Culture of mouse peritoneal macrophages with mouse serum induces lipid bodies that associate with the parasitophorous vacuole and decrease their microbicidal capacity against Toxoplasma gondii

Lipid bodies [lipid droplets (LBs)] are lipid-rich organelles involved in lipid metabolism, signalling and inflammation. Recent findings suggest a role for LBs in host response to infection; however, the potential functions of this organelle in Toxoplasma gondii infection and how it alters macrophage microbicidal capacity during infection are not well understood. Here, we investigated the role of host LBs in T. gondii infection in mouse peritoneal macrophages in vitro. Macrophages cultured with mouse serum (MS) had higher numbers of LBs than those cultured in foetal bovine serum and can function as a model to study the role of LBs during intracellular pathogen infection. LBs were found in association with the parasitophorous vacuole, suggesting that T. gondii may benefit from this lipid source. Moreover, increased numbers of macrophage LBs correlated with high prostaglandin E2 (PGE2) production and decreased nitric oxide (NO) synthesis. Accordingly, LB-enriched macrophages cultured with MS were less efficient at controlling T. gondii growth. Treatment of macrophages cultured with MS with indomethacin, an inhibitor of PGE2 production, increased the microbicidal capacity against T. gondii. Collectively, these results suggest that culture with MS caused a decrease in microbicidal activity of macrophages against T. gondii by increasing PGE2 while lowering NO production.

Developmental effects of basic fibroblast growth factor and platelet-derived growth factor on glial cells in a three-dimensional cell culture system.

In order to study peptide growth factor action in a three-dimensional cellular environment, aggregating cell cultures prepared from 15-day fetal rat telencephalon were grown in a chemically defined medium and treated during an early developmental stage with either bovine fibroblast growth factor (bFGF) or platelet-derived growth factor (PDGF homodimers AA and BB). A single dose (5-50 ng/ml) of either growth factor given to the cultures on day 3 greatly enhanced the developmental increase of the two glia-specific enzyme activities, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) and glutamine synthetase (GS), whereas it had relatively little effect on total protein and DNA content. Distinct patterns of dose-dependency were found for CNP and GS stimulation. At low concentrations of bFGF (0.5-5 ng/ml) and at all PDGF concentrations applied, the oligodendroglial marker enzyme CNP was the most affected. A relatively small but significant mitogenic effect was observed after treatment with PDGF, particularly at higher concentrations or after repetitive stimulation. The two PDGF homodimers AA and BB were similar in their biological effects and potency. The present results show that under histotypic conditions both growth factors, bFGF and PDGF, promote the maturation rather than the proliferation of immature oligodendrocytes and astrocytes.

The Impact of Personality and Culture on the Job Demands-Control Model of Job Stress

Among the various work stress models, one of the most popular has been the job demands-control (JDC) model developed by Karasek (1979), which postulates that work-related strain is highest under work conditions characterized by high demands and low autonomy. The absence of social support at work further increases negative outcomes. This model, however, does not apply equally to all individuals and to all cultures. This review demonstrates how various individual characteristics, especially some personality dimensions, influence the JDC model and could thus be considered buffering or moderator factors. Moreover, we review how the cultural context impacts this model as suggested by results obtained in European, American, and Asian contexts. Yet there are almost no data from Africa or South America. More crosscultural studies including populations from these continents would be valuable for a better understanding of the impact of the cultural context on the JDC model.

Exposition internationale des industries et du travail de Turin, 1911. Groupe XVI. Classe 90 (A et B). Produits de la grande culture. M. le Dr Bousquet, rapporteur. Classe 102 B. Corps gras, huiles végétales et animales, suifs, cires, etc. M. C. Artus, rapporteur. Classe 80. Météorologie, géognosie et géologie agricoles. M. le Dr Thouvenin, rapporteur

Comprend : Corps gras, huiles végétales et animales, suifs, cires

Institut Pasteur, laboratoire du professeur [Jean] Danysz, préparation du virus contre les rats, 1re préparation du bouillon de culture : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57064

Vancomycin-intermediate Staphylococcus aureus selected during vancomycin therapy of experimental endocarditis are not detected by culture-based diagnostic procedures and persist after treatment arrest.

OBJECTIVES: Laboratory detection of vancomycin-intermediate Staphylococcus aureus (VISA) and their heterogeneous VISA (hVISA) precursors is difficult. Thus, it is possible that vancomycin failures against supposedly vancomycin-susceptible S. aureus are due to undiagnosed VISA or hVISA. We tested this hypothesis in experimental endocarditis.¦METHODS: Rats with aortic valve infection due to the vancomycin-susceptible (MIC 2 mg/L), methicillin-resistant S. aureus M1V2 were treated for 2 days with doses of vancomycin that mimicked the pharmacokinetics seen in humans following intravenous administration of 1 g of the drug every 12 h. Half of the treated animals were killed 8 h after treatment arrest and half 3 days thereafter. Population analyses were done directly on vegetation homogenates or after one subculture in drug-free medium to mimic standard diagnostic procedures.¦RESULTS: Vancomycin cured 14 of 26 animals (54%; P<0.05 versus controls) after 2 days of treatment. When vegetation homogenates were plated directly on vancomycin-containing plates, 6 of 13 rats killed 8 h after treatment arrest had positive cultures, 1 of which harboured hVISA. Likewise, 6 of 13 rats killed 3 days thereafter had positive valve cultures, 5 of which harboured hVISA. However, one subculture of vegetations in drug-free broth was enough to revert all the hVISA phenotypes to the susceptible pattern of the parent. Thus, vancomycin selected for hVISA during therapy of experimental endocarditis due to vancomycin-susceptible S. aureus. These hVISA were associated with vancomycin failure. The hVISA phenotype persisted in vivo, even after vancomycin arrest, but was missed in vitro after a single passage of the vegetation homogenate on drug-free medium.¦CONCLUSIONS: hVISA might escape detection in clinical samples if they are subcultured before susceptibility tests.