Delineation of the endemic and sporadic methicillin-resistant Staphylococcus aureus clones in a Czech hospital

The aim of this study was to define the endemic clones of methicillin-resistant Staphylococcus aureus (MRSA) among strains collected between September, 2001, and February, 2003, at the regional hospital of Novy Jicín, Czech Republic. The isolates were characterized by susceptibility tests, HindIII ribotyping, and pulsed-field gel electrophoresis. Representatives of each clonal type were analyzed by multilocus sequence typing and staphylococcal cassette chromosome mec (SCCmec) typing. The prevalence of the most important macrolide (ermA, ermB, ermC, and msrA) and aminoglycoside (aac6'-aph2", aph3', and ant4') resistance genes was evaluated as well. Our results document the existence of two international MRSA clones: (1) the Iberian clone (ST247:SCCmec IA:PFGE A:ribotype H2), endemic in the hospital and associated to a single multiresistant phenotype; and (2) clone EMRSA-15 (ST22:SCCmec IV:PFGE H-ribotype H7), appearing in the beginning of 2002 and associated with three phenotypes. These two clones could be distinguished by antibiogram, distribution of macrolide and aminoglycoside resistance genes (ermA, aac6'-aph2", ant4' versus ermC and msrA in a few isolates), production of beta-lactamase, and presence of enterotoxin A (in the Iberian clone).     

Intracellular lectin-binding sites in symbiont-bearingCrithidia species

Crithidia oncopelti, C. deanei, andC. desouzai are flagellates of the Trypanosomatidae family that present bacterium-like endosymbionts in their cytoplasm. Direct and indirect lectin-gold labeling techniques were used at the electron microscopic level in Lowicryl K4M-embedded cells to demonstrate the presence of intracellular lectin-binding sites. We used the lectinsUlex europaeus I, Griffonia simplicifolia II, Ricinus communis I, Arachis hypogaea, G. simplicifolia I, Wistaria floribunda, Limulus polyphemus, andCanavalia ensiformis, which recognize -l-fucose, - and -N-acetylglucosamine, -galactose and -N-acetylgalactosamine, -galactose, -galactose, -N-acetylgalactosamine, sialic acid and -d-mannose, and -d-glucose residues, respectively. The nucleus was the cellular structure most frequently labeled by the lectins. The Golgi complex was seldom labeled, whereas the endoplasmic reticulum and the flagellar pocket presented a large number of binding sites. Symbionts had their two unit membranes weakly labeled by the different lectins but displayed no labeling of the space between the membranes.     

Three-year assessment of methicillin-resistant Staphylococcus aureus clones in Latin America from 1996 to 1998

Four hundred ninety-nine methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered from 1996 to 1998 from 22 hospitals in five countries of Latin America-Argentina, Brazil, Chile, Uruguay and Mexico-were examined for antimicrobial susceptibility and clonal type in order to define the endemic clones in those hospitals. The hybridization of ClaI restriction digests with the mecA- and Tn554-specific DNA probes combined with pulsed-field gel electrophoresis of chromosomal SmaI digests (ClaI-mecA::ClaI-Tn554::PFGE clonal types) documented not only the predominance and persistence of the Brazilian clone (XI::B::B) in Brazil (97%) and Argentina (86%) but also its massive dissemination to Uruguay (100%). Moreover, a close relative of the Brazilian clone (XI::kappa::B) was highly represented in Chile (53%) together with a novel clone (47%) (II::E'::F) resistant to pencillin, oxacillin, ciprofloxacin, chloramphenicol, clindamycin, erythromycin, and gentamicin. A unique clonal type (I::NH::M) was detected in Mexico among pediatric isolates and was resistant to penicillin, oxacillin, and gentamicin only. This study clearly documented the very large capacity for geographic expansion and the persistence of the Brazilian clone, contributing not only to the increasing uniformity of the MRSA in South America but worldwide as well.     

Molecular epidemiology of methicillin-resistant Staphylococcus aureus in Colombian hospitals: dominance of a single unique multidrug-resistant clone

The first study on the molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) isolates from Colombia was performed as part of a global surveillance established by the CEM/NET Initiative, under Project RESIST. Seventy-six MRSA isolates recovered from five hospitals during 1996-1998 were analyzed by the hybridization of ClaI restriction digests with mecA- and Tn554-specific probes, and by pulsed-field gel electrophoresis (PFGE) of chromosomal SmaI digests. All MRSA isolates, with one exception, belonged to a single clonal type II::NH::D. This clone, which was previously described among MRSA isolates recovered in the early 1990s in European and New York and South American hospitals, showed resistance to beta-lactam antibiotics only and appeared to be associated almost exclusively with pediatric infections ("Pediatric clone" of MRSA). While sharing identical molecular typing properties with the Pediatric clone, the Colombian isolates differed by extensive multidrug resistance and were recovered from patients of all ages. It is also noteworthy that the Brazilian clone of MRSA (XI::B::B), another multidrug-resistant international clone currently widely spread in Brazil, Argentina, Uruguay, Chile, and also in several European countries, was completely absent from this set of isolates from Colombia.     

Differential effects of eight metal ions on lymphocyte differentiation antigens in vitro

In vitro studies were conducted to determine the effects of metal ions known to be released from metallic implants in vivo on the expression of lymphocyte surface antigens. Normal human peripheral blood lymphocytes were exposed to various concentrations of metal ions (Fe3+, Ni2+, Co2+, Mo6+, V5+, Cr6+, Cr3+, and Ti3+) for 30 min at 37 degrees C in a 5% CO2 atmosphere, and then analyzed for their ability to form rosettes with sheep red blood cells. Following this preliminary analysis, lymphocytes were exposed to the metal ions found to inhibit the E-rosette reaction (Fe3+, Ni2+, and Co2+) in order to determine which of the following surface antigens were affected: CD2, CD3, CD4, CD8, CD1, CD22, CD10, and HLA-DR. Our results showed that the in vitro treatment of lymphocytes with Fe3+ or Co2+ caused inhibition of CD2 only, whereas Ni2+ caused inhibition of both CD2 and CD3 antigens. These findings suggest that Fe3+, Co2+, and Ni2+ ions may interfere with T cell activation since both CD2 and CD3 are involved in that process.     

Developmental changes in calcium dynamics, protein kinase C distribution and endoplasmic reticulum organization in human preimplantation embryos

Developmental changes in the Ca²⁺ dynamics of human zygotesand preimplantation embryos were related to changes in the distributionof endoplasmic reticulum (ER) and protein kinase C (PKC). Thefertilization-induced Ca²⁺ oscillations were typically observedover >5 h, were ryanodine-sensitive and showed a periphery-to-centrepropagation of Ca²⁺ waves. At the same time, ER and PKC wereaccumulated in the cell periphery. After the appearance of pronuclei,ryanodine-sensitive Ca²⁺ oscillations of lower amplitude andfrequency were observed until the pronuclear breakdown. However,Ca²⁺ waves then began in the perinuclear region, in the areaof ER and PKC accumulation and spread towards the cell periphery.During the second to fourth cell cycle, small sinusoidal Ca²⁺fluctuations were observed; sparse higher-amplitude Ca²⁺ spikes,superimposed on these basal fluctuations, appeared shortly beforecell division. The sinusoidal Ca²⁺ fluctuations were asynchronousin individual blastomeres and disappeared progressively in arrestedembryos. The direction of Ca²⁺ wave propagation and the distributionof ER and PKC were similar to the situation observed in pronuclearzygotes. In contrast to the zygotes, ryanodine did not arrestthe Ca²⁺ oscillations but augmented their amplitude and frequency.These data suggest that human pre-embryos use different mechanismsof Ca²⁺ signalling in the early post-fertilization period, duringthe pronuclear development and during cleavage. calcium dynamics/endoplasmic reticulum/human preimplantation embryos/protein kinase C/ryanodine     

Clinical and molecular genetic features of pulmonary hypertension in patients with hereditary hemorrhagic telangiectasia

BACKGROUND: Most patients with familial primary pulmonary hypertension have defects in the gene for bone morphogenetic protein receptor II (BMPR2), a member of the transforming growth factor beta (TGF-beta) superfamily of receptors. Because patients with hereditary hemorrhagic telangiectasia may have lung disease that is indistinguishable from primary pulmonary hypertension, we investigated the genetic basis of lung disease in these patients. METHODS: We evaluated members of five kindreds plus one individual patient with hereditary hemorrhagic telangiectasia and identified 10 cases of pulmonary hypertension. In the two largest families, we used microsatellite markers to test for linkage to genes encoding TGF-beta-receptor proteins, including endoglin and activin-receptor-like kinase 1 (ALK1), and BMPR2. In subjects with hereditary hemorrhagic telangiectasia and pulmonary hypertension, we also scanned ALK1 and BMPR2 for mutations. RESULTS: We identified suggestive linkage of pulmonary hypertension with hereditary hemorrhagic telangiectasia on chromosome 12q13, a region that includes ALK1. We identified amino acid changes in activin-receptor-like kinase 1 that were inherited in subjects who had a disorder with clinical and histologic features indistinguishable from those of primary pulmonary hypertension. Immunohistochemical analysis in four subjects and one control showed pulmonary vascular endothelial expression of activin-receptor-like kinase 1 in normal and diseased pulmonary arteries. CONCLUSIONS: Pulmonary hypertension in association with hereditary hemorrhagic telangiectasia can involve mutations in ALK1. These mutations are associated with diverse effects, including the vascular dilatation characteristic of hereditary hemorrhagic telangiectasia and the occlusion of small pulmonary arteries that is typical of primary pulmonary hypertension.     

Nitric oxide mediates the inhibition of neutrophil migration induced by systemic administration of LPS

To investigate the role of NO in the inhibition of neutrophil migration by circulating endotoxin, mice were pretreated with NO synthase inhibitors or with a free radical scavenger (D-penicillamine), before intravenous LPS injection. LPS dose-dependently inhibited the thioglycollate-induced neutrophil migration into the peritoneal cavities. Aminoguanidine, a selective inducible NO synthase inhibitor, abolished the inhibition of neutrophil migration and the increase in serum nitrate levels induced by a nonlethal dose of LPS. During lethal endotoxemia aminoguanidine partially abolished the neutrophil migration inhibition. Additionally, D-penicillamine prevented the inhibition of neutrophil migration caused by LPS. However, Nitro-L-Arginine, a selective constitutive NO synthase inhibitor, did not prevent neutrophil migration inhibition. Aminoguanidine treatment did not affect the systemic increased levels of TNF-, IL-1, and IL-10, suggesting that NO is the final mediator involved in the inhibition of neutrophil migration. Our results suggest that NO released by the inducible NO synthase mediates the inhibition of neutrophil migration mediated by circulating LPS.     

Fluconazole induces genotoxicity in cultured human peripheral blood mononuclear cells via immunomodulation of TNF-α, IL-6, and IL-10: new challenges for safe therapeutic regimens

Context: Fluconazole (FNZ) is a drug used in antifungal therapy. However, the minimum FNZ dose to interfering with immune responses or inducing DNA damage is still unknown.

Objective: This study investigated the toxicological profile of FNZ on cultured human peripheral blood mononuclear cells (PBMCs) treated with different concentrations of this azole.

Materials and methods: Cultured PBMCs were exposed to FNZ (6, 12, 30, 60 and 120?μg/mL) and the toxicological profile was assessed by the following parameters: cytotoxic and nuclear division index (necrotic, apoptotic and viable cells), DNA damage (alkaline comet test), mutagenic potential (micronucleus test), cytokine modulation (IL-1, IL-6, IL-10, TNF-α, IFN-γ), and predictive toxicity (Osiris^® and LAZAR^® programs).

Results: Our results demonstrated that FNZ induced cellular DNA damage and mutagenicity at concentrations above the plasma peak (>30?μg/mL) and 6?μg/mL, respectively, which was associated with increased TNF-α, and decrease IL-6 and IL-10 concentrations. These effects may be related to increased apoptosis and cytotoxic nuclear division index in the cultured PBMCs. In silico results indicated potential mutagenic, tumorigenic, irritant, and carcinogenic effects, which were partially confirmed by the above assays.

Discussion and conclusions: Together, these findings suggest the need to rationalize the use of FNZ, especially if it is used for long periods or with concomitant pathologies requiring azole therapy that may increase FNZ's plasma concentration.