Neuropathogenesis of Japanese Encephalitis in a Primate Model

Background

Japanese encephalitis (JE) is a major cause of mortality and morbidity for which there is no treatment. In addition to direct viral cytopathology, the inflammatory response is postulated to contribute to the pathogenesis. Our goal was to determine the contribution of bystander effects and inflammatory mediators to neuronal cell death.

Methodology/Principal Findings

Material from a macaque model was used to characterize the inflammatory response and cytopathic effects of JE virus (JEV). Intranasal JEV infection induced a non-suppurative encephalitis, dominated by perivascular, infiltrates of mostly T cells, alongside endothelial cell activation, vascular damage and blood brain barrier (BBB) leakage; in the adjacent parenchyma there was macrophage infiltration, astrocyte and microglia activation. JEV antigen was mostly in neurons, but there was no correlation between intensity of viral infection and degree of inflammatory response. Apoptotic cell death occurred in both infected and non-infected neurons. Interferon-α, which is a microglial activator, was also expressed by both. Tumour Necrosis Factor-α, inducible nitric oxide synthase and nitrotyrosine were expressed by microglial cells, astrocytes and macrophages. The same cells expressed matrix metalloproteinase (MMP)-2 whilst MMP-9 was expressed by neurons.

Conclusions/Significance

The results are consistent with JEV inducing neuronal apoptotic death and release of cytokines that initiate microglial activation and release of pro-inflammatory and apoptotic mediators with subsequent apoptotic death of both infected and uninfected neurons. Activation of astrocytes, microglial and endothelial cells likely contributes to inflammatory cell recruitment and BBB breakdown. It appears that neuronal apoptotic death and activation of microglial cells and astrocytes play a crucial role in the pathogenesis of JE.     

Age-specific survival and fecundity and their effects on the intrinsic rate of increase of Aphelinus gossypii (Hym., Aphelinidae), a parasitoid of Aphis gossypii (Hom., Aphididae)

Abstract: The age-specific survival and fecundity of female adults of the aphidophagous parasitoid, Aphelinus gossypii Timberlake (Hym., Aphelinidae), were determined at a host density of 50 Aphis gossypii Glover (Hom., Aphididae) per leaf of Ageratum houstonianum Mill each day at 25°C. The age-specific mummy production, emergence rate and sex ratio of progeny were calculated. The implication of these results in terms of potential population growth of A. gossypii and related species is discussed. The age-specific survival curve ( l _x ) of females exhibited a Type I pattern, which resulted in little difference between Σ m _x and Σ l _x   m _x . The l _x curve of males exhibited a Type II pattern, and their survival time was much shorter than that of females. Each mated female produced on average 598.9 ± 64.0 aphid mummies, and preyed on 87.9±6.2 aphids. Most of the biological performance parameters were not different significantly between mated and virgin females. The highly female-biased sex ratio of offspring produced by mated females soon after their emergence resulted in a high fecundity rate ( m _x ) during the early reproductive period. Therefore, although the sex ratio of progeny was male-biased during the entire reproductive period, the intrinsic rate of increase estimated using age-specific sex ratios was larger than that estimated using a constant sex ratio of 0.5. These results indicate that the high survival and the adaptation of producing mostly female offspring during the early reproductive period contribute much to the population increase potential of this parasitoid.     

Induction of vimentin modification and vimentin-HSP72 association by withangulatin A in 9L rat brain tumor cells

Withangulatin A induced cell rounding up and the morphological alteration resulted from the reorganization of all of the major cytoskeletal components, i.e., vimentin, tubulin, and actin, as revealed by immunofluorescence techniques. When the withangulatin A-treated cells changed to a round-up morphology, vimentin intermediate filaments were found to be collapsed and clustered around the nucleus. The alteration was accompanied by characteristic changes of vimentin molecules, including augmentation of phosphorylation, retardation of electrophoretic mobility, and decrease in detergent extractability. The levels of vimentin phosphorylation were augmented by 2.5- and 1.8-fold in cells incubated with 50 μM withangulatin A for 1 and 3 h, respectively. The electrophoretic mobility of vimentin was partially retarded in cells treated with withangulatin A for 1 h at 10 μM and a completely upshift mobility was observed after 5 h treatment at 50 μM. In addition, vimentin molecules became less extractable by nonident P-40 after the cells were treated with withangulatin A and this effect was dose dependent. The decrease in solubility of vimentin was accompanied by the redistribution of HSP72 into the detergent nonextractable fraction and these two events were well correlated. Our results suggest that withangulatin A induced the modification of vimentin, which resulted in the alteration of cell morphology and redistribution of intracellular HSP72, an event that may play an important role in the induction of heat-shock response.     

A Truncated AdeS Kinase Protein Generated by ISAba1 Insertion Correlates with Tigecycline Resistance in Acinetobacter baumannii

Over-expression of AdeABC efflux pump stimulated continuously by the mutated AdeRS two component system has been found to result in antimicrobial resistance, even tigecycline (TGC) resistance, in multidrug-resistant Acinetobacter baumannii (MRAB). Although the insertion sequence, ISAba1, contributes to one of the AdeRS mutations, the detail mechanism remains unclear. In the present study we collected 130 TGC-resistant isolates from 317 carbapenem resistant MRAB (MRAB-C) isolates, and 38 of them were characterized with ISAba1 insertion in the adeS gene. The relationship between the expression of AdeABC efflux pump and TGC resistant was verified indirectly by successfully reducing TGC resistance with NMP, an efflux pump inhibitor. Further analysis showed that the remaining gene following the ISAba1 insertion was still transcribed to generate a truncated AdeS protein by the Pout promoter on ISAba1 instead of frame shift or pre-termination. Through introducing a series of recombinant adeRS constructs into a adeRS knockout strain, we demonstrated the truncated AdeS protein was constitutively produced and stimulating the expression of AdeABC efflux pump via interaction with AdeR. Our findings suggest a mechanism of antimicrobial resistance induced by an aberrant cytoplasmic sensor derived from an insertion element.     

Sleep apnea and risk of pneumonia: a nationwide population-based study

Background:

Evidence evaluating the risk of pneumonia in patients with obstructive sleep apnea is limited and mostly focuses on patients who receive continuous positive airway pressure (CPAP) therapy or on pediatric patients. We aimed to explore the risk of incident pneumonia among adults with sleep apnea, either with or without the need of CPAP therapy.

Methods:

From Jan. 1, 2000, we identified adult patients with sleep apnea from the Taiwan National Health Insurance Research Database. A control cohort without sleep apnea, matched for age, sex and comorbidities, was selected for comparison. The 2 cohorts were followed until Dec. 31, 2010, and observed for occurrence of pneumonia.

Results:

Of the 34 100 patients (6816 study patients and 27 284 matched controls), 2757 (8.09%) had pneumonia during a mean follow-up period of 4.50 years, including 638 (9.36%) study patients and 2119 (7.77%) controls. Kaplan–Meier analysis showed a higher incidence of pneumonia among patients with sleep apnea (log rank test, p < 0.001). After multivariate adjustment, patients with sleep apnea experienced a 1.20-fold (95% confidence interval 1.10–1.31) increase in incident pneumonia. The risk was even higher among patients who received CPAP therapy.

Interpretation:

Sleep apnea appeared to confer a higher risk for future pneumonia, possibly in a severity-dependent manner.Obstructive sleep apnea is a prevalent disorder that affects about 20% of Americans and probably a higher percentage of Asian people.^1,2 This disease is characterized by intermittent collapse of the upper airway during sleep that leads to intermittent hypoxemia and sleep fragmentation.³ Its close linkage to a variety of cardiovascular diseases and neurocognitive dysfunction has been demonstrated in the recent decade.^4,5Patients with obstructive sleep apnea were reported to have a higher risk of pulmonary aspiration of pharyngeal contents during sleep.⁶ Moreover, immune perturbations secondary to disrupted sleep may render them susceptible to invasion of pathogens.⁷ Both could potentiate the emergence of pneumonia. However, there are few studies addressing the relation between sleep apnea and pneumonia, and most of the studies involve small samples, are cross-sectional in design or lack information associated with development of pneumonia.^8–11 We conducted this nationwide population-based study to determine whether sleep apnea predisposed the development of pneumonia.     

Stochastically determined directed movement explains the dominant small-scale mitochondrial movements within non-neuronal tissue culture cells

The apparently stationary phase of mitochondrial motion was investigated in epithelial cells by spinning disk confocal light microscopy combined with image correlation based single particle tracking using custom software producing sub-pixel accuracy measurements (∼5 nm) at 10-12 Hz frame-rates. The analysis of these data suggests that the previously described stationary, or anchored phase, in mitochondrial movement actually comprise Brownian diffusion, interspersed with frequent and brief motor-driven events whose duration are stochastically determined. We have therefore discovered a new aspect of mitochondrial behavior, which we call stochastically determined, directed movement.