used, and that requires microfilament integrity, but is not affected by an impairment of microtubule organization. Intracellular replication assays suggested that P. nigrescens probably multiplies within Kb epithelial cells, causing extensive cell alterations. Invasion of gingival epithelial cells could consequently be a basic step in the virulence mechanism of the species.

Journal Article↗

PubMedDate not supplied