Recent information has revealed the functional diversity and importance of mitochondria in many cellular processes including orchestrating the innate immune response. Intriguingly, several infectious ...agents, such as Toxoplasma, Legionella, and Chlamydia, have been reported to grow within vacuoles surrounded by host mitochondria. Although many hypotheses have been proposed for the existence of host mitochondrial association (HMA), the causes and biological consequences of HMA have remained unanswered. Here we show that HMA is present in type I and III strains of Toxoplasma but missing in type II strains, both in vitro and in vivo. Analysis of F1 progeny from a type II×III cross revealed that HMA is a Mendelian trait that we could map. We use bioinformatics to select potential candidates and experimentally identify the polymorphic parasite protein involved, mitochondrial association factor 1 (MAF1). We show that introducing the type I (HMA+) MAF1 allele into type II (HMA-) parasites results in conversion to HMA+ and deletion of MAF1 in type I parasites results in a loss of HMA. We observe that the loss and gain of HMA are associated with alterations in the transcription of host cell immune genes and the in vivo cytokine response during murine infection. Lastly, we use exogenous expression of MAF1 to show that it binds host mitochondria and thus MAF1 is the parasite protein directly responsible for HMA. Our findings suggest that association with host mitochondria may represent a novel means by which Toxoplasma tachyzoites manipulate the host. The existence of naturally occurring HMA+ and HMA- strains of Toxoplasma, Legionella, and Chlamydia indicates the existence of evolutionary niches where HMA is either advantageous or disadvantageous, likely reflecting tradeoffs in metabolism, immune regulation, and other functions of mitochondria.
Objective
Delayed cerebral ischemia (DCI) is a common, disabling complication of subarachnoid hemorrhage (SAH). Preventing DCI is a key focus of neurocritical care, but interventions carry risk and ...cannot be applied indiscriminately. Although retrospective studies have identified continuous electroencephalographic (cEEG) measures associated with DCI, no study has characterized the accuracy of cEEG with sufficient rigor to justify using it to triage patients to interventions or clinical trials. We therefore prospectively assessed the accuracy of cEEG for predicting DCI, following the Standards for Reporting Diagnostic Accuracy Studies.
Methods
We prospectively performed cEEG in nontraumatic, high‐grade SAH patients at a single institution. The index test consisted of clinical neurophysiologists prospectively reporting prespecified EEG alarms: (1) decreasing relative alpha variability, (2) decreasing alpha‐delta ratio, (3) worsening focal slowing, or (4) late appearing epileptiform abnormalities. The diagnostic reference standard was DCI determined by blinded, adjudicated review. Primary outcome measures were sensitivity and specificity of cEEG for subsequent DCI, determined by multistate survival analysis, adjusted for baseline risk.
Results
One hundred three of 227 consecutive patients were eligible and underwent cEEG monitoring (7.7‐day mean duration). EEG alarms occurred in 96.2% of patients with and 19.6% without subsequent DCI (1.9‐day median latency, interquartile range = 0.9–4.1). Among alarm subtypes, late onset epileptiform abnormalities had the highest predictive value. Prespecified EEG findings predicted DCI among patients with low (91% sensitivity, 83% specificity) and high (95% sensitivity, 77% specificity) baseline risk.
Interpretation
cEEG accurately predicts DCI following SAH and may help target therapies to patients at highest risk of secondary brain injury. Ann Neurol 2018;83:958–969
•Physical and chemical properties influencing the reactivity of fly ash (FA) were assessed.•Optimum activator dosages were identified giving compressive strength of 70MPa.•FA samples cured at 70°C ...were considerably stronger than samples cured at 50°C.•Partial FA replacement with ggbs leads to increases in the compressive strength.•Microstructural investigations on paste indicated the nature of reaction products.
Several factors affecting the reactivity of fly ash (FA) as a precursor for geopolymer concrete have been investigated. These include physical and chemical properties of various FA sources, inclusion of ground granulated blast furnace slag (ggbs), chemical activator dosages and curing temperature. Alkali-activated FA was found to require elevated curing temperatures and high alkali concentrations. A mixture of sodium hydroxide and sodium silicate was used and this was shown to result in high strengths, as high as 70MPa at 28days. The presence of silicates in solution was found to be an important parameter affecting strength. Detailed physical and chemical characterisation was carried out on thirteen FA sources from the UK. The most important factor affecting the reactivity was found to be the particle size of FA. The loss on ignition (LOI) and the amorphous content are also important parameters that need to be considered for the selection of FA for use in geopolymer concrete. The partial replacement of FA with ggbs was found to be beneficial in not only avoiding the need for elevated curing temperatures but also in improving compressive strengths. Microstructural characterisation with scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) was performed on FA/ggbs pastes. The reaction product of FA and ggbs in these binary systems was calcium aluminium silicate hydrate gel (C–A–S–H) with inclusion of Na in the structure.
Models of migration between regions are often based on the assumption that individual moves can be modelled by a Poisson distribution whose parameter is a function of origin and destination ...characteristics, and generalized cost; this is true of Poisson regression models and spatial interaction models. The Poisson assumption is that each individual acts independently from others making the same move. In fact, migration is usually engaged in by household groups, not independent individuals, making the Poisson assumption invalid. It is possible instead to construct a model in which the probability of a household moving is given by a Poisson model and the number of individuals in a moving household is given by an observed household-size distribution. This generalized Poisson model is explained and fitted to a set of data on local-level migration within the English county of Hereford and Worcester. However, the sparse nature of the data set raises problems in assessing goodness of fit because the deviance value is unusually low. This is tackled here with a simulation methodology.
Alcohol consumption has been inconsistently associated with breast cancer risk. Recent studies suggest that genetic polymorphisms of glutathione S-transferases (GSTs) may modify this relation. To ...determine if breast cancer risk is associated with GSTM1 and GSTT1 genetic polymorphisms, and to evaluate the effect modification between GST genotypes and alcohol consumption in the risk of breast cancer, we conducted a case-control study in the state of Connecticut in the period 1998 and 2001. Cases were histologically confirmed, incident breast cancer patients in New Haven County, CT. Controls were randomly selected from women histologically confirmed to be without breast cancer. The study results show that, while GSTM1 genotypes were not associated with breast cancer risk, GSTT1-null genotype was associated with a significant 90% increased risk for postmenopausal women (OR=1.9, 95% CI 1.2-3.0). Analysis by GST genotypes and alcohol consumption shows that GSTM1A ever-drinking women had a 2.5-fold (OR=2.5, 95% CI 1.1-5.5) increased risk of breast cancer compared to the GSTM1A never-drinkers, and the risk increases with duration and daily amount of alcohol consumption. Postmenopausal women with GSTT1-null genotype, who consumed a lifetime of >250 kg of spirit-equivalents, had an almost seven-fold increased risk (OR=6.8, 95% CI 1.4-33.9), and drinking commencing at younger ages appears to carry a higher risk. An OR of 8.2 (95% CI 1.2-57.4) was observed for those with GSTM1A, and GSTT1-null genotypes who had consumed a lifetime of >250 kg of spirit-equivalents. In conclusion, alcohol consumption may increase breast cancer risk among those who carry susceptible GST genotypes.
Joubert syndrome (JS) is a recessive neurodevelopmental disorder characterised by hypotonia, ataxia, cognitive impairment, abnormal eye movements, respiratory control disturbances and a distinctive ...mid-hindbrain malformation. JS demonstrates substantial phenotypic variability and genetic heterogeneity. This study provides a comprehensive view of the current genetic basis, phenotypic range and gene-phenotype associations in JS.
We sequenced 27 JS-associated genes in 440 affected individuals (375 families) from a cohort of 532 individuals (440 families) with JS, using molecular inversion probe-based targeted capture and next-generation sequencing. Variant pathogenicity was defined using the Combined Annotation Dependent Depletion algorithm with an optimised score cut-off.
We identified presumed causal variants in 62% of pedigrees, including the first B9D2 mutations associated with JS. 253 different mutations in 23 genes highlight the extreme genetic heterogeneity of JS. Phenotypic analysis revealed that only 34% of individuals have a 'pure JS' phenotype. Retinal disease is present in 30% of individuals, renal disease in 25%, coloboma in 17%, polydactyly in 15%, liver fibrosis in 14% and encephalocele in 8%. Loss of CEP290 function is associated with retinal dystrophy, while loss of TMEM67 function is associated with liver fibrosis and coloboma, but we observe no clear-cut distinction between JS subtypes.
This work illustrates how combining advanced sequencing techniques with phenotypic data addresses extreme genetic heterogeneity to provide diagnostic and carrier testing, guide medical monitoring for progressive complications, facilitate interpretation of genome-wide sequencing results in individuals with a variety of phenotypes and enable gene-specific treatments in the future.
Abstract Objectives: To examine the effects of migration, diversity of migrant origins, commuting, and socioeconomic status on the incidence of acute lymphoblastic leukaemia in childhood. Design: ...Poisson regression analysis of incidence rates in relation to the variables of interest. Setting: The 403 county districts of England and Wales during 1979–85. Subjects: Children aged under 15 years. Results: There were significant trends in the incidence of lymphoblastic leukaemia at ages 0–4 and 5–9 years with the proportion of children in a district who had recently entered the district. While there was no consistent relation between the proportion of recent incomers in the total population of a district and its incidence rate, the combination of higher migration with greater diversity of origins or distance moved was associated with higher incidence in both age groups. Incidence increased significantly at age 0–4 with the level of employment in a district and at age 5–9 with the proportion of households with access to a car. No significant trends were found with commuting. Conclusions: The results for level of child migration and diversity of total migration provide evidence of an effect of population mixing on the incidence of childhood leukaemia which is not restricted to areas experiencing the most extreme levels of mixing. Key messages Population mixing even at relatively low levels may be important in the aetiology of childhood leukaemia The results provide further epidemiological evi- dence that childhood leukaemia might be a rare response to infection Previous studies finding increased incidence in more affluent areas may have been indirectly observing a population mixing effect
Introduction Radiation therapy is an integral part of the treatment of head and neck cancer. Factors predicting radiation response are ill defined. The aim of this study was to identify genetic ...aberrations associated with radiation response in cell lines derived from head and neck squamous cell carcinomas (HNSCC) using comparative genomic hybridization (CGH) for genome‐wide screening.
Methods Five cell lines derived from HNSCC were subjected to a single course of radiation (400 cGy) in parallel with a similarly handled, untreated control. Cellular response to radiation was determined on posttreatment days 1, 2, 3, 4, and 5 using a cell viability assay (MTT assay). Radiation response was defined as 35% or greater decrease in cell survival relative to control. Tumor doubling time was determined by cell counts performed at day 0 and 1 for each cell line. All experiments were done in quadruplicate. CGH analysis was performed by differentially labeling DNA from tumor and normal tissue with fluorescent agents. The labeled DNAs were simultaneously hybridized to normal metaphase chromosomes. Image analysis for fluorescence intensity along the entire length of each metaphase chromosome allowed generation of a color ratio, which was used to detect copy number changes.
Results Radioresistance was identified in two of five cell lines. The tumor doubling time was not a predictor of radiation response. CGH identified a complex pattern of aberrations, with gain of 3q common to all cell lines. The number of genetic aberration was higher in radiation‐sensitive cell lines than in radiation‐resistant ones. No recurrent aberrations were unique to the radiation‐resistant cell lines. Recurrent gains at 7p and 17q and losses at 5q, 7q, and 18q were unique to the radiation‐sensitive cell lines.
Conclusions The number of aberrations identified by CGH analysis may be a predictor of radiation response. A large study of primary tumors is warranted to confirm this association and identify specific genetic aberrations associated with radiation response.
We report on the discovery of eight repeating fast radio burst (FRB) sources found using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. These sources span a dispersion measure ...(DM) range of 103.5 to 1281 pc cm\(^{-3}\). They display varying degrees of activity: six sources were detected twice, another three times, and one ten times. These eight repeating FRBs likely represent the bright and/or high-rate end of a distribution of infrequently repeating sources. For all sources, we determine sky coordinates with uncertainties of \(\sim\)10\(^\prime\). FRB 180916.J0158+65 has a burst-averaged DM = \(349.2 \pm 0.3\) pc cm\(^{-3}\) and a low DM excess over the modelled Galactic maximum (as low as \(\sim\)20 pc cm\(^{-3}\)); this source also has a Faraday rotation measure (RM) of \(-114.6 \pm 0.6\) rad m\(^{-2}\), much lower than the RM measured for FRB 121102. FRB 181030.J1054+73 has the lowest DM for a repeater, \(103.5 \pm 0.3\) pc cm\(^{-3}\), with a DM excess of \(\sim\) 70 pc cm\(^{-3}\). Both sources are interesting targets for multi-wavelength follow-up due to their apparent proximity. The DM distribution of our repeater sample is statistically indistinguishable from that of the first 12 CHIME/FRB sources that have not repeated. We find, with 4\(\sigma\) significance, that repeater bursts are generally wider than those of CHIME/FRB bursts that have not repeated, suggesting different emission mechanisms. Our repeater events show complex morphologies that are reminiscent of the first two discovered repeating FRBs. The repetitive behavior of these sources will enable interferometric localizations and subsequent host galaxy identifications.
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