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We have studied the effect of H2O2 on the activity of the Escherichia coli Cu,ZnSOD showing that, unlike the bovine enzyme, this bacterial Cu,ZnSOD is highly resistant to inactivation by hydrogen peroxide. In view of the key role played by oxygen radicals in bacterial killing by phagocytes, we have tested the ability of E. coli strains expressing different amounts of Cu,ZnSOD in the periplasmic space to survive the phagocytic attack of activated macrophages. Overexpression of the enzyme effectively protected the bacterial cell from macrophage killing. The results obtained support the hypothesis that in pathogenic bacteria periplasmic Cu,ZnSOD may reduce the oxyradical damages induced by the respiratory burst and therefore be important in virulence.

We developed a method of identification of Listeria monocytogenes based on colony hybridization with nonradioactively labeled DNA probes, represented by the hly and inlA virulence-associated genes. The procedure described in this paper results simple, rapid, specific and reproducible. Since it can be performed in a short time, the above technique can be applied to detect L. monocytogenes from different source and constitutes a noteworthy and alternative tool to identify this gram-positive pathogenic bacterium.

The effect of growth hormone (GH) on the release of IL-1alpha and IFN-gamma from murine splenocytes was investigated. Their release from splenocytes activated by Salmonella enterica serovar Typhimurium lipopolysaccharide (LPS) 0.5 microg/ml was increased by c. 65% in the presence of GH 100 pg/ml. With splenocytes activated by S. Typhimurium porins 5 microg/ml, GH increased the production of both IL-1alpha and IFN-gamma by c. 56%. Polymyxin treatment abolished the cytokine-releasing activity of LPS but had no effect on the activity of the porin preparation.

The aim of this study was to verify whether Salmonella typhimurium porins can affect the expression of interleukin-1 (IL-1) and interleukin-6 (IL-6) genes. Human monocytes were treated with porins, and total RNAs were analysed by Northern blotting to evaluate the expression of IL-1 alpha, IL-1 beta and IL-6 in both treated and untreated cell cultures. Porins induced a significant increase in IL-1 and IL-6 transcripts. This increase was related to the dose of porins, and it peaked 5 hr after treatment. The same results were obtained when polymyxin B was added to the porin preparation to eliminate eventual traces of lipopolysaccharide (LPS) associated with porins. The porins-mediated increase in interleukin transcripts did not require de novo protein synthesis, and it was because of the enhanced half-life of IL-1 and IL-6 mRNAs, rather an increased rate of gene transcription. These data suggest that porins may affect inflammatory and immunological responses by enhancing the expression of cytokine genes.

The regulation by peptide hormones (Growth Hormone, Prolactin, Insulin) of cytokine secretion by splenocytes stimulated with Staphylococcal Enterotoxin A was studied. Growth hormone increases the release of IFN-gamma from splenocytes stimulated with Enterotoxin A by 50% but considerably decreases IL-1 alpha release by 93%. Prolactin decreases the release of IL-1 alpha by 80%, but has no significant effects on IFN-gamma release. Insulin causes a 50% decrease in IFN-gamma and 95% decrease in IL-1 alpha. IL-4 release was not changed. The results are discussed in terms of the possibility of an interesting function for these endocrine peptides which expands their range of biologic activities within the immune system.

The response of Salmonella typhimurium to low nutrient levels was determined by measuring the concentrations of lipids, carbohydrates, DNA, RNA, and proteins over a 32-day starvation period. Ultrastructural integrity was observed by transmission electron microscopy. Lipid and carbohydrate content of bacterial cells rapidly declined within the first 16 days, while DNA and proteins exhibited a more gradual decline over the 32 days of starvation. In contrast, RNA content did not decrease appreciably upon nutrient starvation. Structural damage occurred especially after 16 days of starvation. After 32 days of nutrient deprivation, we recorded degenerative cellular forms, a coccoidal cell shape, a decrease in cellular volume, and the loss of the three-layered outer membrane. The morphological and structural alterations correlated with virulence in infected animals. We observed a decrease in virulence of S. typhimurium after 9, 16, and 32 days of starvation, reaching a maximal decrease after 32 days of nutrient deprivation. The decrease in virulence correlated to surface hydrophobicity alterations, adherence to eukaryotic cells, and phagocytosis.

The authors describe a case of Spigelian hernia observed and treated. This hernia is uncommon, although the true incidence is probably greater than the small number of patients reported in literature. The signs and symptoms of the hernia are not always characteristic and then a correct diagnosis can be difficult. Sometime instrumental examination is essential for diagnosis, when clinical examination is not clear. Surgical repair as mandatory for a correct reconstruction of the abdominal wall and a prevention of recurrences.