Entity

Time filter

Source Type

Spiez, Switzerland

Liechti F.D.,University of Bern | Grandgirard D.,University of Bern | Leib S.L.,University of Bern | Leib S.L.,Spiez Laboratory
Future Microbiology | Year: 2015

Bacterial meningitis is associated with high mortality and morbidity rates. Bacterial components induce an overshooting inflammatory reaction, eventually leading to brain damage. Pathological correlates of neurofunctional deficits include cortical necrosis, damage of the inner ear and hippocampal apoptosis. The hippocampal dentate gyrus is important for memory acquisition and harbors a neuronal stem cell niche, thus being potentially well equipped for regeneration. Adjuvant therapies aimed at decreasing the inflammatory reaction, for example, dexamethasone, and those protecting the brain from injury have been evaluated in animal models of the disease. They include nonbacteriolytic antibiotics (e.g., daptomycin), metalloproteinase inhibitors and modulators of the immunological response, for example, granulocyte colony-stimulating factor. Increasing research interest has recently been focused on interventions aimed at supporting regenerative processes. © 2015 Future Medicine Ltd. Source


Liechti F.D.,University of Bern | Grandgirard D.,University of Bern | Leppert D.,Hoffmann-La Roche | Leib S.L.,University of Bern | Leib S.L.,Spiez Laboratory
Infection and Immunity | Year: 2014

Pneumococcal meningitis (PM) results in high mortality rates and long-lasting neurological deficits. Hippocampal apoptosis and cortical necrosis are histopathological correlates of neurofunctional sequelae in rodent models and are frequently observed in autopsy studies of patients who die of PM. In experimental PM, inhibition of matrix metalloproteinases (MMPs) and/or tumor necrosis factor (TNF)-converting enzyme (TACE) has been shown to reduce brain injury and the associated impairment of neurocognitive function. However, none of the compounds evaluated in these studies entered clinical development. Here, we evaluated two second-generation MMP and TACE inhibitors with higher selectivity and improved oral availability. Ro 32-3555 (Trocade, cipemastat) preferentially inhibits collagenases (MMP-1, -8, and -13) and gelatinase B (MMP-9), while Ro 32-7315 is an efficient inhibitor of TACE. PM was induced in infant rats by the intracisternal injection of live Streptococcus pneumoniae. Ro 32-3555 and Ro 32-7315 were injected intraperitoneally, starting at 3 h postinfection. Antibiotic (ceftriaxone) therapy was initiated at 18 h postinfection, and clinical parameters (weight, clinical score, mortality rate) were recorded. Myeloperoxidase activities, concentrations of cytokines and chemokines, concentrations of MMP-2 and MMP-9, and collagen concentrations were measured in the cerebrospinal fluid. Animals were sacrificed at 42 h postinfection, and their brains were assessed by histomorphometry for hippocampal apoptosis and cortical necrosis. Both compounds, while exhibiting disparate MMP and TACE inhibitory profiles, decreased hippocampal apoptosis and cortical injury. Ro 32-3555 reduced mortality rates and cerebrospinal fluid TNF, interleukin-1β (IL-1β) and collagen levels, while Ro 32-7315 reduced weight loss and cerebrospinal fluid TNF and IL-6 levels. © 2014, American Society for Microbiology. Source


An LC-UV-SPE NMR method for the analysis of polar hydrolysis products of the chemical warfare agents known as sulfur mustards at low ppm levels in environmental samples is developed. The hydrolysis products thiodiglycol (I), bis(2-hydroxyethylthio)methane (II), 1,2-bis(2-hydroxyethylthio)ethane (III), 1,3-bis(2-hydroxyethylthio)propane (IV), 1,4-bis(2-hydroxyethylthio)butane (V), 1,5-bis(2-hydroxyethylthio)pentane (VI), bis(2-hydroxymethylthioethyl)ether (VII) and bis(2-hydroxyethylthioethyl)ether (VIII) are baseline separated within 11min by the LC gradient program and trapped post-column on SPE cartridges. After elution in 2mm o.d. NMR tubes 1H NMR spectra were recorded. Recoveries vary from 43±5 for I to 102±5% for VI and are limited by volume breakthrough. The detection limits of the LC-SPE NMR method vary between 200ng for V and 450ng for I. Increasing the injection volume is shown to be more effective than multiple trapping for the analytes I-VIII to increase the amount of material trapped on the SPE cartridges. The applicability of the developed method to the analysis of environmental samples was tested by the analysis of sample 293 provided by the 29th Official OPCW (Organization for the Prohibition of Chemical Weapons) Proficiency Test. The chromatographic and 1H NMR data obtained by the method are highly reproducible and provide acceptable data for the identification of chemicals related to CWC (Chemical Weapons Convention) in case an off-site analysis for the verification of the CWC or OPCW Proficiency Tests according to the OPCW criteria for the acceptance of chromatographic and 1H NMR spectral data. © 2013 Elsevier B.V. Source


Liechti F.D.,University of Bern | Grandgirard D.,University of Bern | Leib S.L.,University of Bern | Leib S.L.,Spiez Laboratory
Neuroscience | Year: 2015

Background: High mortality and morbidity rates are observed in patients with bacterial meningitis (BM) and urge for new adjuvant treatments in addition to standard antibiotic therapies. In BM the hippocampal dentate gyrus is injured by apoptosis while in cortical areas ischemic necrosis occurs. Experimental therapies aimed at reducing the inflammatory response and brain damage have successfully been evaluated in animal models of BM. Fluoxetine (FLX) is an anti-depressant of the selective serotonin reuptake inhibitors (SSRI) and was previously shown to be neuroprotective in vitro and in vivo. We therefore assessed the neuroprotective effect of FLX in experimental pneumococcal meningitis. Methods: Infant rats were infected intracisternally with live Streptococcus pneumoniae. Intraperitoneal treatment with FLX (10mgkg-1d-1) or an equal volume of NaCl was initiated 15min later. 18, 27, and 42h after infection, the animals were clinically (weight, clinical score, mortality) evaluated and subject to a cisternal puncture and inflammatory parameters (i.e., cyto-/chemokines, myeloperoxidase activity, matrix metalloproteinase concentrations) were measured in cerebrospinal fluid (CSF) samples. At 42h after infection, animals were sacrificed and the brains collected for histomorphometrical analysis of brain damage. Results: A significant lower number of animals treated with FLX showed relevant hippocampal apoptosis when compared to littermates (9/19 animals vs 18/23, P=. 0.038). A trend for less damage in cortical areas was observed in FLX-treated animals compared to controls (13/19 vs 13/23, P=. ns). Clinical and inflammatory parameters were not affected by FLX treatment. Conclusion: A significant neuroprotective effect of FLX on the hippocampus was observed in acute pneumococcal meningitis in infant rats. © 2015 IBRO. Source


Blaser C.,University of Bern | Wittwer M.,Spiez Laboratory | Grandgirard D.,University of Bern | Leib S.L.,University of Bern
PLoS ONE | Year: 2011

Streptococcus pneumoniae is the most common pathogen causing non-epidemic bacterial meningitis worldwide. The immune response and inflammatory processes contribute to the pathophysiology. Hence, the anti-inflammatory dexamethasone is advocated as adjuvant treatment although its clinical efficacy remains a question at issue. In experimental models of pneumococcal meningitis, dexamethasone increased neuronal damage in the dentate gyrus. Here, we investigated expressional changes in the hippocampus and cortex at 72 h after infection when dexamethasone was given to infant rats with pneumococcal meningitis. Nursing Wistar rats were intracisternally infected with Streptococcus pneumoniae to induce experimental meningitis or were sham-infected with pyrogen-free saline. Besides antibiotics, animals were either treated with dexamethasone or saline. Expressional changes were assessed by the use of GeneChip® Rat Exon 1.0 ST Arrays and quantitative real-time PCR. Protein levels of brain-derived neurotrophic factor, cytokines and chemokines were evaluated in immunoassays using Luminex xMAP® technology. In infected animals, 213 and 264 genes were significantly regulated by dexamethasone in the hippocampus and cortex respectively. Separately for the cortex and the hippocampus, Gene Ontology analysis identified clusters of biological processes which were assigned to the predefined categories "inflammation", "growth", "apoptosis" and others. Dexamethasone affected the expression of genes and protein levels of chemokines reflecting diminished activation of microglia. Dexamethasone-induced changes of genes related to apoptosis suggest the downregulation of the Akt-survival pathway and the induction of caspase-independent apoptosis. Signalling of pro-neurogenic pathways such as transforming growth factor pathway was reduced by dexamethasone resulting in a lack of pro-survival triggers. The anti-inflammatory properties of dexamethasone were observed on gene and protein level in experimental pneumococcal meningitis. Further dexamethasone-induced expressional changes reflect an increase of pro-apoptotic signals and a decrease of pro-neurogenic processes. The findings may help to identify potential mechanisms leading to apoptosis by dexamethasone in experimental pneumococcal meningitis. © 2011 Blaser, et al. Source

Discover hidden collaborations