Controversies in the management of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) remains a rare but significant disease, which affects mainly young males in association with inflammatory bowel disease. There have been few advances in the understanding of the pathogenesis of the condition and no therapeutics with proven mortality benefit aside from liver transplantation. There remain areas of controversy in the management of PSC which include the differentiation from other cholangiopathies, in particular immunoglobulin G4 related sclerosing cholangitis, the management of dominant biliary strictures, and the role of ursodeoxycholic acid. In addition, the timing of liver transplantation in PSC remains difficult to predict with standard liver severity scores. In this review, we address these controversies and highlight the latest evidence base in the management of PSC

Quadratic resource value assessment during mantis shrimp (Stomatopoda) contests

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordResource value assessment, in which competitors adjust behaviours according to the perceived value of a contested resource, is well described in animal contests. Such assessment is usually assumed to be categorical or linear; for example, males fight more aggressively when females are present than absent, or as female fecundity increases. Here, to our knowledge for the first time, we show quadratic resource value assessment, in which resource value is highest at a certain level and decreases in either direction. The mantis shrimp Neogonodactylus bredini occupies coral rubble burrows in a size-assortative manner: individuals of a certain body size inhabit burrows of a certain size. Using mock burrows of various sizes, we tested whether mantis shrimp (1) chose burrows predicted to be the best fit for their body size and (2) were more aggressive during, endured higher costs during and were more likely to win contests over burrows predicted to be best fit. Individuals chose burrows larger than their predicted best fit burrows. In contests, intruders without burrows were more likely to evict burrow residents when the burrow was slightly smaller than the intruder's predicted best fit size. Intruder success decreased as relative burrow size increased or decreased from this value. Intruders won by delivering more strikes and by being aggressive first. In contrast to intruders, burrow residents showed little evidence of resource value assessment. A literature review revealed that quadratic resource value assessment may play a role in contests over resources from territories to parasite hosts. Therefore, our results impact theoretical models of contest behaviour and may lend insight to how contests affect resource distributions.National Science Foundation (NSF)Human Frontiers Science Progra

Linear-scaling time-dependent density-functional theory in the linear response formalism

We present an implementation of time-dependent density-functional theory (TDDFT) in the linear response formalism enabling the calculation of low energy optical absorption spectra for large molecules and nanostructures. The method avoids any explicit reference to canonical representations of either occupied or virtual Kohn-Sham states and thus achieves linear-scaling computational effort with system size. In contrast to conventional localised orbital formulations, where a single set of localised functions is used to span the occupied and unoccupied state manifold, we make use of two sets of in situ optimised localised orbitals, one for the occupied and one for the unoccupied space. This double representation approach avoids known problems of spanning the space of unoccupied Kohn-Sham states with a minimal set of localised orbitals optimised for the occupied space, while the in situ optimisation procedure allows for efficient calculations with a minimal number of functions. The method is applied to a number of medium sized organic molecules and a good agreement with traditional TDDFT methods is observed. Furthermore, linear scaling of computational cost with system size is demonstrated on a system of carbon nanotubes

A combined thermodynamics and first principles study of the electronic, lattice and magnetic contributions to the magnetocaloric effect in La0.75Ca0.25MnO3

Manganites with the formula La1−x Ca x MnO3 for 0.2  <  x  <  0.5 undergo a magnetic field driven transition from a paramagnetic to ferromagnetic state, which is accompanied by changes in the lattice and electronic structure. An isotropic expansion of the La0.75Ca0.25MnO3 cell at the phase transition has been observed experimentally. It is expected that there will be a large entropy change at the transition due to its first order nature. Doped lanthanum manganite (LMO) is therefore of interest as the active component in a magnetocaloric cooling device. However, the maximum obtained value for the entropy change in Ca-doped manganites merely reaches a moderate value in the field of a permanent magnet. The present theoretical work aims to shed light on this discrepancy. A combination of finite temperature statistical mechanics and first principles theory is applied to determine individual contributions to the total entropy change of the system by treating the electronic, lattice and magnetic components independently. Hybrid-exchange density functional (B3LYP) calculations and Monte Carlo simulations are performed for La0.75Ca0.25MnO3. Through the analysis of individual entropy contributions, it is found that the electronic and lattice entropy changes oppose the magnetic entropy change. The results highlighted in the present work demonstrate how the electronic and vibrational entropy contributions can have a deleterious effect on the total entropy change and thus the potential cooling power of doped LMO in a magnetocaloric device

Interpopulation hybridization results in widespread viability selection across the genome in Tigriopus californicus

Background: Genetic interactions within hybrids influence their overall fitness. Understanding the details of these interactions can improve our understanding of speciation. One experimental approach is to investigate deviations from Mendelian expectations (segregation distortion) in the inheritance of mapped genetic markers. In this study, we used the copepod Tigriopus californicus, a species which exhibits high genetic divergence between populations and a general pattern of reduced fitness in F2 interpopulation hybrids. Previous studies have implicated both nuclear-cytoplasmic and nuclear-nuclear interactions in causing this fitness reduction. We identified and mapped population-diagnostic single nucleotide polymorphisms (SNPs) and used these to examine segregation distortion across the genome within F2 hybrids.Results: We generated a linkage map which included 45 newly elucidated SNPs and 8 population-diagnostic microsatellites used in previous studies. The map, the first available for the Copepoda, was estimated to cover 75% of the genome and included markers on all 12 T. californicus chromosomes. We observed little segregation distortion in newly hatched F2 hybrid larvae (fewer than 10% of markers at p < 0.05), but strikingly higher distortion in F2 hybrid adult males (45% of markers at p < 0.05). Hence, segregation distortion was primarily caused by selection against particular genetic combinations which acted between hatching and maturity. Distorted markers were not distributed randomly across the genome but clustered on particular chromosomes. In contrast to other studies in this species we found little evidence for cytonuclear coadaptation. Instead, different linkage groups exhibited markedly different patterns of distortion, which appear to have been influenced by nuclear-nuclear epistatic interactions and may also reflect genetic load carried within the parental lines.Conclusion: Adult male F2 hybrids between two populations of T. californius exhibit dramatic segregation distortion across the genome. Distorted loci are clustered within specific linkage groups, and the direction of distortion differs between chromosomes. This segregation distortion is due to selection acting between hatching and adulthood

Disentangling the effects of cannabis and cigarette smoking on impulsivity

BACKGROUND: Cannabis smoking and cigarette smoking often co-occur, yet limited research has investigated the potentially different role impulsivity may play when these behaviours occur in isolation, compared with in combination. AIMS: This study examined trait and behavioural impulsivity as a function of both cigarette and cannabis smoking. METHODS: Trait impulsivity (BIS-11) was compared between 44 non-smokers, 76 cigarette only, 47 cannabis only and 58 cannabis plus cigarette smokers. The effects of cigarette and cannabis smoking on behavioural impulsivity (stop-signal and information sampling tasks) were then assessed in 87 of these participants during a laboratory session. RESULTS: Trait impulsivity was significantly higher in cigarette smokers than non-smokers, irrespective of cannabis use, except for motor impulsivity, where cigarette smoking was only associated with elevated trait impulsivity in non-smokers of cannabis. Dimensions of trait impulsivity were significantly positively related to cigarette smoking frequency and nicotine dependence, but not to cannabis smoking frequency or dependence. Smoking cigarettes or cannabis was associated with significantly impaired reflection impulsivity relative to not smoking either substance. However, no additional increases in reflection impulsivity were observed in those who smoked both cigarettes and cannabis. No group differences in response inhibition were detected. CONCLUSIONS: Heightened trait impulsivity appears to be uniquely related to cigarette smoking, whilst the smoking of cigarettes or cannabis is associated with impairments in reflection impulsivity. Improved outcomes for treating cannabis dependence may result from encouraging concomitant cigarette smokers to cease using both drugs simultaneously in order to reduce heightened impulsivity and risk of relapse

Reticulate evolution in Panicum (Poaceae): the origin of tetraploid broomcorn millet, P. miliaceum.

Panicum miliaceum (broomcorn millet) is a tetraploid cereal, which was among the first domesticated crops, but is now a minor crop despite its high water use efficiency. The ancestors of this species have not been determined; we aimed to identify likely candidates within the genus, where phylogenies are poorly resolved. Nuclear and chloroplast DNA sequences from P. miliaceum and a range of diploid and tetraploid relatives were used to develop phylogenies of the diploid and tetraploid species. Chromosomal in situ hybridization with genomic DNA as a probe was used to characterize the genomes in the tetraploid P. miliaceum and a tetraploid accession of P. repens. In situ hybridization showed that half the chromosomes of P. miliaceum hybridized more strongly with labelled genomic DNA from P. capillare, and half with labelled DNA from P. repens. Genomic DNA probes differentiated two sets of 18 chromosomes in the tetraploid P. repens. Our phylogenetic data support the allotetraploid origin of P. miliaceum, with the maternal ancestor being P. capillare (or a close relative) and the other genome being shared with P. repens. Our P. repens accession was also an allotetraploid with two dissimilar but closely related genomes, the maternal genome being similar to P. sumatrense. Further collection of Panicum species, particularly from the Old World, is required. It is important to identify why the water-efficient P. miliaceum is now of minimal importance in agriculture, and it may be valuable to exploit the diversity in this species and its ancestors

Characterization of the Taenia spp HDP2 sequence and development of a novel PCR-based assay for discrimination of Taenia saginata from Taenia asiatica

A previously described Taenia saginata HDP2 DNA sequence, a 4-kb polymorphic fragment, was previously used as the basis for developing PCR diagnostic protocols for the species-specific discrimination of T. saginata from T. solium and for the differentiation of T. saginata from T. asiatica. The latter was shown subsequently to lack the required specificity, so we undertook genetic studies of the HDP2 sequence from T. saginata and T. asiatica to determine why, and to develop a novel HDP2-PCR protocol for the simultaneous unambiguous identification of human taeniids. Sequencing and further analysis of the HDP2 DNA fragments of 19 Asiatic isolates of T. saginata and T. asiatica indicated that the HDP2 sequences of both species exhibited clear genomic variability, due to polymorphic variable fragments, that could correspond to the non-transcribed region of ribosomal DNA. This newly observed polymorphism allowed us to develop a novel, reproducible and reliable HDP2-PCR protocol which permitted the simultaneous discrimination of all T. saginata and T. asiatica isolates examined. This species-specific identification was based on, and facilitated by, the clear size difference in amplicon profiles generated: fragments of 1300 bp, 600 bp and 300 bp were produced for T. asiatica, amplicons of 1300 bp and 300 bp being obtained for T. saginata. Control T. solium samples produced one amplicon of 600 bp with the HDP2-PCR protocol. The assay has the potential to prove useful as a diagnostic tool in areas such as South East Asia where T. saginata, T. asiatica and T. solium coexist

The bright optical afterglow of the nearby gamma-ray burst of 29 March 2003

Many past studies of cosmological gamma-ray bursts (GRBs) have been limited because of the large distance to typical GRBs, resulting in faint afterglows. There has long been a recognition that a nearby GRB would shed light on the origin of these mysterious cosmic explosions, as well as the physics of their fireballs. However, GRBs nearer than z=0.2 are extremely rare, with an estimated rate of localisation of one every decade. Here, we report the discovery of bright optical afterglow emission from GRB 030329. Our prompt dissemination and the brilliance of the afterglow resulted in extensive followup (more than 65 telescopes) from radio through X-ray bands, as well as measurement of the redshift, z=0.169. The gamma-ray and afterglow properties of GRB 030329 are similar to those of cosmological GRBs (after accounting for the small distance), making this the nearest known cosmological GRB. Observations have already securely identified the progenitor as a massive star that exploded as a supernova, and we anticipate futher revelations of the GRB phenomenon from studies of this source.Comment: 13 pages, 4 figures. Original tex