Stability, fatty acid composition and sensory properties of the M. Longissimus muscle from beef steers grazing either chicory/ryegrass or ryegrass.

Research has shown both production and health benefits for the use of chicory (Cichorium intybus) within ruminant diets. Despite this, little was known about the effects of this forage, containing differing fatty acid profiles and secondary plant compounds compared with ryegrass, on beef stability, fatty acid composition or sensory properties. An experiment was conducted to investigate whether the inclusion of chicory in the diet of grazing beef steers would alter these three properties in the M. Longissimus muscle when compared with beef steers grazing perennial ryegrass (Lolium perenne). Triplicate 2 ha plots were established with a chicory (cv. Puna II)/perennial ryegrass mix or a perennial ryegrass control. A core group of 36 Belgian Blue - cross steers were used within a 2-year beef finishing experiment (n=6/replicate plot). In the 2nd grazing year, steers were slaughtered as they reached a target fat class of 3. Muscle pH was checked 2 and 48 h post-slaughter. A section of the hindloin joint containing the M. Longissimus lumborum muscle was removed and a 20 mm-thick steak was cut and muscle samples were taken for analysis of vitamin E and fatty acid analysis. The remaining section of the loin was vacuum packed in modified atmosphere packs and subjected to simulated retail display. A section of the conditioned loin was used for sensory analysis. Data on pH, vitamin E concentration and colour stability in a simulated retail display showed there were no effects of including chicory in the diet of grazing beef steers on meat stability. There were also no differences found in the fatty acid composition or the overall eating quality of the steaks from the two treatments. In conclusion, there were no substantive effects of including chicory in the swards of grazing beef cattle on meat stability, fatty acid composition or sensory properties of the M. Longissimus muscle when compared with beef steers grazing ryegrass-only swards.

Status Report--Retracing the history of the early development of national chronic disease surveillance in Canada and the major role of the Laboratory Centre for Disease Control (LCDC) from 1972 to 2000.

TITRE: Rapport d'étape - Historique des débuts de la surveillance nationale des maladies chroniques au Canada et rôle majeur du Laboratoire de lutte contre la maladie (LLCM) de 1972 à 2000. INTRODUCTION: La surveillance de la santé consiste en l'utilisation systématique et continue de données sur la santé recueillies régulièrement en vue d'orienter les mesures de santé publique en temps opportun. Ce document décrit la création et l'essor des systèmes nationaux de surveillance au Canada et les répercussions de ces systèmes sur la prévention des maladies chroniques et des blessures. En 2008, les auteurs ont commencé à retracer l'historique des débuts de la surveillance nationale des maladies chroniques au Canada, en commençant à 1960, et ils ont poursuivi leur examen jusqu'en 2000. Une publication de 1967 a retracé l'historique de la création du Laboratoire d'hygiène de 1921 à 1967. Notre étude fait suite à cette publication et décrit l'historique de l'établissement de la surveillance nationale des maladies chroniques au Canada, à la fois avant et après la création du Laboratoire de lutte contre la maladie (LCDC).

Pharmacology of capsaicin-, anandamide-, and N-arachidonoyl-dopamine-evoked cell death in a homogeneous transient receptor potential vanilloid subtype 1 receptor population.

BACKGROUND: Transient receptor potential vanilloid subtype 1 (TRPV1) receptor is a primary pain-sensing relay at peripheral sensory nerve endings and is also widespread in the brain, where it is implicated in neurodegeneration. Previous studies of TRPV1 neurotoxicity have utilized heterogeneous receptor populations, non-selective ligands, or non-neuronal cell types. Here, we explored the pharmacology of TRPV1-induced cytotoxicity in a homogeneous, neurone-like cellular environment. METHODS: Cell death was examined in a human neurone-like cell line, stably expressing recombinant human TRPV1. Cytotoxicity was quantified in terms of nuclear morphology and mitochondrial complex II activity. Immunocytochemical markers of apoptotic cell death were also examined. RESULTS: The TRPV1-selective agonist capsaicin, and the endovanilloids anandamide and N-arachidonoyl-dopamine (NADA), induced TRPV1-dependent delayed cell death in a concentration- and time-dependent manner. Capsaicin exposure time was significantly correlated with potency (r(2)=0.91, P=0.01). Release of cytochrome c from mitochondria, activation of caspase-3, and condensed nuclear chromatin were evident 6 h after capsaicin exposure, but cytotoxicity was unaffected by a pan-caspase inhibitor (zVAD-fmk, 50 microM). CONCLUSIONS: We conclude that capsaicin, anandamide, and NADA can initiate TRPV1-dependent delayed cell death in neurone-like cells. This is an apoptosis-like process, but independent of caspase activity.

In vivo accuracy of multispectral magnetic resonance imaging for identifying lipid-rich necrotic cores and intraplaque hemorrhage in advanced human carotid plaques.

BACKGROUND: High-resolution MRI has been shown to be capable of identifying plaque constituents, such as the necrotic core and intraplaque hemorrhage, in human carotid atherosclerosis. The purpose of this study was to evaluate differential contrast-weighted images, specifically a multispectral MR technique, to improve the accuracy of identifying the lipid-rich necrotic core and acute intraplaque hemorrhage in vivo. METHODS AND RESULTS: Eighteen patients scheduled for carotid endarterectomy underwent a preoperative carotid MRI examination in a 1.5-T GE Signa scanner using a protocol that generated 4 contrast weightings (T1, T2, proton density, and 3D time of flight). MR images of the vessel wall were examined for the presence of a lipid-rich necrotic core and/or intraplaque hemorrhage. Ninety cross sections were compared with matched histological sections of the excised specimen in a double-blinded fashion. Overall accuracy (95% CI) of multispectral MRI was 87% (80% to 94%), sensitivity was 85% (78% to 92%), and specificity was 92% (86% to 98%). There was good agreement between MRI and histological findings, with a value of kappa=0.69 (0.53 to 0.85). CONCLUSIONS: Multispectral MRI can identify the lipid-rich necrotic core in human carotid atherosclerosis in vivo with high sensitivity and specificity. This MRI technique provides a noninvasive tool to study the pathogenesis and natural history of carotid atherosclerosis. Furthermore, it will permit a direct assessment of the effect of pharmacological therapy, such as aggressive lipid lowering, on plaque lipid composition.

Cell-cycle, phase-specific activation of Maize streak virus promoters.

It is believed that geminiviral DNA replication is coupled to the cell-cycle regulatory complex of the plant cell and that the virus-early (complementary or C sense) gene products REP and REPA may be able to manipulate the regulation of the cycle. In this study, we examined expression from the promoters of Maize streak virus (MSV) in transgenic maize plants and cells to determine whether they showed cell-cycle specificity. Histochemical staining of plant roots containing "long and short" C-sense promoter sequences upstream of the GUS (beta-glucuronidase) reporter gene showed that promoter activity was restricted to the meristematic region of the roots and was enhanced by 2,4-dichlorophenoxy acetic acid (2,4-D) treatment. Analysis of reporter gene and cell-cycle-specific gene transcript levels coupled with flow cytometric data in synchronized transgenic maize cells revealed that all of the MSV promoters showed cell-cycle specificity. The coat protein gene promoter showed highest activity in early G2, whereas the C-sense promoter sequences produced two peaks of activity in the S and G2 cell-cycle phases.

Structure of the Maize streak virus geminate particle.

The Geminiviridae is an extensive family of plant viruses responsible for economically devastating diseases in crops worldwide. Geminiviruses package circular, single-stranded DNA (ssDNA) genomes. The characteristic twinned or "geminate" particles, which consist of two joined, incomplete T = 1 icosahedra, are unique among viruses. We have determined the first structure of a geminivirus particle, the Nigerian strain of Maize streak virus (MSV-N), using cryo-electron microscopy and three-dimensional image reconstruction methods. The particle, of dimensions 220 x 380 A, has an overall 52-point-group symmetry, in which each half particle "head" consists of the coat protein (CP) arranged with quasi-icosahedral symmetry. We have modeled the MSV-N CP as an eight-stranded, antiparallel beta-barrel motif (a structural motif common to all known ssDNA viruses) with an N-terminal alpha-helix. This has produced a model of the geminate particle in which 110 copies of the CP nicely fit into the reconstructed density map. The reconstructed density map and MSV-N pseudo-atomic model demonstrate that the geminate particle has a stable, defined structure.

Replicase-derived resistance against pea early browning virus in Nicotiana benthamiana is an unstable resistance based upon posttranscriptional gene silencing.

Virus resistance in Nicotiana benthamiana plants containing a translatable Pea early browning virus (PEBV) 54K sequence from the 201K replicase gene has been reported previously. Resistant plants contain multiple transgene copies divided between two loci. Analysis of a genetic series containing the two loci in separate homozygous or heterozygous condition suggest that only one of the loci is necessary to induce the resistance. The resistance observed in R2 and R3 generations of lines containing both transgene loci in homozygous condition became less consistent in R4 and R5 generations. This inversely correlated with steady-state transgene transcript levels of the segregating populations. The use of recombinant Potato virus X vectors carrying PEBV 54K sequences showed that the resistance is based upon posttranscriptional gene silencing, is non-strand specific, and recognizes 3' located sequences within the PEBV 54K sequence.

A single amino acid change in the coat protein of Maize streak virus abolishes systemic infection, but not interaction with viral DNA or movement protein.

Summary Functional coat protein (CP) is important for host plant infection by monopartite geminiviruses. We identified a proline-cysteine-lysine (PCK) motif at amino acids 180-182 of the maize streak virus (MSV) CP that is conserved in most of the cereal-infecting Mastreviruses. Substitution of the lysine (K) with a valine (V) in the CP of MSV to produce mutant MSVCP182V abolished systemic infection in maize plants, although the mutant replicated around the inoculation site and, unlike other MSV CP mutants, enabled single-stranded (ss) DNA accumulation in suspension cells. The stability of the mutant protein, CP182V, in infected cells was confirmed by immunoblotting, but virions could not be detected. Like the wild-type (wt) CP, CP182V localized to the nucleus when expressed in insect and tobacco cells, and the Escherichia coli-expressed protein bound both ss and double-stranded DNA and interacted with movement protein in vitro. Taken together, these data suggest that mutation of amino acid 182 affects virion formation of MSV, either by affecting encapsidation per se or by affecting particle stability, and that virions are necessary for the long-distance movement of MSV in maize plants.

Intracellular and intercellular movement of maize streak geminivirus V1 and V2 proteins transiently expressed as green fluorescent protein fusions.

Transient expression of the maize streak geminivirus virion-sense proteins V1 and V2 (movement protein, MP, and coat protein, CP, respectively) in maize leaves allowed investigation of their roles in inter- and intracellular movement. Bombardment of a construct directing expression of a V1:green fluorescent protein (GFP) fusion product resulted in significantly increased spread of fluorescence from the bombarded cell to adjacent cells compared to that obtained following expression of free GFP. A mutant V1:GFP fusion product exhibited markedly less movement than the V1:GFP protein. Thus, the MSV V1 protein moves from cell to cell in the absence of other viral proteins. However, V1:GFP did not localize to plasmodesmata in maize or tobacco leaves although a tobacco mosaic virus MP:GFP fusion protein was shown to do so in tobacco. The CP:GFP fusion product targeted exclusively to the nucleus and did not move from cell to cell or exit the nucleus when expressed alone. When coexpressed with V1, some CP:GFP fluorescence was seen at the cell periphery in a proportion of cells, but in no case was cell-to-cell movement of CP:GFP detected. The likely roles of V1 and CP in MSV movement are discussed.

Maize streak virus coat protein is karyophyllic and facilitates nuclear transport of viral DNA.

Transport of maize streak virus (MSV) DNA into the nucleus of host cells is essential for virus replication and the presence of virus particles in the nuclei of infected cells implies that coat protein (CP) must enter the nucleus. To see if CP is imported into the nucleus in the absence of other viral gene products, the MSV CP gene was expressed in insect cells with a baculovirus vector system, and also in tobacco protoplasts with a cauliflower mosaic virus (CaMV) 35S promoter-driven transient gene expression vector. Immunofluorescent staining showed that the CP accumulated in the nuclei of both insect and tobacco cells. Mutagenesis of a potential nuclear localization signal in the CP resulted in cytoplasmic accumulation of the mutant protein. We have shown previously that the CP binds to single-stranded (ss) and double-stranded (ds) viral DNA. To investigate if CP might also be involved in viral DNA nuclear transport, Escherichia coli-expressed CP, together with TOTO-1-labeled viral ss or ds DNA, was microinjected into maize and tobacco epidermal cells. Both ss and ds DNA moved into the nucleus when co-injected with the CP but not with E. coli proteins alone. These results suggest that, in addition to entering the nucleus where it is required for encapsidation of the viral ss DNA, the MSV CP facilitates the rapid transport of viral (ss or ds) DNA into the nucleus.

Bean yellow dwarf virus RepA, but not rep, binds to maize retinoblastoma protein, and the virus tolerates mutations in the consensus binding motif.

It has previously been reported that complementary-sense gene products of wheat dwarf virus (WDV), a geminivirus of the genus Mastrevirus that infects monocotyledonous plants, bind to human and maize retinoblastoma (Rb) protein. Rb proteins control cell-cycle progression by sequestering transcription factors required for entry into S-phase, suggesting that the virus modifies the cellular environment to produce conditions suitable for viral DNA replication. Using a yeast two-hybrid assay, we have investigated whether the complementary-sense gene products of bean yellow dwarf virus, a mastrevirus that is adapted to dicotyledonous plants, also bind maize Rb protein. We demonstrate that whereas RepA binds to Rb protein, Rep does not, suggesting that RepA alone regulates host gene expression and progression of cells to S-phase. RepA mutants containing L --> I, C --> S, C --> G, and E --> Q mutations within the consensus Rb protein binding motif LXCXE retained the ability to bind to Rb, but with reduced efficiency. Most notably, the E --> Q mutation reduced binding by approximately 95%. Nonetheless, all LXCXE mutants were able to replicate in tobacco protoplasts and to systemically infect Nicotiana benthamiana and bean, in which they produced wild-type symptoms.