bluuebunny/crossref_metadata_2025 huggingface dataset:
Chicken W: A genetically uniform chromosome in a highly variable genome
Authors: Berlin Sofia , Ellegren Hans
Published: November 2004

The Y chromosome of organisms with male heterogamety is expected to show reduced levels of genetic diversity, because the effective population size is one-fourth that of autosomes. However, studies in mammals, flies, and plants show that Y chromosome diversity is lower than expected even when differences in effective population size are taken into account. This may be explained by skewed reproductive success among males, leading to low male effective population size, or by a strong role of selection in shaping levels of nucleotide diversity in nonrecombining chromosomes. We tested these hypotheses in a system with female heterogamety by estimating nucleotide diversity in the female-specific W chromosome of the domestic chicken by resequencing of 7,643 base pairs in 47 birds from 10 highly divergent breeds. The screening revealed only one single segregating site, which is in sharp contrast to our previous observation, using a similar panel of birds of, on average, one segregating site every 39 base pairs in autosomal sequence. When taking sex-specific mutation rates and differences in effective population size into account, the observed degree of W chromosome polymorphism is 28-fold lower than expected for the frequency of segregating sites and 13-fold lower than expected for estimates of nucleotide diversity (autosomes, 6.5 × 10
–3
; W, 7.0 × 10
–5
). We note that selection is the only factor that can explain the reduced diversity in the sex-limited chromosome irrespective of mode of reproduction or whether there is male or female heterogamety. Reduced variability in female-specific W chromosomes is not easily explained by sexual selection.
Computational modeling reveals how interplay between components of a GTPase-cycle module regulates signal transduction
Authors: Bornheimer Scott J. , Maurya Mano R. , Farquhar Marilyn Gist , Subramaniam Shankar
Published: November 2004

Heterotrimeric G protein signaling is regulated by signaling modules composed of heterotrimeric G proteins, active G protein-coupled receptors (Rs), which activate G proteins, and GTPase-activating proteins (GAPs), which deactivate G proteins. We term these modules GTPase-cycle modules. The local concentrations of these proteins are spatially regulated between plasma membrane microdomains and between the plasma membrane and cytosol, but no data or models are available that quantitatively explain the effect of such regulation on signaling. We present a computational model of the GTPase-cycle module that predicts that the interplay of local G protein, R, and GAP concentrations gives rise to 16 distinct signaling regimes and numerous intermediate signaling phenomena. The regimes suggest alternative modes of the GTPase-cycle module that occur based on defined local concentrations of the component proteins. In one mode, signaling occurs while G protein and receptor are unclustered and GAP eliminates signaling; in another, G protein and receptor are clustered and GAP can rapidly modulate signaling but does not eliminate it. Experimental data from multiple GTPase-cycle modules is interpreted in light of these predictions. The latter mode explains previously paradoxical data in which GAP does not alter maximal current amplitude of G protein-activated ion channels, but hastens signaling. The predictions indicate how variations in local concentrations of the component proteins create GTPase-cycle modules with distinctive phenotypes. They provide a quantitative framework for investigating how regulation of local concentrations of components of the GTPase-cycle module affects signaling.
Multiple rare variants in different genes account for multifactorial inherited susceptibility to colorectal adenomas
Authors: Fearnhead Nicola S. , Wilding Jennifer L. , Winney Bruce , Tonks Susan , Bartlett Sylvia , Bicknell David C. , Tomlinson Ian P. M. , Mortensen Neil J. McC. , Bodmer Walter F.
Published: November 2004

Clear-cut inherited Mendelian traits, such as familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer, account for <4% of colorectal cancers. Another 20% of all colorectal cancers are thought to occur in individuals with a significant inherited multifactorial susceptibility to colorectal cancer that is not obviously familial. Incompletely penetrant, comparatively rare missense variants in the adenomatous polyposis coli gene, which is responsible for familial adenomatous polyposis, have been described in patients with multiple colorectal adenomas. These variants represent a category of variation that has been suggested, quite generally, to account for a substantial fraction of such multifactorial inherited susceptibility. The aim of this study was to explore this rare variant hypothesis for multifactorial inheritance by using multiple colorectal adenomas as the model. Patients with multiple adenomas were screened for germ-line variants in a panel of candidate genes. Germ-line DNA was obtained from 124 patients with between 3 and 100 histologically proven synchronous or metachronous adenomatous polyps. All patients were tested for the adenomatous polyposis coli variants
I1307K
and
E1317Q
, and variants were also sought in
AXIN1
(axin),
CTNNB1
(β-catenin), and the mismatch repair genes
hMLH1
and
hMSH2
. The control group consisted of 483 random controls. Thirty of 124 (24.9%) patients carried potentially pathogenic germ-line variants as compared with 55 (≈12%) of the controls. This overall difference is highly significant, suggesting that many rare variants collectively contribute to the inherited susceptibility to colorectal adenomas.
Nutritional status induces divergent variations of GLUT4 protein content, but not lipoprotein lipase activity, between adipose tissues and muscles in adult cattle
Authors: Bonnet Muriel , Faulconnier Yannick , Hocquette Jean-François , Bocquier François , Leroux Christine , Martin Patrice , Chilliard Yves
Published: November 2004

Metabolic adaptations to variations in food supply are incompletely understood in ruminant animal adipose tissue (AT) and muscle. To explore this, we studied lipid metabolism and glucose transport potential in one internal and one external AT, as well as in one oxidative and one glycolytic muscle from control, 7 d underfed and 21 d refed adult cows. Refeeding increased (+79 to +307 %) the activities of enzymes involved inde novolipogenesis (fatty acid synthase, malic enzyme, glucose-6-phosphate dehydrogenase) in perirenal and subcutaneous AT; underfeeding did not modify these variables. Underfeeding decreased the activities of lipoprotein lipase (LPL) in perirenal AT (−70 %) and cardiac muscle (−67 %), but did not modify the activities in subcutaneous AT andlongissimus thoracis. Refeeding increased LPL activities in all tissues (+40 to +553 %) to levels comparable with (cardiac muscle) or greater than (AT,longissimus thoracis) those observed in control cows. Such variations in perirenal and cardiac muscle LPL activities did not result from variations in LPL mRNA levels, but suggest a post-transcriptional regulation of LPL in these nutritional conditions. Underfeeding did not modify GLUT4 contents in perirenal AT and muscles, while refeeding increased it only in perirenal AT (+250 %). Our present results contrast with previous results in rats, where LPL is regulated in opposite directions in AT and muscles, and GLUT4 is generally increased by fasting and decreased by refeeding in skeletal muscles. The present results highlight the bovine specificity of the response, which probably arises in part from peculiarities of ruminant animals for nutrient digestion and absorption.
Food and drinking patterns as predictors of 6-year BMI-adjusted changes in waist circumference
Authors: Halkjær Jytte , Sørensen Thorkild IA , Tjønneland Anne , Togo Per , Holst Claus , Heitmann Berit L
Published: November 2004

Few studies have investigated the prospective associations between diet or drinking patterns and abdominal obesity; we therefore investigated whether food and beverage groups or patterns predicted 6-year changes in waist circumference (WC) and whether these associations were independent of concurrent changes in BMI as a measure of general obesity. The subjects were 2300 middle-aged men and women with repeated measurements of dietary intake, BMI and WC from 1982 to 1993. Intakes from ten food groups and from coffee, tea, wine, beer and spirits were assessed; gender-specific food factors were identified by factor analyses. Multiple linear regression analyses were done before and after adjustment for concurrent changes in BMI. A high intake of potatoes seemed to prevent gain in WC for men, while a high intake of refined bread was associated with gain in WC for women. The association persisted for refined bread, but not for potatoes, after adjustment for concurrent BMI changes. Among women, but not men, high intakes of beer and spirits were associated with gain in WC in both models. A high intake of coffee for women and moderate to high intake of tea for men were associated with gain in WC, but the associations were weakened, especially for women, after adjustment for BMI changes. None of the food factors was associated with WC changes. Based on the present study, we conclude that very few food items and no food patterns seem to predict changes in WC, whereas high intakes of beer and spirits among women, and moderate to high tea intake among men, may promote gain in WC.
Common Vascular Changes in the Jugular Vein of Saline Controls in Continuous Infusion Studies in the Beagle Dog
Authors: Lilbert Juliette , Mowat Vasanthi
Published: November 2004

This review was performed to assess the nature and incidence of procedure-related background changes in control dogs receiving saline by continuous infusion, and to compare them with data from a similar review previously done in Cynomolgus monkeys. Data were collected from 14 dog studies performed over an 8-year period (i.e., 86 animals in total). The review was restricted to lesions at the injection site, in the lungs and at the catheter's entry point. The most frequently seen changes were endothelial hyperplasia (67.4%) and intimal thickening at the injection site (80.2%) and interstitial pneumonitis in the lungs (52.6%), all seen at a higher incidence in dogs than in primates. Although incidences of thrombosis at the injection site were similar in both dogs (27.9%) and monkeys (34.1%), the incidences of thromboemboli and secondary infarction in the lungs were much higher in dogs. This suggests that dogs have a greater propensity to thrombus formation and fragmentation at the injection site. However the fact that the femoral vein is used in monkeys and the jugular vein in dogs may explain this difference. The larger diameter of the jugular vein in the dog with its greater turbulence of blood flow possibly predisposes to fragmentation and dispersal of thrombi.
Progressive Glomerulonephritis and Histiocytic Sarcoma Associated with Macrophage Functional Defects in CYP1B1-Deficient Mice
Authors: Ward Jerrold M. , Nikolov Nikolay P. , Tschetter Jolynne R. , Kopp Jeffrey B. , Gonzalez Frank J. , Kimura Shioko , Siegel Richard M.
Published: November 2004

The cytochrome P450 CYP1B1 enzyme metabolically activates polycyclic aromatic hydrocarbons and is a major P450 isoenzyme in human monocytes and macrophages. We have shown previously that mice deficient in CYP1B1 were resistant to induced tumors after 7,12-dimethylbenz[a]anthracene exposure. The pathology of aging CYP1B1 null mice on a B6; 129 background was studied in groups of 29 males and 30 females. By 12 months, 50% of the female mice had developed a unusual progressive glomerulonephritis while males had similar renal lesions later in life. This disease followed a sequence of proliferative, membranoproliferative and sclerotic glomerulonephritis. Anti-DNA antibodies were found in the blood of the mice along with immune deposits containing immunoglobulins in subepithelial locations of the glomerular basement membrane. The lesions were unlike those found in aging wild-type B6;129 mice or mice of other strains. We found that macrophages from CYP1B1-null mice were impaired in the phagocytosis of apoptotic, necrotic, and opsonized cells. This suggests a generalized defect in the phagocytic activity of CYP1B1-null mouse macrophages. Male mice also developed a high incidence (62—64%) of histiocytic sarcomas. Our study provides evidence that deficiency of CYP1B1 can play a role in the development of glomerular disease, normal processing of catabolic DNA and tumors of the mononuclear phagocyte system. The function of CYP1B1 in histiocytes and macrophages may involve both self-tolerance and tumor suppression.
Pregnancy-associated Malaria and the Prospects for Syndrome-specific Antimalaria Vaccines
Authors: Smith Joseph D. , Deitsch Kirk W.
Published: November 2004

Aided by the Plasmodium falciparum genome project, recent discoveries regarding the molecular basis of malaria pathogenesis have led to a better understanding of the interactions between host and parasite. Although vaccines that prevent infection by malaria parasites remain only hopes for the future, there are now more immediate prospects for vaccines that protect against specific disease syndromes. Here, we discuss the latest advances in the development of a vaccine that specifically targets pregnancy-associated malaria (PAM).
Melatonin desensitizes endogenous MT2 melatonin receptors in the rat suprachiasmatic nucleus: relevance for defining the periods of sensitivity of the mammalian circadian clock to melatonin
Authors: Gerdin Matthew J. , Masana Monica I. , Rivera-Bermúdez MoiséS A. , Hudson Randall L. , Earnest David J. , Gillette Martha U. , Dubocovich Margarita L.
Published: November 2004

The hormone melatonin phase shifts circadian rhythms generated by the mammalian biological clock, the suprachiasmatic nucleus (SCN) of the hypothalamus, through activation of G protein‐coupled MT2 melatonin receptors. This study demonstrated that pretreatment with physiological concentrations of melatonin (30–300 pM or 7–70 pg/mL) decreased the number of hMT2 melatonin receptors heterologously expressed in mammalian cells in a time and concentration‐dependent manner. Furthermore, hMT2‐GFP melatonin receptors heterologously expressed in immortalized SCN2.2 cells or in non‐neuronal mammalian cells were internalized upon pretreatment with both physiological (300 pM or 70 pg/mL) and supraphysiological (10 nM or 2.3 ng/mL) concentrations of melatonin. The decrease in MT2 melatonin receptor number induced by melatonin (300 pM for 1 h) was reversible and reached almost full recovery after 8 h; however, after treatment with 10 nM melatonin full recovery was not attained even after 24 h. This recovery process was partially protein synthesis dependent. Furthermore, exposure to physiological concentrations of melatonin (300 pM) for a time mimicking the nocturnal surge (8 h) desensitized functional responses mediated through melatonin activation of endogenous MT2 receptors, i.e., stimulation of protein kinase C (PKC) in immortalized SCN2.2 cells and phase shifts of circadian rhythms of neuronal firing in the rat SCN brain slice. We conclude that in vivo the nightly secretion of melatonin desensitizes endogenous MT2 melatonin receptors in the mammalian SCN thereby providing a temporally integrated profile of sensitivity of the mammalian biological clock to a melatonin signal.—Gerdin, M. J., Masana, M. I., Rivera‐Bermúdez, M. A., Hudson, R. L., Earnest, D. J., Gillette, M. Ú., Dubocovich, M. L. Melatonin desensitizes endogenous MT2 melatonin receptors in the rat suprachiasmatic nucleus: relevance for defining the periods of sensitivity of the mammalian circadian clock to melatonin. FASEB J. 18, 1646–1656 (2004)
MMP‐2 null mice exhibit an early onset and severe experimental autoimmune encephalomyelitis due to an increase in MMP‐9 expression and activity
Authors: Esparza Jordi , Kruse Meghan , Lee Janet , Michaud Michael , Madri Joseph A.
Published: November 2004

Matrix metalloproteinase‐2 (MMP‐2;gelatinase A) is known to degrade a broad range of extracellular matrix components and chemokines, and has important roles in the processes of cell migration, invasion, and involution during development, as well as during tumor growth and metastasis and in inflammation and repair. To better elucidate the roles of this matrix metalloproteinase in the development and progression of experimental autoimmune encephalomyelitis, we used MMP‐2‐deficient (KO) mice. Surprisingly, we found that MMP‐2 KO mice exhibited an earlier onset and more severe disease than did their wild‐type (WT) counterparts. WT mice engrafted with MMP‐2 KO bone marrow exhibited a similar earlier onset and more severe clinical disease score than WT mice engrafted with WT bone marrow. Lymphocytes derived from MMP‐2 KO mice exhibited increased transmigration through endothelial cell monolayers as well as through collagen type IV and laminin‐coated BD BIOCOAT inserts®, which correlated with a 3‐fold increase in expression of MMP‐9 and was abrogated by inhibition of MMP activity. We demonstrated a correlation between expression levels of MMP‐9 and MT1‐MMP expression and suggest a signaling pathway involving tethering of MMP‐2 to MT1‐MMP as a modulator of MMP‐9 expression. Last, we discuss other possible MMP‐2‐mediated mechanisms which may contribute to the observed phenotype.—Esparza, J., Kruse, M., Lee, J., Michaud, M., Madri, J. A. MMP‐2 null mice exhibit an early onset and severe experimental autoimmune encephalomyelitis due to an increase in MMP‐9 expression and activity. FASEB J. 18, 1682–1691 (2004)
YY1 DNA binding and PcG recruitment requires CtBP
Authors: Srinivasan Lakshmi , Atchison Michael L.
Published: November 2004

We found that mammalian Polycomb group (PcG) protein YY1 can bind to Polycomb response elements in Drosophila embryos and can recruit other PcG proteins to DNA. PcG recruitment results in deacetylation and methylation of histone H3. In a CtBP mutant background, recruitment of PcG proteins and concomitant histone modifications do not occur. Surprisingly, YY1 DNA binding in vivo is also ablated. CtBP mutation does not result in YY1 degradation or transport from the nucleus, suggesting a mechanism whereby YY1 DNA binding ability is masked. These results reveal a new role for CtBP in controlling YY1 DNA binding and recruitment of PcG proteins to DNA.
PAF1-complex-mediated histone methylation of FLOWERING LOCUS C chromatin is required for the vernalization-responsive, winter-annual habit in Arabidopsis
Authors: He Yuehui , Doyle Mark R. , Amasino Richard M.
Published: November 2004

The winter-annual habit (which typically involves a requirement for exposure to the cold of winter to flower in the spring) in Arabidopsis thaliana is mainly due to the repression of flowering by relatively high levels of FLC expression. Exposure to prolonged cold attenuates FLC expression through a process known as vernalization and thus permits flowering to occur in the spring. Here we show that the elevated FLC expression characteristic of nonvernalized winter annuals requires two genes, EARLY FLOWERING 7 (ELF7) and EARLY FLOWERING 8 (ELF8), that are homologs of components of the PAF1 complex of Saccharomyces cerevisiae. Furthermore, ELF7 and ELF8 are also required for the expression of other genes in the FLC clade of flowering repressors such as MAF2 and FLM. FLC, FLM, and MAF2 are involved in multiple flowering pathways that account for the broad effects of elf7 and elf8 mutations on flowering behavior. ELF7 and ELF8 are required for the enhancement of histone 3 trimethylation at Lys 4 in FLC chromatin. This modification of FLC chromatin appears to be required to elevate FLC expression to levels that can delay flowering in plants that have not been vernalized. A model of the role of ELF7, ELF8, and other previously described genes in the modification of the chromatin of flowering repressors is presented.
Skp2-dependent degradation of p27kip1 is essential for cell cycle progression
Authors: Kossatz Uta , Dietrich Nils , Zender Lars , Buer Jan , Manns Michael P. , Malek Nisar P.
Published: November 2004

The activity of the SCFskp2 E3 ligase is required for the proteolytic turnover of several proteins involved in cell cycle control and transcriptional regulation. Loss of skp2 in the mouse leads to a complex phenotype including changes in cell size and DNA content as well as severe proliferation defects. Here we show that the loss of a single skp2 substrate, namely, the cyclin kinase inhibitor p27kip1, reverts the phenotype of skp2 knockout hepatocytes to normal. By comparing the kinetics of p27 turnover and cell cycle progression in skp2 knockout and p27T187A knock-in mice, we define a short period in G1 in which p27 is able to block the cell cycle after the exit from quiescence. Loss of p27 turnover during this period prevents mitotic division and instead leads to compensatory cell growth.
Patterns of large-scale genomic variation in virulent and avirulent Burkholderia species
Authors: Ong Catherine , Ooi Chia Huey , Wang Dongling , Chong Hweeling , Ng Kim Chong , Rodrigues Fiona , Lee May Ann , Tan Patrick
Published: November 2004

The human diseases melioidosis and glanders are caused by the bacteria Burkholderia pseudomallei and B. mallei respectively, and both species are regarded as potential biowarfare agents. We used B. pseudomallei DNA microarrays to compare the genomes of several clinical and environmental isolates of B. pseudomallei, B. mallei, and B. thailandensis, a closely related but avirulent species. Open reading frames (ORFs) deleted between the three species were associated with diverse cellular functions, including nitrogen and iron metabolism, quorum sensing, and polysaccharide production. Deleted ORFs in B. mallei exhibited significant genomic clustering, whereas deletions in B. thailandensis were more uniformly dispersed, suggesting that B. mallei and B. thailandensis may have diverged from B. pseudomallei and each other via distinct mechanisms. The genomes of independent B. pseudomallei isolates were highly conserved with a large-scale variance of less than 3% between isolates, and at least three distinct molecular subtypes could be defined. An analysis of subtype-specific genomic regions suggests that DNA loss has played an important role in the evolutionary radiation of B. pseudomallei in the natural environment. Our results raise several hypotheses concerning the possible mechanisms underlying the diverse biological properties exhibited by members of the Burkholderia family.
A Gene Regulatory Network Model for Cell-Fate Determination duringArabidopsis thalianaFlower Development That Is Robust and Recovers Experimental Gene Expression Profiles[W]
Authors: Espinosa-Soto Carlos , Padilla-Longoria Pablo , Alvarez-Buylla Elena R.
Published: November 2004

Flowers are icons in developmental studies of complex structures. The vast majority of 250,000 angiosperm plant species have flowers with a conserved organ plan bearing sepals, petals, stamens, and carpels in the center. The combinatorial model for the activity of the so-called ABC homeotic floral genes has guided extensive experimental studies in Arabidopsis thaliana and many other plant species. However, a mechanistic and dynamical explanation for the ABC model and prevalence among flowering plants is lacking. Here, we put forward a simple discrete model that postulates logical rules that formally summarize published ABC and non-ABC gene interaction data for Arabidopsis floral organ cell fate determination and integrates this data into a dynamic network model. This model shows that all possible initial conditions converge to few steady gene activity states that match gene expression profiles observed experimentally in primordial floral organ cells of wild-type and mutant plants. Therefore, the network proposed here provides a dynamical explanation for the ABC model and shows that precise signaling pathways are not required to restrain cell types to those found in Arabidopsis, but these are rather determined by the overall gene network dynamics. Furthermore, we performed robustness analyses that clearly show that the cell types recovered depend on the network architecture rather than on specific values of the model's gene interaction parameters. These results support the hypothesis that such a network constitutes a developmental module, and hence provide a possible explanation for the overall conservation of the ABC model and overall floral plan among angiosperms. In addition, we have been able to predict the effects of differences in network architecture between Arabidopsis and Petunia hybrida.
Structure-Function Analysis of the Presumptive Arabidopsis Auxin Permease AUX1[W]
Authors: Swarup Ranjan , Kargul Joanna , Marchant Alan , Zadik Daniel , Rahman Abidur , Mills Rebecca , Yemm Anthony , May Sean , Williams Lorraine , Millner Paul , Tsurumi Seiji , Moore Ian , Napier Richard , Kerr Ian D. , Bennett Malcolm J.
Published: November 2004

We have investigated the subcellular localization, the domain topology, and the amino acid residues that are critical for the function of the presumptive Arabidopsis thaliana auxin influx carrier AUX1. Biochemical fractionation experiments and confocal studies using an N-terminal yellow fluorescent protein (YFP) fusion observed that AUX1 colocalized with plasma membrane (PM) markers. Because of its PM localization, we were able to take advantage of the steep pH gradient that exists across the plant cell PM to investigate AUX1 topology using YFP as a pH-sensitive probe. The YFP-coding sequence was inserted in selected AUX1 hydrophilic loops to orient surface domains on either apoplastic or cytoplasmic faces of the PM based on the absence or presence of YFP fluorescence, respectively. We were able to demonstrate in conjunction with helix prediction programs that AUX1 represents a polytopic membrane protein composed of 11 transmembrane spanning domains. In parallel, a large aux1 allelic series containing null, partial-loss-of-function, and conditional mutations was characterized to identify the functionally important domains and amino acid residues within the AUX1 polypeptide. Whereas almost all partial-loss-of-function and null alleles cluster in the core permease region, the sole conditional allele aux1-7 modifies the function of the external C-terminal domain.
A Puromycin-Sensitive Aminopeptidase Is Essential for Meiosis inArabidopsis thaliana [W]
Authors: Saénchez-Moraén Eugenio , Jones Gareth H. , Franklin F. Christopher H. , Santos Juan Luis
Published: November 2004

Puromycin-sensitive aminopeptidases (PSAs) participate in a variety of proteolytic events essential for cell growth and viability, and in fertility in a broad range of organisms. We have identified and characterized an Arabidopsis thaliana mutant (mpa1) from a pool of T-DNA tagged lines that lacks PSA activity. This line exhibits reduced fertility, producing shorter siliques (fruits) bearing a lower number of seeds compared with wild-type plants. Cytogenetic characterization of meiosis in the mutant line reveals that both male and female meiosis are defective. In mpa1, early prophase I appears normal, but after pachytene most of the homologous chromosomes are desynaptic, thus, by metaphase I a high level of univalence is observed subsequently leading to abnormal chromosome segregation. Wild-type plants treated with specific inhibitors of PSA show a very similar desynaptic phenotype to that of the mutant line. A fluorescent PSA-specific bioprobe, DAMPAQ-22, reveals that the protein is maximally expressed in wild-type meiocytes during prophase I and is absent in mpa1. Immunolocalization of meiotic proteins showed that the meiotic recombination pathway is disrupted in mpa1. Chromosome pairing and early recombination appears normal, but progression to later stages of recombination and complete synapsis of homologous chromosomes are blocked.
A Mechanism Related to the Yeast Transcriptional Regulator Paf1c Is Required for Expression of the ArabidopsisFLC/MAFMADS Box Gene Family[W]
Authors: Oh Sookyung , Zhang Hua , Ludwig Philip , van Nocker Steven
Published: November 2004

The Arabidopsis thaliana VERNALIZATION INDEPENDENCE (VIP) gene class has multiple functions in development, including repression of flowering through activation of the MADSbox gene FLC. Epigenetic silencing of FLC plays a substantial role in the promotion of flowering through cold (vernalization). To better understand how VIP genes influence development, we undertook a genetic and molecular study of the previously uncharacterized VIP5 and VIP6 genes. We found that loss of function of these genes also resulted in downregulation of other members of the FLC/MAF gene family, including the photoperiodic pathway regulator MAF1/FLM. We cloned VIP5 and VIP6 through mapping and transcriptional profiling. Both proteins are closely related to distinct components of budding yeast Paf1C, a transcription factor that assists in establishment and maintenance of transcription-promotive chromatin modifications such as ubiquitination of H2B by Bre1/Rad6 and methylation of histone H3 lysine-4 by the trithorax-related histone methylase Set1. Genetic analysis and coimmunoprecipitation experiments suggest that VIP5 and VIP6 function in the same mechanism as the previously described VIP3 and VIP4. Our findings suggest that an evolutionarily conserved transcriptional mechanism plays an essential role in the maintenance of gene expression in higher eukaryotes and has a central function in flowering.
Quality improvement techniques to improve patient satisfaction
Authors: Torres E. Joseph , Guo Kristina L.
Published: November 2004

This paper describes several approaches for implementing quality improvement initiatives to improve patient satisfaction, which enables health‐care organizations to position themselves for success in today's global and increasingly competitive environment. Specifically, measuring the views of patients, improving patient satisfaction through a community‐wide effort, and using a Six Sigma program are discussed. Each of these programs can be an effective mechanism for quality improvement. A key component to quality improvement techniques involves collaborative efforts by all health‐care professionals and managers as they seek to increase patient satisfaction.
Field metabolic rates of black‐browed albatrosses Thalassarche melanophrys during the incubation stage
Authors: Shaffer Scott A. , Costa Daniel P. , Weimerskirch Henri
Published: November 2004

Field metabolic rates (FMR) and activity patterns of black‐browed albatrosses Thalassarche melanophrys were measured while at sea and on nest during the incubation stage at Kerguelen Island, southwestern Indian Ocean. Activity‐specific metabolic rates of five albatrosses at sea (FMRat‐sea) were measured using doubly labeled water (DLW), and by equipping birds with wet‐dry activity data loggers that determined when birds were in flight or on the water. The metabolic rates of four birds incubating their eggs (FMRon‐nest) were also measured using DLW. The mean±SD FMRat‐sea of albatrosses was 611±96 kJ kg−1 d−1 compared to FMRon‐nest of 196±52 kJ kg−1 d−1. While at sea, albatrosses spent 52.9±8.2% (N=3) of their time in flight and they landed on the water 41.2±13.9 times per day. The FMR of black‐browed albatrosses appear to be intermediate to that of three other albatross species. Based on at‐sea activity, the power requirement of flight was estimated to be 8.7 W kg−1 (or 4.0×predicted BMR), which is high compared to other albatross species, but may be explained by the high activity levels of the birds when at sea. The FMRat‐sea of albatrosses, when scaled with body mass, are lower than other seabirds of similar body size, which probably reflects the economical nature of their soaring flight.
Why do eastern curlews Numenius madagascariensis feed on prey that lowers intake rate before migration?
Authors: Zharikov Yuri , Skilleter Gregory A.
Published: November 2004

Eastern curlews Numenius madagascariensis spending the nonbreeding season in eastern Australia foraged on three intertidal decapods: soldier crab Mictyris longicarpus, sentinel crab Macrophthalmus crassipes and ghost‐shrimp Trypaea australiensis. Due to their ecology, these crustaceans were spatially segregated (=distributed in ‘patches’) and the curlews intermittently consumed more than one prey type. It was predicted that if the curlews behaved as intake rate maximizers, the time spent foraging on a particular prey (patch) would reflect relative availabilities of the prey types and thus prey‐specific intake rates would be equal. During the mid‐nonbreeding period (November–December), Mictyris and Macrophthalmus were primarily consumed and prey‐specific intake rates were statistically indistinguishable (8.8 versus 10.1 kJ×min−1). Prior to migration (February), Mictyris and Trypaea were hunted and the respective intake rates were significantly different (8.9 versus 2.3 kJ×min−1). Time allocation to Trypaea‐hunting was independent of the availability of Mictyris. Thus, consumption of Trypaea depressed the overall intake rate. Six hypotheses for consuming Trypaea before migration were examined. Five hypotheses: the possible error by the predator, prey specialization, observer overestimation of time spent hunting Trypaea, supplementary prey and the choice of higher quality prey due to a digestive bottleneck, were deemed unsatisfactory. The explanation for consumption of a low intake‐rate but high quality prey (Trypaea) deemed plausible was diet optimisation by the curlews in response to the pre‐migratory modulation (decrease in size/processing capacity) of their digestive system. With a seasonal decrease in the average intake rate, the estimated intake per low tide increased from 1233 to 1508 kJ between the mid‐nonbreeding and pre‐migratory periods by increasing the overall time spent on the sandflats and the proportion of time spent foraging.
Extra‐pair paternity, testes size and testosterone level in relation to colour polymorphism in the barn owlTyto alba
Authors: Roulin Alexandre , Müller Wendt , Sasvári Lajos , Dijkstra Cor , Ducrest Anne‐Lyse , Riols Christian , Wink Michael , Lubjuhn Thomas
Published: November 2004

In many bird populations, individuals display one of several genetically inherited colour morphs. Colour polymorphism can be maintained by several mechanisms one of which being frequency‐dependent selection with colour morphs signalling alternative mating strategies. One morph may be dominant and territorial, and another one adopt a sneaky behaviour to gain access to fertile females. We tested this hypothesis in the barn owlTyto albain which coloration varies from reddish‐brown to white. This trait is heritable and neither sensitive to the environment in which individuals live nor to body condition. In Switzerland, reddish‐brown males were observed to feed their brood at a higher rate and to produce more offspring than white males. This observation lead us to hypothesize that white males may equalise fitness by investing more effort in extra‐pair copulations. This hypothesis predicts that lighter coloured males produce more extra‐pair young, have larger testes and higher levels of circulating testosterone. However, our results are not consistent with these three predictions. First, paternity analyses of 54 broods with a total of 211 offspring revealed that only one young was not sired by the male that was feeding it. Second, testes size was not correlated with male plumage coloration suggesting that white males are not sexually more active. Finally, in nestlings at the time of feather growth testosterone level was not related to plumage coloration suggesting that this androgen is not required for the expression of this plumage trait. Our study therefore indicates that in the barn owl colour polymorphism plays no role in the probability of producing extra‐pair young.
The impact of workplace support and identity on training transfer: a case study of drug and alcohol safety training in Australia
Authors: Pidd Ken
Published: November 2004

Previous research has indicated that the transfer climate of work organisations is an important factor in determining the degree to which knowledge, skills and abilities gained in training transfer to the workplace. In particular, workplace social support from supervisors and coworkers is consistently cited as an important factor that can facilitate or inhibit training transfer. However, research evidence regarding the impact of workplace social support on training transfer is mixed. In order to address this issue a study was conducted to identify under what conditions workplace social support impacts on training transfer. This study evaluated a workplace drug and alcohol training programme* to examine the impact of workplace social support and identification with workplace groups on training transfer. Results indicated that the influence of workplace social support on training transfer was moderated by the degree to which trainees identified with workplace groups that provided this support. This study supports the proposition that in order to fully understand training transfer, and to design effective training programmes, training research and practice needs to focus on both the personal and situational factors that may interact to influence learning and transfer.
Rapid hip bone loss in active Crohn's disease patients receiving short‐term corticosteroid therapy
Authors: Tobias J. H. , Sasi M. R. , Greenwood R. , Probert C. S. J.
Published: November 2004

Background : Uncertainty over whether corticosteroids cause bone loss in patients with Crohn's disease may reflect their short, intermittent use.

Aim : We investigated whether a 2‐month course of prednisolone is associated with detectable bone loss.

Methods : Fifteen patients with active Crohn's disease and 19 controls with inactive Crohn's disease were recruited. Bone mineral density of the lumbar spine and hip was measured at baseline and 2 and 8 months.

Results : At 2 months, significant bone loss was found in patients with active disease (femoral neck −2.7%, P < 0.002; Ward's triangle −3.9%, P < 0.01). Although bone mineral density was still lower at 8 months, these differences were no longer significant (−1.3% and −3.4%, femoral neck and Ward's triangle, respectively). No significant change in hip bone mineral density was observed in controls. Previous corticosteroid use was not significantly associated with baseline bone mineral density, although significant independent associations were observed between weight, site of disease and lumbar spine bone mineral density, and between dietary calcium deficiency and femoral neck and Ward's triangle bone mineral density.

Conclusion : Significant bone loss at the hip can be detected in patients receiving corticosteroid treatment for 2 months for active Crohn's disease ; however, it remains unclear whether this is because of disease activity or its treatment. This rapid bone loss may represent a risk factor for fracture and justify bone protective therapy.
The new DR‐70 immunoassay detects cancer of the gastrointestinal tract: a validation study
Authors: Kerber A. , Trojan J. , Herrlinger K. , Zgouras D. , Caspary W. F. , Braden B.
Published: November 2004

Background : Malignant cells characteristically possess high levels of plasminogen activator, which induce local fibrinolysis. The DR‐70 immunoassay is a newly developed test, which quantifies fibrin degradation products in serum by a proprietary antibody.

Aim : To evaluate the DR‐70 immunoassay as a detection assay for the presence of gastrointestinal cancers.

Methods : We prospectively collected blood sera of 85 patients with histologically proven tumour and 100 healthy blood donors. Ten microlitres of the sera was used for the DR‐70 immunoassay. Nineteen patients had a hepatocellular and 10 cholangiocellular carcinoma, 13 cancer of the pancreas, 30 colorectal cancer, 10 stomach cancer and three cancer of the oesophagus.

Results : Receiver–operator curve analysis revealed <0.7 μg/mL as the best cut‐off value to distinguish between patients with cancer and healthy controls. Using this cut‐off value, the DR‐70 immunoassay showed a good clinical performance with a sensitivity of 91% and a specificity of 93%. Patients with advanced tumour spread showed significantly higher DR‐70 values than those with early‐stage tumours (P < 0.0003).

Conclusion : The DR‐70 immunoassay reliably differs between cancer patients and healthy controls. Therefore, it promises to become a useful test for the detection of cancer in clinical practice.
Clinical and functional responses to salbutamol inhaled via different devices in asthmatic patients with induced bronchoconstriction
Authors: Lavorini Federico , Geri Pietro , Luperini Martina , Maluccio Nazzarena M. , Mariani Laura , Marmai Cecilia , Pistolesi Massimo , Fontana Giovanni A.
Published: November 2004

Aims

This study aimed at evaluating changes in airway patency, lung volumes and perception of breathing discomfort intensity following salbutamol administration via the Diskus dry‐powder inhaler (DPI) or a pressurized metered‐dose inhaler with the Volumatic valved holding chamber (pMDI + Volumatic) in asthmatic patients with methacholine‐induced bronchoconstriction.

Methods

On six different study days, 18 patients inhaled methacholine until forced expiratory volume in 1 s (FEV1) decreased by approximately 35% of baseline. Following placebo, 200 and 400 µg of salbutamol through the pMDI + Volumatic or the Diskus, changes in FEV1, volume‐adjusted mean forced expiratory flow from 25 to 75% of the forced vital capacity (isoFEF25−75), lung volumes and breathing discomfort intensity, assessed by visual analogue scale (VAS) score, were repeatedly measured over a 60‐min observation period.

Results

Induced bronchoconstriction was accompanied by obvious reductions in lung volumes and increases in VAS score. After salbutamol administration, FEV1 and VAS score changes were similar in all experimental conditions. However, following 400 µg salbutamol via pMDI + Volumatic, isoFEF25−75 values increased up to 4.48 l s−1 (95% confidence interval 4.06, 4.90), a significantly (P < 0.01) higher value than those attained in all other experimental conditions. Independently of the salbutamol dose, lung volumes rose to significantly (P < 0.01) higher levels in pMDI + Volumatic than in Diskus trials. The low salbutamol dose via the pMDI + Volumatic and the high dose via the DPI increased isoFEF25−75 and lung volumes to similar extents.

Conclusions

Salbutamol via the pMDI + Volumatic provides greater isoFEF25−75 and lung volume increases in asthmatic patients with induced bronchoconstriction; salbutamol‐induced changes in VAS scores poorly reflect those in small airway patency. The lack of differences in FEV1 increases observed after 200 and 400 µg salbutamol may reflect attainment of the flat portion of the dose–response curve using either device.
Internet based clinical trial protocols – as applied to a study of warfarin pharmacogenetics
Authors: Lindh Jonatan D. , Kublickas Marius , Westgren Magnus , Rane Anders
Published: November 2004

Aims

To describe and evaluate the use of an Internet‐based study protocol in a multicentre study of genetic risk factors in anticoagulant treatment.

Methods

A web‐based study protocol, similar to existing anticoagulation medical record systems, was developed for entry of clinical data. It was also supplied with a separate interface for study monitoring. Measures were taken to assure the confidentiality of transferred data. In addition, software modifications were made to enable automated transfer of clinical data from an existing medical record system to the study database.

Results

The system has been in use since March 2002, and at present 39 centres have included 909 patients with a dropout rate of 2.8%. The need for education of participating clinicians has been satisfactorily provided for by means of written instructions and telephone support.

Conclusions

Our study demonstrates the usability of Internet‐based data acquisition techniques in a full‐scale multicentre clinical trial. The main advantages of such a protocol are automated data validation and standardization, fast data transfer independent of geographical distance, user feedback, synchronization of protocol updates and automatic data formatting facilitating statistical analyses. Safety and accessibility are possibly cumbersome areas and should be addressed duly.
Detection of p53 dysfunction by flow cytometry in chronic lymphocytic leukaemia
Authors: Carter A. , Lin K. , Sherrington P. D. , Pettitt A. R.
Published: November 2004

In chronic lymphocytic leukaemia (CLL) cells, functional impairment of the p53 pathway is detectable by Western blotting as impaired up‐regulation of p21 (a transcriptional target of p53) in response to ionizing radiation (IR). The type A defect is characterized by baseline p53 overexpression and is associated with TP53 mutation. The type B defect is characterized by impaired IR‐induced p53 up‐regulation and is associated with inactivation of the ataxia telangiectasia‐mutated gene (ATM). Both abnormalities are strongly associated with adverse clinical outcome. In the present study, flow cytometry was found to be an effective alternative to Western blotting in the detection of p53 dysfunction in CLL.
CD40 stimulation of B‐cell chronic lymphocytic leukaemia cells enhances the anti‐apoptotic profile, but also Bid expression and cells remain susceptible to autologous cytotoxic T‐lymphocyte attack
Authors: Kater Arnon P. , Evers Ludo M. , Remmerswaal Ester B. M. , Jaspers Annelieke , Oosterwijk Michiel F. , van Lier René A. W. , van Oers Marinus H. J. , Eldering Eric
Published: November 2004

To enhance the poor antigen‐presenting capacity of B‐cell chronic lymphocytic leukaemia (B‐CLL), CD40 triggering has been considered as an active immunotherapy. However, CD40 stimulation also has an anti‐apoptotic effect and may further impair the dysregulated response of B‐CLL to apoptotic stimuli. Therefore, we measured the expression of virtually all regulators of apoptosis before and after CD40 stimulation. These findings were correlated with sensitivity for chemotherapy‐ and death‐receptor‐induced apoptosis and T‐cell‐mediated killing. CD40 stimulation enhanced the constitutive anti‐apoptotic profile of B‐CLL cells by upregulation of Bcl‐xL and Bfl‐1 and downregulation of the BH3‐only protein Harakiri. Unexpectedly, the BH3‐only protein Bid was strongly induced. Functionally, CD40‐stimulated B‐CLL cells became resistant to drug‐induced apoptosis and, despite upregulation of CD95 and Bid, were not sensitive to CD95L. In contrast, autologous T cell killing, triggered by loading CLL cells with viral (CMV) peptides, was very efficient both before and after CD40 stimulation. Upon CTL interaction, CLL targets underwent mitochondrial depolarization and caspase‐3 activation. Thus, despite an increased anti‐apoptotic profile, CD40 triggered B‐CLL cells remain excellent targets for resident cytotoxic T cells. These data support therapeutic exploitation of CD40 stimulation in B‐CLL, provided that a strong CTL component is induced.