Intra- and inter-species mobilisation of non-conjugative plasmids in staphylococci.

The ability of Staphylococcus aureus conjugative plasmids to mobilise non-conjugative resistance plasmids from clinical isolates of S. aureus and S. epidermidis was studied. Plasmids which could not be transferred by transduction or mixed-culture transfer were transferred from phage-typable and non-typable S. aureus and from S. epidermidis. Plasmids encoding single resistance determinants were transferred by mobilisation whereas multiple-resistance plasmids were transferred as co-integrates between the conjugative and non-conjugative plasmids. This study demonstrates that mobilisation is a useful tool for the transfer and study of staphylococcal plasmids and illustrates how antibiotic resistance could be transferred between staphylococci in vivo.     

In vivo clearance of an intracellular bacterium, Francisella tularensis LVS, is dependent on the p40 subunit of interleukin-12 (IL-12) but not on IL-12 p70

To determine the role of interleukin-12 (IL-12) in primary and secondary immunity to a model intracellular bacterium, we have comprehensively evaluated infection with Francisella tularensis LVS in three murine models of IL-12 deficiency. Mice lacking the p40 protein of IL-12 (p40 knockout [KO] mice) and mice treated in vivo with neutralizing anti-IL-12 antibodies survived large doses of primary and secondary LVS infection but never cleared bacteria and exhibited a chronic infection. In dramatic contrast, mice lacking the p35 protein (p35 KO mice) of heterodimeric IL-12 readily survived large doses of primary sublethal LVS infection as well as maximal secondary lethal challenge, with only a slight delay in clearance of bacteria. LVS-immune wild-type (WT) lymphocytes produced large amounts of gamma interferon (IFN-gamma), but p35 KO and p40 KO lymphocytes produced much less; nonetheless, similar amounts of NO were found in all cultures containing immune lymphocytes, and all immune lymphocytes were equally capable of controlling intracellular growth of LVS in vitro. Purified CD4(+) and CD8(+) T cells from both WT and p40 KO mice controlled intracellular growth, even though T cells from WT mice produced much more IFN-gamma than those from p40 KO mice, and p40 KO T cells did not adopt a Th2 phenotype. Thus, while IL-12 p70 stimulation of IFN-gamma production may be important for bacteriostasis, IL-12 p70 is not necessary for appropriate development of LVS-immune T cells that are capable of controlling intracellular bacterial growth and for clearance of primary or secondary LVS infection. Instead, an additional mechanism dependent on the IL-12 p40 protein, either alone or in another complex such as the newly discovered heterodimer IL-23, appears to be responsible for actual clearance of this intracellular bacterium.     

CD4+ T-cell memory: generation and multi-faceted roles for CD4+ T cells in protective immunity to influenza

Summary: We have outlined the carefully orchestrated process of CD4⁺ T‐cell differentiation from naïve to effector and from effector to memory cells with a focus on how these processes can be studied in vivo in responses to pathogen infection. We emphasize that the regulatory factors that determine the quality and quantity of the effector and memory cells generated include (i) the antigen dose during the initial T‐cell interaction with antigen‐presenting cells; (ii) the dose and duration of repeated interactions; and (iii) the milieu of inflammatory and growth cytokines that responding CD4⁺ T cells encounter. We suggest that heterogeneity in these regulatory factors leads to the generation of a spectrum of effectors with different functional attributes. Furthermore, we suggest that it is the presence of effectors at different stages along a pathway of progressive linear differentiation that leads to a related spectrum of memory cells. Our studies particularly highlight the multifaceted roles of CD4⁺ effector and memory T cells in protective responses to influenza infection and support the concept that efficient priming of CD4⁺ T cells that react to shared influenza proteins could contribute greatly to vaccine strategies for influenza.     

Routine mortality monitoring for detecting mass murder in UK general practice: test of effectiveness using modelling.

BACKGROUND: The Shipman Inquiry recommended mortality rate monitoring if it could be 'shown to be workable' in detecting a future mass murderer in general practice. AIM: To examine the effectiveness of cumulative sum (CUSUM) charts, cross-sectional Shewhart charts, and exponentially-weighted, moving-average control charts in mortality monitoring at practice level. DESIGN OF STUDY: Analysis of Scottish routine general practice data combined with estimation of control chart effectiveness in detecting a 'murderer' in a simulated dataset. METHOD: Practice stability was calculated from routine data to determine feasible lengths of monitoring. A simulated dataset of 405,000 'patients' was created, registered with 75 'practices' whose underlying mortality rates varied with the same distribution as case-mix-adjusted mortality in all Scottish practices. The sensitivity of each chart to detect five and 10 excess deaths was examined in repeated simulations. The sensitivity of control charts to excess deaths in simulated data, and the number of alarm signals when control charts were applied to routine data were estimated. RESULTS: Practice instability limited the length of monitoring and modelling was consequently restricted to a 3-year period. Monitoring mortality over 3 years, CUSUM charts were most sensitive but only reliably achieved >50% successful detection for 10 excess deaths per year and generated multiple false alarms (>15%). CONCLUSION: At best, mortality monitoring can act as a backstop to detect a particularly prolific serial killer when other means of detection have failed. Policy should focus on changes likely to improve detection of individual murders, such as reform of death certification and the coroner system.     

Combined natural killer cell and dendritic cell functional deficiency in KARAP/DAP12 loss-of-function mutant mice

KARAP/DAP12 is a transmembrane polypeptide with an intracytoplasmic immunoreceptor tyrosine-based activation motif (ITAM). KARAP/DAP12 is associated with several activating cell surface receptors in hematopoietic cells. Here, we report that knockin mice bearing a nonfunctional KARAP/DAP12 ITAM present altered innate immune responses. Although in these mice NK cells are present and their repertoire of inhibitory MHC class I receptors is intact, the NK cell spectrum of natural cytotoxicity toward tumor cell targets is restricted. KARAP/DAP12 loss-of-function mutant mice also exhibit a dramatic accumulation of dendritic cells in muco-cutaneous epithelia, associated with an impaired hapten-specific contact sensitivity. Thus, despite its homology with CD3zeta and FcRgamma, KARAP/DAP12 plays a specific role in innate immunity, emphasizing the nonredundancy of these ITAM-bearing polypeptides in hematopoietic cells.     

Impact of hemochromatosis screening in patients with indeterminate results: the hemochromatosis and iron overload screening study.

PURPOSE: Assess the quality of life impact of receiving indeterminate test results for hemochromatosis, a disorder involving HFE genetic mutations and/or elevated serum transferrin saturation and ferritin. METHODS: The study sample was from the Hemochromatosis and Iron Overload Screening Study, a large observational study of hemochromatosis among primary care patients in the US and Canada using HFE genotype and serum transferrin saturation and ferritin screening. Study subjects included 2,304 patients found with hemochromatosis risk of uncertain clinical significance. Assessed was SF-36 general health and emotional well-being before screening and six weeks after participants received their test results. Health worries were assessed after screening. RESULTS: Of the study subjects, 1,268 participants (51.5%) completed both assessments. Compared to normal controls, those with HFE mutations or elevated serum transferrin saturation and ferritin levels of uncertain significance were more likely to report diminished general health and mental well-being, and more health worries. These effects were associated with participants' belief of having tested positive for hemochromatosis or iron overload. CONCLUSION: Notification of indeterminate results from screening may be associated with mild negative effects on well-being, and might be a potential participant risk in screening programs for disorders with uncertain genotype-phenotype.     

Pelvic inflammatory disease: sonographic-pathologic correlation

A retrospective analysis of the sonographic findings in 65 women with pelvic inflammatory disease was correlated with pathologic findings at surgery and laparoscopy. Abnormal sonograms could be classified into one of the following three groups: Type I pattern (endometritis); Type II pattern (focal mass); Type III pattern (total pelvic distortion). A simulated uterine appearance, the "pseudouterus sign," was observed in three patients with previous hysterectomy. Various pathologic entities of the pelvic inflammatory disease spectrum could not be reliably distinguished sonographically.