Detecting the temporal status of blood-borne prions in transmissible spongiform encephalopathy-infected hosts

2015 Spring.Includes bibliographical references.Transmissible spongiform encephalopathies (TSEs), or prion diseases, are infectious, fatal neurodegenerative diseases with a protracted subclinical disease state spanning months to years. Prion diseases develop when the normal cellular prion protein (PrPC) undergoes a conformational change into an aberrant, disease-causing, isoform (PrPSc/PrPres/PrPD), which aggregates into amyloid fibrils. Prions are unique from all other infectious diseases in that they lack nucleic acid. Prion diseases are known to naturally occur in cattle, sheep, mink, cervids, and humans; however, the exact mechanisms of transmission are unknown. Sufficient infectious prions to transmit and cause disease are known to be present in tissues and bodily fluids of all TSE-infected mammals during clinical and subclinical stages of disease. Extensive extraneural PrPSc-deposition has been observed in chronic wasting disease (CWD)-infected cervids and transmissible mink encephalopathy (TME)-infected hamsters and is very similar to what has been described for variant Creutzfeldt-Jacob disease (vCJD)-infected humans. Importantly, blood taken from humans and animals lacking overt clinical symptoms is capable of transmitting disease through transfusion. In this thesis we set out to answer questions regarding hematogenous prions: 1) How long does it take for prions to enter the blood after initial TSE exposure? 2) Are hematogenous prions present in all animals infected with CWD and TME? and 3) Does the route of prion entry affect the temporal status of hematogenous prions. To answer these questions, we analyzed longitudinally-collected whole blood samples from TSE-exposed animals by a modified version of the highly sensitive in vitro amyloid-amplification assay "real-time quaking-induced conversion" (RT-QuIC) we termed whole blood (wb) RT-QuIC. Longitudinal whole blood samples (15 minutes post exposure-terminal disease) were collected from experimental CWD-exposed (oral, aerosol, and intravenous inoculation) white-tailed and Reeves' muntjac deer and TME-exposed (extranasal inoculation) Syrian hamsters. We detected PrP conversion-competent amyloid in the blood of 100% of infected animals as early as 15 minutes post inoculation throughout terminal clinical TSE disease. These results were observed for all inoculation routes. Furthermore, we observed the presence of prions in the blood in two phases--a primary and secondary prionemia. The results of this work suggest that: 1) inoculated prions traverse mucosal barriers and enter the blood within 15 minutes of exposure; 2) the route of inoculation has little effect on the temporal status of prions in the blood; 3) there are two distinct phases of prionemia representing the initial inoculum (primary prionemia) and de novo host-generated prions (secondary prionemia); and 4) the observed characteristics of prionemia can be recapitulated in various TSE-host combinations and may recapitulated the extraneural pathogenesis of human TSEs

Applying genetic algorithms to multi-objective land use planning.

This paper explores the application of multi-objective genetic algorithms (mGAs) to rural land-use planning, a spatial allocation problem. Two mGAs are proposed. Both share an underlying structure of: fitness assignment using Pareto-dominance ranking, niche induction and an individual replacement strategy. They are differentiated by their representations: a fixed-length genotype composed of genes that map directly to a land parcel's use, and a variable-length, order-dependent representation making allocations indirectly via a greedy algorithm. The latter representation requires additional breeding operators to be defined and post-processing of the genotype structure, to identify and remove duplicate genotypes. The two mGAs are compared on a real land-use planning problem, and the strengths and weaknesses of the underlying framework - and of each representation - are identified

Increased SK3 expression in DM1 lens cells leads to impaired growth through a greater calcium-induced fragility

Although cataract is a characteristic feature of myotonic dystrophy type 1 (DM1), little is known of the underlying mechanisms. We generated four lens epithelial cell lines derived from DM1 cataracts and two from age-matched, non-DM cataracts. Small-pool PCR revealed typical large triplet repeat expansions in the DM1 cells. Furthermore, real-time PCR analysis showed reduced SIX5 expression and increased expression of the Ca2+-activated K+ channel SK3 in the DM1 cells. These cells also exhibited longer population doubling times which did not arise through reduced proliferation, but rather increased cell death as shown by increased release of lactate dehydrogenase (LDH). Using 86Rb+ as a tracer for K+, we found no difference in the resting K+ influx or efflux kinetics. In all cases, the ouabain sensitive component of the influx contributed ~50% of the total. However, stimulating internal Ca2+ by exposure to ionomycin not only caused greater stimulation of K+ (86Rb) efflux in the DM1 cells but also induced a higher rate of cell death (LDH assay). Since both the hyper-stimulation of K+ efflux and cell death were reduced by the highly specific SK inhibitor apamin, we suggest that increased expression of SK3 has a critical role in the increased Ca2+-induced fragility in DM1 cells. The present data, therefore, both help explain the lower epithelial cell density previously observed in DM1 cataracts and provide general insights into mechanisms underlying the fragility of other DM1-affected tissues

From Dose to Response: In Vivo Nanoparticle Processing and Potential Toxicity

Adverse human health impacts due to occupational and environmental exposures to manufactured nanoparticles are of concern and pose a potential threat to the continued industrial use and integration of nanomaterials into commercial products. This chapter addresses the inter-relationship between dose and response and will elucidate on how the dynamic chemical and physical transformation and breakdown of the nanoparticles at the cellular and subcellular levels can lead to the in vivo formation of new reaction products. The dose-response relationship is complicated by the continuous physicochemical transformations in the nanoparticles induced by the dynamics of the biological system, where dose, bio-processing, and response are related in a non-linear manner. Nanoscale alterations are monitored using high-resolution imaging combined with in situ elemental analysis and emphasis is placed on the importance of the precision of characterization. The result is an in-depth understanding of the starting particles, the particle transformation in a biological environment, and the physiological response

Sex Differences in Cardiometabolic Risk Factors among Hispanic/Latino Youth

To determine the prevalence of obesity and cardiometabolic risk in US Hispanic/Latino youth and examine whether there are disparities by sex in cardiometabolic risk factors

Advances in Sample Preparation at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS): Investigation of Carbonate Secondary Standards

The development of robust sample preparation techniques for ocean science research has been a hallmark of NOSAMS since its inception. Improvements to our standard methods include reducing the minimum size of the samples we can analyze, building modular graphite reactors of different sizes that we can swap in and out depending on our sample stream, and modifying our carbonate acidification methods to improve handling of the smaller samples we now receive. A relatively new instrument, the Ramped PyrOx, which allows the separation of organic matter into thermal fractions, has attracted much interest as a research and development tool. We will also discuss our progress on incorporating a Picarro isotope analyzer into our sample preparation options

Disease-driven Reduction in Human Mobility Influences Human-Mosquito Contacts and Dengue Transmission Dynamics

Heterogeneous exposure to mosquitoes determines an individual’s contribution to vector-borne pathogen transmission. Particularly for dengue virus (DENV), there is a major difficulty in quantifying human-vector contacts due to the unknown coupled effect of key heterogeneities. To test the hypothesis that the reduction of human out-of-home mobility due to dengue illness will significantly influence population-level dynamics and the structure of DENV transmission chains, we extended an existing modeling framework to include social structure, disease-driven mobility reductions, and heterogeneous transmissibility from different infectious groups. Compared to a baseline model, naïve to human pre-symptomatic infectiousness and disease-driven mobility changes, a model including both parameters predicted an increase of 37% in the probability of a DENV outbreak occurring; a model including mobility change alone predicted a 15.5% increase compared to the baseline model. At the individual level, models including mobility change led to a reduction of the importance of out-of-home onward transmission (R, the fraction of secondary cases predicted to be generated by an individual) by symptomatic individuals (up to -62%) at the expense of an increase in the relevance of their home (up to +40%). An individual’s positive contribution to R could be predicted by a GAM including a non-linear interaction between an individual’s biting suitability and the number of mosquitoes in their home (\u3e10 mosquitoes and 0.6 individual attractiveness significantly increased R). We conclude that the complex fabric of social relationships and differential behavioral response to dengue illness cause the fraction of symptomatic DENV infections to concentrate transmission in specific locations, whereas asymptomatic carriers (including individuals in their pre-symptomatic period) move the virus throughout the landscape. Our findings point to the difficulty of focusing vector control interventions reactively on the home of symptomatic individuals, as this approach will fail to contain virus propagation by visitors to their house and asymptomatic carriers

Randomised trial of the fascia iliaca block versus the ‘3-in-1’ block for femoral neck fractures in the emergency department

Introduction: Femoral neck fractures are a common and painful injury. Femoral nerve blocks, and a variant of this technique termed the ‘3-in-1’ block, are often used in this patient group, but their effect is variable. The fascia iliaca compartment block (FIB) has been proposed as an alternative, but the relative effectiveness of the two techniques in the early stages of care is unknown. We therefore compared the FIB versus the 3-in-1 block in a randomised trial conducted in two UK emergency departments. Methods: Parallel, two-group randomised equivalence trial. Consenting patients >18 years with a femoral neck fracture were randomly allocated to receive either a FIB or a 3-in-1 block. The primary outcome was pain measured on a 100 mm visual analogue scale at 60 min. The between-group difference was adjusted for centre, age, sex, fracture type, pre-block analgesia and pre-block pain score. Results: 178 patients were randomised and 162 included in the primary analysis. The mean 100 mm visual analogue pain scale score at 60 min was 38 mm in the FIB arm and 35 mm in the 3-in-1 arm. The adjusted difference between the arms was 3 mm, with a 95% CI (−4.7 to 10.8) that excluded a clinically important difference between the two interventions. Conclusions: FIB is equivalent to the 3-in-1 block for immediate pain relief in adult neck of femur fractures

Dengue illness impacts daily human mobility patterns in Iquitos, Peru

Background Human mobility plays a central role in shaping pathogen transmission by generating spatial and/or individual variability in potential pathogen-transmitting contacts. Recent research has shown that symptomatic infection can influence human mobility and pathogen transmission dynamics. Better understanding the complex relationship between symptom severity, infectiousness, and human mobility requires quantification of movement patterns throughout infectiousness. For dengue virus (DENV), human infectiousness peaks 0–2 days after symptom onset, making it paramount to understand human movement patterns from the beginning of illness. Methodology and principal findings Through community-based febrile surveillance and RT-PCR assays, we identified a cohort of DENV+ residents of the city of Iquitos, Peru (n = 63). Using retrospective interviews, we measured the movements of these individuals when healthy and during each day of symptomatic illness. The most dramatic changes in mobility occurred during the first three days after symptom onset; individuals visited significantly fewer locations (Wilcoxon test, p = 0.017) and spent significantly more time at home (Wilcoxon test, p = 0.005), compared to when healthy. By 7–9 days after symptom onset, mobility measures had returned to healthy levels. Throughout an individual’s symptomatic period, the day of illness and their subjective sense of well-being were the most significant predictors for the number of locations and houses they visited. Conclusions/Significance Our study is one of the first to collect and analyze human mobility data at a daily scale during symptomatic infection. Accounting for the observed changes in human mobility throughout illness will improve understanding of the impact of disease on DENV transmission dynamics and the interpretation of public health-based surveillance data

Heterogeneity of Dengue Illness in Community-Based Prospective Study, Iquitos, Peru

Measuring heterogeneity of dengue illness is necessary to define suitable endpoints in dengue vaccine and therapeutic trials and will help clarify behavioral responses to illness. To quantify heterogeneity in dengue illness, including milder cases, we developed the Dengue Illness Perceptions Response (IPR) survey, which captured detailed symptom data, including intensity, duration, and character, and change in routine activities caused by illness. During 2016–2019, we collected IPR data daily during the acute phase of illness for 79 persons with a positive reverse transcription PCR result for dengue virus RNA. Most participants had mild ambulatory disease. However, we measured substantial heterogeneity in illness experience, symptom duration, and maximum reported intensity of individual symptoms. Symptom intensity was a more valuable predicter of major activity change during dengue illness than symptom presence or absence alone. These data suggest that the IPR measures clinically useful heterogeneity in dengue illness experience and its relation to altered human behavior