Neutropenia induced in outbred mice by a simplified low-dose cyclophosphamide regimen: characterization and applicability to diverse experimental models of infectious diseases

BACKGROUND: For its low cost and ease of handling, the mouse remains the preferred experimental animal for preclinical tests. To avoid the interaction of the animal immune system, in vivo antibiotic pharmacodynamic studies often employ cyclophosphamide (CPM) to induce neutropenia. Although high doses (350–450 mg/kg) are still used and their effects on mouse leukocytes have been described, a lower dose (250 mg/kg) is widely preferred today, but the characteristics and applicability of this approach in outbred mice have not been determined. METHODS: Fifteen female ICR mice were injected intraperitoneally with 150 and 100 mg/kg of CPM on days 1 and 4, respectively. Blood samples (~160 μL) were drawn from the retro-orbital sinus of each mouse on days 1, 4, 5, 6, 7 and 11. Leukocytes were counted manually and the number of granulocytes was based on microscopic examination of Wright-stained smears. The impact of neutropenia induced by this method was then determined with a variety of pathogens in three different murine models of human infections: pneumonia (Klebsiella pneumoniae, Streptococcus pneumoniae, Staphylococcus aureus), meningoencephalitis (S. pneumoniae), and the thigh model (S. aureus, Escherichia coli, Bacteroides fragilis). RESULTS: The basal count of leukocytes was within the normal range for outbred mice. On day 4, there was an 84% reduction in total white blood cells, and by day 5 the leukopenia reached its nadir (370 ± 84 cells/mm(3)). Profound neutropenia (≤10 neutrophils/mm(3)) was demonstrated at day 4 and persisted through days 5 and 6. Lymphocytes and monocytes had a 92% and 96% decline between days 1 and 5, respectively. Leukocytes recovered completely by day 11. Mice immunosupressed under this protocol displayed clinical and microbiological patterns of progressive and lethal infectious diseases after inoculation in different organs with diverse human pathogens. CONCLUSION: A CPM total dose of 250 mg/kg is sufficient to induce profound and sustained neutropenia (<10 neutrophils/mm(3)) at least during 3 days in outbred mice, is simpler than previously described methods, and allows successful induction of infection in a variety of experimental models

Predicting Decisions in Human Social Interactions Using Real-Time fMRI and Pattern Classification

Negotiation and trade typically require a mutual interaction while simultaneously resting in uncertainty which decision the partner ultimately will make at the end of the process. Assessing already during the negotiation in which direction one's counterpart tends would provide a tremendous advantage. Recently, neuroimaging techniques combined with multivariate pattern classification of the acquired data have made it possible to discriminate subjective states of mind on the basis of their neuronal activation signature. However, to enable an online-assessment of the participant's mind state both approaches need to be extended to a real-time technique. By combining real-time functional magnetic resonance imaging (fMRI) and online pattern classification techniques, we show that it is possible to predict human behavior during social interaction before the interacting partner communicates a specific decision. Average accuracy reached approximately 70% when we predicted online the decisions of volunteers playing the ultimatum game, a well-known paradigm in economic game theory. Our results demonstrate the successful online analysis of complex emotional and cognitive states using real-time fMRI, which will enable a major breakthrough for social fMRI by providing information about mental states of partners already during the mutual interaction. Interestingly, an additional whole brain classification across subjects confirmed the online results: anterior insula, ventral striatum, and lateral orbitofrontal cortex, known to act in emotional self-regulation and reward processing for adjustment of behavior, appeared to be strong determinants of later overt behavior in the ultimatum game. Using whole brain classification we were also able to discriminate between brain processes related to subjective emotional and motivational states and brain processes related to the evaluation of objective financial incentives

Influence of endogenous pro-inflammatory cytokines on neutrophil-mediated damage of Candida albicans pseudohyphae, quantified in a modified tetrazolium dye assay.

Contains fulltext : 48033.pdf (publisher's version ) (Closed access)For quantitative assessment of polymorphonuclear granulocyte (PMN)-mediated pseudohyphal damage, an improved tetrazolium (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide; XTT) dye assay was developed. The modified assay proved to be a reliable indicator of viable pseudohyphal inoculum sizes. In addition, the influence of various endogenous pro-inflammatory cytokines on the capacity of PMN to damage Candida albicans pseudohyphae was investigated. PMN obtained from mice in which the genes encoding for tumor necrosis factor-alpha/lymphotoxin-alpha (TNF/LT), interferon-gamma (IFNgamma), interleukin (IL)-1alpha, or IL-1beta were disrupted, showed a significantly reduced pseudohyphal damage capacity in comparison with control PMN. The reduction amounted 25% for TNF-/- LT-/-, 11% for IFNgamma-/-, 21% for IL-1alpha-/-, and 34% for IL-1alpha-/-beta-/- PMN. In contrast, deficiency of IL-12 or IL-18 did not result in a diminished capacity to damage pseudohyphae and the capacity of PMN to damage Candida pseudohyphae was even slightly increased by 10% in IL-18-/- mice. These data suggest that endogenous pro-inflammatory cytokines are able to modulate antihyphal activity of PMN, the main effector cells against disseminated candidiasis by virtue of their capacity to kill both Candida blastoconidia and pseudohyphae

Increased susceptibility to systemic candidiasis in interleukin-6 deficient mice

Item does not contain fulltex