Correlation between Infectivity and Disease Associated Prion Protein in the Nervous System and Selected Edible Tissues of Naturally Affected Scrapie Sheep

The transmissible spongiform encephalopathies (TSEs) or prion diseases are a group of fatal neurodegenerative disorders characterised by the accumulation of a pathological form of a host protein known as prion protein (PrP). The validation of abnormal PrP detection techniques is fundamental to allow the use of high-throughput laboratory based tests, avoiding the limitations of bioassays. We used scrapie, a prototype TSE, to examine the relationship between infectivity and laboratory based diagnostic tools. The data may help to optimise strategies to prevent exposure of humans to small ruminant TSE material via the food chain. Abnormal PrP distribution/accumulation was assessed by immunohistochemistry (IHC), Western blot (WB) and ELISA in samples from four animals. In addition, infectivity was detected using a sensitive bank vole bioassay with selected samples from two of the four sheep and protein misfolding cyclic amplification using bank vole brain as substrate (vPMCA) was also carried out in selected samples from one animal. Lymph nodes, oculomotor muscles, sciatic nerve and kidney were positive by IHC, WB and ELISA, although at levels 100–1000 fold lower than the brain, and contained detectable infectivity by bioassay. Tissues not infectious by bioassay were also negative by all laboratory tests including PMCA. Although discrepancies were observed in tissues with very low levels of abnormal PrP, there was an overall good correlation between IHC, WB, ELISA and bioassay results. Most importantly, there was a good correlation between the detection of abnormal PrP in tissues using laboratory tests and the levels of infectivity even when the titre was low. These findings provide useful information for risk modellers and represent a first step toward the validation of laboratory tests used to quantify prion infectivity, which would greatly aid TSE risk assessment policies.     

Fluvastatin Interferes with Hepatitis C Virus Replication via Microtubule Bundling and a Doublecortin-like Kinase-Mediated Mechanism

Hepatitis C virus (HCV)-induced alterations in lipid metabolism and cellular protein expression contribute to viral pathogenesis. The mechanism of pleiotropic actions of cholesterol-lowering drugs, statins, against HCV and multiple cancers are not well understood. We investigated effects of fluvastatin (FLV) on microtubule-associated and cancer stem cell marker (CSC), doublecortin-like kinase 1 (DCLK1) during HCV-induced hepatocarcinogenesis. HCV replication models, cancer cell lines and normal human hepatocytes were used to investigate the antiviral and antitumor effects of statins. FLV treatment resulted in induction of microtubule bundling, cell-cycle arrest and alterations in cellular DCLK1 distribution in HCV-expressing hepatoma cells. These events adversely affected the survival of liver-derived tumor cells without affecting normal human hepatocytes. FLV downregulated HCV replication in cell culture where the ATP pool and cell viability were not compromised. Pravastatin did not exhibit these effects on HCV replication, microtubules and cancer cells. The levels of miR-122 that regulates liver homeostasis and provides HCV genomic stability remained at steady state whereas DCLK1 mRNA levels were considerably reduced during FLV treatment. We further demonstrated that HCV replication was increased with DCLK1 overexpression. In conclusion, unique effects of FLV on microtubules and their binding partner DCLK1 are likely to contribute to its anti-HCV and antitumor activities in addition to its known inhibitory effects on 3-hydroxy-3-methylglutary-CoA reductase (HMGCR).     

Estimating surface area of sponges and gorgonians as indicators of habitat availability on Caribbean coral reefs

A rapid method to estimate the three-dimensional (3D) surface area (SA) of marine gorgonians and sponges from field measurements of colony height, diameter, and morphology was developed as an indicator of habitat availability for fish and invertebrates. Colony characteristics for sponges and gorgonians were compiled from field measurements, expert judgment, and taxonomic literature, and employed to generate 3D images using computer-aided design software. The images were used to test various statistical models and geometric surrogates that best estimated SA using only height and diameter measurements. A morphological classification system was devised using shapes and relative proportions of sponges and gorgonians which are commonly found in shallow waters (<25 m depth) of the Central Western Atlantic Ocean. Regression models (linear, quadratic, or cubic) were found to be more robust than geometric surrogates, exhibiting greater accuracy at range extremes. Statistical models explained over 90% of the variation in SA and forecast errors of less than 20%. The best models for estimating SA are presented for eight sponge and nine gorgonian morphologies. Application of these methods with existing estimators for stony corals SA can be used as an indicator of structural habitat availability, which is an important ecosystem service of coral reefs.     

Mathematical Models of Memory CD8+ T-Cell Repertoire Dynamics in Response to Viral Infections

Immunity to diseases is conferred by pathogen-specific memory cells that prevent disease reoccurrences. A broad repertoire of memory T-cells must be developed and maintained to effectively protect against viral invasions; yet, the total number of memory T-cells is constrained between infections. Thus, creating memory to new infections can require attrition of some existing memory cells. Furthermore, some viruses induce memory T-cell death early in an infection, after which surviving cells proliferate to refill the memory compartment. We develop mathematical models of cellular attrition and proliferation in order to examine how new viral infections impact existing immunity. With these probabilistic models, we qualitatively and quantitatively predict how the composition and diversity of the memory repertoire changes as a result of viral infections. In addition, we calculate how often immunity to prior diseases is lost due to new infections. Comparing our results across multiple general infection types allows us to draw conclusions about, which types of viral effects most drastically alter existing immunity. We find that early memory attrition does not permanently alter the repertoire composition, while infections that spark substantial new memory generation drastically shift the repertoire and hasten the decline of existing immunity.     

Bupivacaine is an effective potassium channel blocker in heart

The local anesthetic agent bupivacaine increases action potential duration in isolated frog atrial myocytes, and blocks two potassium conductances, IK and IK1. The effective concentrations, particularly for IK, are similar to those which depress the sodium conductance. Potassium channel block may thus contribute to bupivacaine's reported cardiotoxicity.