Pathogenic mechanisms and current epidemiological status of HEV infection in asymptomatic blood donors and patients with chronic diseases.

In recent years, the seroprevalence of anti-hepatitis E virus immunoglobulins (HEV) has increased in European countries with significant variability among the different geographical areas. HEV infection is spread in a wide range of animal species of which domestic pigs and wild boar represent the main reservoirs of genotype 3 and 4 (the genotypes present also in Europe). European citizens are incidental hosts, mainly infected by direct contact or consumption of foods derived from undercooked or insufficient hygiene handling infected pork products or wild boar meat. Epidemiologically, the HEV incidence is low in humans but serological data show a high proportion of subclinical infection caused by genotypes 3 or 4. In the general population, asymptomatic infection represents a high potential risk in particular subjects such as blood component recipients or occupationally exposed workers. This review offers a landscape of the current epidemiological status of HEV infection (genotypes 1, 2, 3, 4, 7) both in European asymptomatic subjects, patients with chronic diseases, and domestic pig impact on humans. We also underline advantages/disadvantages of high sensitivity and specificity tests using for detecting viral RNA or anti-HEV antibodies.

Phospholamban ablation rescues the enhanced propensity to arrhythmias of mice with CaMKII-constitutive phosphorylation of RyR2 at site S2814.

KEY POINTS: Mice with Ca(2+) -calmodulin-dependent protein kinase (CaMKII) constitutive pseudo-phosphorylation of the ryanodine receptor RyR2 at Ser2814 (S2814D(+/+) mice) exhibit a higher open probability of RyR2, higher sarcoplasmic reticulum (SR) Ca(2+) leak in diastole and increased propensity to arrhythmias under stress conditions. We generated phospholamban (PLN)-deficient S2814D(+/+) knock-in mice by crossing two colonies, S2814D(+/+) and PLNKO mice, to test the hypothesis that PLN ablation can prevent the propensity to arrhythmias of S2814D(+/+) mice. PLN ablation partially rescues the altered intracellular Ca(2+) dynamics of S2814D(+/+) hearts and myocytes, but enhances SR Ca(2+) sparks and leak on confocal microscopy. PLN ablation diminishes ventricular arrhythmias promoted by CaMKII phosphorylation of S2814 on RyR2. PLN ablation aborts the arrhythmogenic SR Ca(2+) waves of S2814D(+/+) and transforms them into non-propagating events. A mathematical human myocyte model replicates these results and predicts the increase in SR Ca(2+) uptake required to prevent the arrhythmias induced by a CaMKII-dependent leaky RyR2. ABSTRACT: Mice with constitutive pseudo-phosphorylation at Ser2814-RyR2 (S2814D(+/+) ) have increased propensity to arrhythmias under ß-adrenergic stress conditions. Although abnormal Ca(2+) release from the sarcoplasmic reticulum (SR) has been linked to arrhythmogenesis, the role played by SR Ca(2+) uptake remains controversial. We tested the hypothesis that an increase in SR Ca(2+) uptake is able to rescue the increased arrhythmia propensity of S2814D(+/+) mice. We generated phospholamban (PLN)-deficient/S2814D(+/+) knock-in mice by crossing two colonies, S2814D(+/+) and PLNKO mice (SD(+/+) /KO). SD(+/+) /KO myocytes exhibited both increased SR Ca(2+) uptake seen in PLN knock-out (PLNKO) myocytes and diminished SR Ca(2+) load (relative to PLNKO), a characteristic of S2814D(+/+) myocytes. Ventricular arrhythmias evoked by catecholaminergic challenge (caffeine/adrenaline) in S2814D(+/+) mice in vivo or programmed electric stimulation and high extracellular Ca(2+) in S2814D(+) /(-) hearts ex vivo were significantly diminished by PLN ablation. At the myocyte level, PLN ablation converted the arrhythmogenic Ca(2+) waves evoked by high extracellular Ca(2+) provocation in S2814D(+/+) mice into non-propagated Ca(2+) mini-waves on confocal microscopy. Myocyte Ca(2+) waves, typical of S2814D(+/+) mice, could be evoked in SD(+/+) /KO cells by partially inhibiting SERCA2a. A mathematical human myocyte model replicated these results and allowed for predicting the increase in SR Ca(2+) uptake required to prevent the arrhythmias induced by a Ca(2+) -calmodulin-dependent protein kinase (CaMKII)-dependent leaky RyR2. Our results demonstrate that increasing SR Ca(2+) uptake by PLN ablation can prevent the arrhythmic events triggered by SR Ca(2+) leak due to CaMKII-dependent phosphorylation of the RyR2-S2814 site and underscore the benefits of increasing SERCA2a activity on SR Ca(2+) -triggered arrhythmias.

Distribution of mecA among methicillin-resistant clinical staphylococcal strains isolated at hospitals in Naples, Italy.

Two hundred and twenty strains of Staphylococcus isolated in Naples, Italy, were surveyed for the distribution of the mecA, the structural gene for penicillin-binding protein 2a, which is the genetic determinant for methicillin-resistance in staphylococci. Screening by a cloned mecA, revealed that of 220 strains, 43 were methicillin-resistant (19.5%) and 177 were methicillin-susceptible (80.5%). Among the 43 resistant strains 23 (53.5%) carried mecA in their genome and 20 (46.5%) did not carry mecA, in spite of their resistance to methicillin. Every group was submitted to the AP-PCR profiling. A quantitative analysis of the patterns divided strains into four different clusters for methicillin-resistant mecA-negative and two different clusters for methicillin-resistant mecA-positive with primer 1, while no clusters were noted with primer 7. We conclude that these clinical isolates from our area, were not found to belong to a single clone, although the predominance of four methicillin-resistant mecA-negative genotypes were noted.

Insulin regulates IL-1alpha, Ifn-y and IL-4 release from murine splenocytes stimulated with staphylococcal protein A, toxic shock syndrome toxin-1 and streptococcal lysin S.

In this study, changes were investigated in release of IL-1alpha, IFN-gamma and IL-4 from mouse splenocytes stimulated with staphylococcal protein A (SpA), toxic shock syndrome toxin-1 (TSST-1) or streptococcal lysin S (SLS) in the presence of insulin. The results show that insulin-treated splenocytes stimulated by SpA had a 25% increase in IFN-gamma release and a 50% decrease in IL-4 compared with splenocytes treated with SpA alone. IL-1alpha release was unchanged compared with controls. Insulintreated splenocytes stimulated with TSST-1 had a 30% fall in IL-1alpha and IFN-gamma release compared with controls. There were no changes in IL-4 release. Splenocytes stimulated with SLS after insulin treatment increased their release of IL-1alpha and IFN-gamma by 50%, whereas IL-4 release was unchanged. The data suggest that the insulin may have important functional implications in immunoregulation.

Growth hormone release of interleukin-1 alpha, interferon-gamma and interleukin-4 from murine splenocytes stimulated with staphylococcal protein A, toxic shock syndrome toxin-1 and streptococcal lysin S.

We investigated changes in the IL-1 alpha, IFN-gamma and IL-4 release from splenocytes in the presence of growth hormone (GH). Splenocytes were stimulated with Protein A (PA), Toxic Shock Syndrome Toxin-1 (TSST-1) and Streptolysin S (SLS). In the presence of GH, splenocytes stimulated with PA, induced a 40% and 50% drop in IL-1 alpha and IFN-gamma release respectively, compared to controls, while no changes were shown in IL-4 release. The release of IFN-gamma by TSST-1-stimulated splenocytes fell by 30%, while no changes were shown in IL-1 alpha and IL-4 release after GH. The release of IL-1 alpha by SLS-stimulated splenocytes increased by 50% in the presence of GH. No changes were shown in IFN-gamma and IL-4 release. The results are discussed in terms of the possibility of an expanding function for these endocrine peptides within the immune system.

Prolactin regulates IL-1 alpha, IFN-gamma and IL-4 release from mouse splenocytes stimulated with some staphylococcal and streptococcal toxins.

This study investigates changes in IL-1 alpha, IFN-gamma and IL-4 from mouse splenocytes stimulated with Staphylococcal Protein A (PA), or Toxic Shock Syndrome Toxin-1 (TSST-1), or Streptococcal lysin S (SLS) after exposure to Prolactin (PRL). In the presence of PRL, IL-1 alpha and IFN-gamma induction by PA-stimulated splenocytes was reduced by 74% and 25% respectively. On the other hand, IL-4 release was enormously increased. The ability of TSST-1 to induce IFN-gamma release was decreased by 32% after PRL. IL-1 alpha and IL-4 was unchanged compared to controls. In the presence of PRL, IFN-gamma release from splenocytes stimulated with SLS, was increased by 60%, while no changes were shown in IL-1 alpha and IL-4 release.

Presence of Legionella spp. in thermal springs of the Campania region of south Italy.

Water samples from 66 thermal springs in the Campania region of South Italy were cultured for Legionella spp., Pseudomonas aeruginosa, and indicators of faecal pollution. The temperature of the sources ranged from 21 degrees C to 59.5 degrees C. Legionella pneumophila, serogroup 7-10, was isolated from two out of 60 sources on the Island of Ischia and Legionella dumoffii from one mainland source. The temperatures of these sources were 35.2 degrees C, 48.2 degrees C, and 52.0 degrees C respectively. Twelve sources were positive for P. aeruginosa and 6 for Escherichia coli. Our results found that Legionella spp. were present in only three thermal springs, indicating that in the hydrothermal area of the Campania region the presence of this microbial species is very scarce.

Growth hormone modulates IL-alpha and IFN-gamma release by murine splenocytes activated by LPS or porins of Salmonella typhimurium.

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.

Prolactin and insulin regulate the release of IL-1-alpha and IFN-gamma from murine splenocytes activated with porins or LPS of Salmonella typhimurium.

Murine splenocytes treated with prolactin (PRL) or insulin were stimulated in vitro with porins or lipopolysaccharide (LPS) of Salmonella typhimurium. It was seen that PRL inhibits the release of IFN-gamma from splenocytes treated with porins by about 20% while having no effect on the release of IL-1-alpha. Splenocytes porin-stimulated splenocytes exhibited a remarkable increase in IL-1-alpha release (100%) and a diminished release of IFN-gamma (about 50%) in the presence of insulin. The splenocytes stimulated with LPS had a reduced release of IL-1-alpha (75%) and IFN-gamma (about 50%) when insulin was added. The data suggest that classical endocrine system participates in a bioregulatory feedback loop that may prevent unwanted toxicity from cytokine excess. However, some bacterial products sometimes enormously unbalance this regulatory network.

Effect of growth hormone, prolactin and insulin on the release of IL-1 alpha, IFN-gamma and IL-4 by staphylococcal enterotoxin A-stimulated splenocytes.

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.

Biological activities--lethality, Shwartzman reaction and pyrogenicity--of Salmonella typhimurium porins.

Porins isolated from Salmonella typhimurium and found to contain less than 0.1% w/w of LPS, were found to be lethal at a dose of 100 ng to both LPS-responder (BALB/cByJ) and non-responder (C3H/HeJ) mice sensitized with D-galactosamine. This lethal action could be prevented by anti-TNF-alpha serum given intravenously 10 min before the porin injection but not by polymyxin-B mixed with the porins in a ratio of approximately 300 moles polymyxin-B per mole of porin. The porin preparation was also pyrogenic to rabbits at a dose of 1 microgram/kg and elicited a local Shwartzman reaction when used as the sensitizing and eliciting agent; these reactions were also present when the porins were mixed with polymyxin-B.

Toxic effect on human spermatozoa by Chlamydia trachomatis purified lipopolysaccharide.

We have investigated the effect that lipopolysaccharide extracted from Chlamydia trachomatis has on human spermatozoa. A lipopolysaccharide of 0.1 microgram ml-1 caused a spermatozoa mortality rate of 65 +/- 4% evaluated by eosin exclusion test. The toxic activity occurred rapidly even after brief incubation times, reaching the maximum (100% mortality) within 60 min.

Biological activities of cell envelope fragments of the archaeobacterium Sulfolobus solfataricus: lethal toxicity, local hypersensitivity, pyrogenicity and spleen lymphocyte mitogenicity.

The sensitizing effect and the local and general toxicity related to membrane components of the archaeobacterium Sulfolobus solfataricus was studied. Cell envelope fragments were biologically active but this activity was lost upon separation of the lipid and protein components. The envelope fragments exerted lethal effects on mice sensitized with D-galactosamine that were prevented by pretreatment with anti-TNF-alpha serum. This lethal activity occurred in both LPS-responder (BALB/cByJ) and LPS-nonresponder (C3H/HeJ) mouse strains. In addition, Sulfolobus envelope fragments tested in rabbits caused a local Schwartzman reaction, and showed pyrogenic activity. In vitro, the envelope fragments that act on spleen lymphocytes of the LPS-responder (BALB/cByJ) and LPS-nonresponder (C3H/HeJ) mice caused an uptake of [3H]thymidine similar to that caused by concanavalin A. A similar toxic activity to that exerted by eubacteria is therefore exerted by this non-pathogenic archaeobacterium despite the difference in surface chemistry.

Exchange of phospholipids between Escherichia coli cells and environment.

We studied the exchange of phospholipids between Escherichia coli K-12 cells and the suspension medium containing inactivated guinea-pig serum. In this medium, the release of 3H-labelled phospholipids was proportional both to the quantity of serum and to the temperature of incubation. No phospholipids were released when no guinea-pig serum was added to the medium, or the incubation temperature was 4 degrees C. The release of phospholipids into the medium was accompanied by an uptake of serum phospholipids by the cells, as demonstrated by incorporation of labelled phospholipids from the suspension medium. We conclude that an exchange occurs between the cellular phospholipids and those of the medium. Control tests with 3H-thymidine showed that cellular lysis was not involved.

Molecular organization and dynamics of the outer membrane of Salmonella thyphimurium mutant strains detected by frequency domain fluorometry.

The fluorescence decay of 1,6-diphenyl-1,3,5-hexatriene (DPH) in the outer membrane bilayer of two mutant strains of Salmonella thyphimurium, i.e., SH 5014 and SH 6261, at different temperatures was analyzed in terms of continuous Lorentzian lifetime distributions. The results were compared with those obtained for the free fluorophore in an isotropic nonviscous solvent. The incorporation of DPH in the outer membrane fragments resulted in a broadening of the lifetime distribution which was attributed to the microenvironmental heterogeneity of the membrane bilayer for the extrinsic fluorophore. The differences observed between the two types of membrane bilayers were interpreted in terms of a different molecular organization and, to a lesser extent, in terms of a different fluidity. The comparison between the DPH lifetime distributions obtained using two different excitation wavelengths, i.e., 280 and 350 nm, suggested that the structural organization of the membrane domains, which are richest in proteins, is almost identical in the two examined mutant strains. This observation indicates that the different susceptibility of the two mutant strains toward phagocytosis and complement-mediated lytic action may depend on the molecular organization and dynamics of the lipid regions far from those containing proteins.

Serum-mediated killing of Salmonella typhimurium and Escherichia coli mutants which share a different content of major proteins.

Salmonella typhimurium and Escherichia coli K12 mutants of R chemotype, with varying contents of major proteins, were studied with respect to serum-mediated killing. The mutants demonstrated a different susceptibility to serum lytic action. These results were related to phospholipid and fatty acid content, as well as different physico-chemical surface properties, such as outer membrane fluidity. Tests were carried out on all parameters considered in the literature to demonstrate the resistance to complement. Our results showed that in sensitive strains such as Salmonella strains SH6261, SH6378, SH5551, SH6017 and E. coli PC0479 tests taken alone were not sufficient to explain the resistance to complement. Therefore, complement susceptibility is probably determined by many factors influencing the microheterogeneity of the membrane system.

Porin content modifies resistance of Salmonella typhimurium to phagocytosis.

Mutants of Salmonella typhimurium, which contain different quantities of outer membrane proteins, show different susceptibility to phagocytosis. We correlate susceptibility to phagocytosis with molecular surface characteristics which are responsible for invasiveness and virulence of bacteria.

Protection of Escherichia coli K12 structural integrity by Ca2+ and Mg2+ in bactericidal and bacteriolytic tests.

Escherichia coli K12 suspended in different media showed a loss of phospholipids. Mg2+ and Ca2+ 0.01 M prevented phospholipid loss and stabilized Escherichia coli K12 for bactericidal and bacteriolytic assays.

Clearance studies on the renal action of porins extracted from Salmonella typhimurium.

The effects of porins on renal hemodynamics and on the renal handling of salt and water were studied in rats. The animals injected with 100 micrograms/kg of porins showed an important change in renal potassium handling. In fact the total potassium excretion decreased significantly (p less than 0.02) from 1.11 +/- 0.13 to 0.495 +/- 0.069 muEq/min/100 g and was significantly associated to a reduction of fractional potassium excretion from 21.6 +/- 4.1% to 12.53 +/- 0.95% (p less than 0.001). It is speculated that porins have the capability to close the potassium channels.

Some biological activities of Eikenella corrodens major outer membrane proteins.

Major outer membrane proteins of Eikenella corrodens, an organism frequently isolated from patients with periodontal disease, were tested for some biological activities. Mouse peritoneal macrophages, exposed at low concentrations of the above-mentioned proteins (between 0.05 and 5 micrograms/ml), showed evident and marked morphological modifications consisting of increases in the size and vacuolation of the cells. Higher concentrations showed a toxic effect. Low concentrations resulted in a selective release of lysosomal enzymes without any significant release of lactatedehydrogenase, and cytoplasmic marker; while concentrations of 25-50 micrograms/ml, which were toxic in trypan-blue exclusion test, increased LDH release. Eikenella corrodens major proteins increased the platelet aggregation of ADP and thrombin. The residual complement activity of serum samples incubated with various amounts of proteins at 37 degrees C for 30 minutes appeared strongly reduced with respect to controls, thus showing a consumption of the complement components. These results suggested that Eikenella corrodens major proteins may play a role in the development of periodontal lesions.