Growth rates for subclasses of Av(321)

Pattern classes which avoid 321 and other patterns are shown to have the same growth rates as similar (but strictly larger) classes obtained by adding articulation points to any or all of the other patterns. The method of proof is to show that the elements of the latter classes can be represented as bounded merges of elements of the original class, and that the bounded merge construction does not change growth rates

Coaligned observations of solar magnetic fields at different heights: MSFC Center director's discretionary fund final report (Project No. 88-10)

The objective was to develop the capability for and coaligned observations of the structure and evolution of the Sun's magnetic field at two different heights in the solar atmosphere: the photosphere, which is the lowest region observable with optical telescopes; and the chromosphere, which lies just above the photosphere and is the region where the magnetic field dominates the gas motion so that a well-ordered structure governed by the field is observed. By obtaining this three-dimensional picture of the solar magnetic field, a better understanding can be developed of the magnetic forces that produce and control the dynamic, high-energy phenomena occurring in the solar atmosphere that can affect the entire heliosphere, including the terrestrial environment

Magnetic field configuration associated with solar gamma ray flares in June, 1991

The vector magnetic field configuration of the solar active region AR 6659 that produced very high levels of flare activity in Jun. 1991 is described. The morphology and evolution of the photospheric fields are described for the period 7-10 Jun., and the flares taking place around these dates and their locations relative to the photospheric fields are indicated. By comparing the observed vector field with the potential field calculated from the observed line-of-sight flux, we identify the nonpotential characteristics of the fields along the magnetic neutral lines where the flares were observed. These results are compared with those from the earlier study of gamma-ray flares

Altered electroretinogram b-wave in a Suffolk sheep experimentally infected with scrapie

TRANSMISSIBLE spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases in which an abnormal isoform of the cellular prion protein (PrPSc) accumulates in tissues of the central nervous system. Accumulation of PrPSc occurs in the retina, a rostral projection of the central nervous system, of both natural and nonnatural host species with TSEs (Foster and others 1999, Spraker and others 2002, Head and others 2003, 2005, Hamir and others 2004, 2005, Kercher and others 2004, Greenlee and others 2006, Hortells and others 2006). In retinas from scrapie-affected sheep, PrPSc accumulation is primarily observed in the inner and outer plexiform layers, and in the ganglion cell layer (Jeffrey and others 2001, Greenlee and others 2006). Recent studies have reported few (Hortells and others 2006) or no (Greenlee and others 2006) histological lesions in the retinas of sheep affected with scrapie. However, morphological changes in specific retinal cell types have been demonstrated (Smith and others 2008). Despite the morphological consequences of retinal PrPSc accumulation in sheep (Barnett and Palmer 1971, Smith and others 2008), the functional impact on the retina of these animals is unknown. In the current study, the effect of TSE on retinal function in a scrapie-infected Suffolk sheep using flash electroretinography was investigated

Changes in Retinal Function and Morphology Are Early Clinical Signs of Disease in Cattle with Bovine Spongiform Encephalopathy

Bovine spongiform encephalopathy (BSE) belongs to a group of fatal, transmissible protein misfolding diseases known as transmissible spongiform encephalopathies (TSEs). All TSEs are caused by accumulation of misfolded prion protein (PrPSc) throughout the central nervous system (CNS), which results in neuronal loss and ultimately death. Like other protein misfolding diseases including Parkinson’s disease and Alzheimer’s disease, TSEs are generally not diagnosed until the onset of disease after the appearance of unequivocal clinical signs. As such, identification of the earliest clinical signs of disease may facilitate diagnosis. The retina is the most accessible part of the central nervous system, and retinal pathology in TSE affected animals has been previously reported. Here we describe antemortem changes in retinal function and morphology that are detectable in BSE inoculated animals several months (up to 11 months) prior to the appearance of any other signs of clinical disease. We also demonstrate that differences in the severity of these clinical signs reflect the amount of PrPSc accumulation in the retina and the resulting inflammatory response of the tissue. These results are the earliest reported clinical signs associated with TSE infection and provide a basis for understanding the pathology and evaluating therapeutic interventions

Retinal function and morphology are altered in cattle infected with the prion disease transmissible mink encephalopathy

Transmissible spongiform encephalopathies (TSEs) are a group of diseases that result in progressive and invariably fatal neurologic disease in both animals and humans. TSEs are characterized by the accumulation of an abnormal protease-resistant form of the prion protein in the central nervous system. Transmission of infectious TSEs is believed to occur via ingestion of prion protein–contaminated material. This material is also involved in the transmission of bovine spongiform encephalopathy (“mad cow disease”) to humans, which resulted in the variant form of Creutzfeldt-Jakob disease. Abnormal prion protein has been reported in the retina of TSE-affected cattle, but despite these observations, the specific effect of abnormal prion protein on retinal morphology and function has not been assessed. The objective of this study was to identify and characterize potential functional and morphologic abnormalities in the retinas of cattle infected with a bovine-adapted isolate of transmissible mink encephalopathy. We used electroretinography and immunohistochemistry to examine retinas from 10 noninoculated and 5 transmissible mink encephalopathy–inoculated adult Holstein steers. Here we show altered retinal function, as evidenced by prolonged implicit time of the electroretinogram b-wave, in transmissible mink encephalopathy–infected cattle before the onset of clinical illness. We also demonstrate disruption of rod bipolar cell synaptic terminals, indicated by decreased immunoreactivity for the alpha isoform of protein kinase C and vesicular glutamate transporter 1, and activation of Müller glia, as evidenced by increased glial fibrillary acidic protein and glutamine synthetase expression, in the retinas of these cattle at the time of euthanasia due to clinical deterioration. This is the first study to identify both functional and morphologic alterations in the retinas of TSE-infected cattle. Our results support future efforts to focus on the retina for the development of new strategies for the diagnosis of TSEs

Comparison of Two US Sheep Scrapie Isolates Supports Identification as Separate Strains

Scrapie is a naturally occurring transmissible spongiform encephalopathy of sheep and goats. There are different strains of sheep scrapie that are associated with unique molecular, transmission, and phenotype characteristics. However, in the United States, very little is known about the potential presence of scrapie strains. Scrapie strain and PRNP genotype could both affect susceptibility, potential for transmission, incubation period (IP), and control measures required for eliminating scrapie from a flock. The investigators evaluated 2 US scrapie isolates, No. 13-7 and x124, after intranasal inoculation to compare clinical signs, IPs, spongiform lesions, and patterns of PrPSc deposition in sheep with scrapie-susceptible PRNP genotypes (QQ171). After inoculation with x124, susceptibility and IP were associated with valine at codon 136 (V136) of the prion protein: VV136 sheep had short IPs (6.9 months), those in AV136 sheep were 11.9 months, and AA136 sheep did not develop scrapie. All No. 13-7 inoculated sheep developed scrapie, with IPs of 20.1 months for AA136 sheep, 22.8 months for AV136 sheep, and 26.7 months for VV136 sheep. Patterns of immunoreactivity in the brain were influenced by inoculum isolate and host genotype. Differences in PrPSc profiles versus isolate were most striking when examining brains from sheep with the VV136 genotype. Inoculation into C57BL/6 mice resulted in markedly different attack rates (90.5% for x124 and 5.9% for No. 13-7). Taken together, these data demonstrate that No. 13-7 and x124 represent 2 distinct strains of scrapie with different IPs, genotype susceptibilities, and PrPSc deposition profiles

The XIIIth Banff Conference on Allograft Pathology: The Banff 2015 Heart Meeting Report: Improving Antibody-Mediated Rejection Diagnostics: Strengths, Unmet Needs, and Future Directions.

The 13th Banff Conference on Allograft Pathology was held in Vancouver, British Columbia, Canada from October 5 to 10, 2015. The cardiac session was devoted to current diagnostic issues in heart transplantation with a focus on antibody-mediated rejection (AMR) and small vessel arteriopathy. Specific topics included the strengths and limitations of the current rejection grading system, the central role of microvascular injury in AMR and approaches to semiquantitative assessment of histopathologic and immunophenotypic indicators, the role of AMR in the development of cardiac allograft vasculopathy, the important role of serologic antibody detection in the management of transplant recipients, and the potential application of new molecular approaches to the elucidation of the pathophysiology of AMR and potential for improving the current diagnostic system. Herein we summarize the key points from the presentations, the comprehensive, open and wide-ranging multidisciplinary discussion that was generated, and considerations for future endeavors

Tandem palladium and isothiourea relay catalysis : enantioselective synthesis of α-amino acid derivatives via allylic amination and [2,3]-sigmatropic rearrangement

The research leading to these results (S.S.M.S.) has received funding from the European Union (Marie Curie ITN “SubiCat” PITN-GA-2013-607044) and the ERC under the European Union's Seventh Framework Programme (FP7/2007-2013)/E.R.C. grant agreement no 279850 (T.H.W., J.E.T.). A.D.S. thanks the Royal Society for a Wolfson Research Merit Award.A tandem relay catalytic protocol using both Pd and isothiourea catalysis has been developed for the enantioselective synthesis of α-amino acid derivatives containing two stereogenic centers from readily accessible N,N-disubstituted glycine aryl esters and allylic phosphates. The optimized process uses a bench-stable succinimide-based Pd precatalyst (FurCat) to promote Pd-catalyzed allylic ammonium salt generation from the allylic phosphate and the glycine aryl ester. Subsequent in situ enantioselective [2,3]-sigmatropic rearrangement catalyzed by the isothiourea benzotetramisole forms syn-α-amino acid derivatives with high diastereo- and enantioselectivity. This methodology is most effective using 4-nitrophenylglycine esters and tolerates a variety of substituted cinnamic and styrenyl allylic ethyl phosphates. The use of challenging unsymmetrical N-allyl-N-methylglycine esters is also tolerated under the catalytic relay conditions without compromising stereoselectivity.Publisher PDFPeer reviewe