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Sample records for protein turnover electronic

  1. Protein turnover in sheep

    International Nuclear Information System (INIS)

    Buttery, P.J.

    1981-01-01

    Considerable advances have been made in the knowledge of the mechanisms and control of synthesis and degradation of proteins in animal tissues during the last decade. Most of the work on the measurement of synthetic and degradative rates of the mixed protein fraction from tissues has been conducted in the rat. There have, unfortunately, been few publications describing results of protein turnover studies with ruminants. Consideration is given here to the techniques used to measure protein turnover, and some of the results obtained, particularly with sheep, are summarized. No attempt has been made to discuss directly the situation in parasitized animals; rather the aim is to provide background information which complements other work dealing with the effects of parasites on the nitrogen metabolism of ruminants. (author)

  2. The research methods and model of protein turnover in animal

    International Nuclear Information System (INIS)

    Wu Xilin; Yang Feng

    2002-01-01

    The author discussed the concept and research methods of protein turnover in animal body. The existing problems and the research results of animal protein turnover in recent years were presented. Meanwhile, the measures to improve the models of animal protein turnover were analyzed

  3. Regulatory mechanisms of skeletal muscle protein turnover during exercise

    DEFF Research Database (Denmark)

    Rose, Adam John; Richter, Erik

    2009-01-01

    Skeletal muscle protein turnover is a relatively slow metabolic process that is altered by various physiological stimuli such as feeding/fasting and exercise. During exercise, catabolism of amino acids contributes very little to ATP turnover in working muscle. With regards to protein turnover......, there is now consistent data from tracer studies in rodents and humans showing that global protein synthesis is blunted in working skeletal muscle. Whether there is altered skeletal muscle protein breakdown during exercise remains unclear. The blunting of protein synthesis is believed to be mediated...... downstream of changes in intracellular Ca(2+) and energy turnover. In particular, a signaling cascade involving Ca(2+)-calmodulin-eEF2 kinase-eEF2 is implicated. The possible functional significance of altered protein turnover in working skeletal muscle during exercise is discussed. Further work...

  4. Measurements of protein turnover in man with nitrogen-15

    International Nuclear Information System (INIS)

    Garlick, P.J.; Waterlow, J.C.

    1977-01-01

    Past and present methods of measuring total body protein turnover with 15 N-labelled compounds are reviewed, and a short assessment made of results achieved. Protein turnover in man was first measured by Sprinson and Rittenberg (1949) using 15 N glycine as tracer. The rate of turnover was calculated from the fraction of the dose excreted in urine in the days following a single oral dose of the isotope. In the following years a number of similar methods were devised but interest waned, perhaps because consistent changes in turnover rate under different conditions were not detected. A revival of interest came with the measurement of changes in protein turnover in malnourished and recovering children by Picou and Taylor-Roberts (1969). Nitrogen-15-glycine was infused and measurements were made of the abundance of 15 N in urinary urea, which reached a plateau in about 24 hours. Turnover rates were calculated from the proportion of the infused dose excreted in urea after the plateau had been reached. This method has also been used successfully on adults when the isotope has been given as three-hourly oral doses. In adults, however, plateau labelling in urea is not usually reached for two days. In our laboratory the use of urinary ammonia, which reaches a plateau more quickly than urea, has been examined. In addition, comparisons have been made between constant infusion and single dose of isotope. Halliday and McKeran (1975) infused 15 N-lysine and measured the 15 N abundance in the free lysine of plasma, which reached a plateau in about 12 hours. Turnover in the whole body and turnover of muscle proteins and of plasma albumin were estimated separately. These methods of measuring protein turnover with 15 N are described and results reviewed of the effects of food intake, nutritional status and age. (author)

  5. Investigation on the turnover of plant proteins. 2

    International Nuclear Information System (INIS)

    Becker, R.; Winkler, E.; Jung, K.; Huebner, G.

    1981-01-01

    Based on kinetic analyses of amino acid and protein turnover by means of compartment models the synthesis and degradation of the soluble proteins in etiolated epicotyl segments of Pisum sativum L. as well as their dependence on the herbicide 2'-methyl-4'-chlorophenoxyacetic acid (MCPA) were determined quantitatively. The segments were incubated for 10 h in a medium containing 14 C-leucine and subsequently placed in an inactive medium. The radioactivity in the soluble proteins and in the amino acid fraction was followed up for a total of 24 h. A 3-pool model in which the total measurable amino acid pool was divided into a direct precursor pool for protein synthesis and into a degradation pool was best suited to interpret the data. The turnover rate for the soluble proteins of untreated epicotyl segments was determined to be 0.058 h -1 ; at an MCPA concentration of 10 -4 M this value was nearly doubled. An increased proteolytic activity in the epicotyl segments ran parallel to the change of the turnover rate in dependence on MCPA concentration. The heterogeneity of the soluble protein with respect to the turnover rate was investigated by means of 3 H/ 14 C double labelling for individual protein fractions separated by gel electrophoresis. The results obtained in this way were comparable with those of the total pool turnover. (author)

  6. Systematic analysis of protein turnover in primary cells.

    Science.gov (United States)

    Mathieson, Toby; Franken, Holger; Kosinski, Jan; Kurzawa, Nils; Zinn, Nico; Sweetman, Gavain; Poeckel, Daniel; Ratnu, Vikram S; Schramm, Maike; Becher, Isabelle; Steidel, Michael; Noh, Kyung-Min; Bergamini, Giovanna; Beck, Martin; Bantscheff, Marcus; Savitski, Mikhail M

    2018-02-15

    A better understanding of proteostasis in health and disease requires robust methods to determine protein half-lives. Here we improve the precision and accuracy of peptide ion intensity-based quantification, enabling more accurate protein turnover determination in non-dividing cells by dynamic SILAC-based proteomics. This approach allows exact determination of protein half-lives ranging from 10 to >1000 h. We identified 4000-6000 proteins in several non-dividing cell types, corresponding to 9699 unique protein identifications over the entire data set. We observed similar protein half-lives in B-cells, natural killer cells and monocytes, whereas hepatocytes and mouse embryonic neurons show substantial differences. Our data set extends and statistically validates the previous observation that subunits of protein complexes tend to have coherent turnover. Moreover, analysis of different proteasome and nuclear pore complex assemblies suggests that their turnover rate is architecture dependent. These results illustrate that our approach allows investigating protein turnover and its implications in various cell types.

  7. Changes of Protein Turnover in Aging Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Dhondt, Ineke; Petyuk, Vladislav A.; Bauer, Sophie; Brewer, Heather M.; Smith, Richard D.; Depuydt, Geert; Braeckman, Bart P.

    2017-07-05

    Protein turnover rates severely decline in aging organisms, including C. elegans. However, limited information is available on turnover dynamics at the individual protein level during aging. We followed changes in protein turnover at one-day resolution using a multiple-pulse 15Nlabeling and accurate mass spectrometry approach. Forty percent of the proteome shows gradual slowdown in turnover with age, whereas only few proteins show increased turnover. Decrease in protein turnover was consistent for only a minority of functionally related protein subsets, including tubulins and vitellogenins, whereas randomly diverging turnover patterns with age were the norm. Our data suggests increased heterogeneity of protein turnover of the translation machinery, whereas protein turnover of ubiquitin-proteasome and antioxidant systems are well-preserved over time. Hence, we presume that maintenance of quality control mechanisms is a protective strategy in aging worms, although the ultimate proteome collapse is inescapable.

  8. Control of the Protein Turnover Rates in Lemna minor

    Science.gov (United States)

    Trewavas, A.

    1972-01-01

    The control of protein turnover in Lemna minor has been examined using a method described in the previous paper for determining the rate constants of synthesis and degradation of protein. If Lemna is placed on water, there is a reduction in the rate constants of synthesis of protein and an increase (3- to 6-fold) in the rate constant of degradation. The net effect is a loss of protein from the tissue. Omission of nitrate, phosphate, sulfate, magnesium, or calcium results in increases in the rate constant of degradation of protein. An unusual dual effect of benzyladenine on the turnover constants has been observed. Treatment of Lemna grown on sucrose-mineral salts with benzyladenine results in alterations only in the rate constant of synthesis. Treatment of Lemna grown on water with benzyladenine alters only the rate constant of degradation. Abscisic acid on the other hand alters both rate constants of synthesis and degradation of protein together. Inclusion of growth-inhibiting amino acids in the medium results in a reduction in the rate constants of synthesis and increases in the rate constant of degradation of protein. It is concluded that the rate of turnover of protein in Lemna is very dependent on the composition of the growth medium. Conditions which reduce growth rates also reduce the rates of synthesis of protein and increase those of degradation. PMID:16657895

  9. Electronic alerts and clinician turnover: the influence of user acceptance.

    Science.gov (United States)

    Hysong, Sylvia J; Spitzmuller, Christiane; Espadas, Donna; Sittig, Dean F; Singh, Hardeep

    2014-11-01

    Use of certain components of electronic health records (EHRs), such as EHR-based alerting systems (EASs), might reduce provider satisfaction, a strong precursor to turnover. We examined the impact of factors likely to influence providers' acceptance of an alerting system, designed to facilitate electronic communication in outpatient settings, on provider satisfaction, intentions to quit, and turnover. We conducted a cross-sectional Web-based survey of EAS-related practices from a nationwide sample of primary care providers (PCPs) practicing at Department of Veterans Affairs (VA) medical facilities. Of 5001 invited VA PCPs, 2590 completed the survey. We relied on Venkatesh's Unified Theory of Acceptance and Use of Technology to create survey measures of 4 factors likely to impact user acceptance of EAS: supportive norms, monitoring/ feedback, training, and providers' perceptions of the value (PPOV) of EASs to provider effectiveness. Facility-level PCP turnover was measured via the VA's Service Support Center Human Resources Cube. Hypotheses were tested using structural equation modeling. After accounting for intercorrelations among predictors, monitoring/feedback regarding EASs significantly predicted intention to quit (b = 0.30, P < .01), and PPOV of EASs predicted both overall provider satisfaction (b = 0.58, P < .01) and facility-level provider turnover levels (b = -0.19, P < .05), all without relying on any intervening mechanisms. Design, implementation, and use of EASs might impact provider satisfaction and retention. Institutions should consider strategies to help providers perceive greater value in these clinical tools.

  10. Effects of ractopamine and gender on protein turnover in skeletal ...

    African Journals Online (AJOL)

    Effects of the β-agonist, ractopamine-HCl (ractopamine), on skeletal muscle protein turnover were evaluated in 16 steers (512 kg) and 16 heifers (473 kg). Treatments were arranged in a 2 × 2 factorial design and included gender (steer vs. heifer) and ractopamine (0 or 200 mg/d). Steers were implanted with 120 mg ...

  11. Evolutionary Turnover of Kinetochore Proteins: A Ship of Theseus?

    Science.gov (United States)

    Drinnenberg, Ines A; Henikoff, Steven; Malik, Harmit S

    2016-07-01

    The kinetochore is a multiprotein complex that mediates the attachment of a eukaryotic chromosome to the mitotic spindle. The protein composition of kinetochores is similar across species as divergent as yeast and human. However, recent findings have revealed an unexpected degree of compositional diversity in kinetochores. For example, kinetochore proteins that are essential in some species have been lost in others, whereas new kinetochore proteins have emerged in other lineages. Even in lineages with similar kinetochore composition, individual kinetochore proteins have functionally diverged to acquire either essential or redundant roles. Thus, despite functional conservation, the repertoire of kinetochore proteins has undergone recurrent evolutionary turnover. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Growth rate correlates negatively with protein turnover in Arabidopsis accessions.

    Science.gov (United States)

    Ishihara, Hirofumi; Moraes, Thiago Alexandre; Pyl, Eva-Theresa; Schulze, Waltraud X; Obata, Toshihiro; Scheffel, André; Fernie, Alisdair R; Sulpice, Ronan; Stitt, Mark

    2017-08-01

    Previous studies with Arabidopsis accessions revealed that biomass correlates negatively to dusk starch content and total protein, and positively to the maximum activities of enzymes in photosynthesis. We hypothesized that large accessions have lower ribosome abundance and lower rates of protein synthesis, and that this is compensated by lower rates of protein degradation. This would increase growth efficiency and allow more investment in photosynthetic machinery. We analysed ribosome abundance and polysome loading in 19 accessions, modelled the rates of protein synthesis and compared them with the observed rate of growth. Large accessions contained less ribosomes than small accessions, due mainly to cytosolic ribosome abundance falling at night in large accessions. The modelled rates of protein synthesis resembled those required for growth in large accessions, but were up to 30% in excess in small accessions. We then employed 13 CO 2 pulse-chase labelling to measure the rates of protein synthesis and degradation in 13 accessions. Small accessions had a slightly higher rate of protein synthesis and much higher rates of protein degradation than large accessions. Protein turnover was negligible in large accessions but equivalent to up to 30% of synthesised protein day -1 in small accessions. We discuss to what extent the decrease in growth in small accessions can be quantitatively explained by known costs of protein turnover and what factors may lead to the altered diurnal dynamics and increase of ribosome abundance in small accessions, and propose that there is a trade-off between protein turnover and maximisation of growth rate. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  13. A high protein diet upregulated whole-body protein turnover during energy deficit

    Science.gov (United States)

    The effects of higher protein diets and sustained energy deficit (ED) on whole-body protein turnover (WBPTO) are not well described. This study examined whether dietary protein level influences whole-body protein breakdown (Ra), non-oxidative leucine disposal (NOLD), and oxidation (Ox) during ED. ...

  14. Feasibility of protein turnover studies in prototroph Saccharomyces cerevisiae strains.

    Science.gov (United States)

    Martin-Perez, Miguel; Villén, Judit

    2015-04-07

    Quantitative proteomics studies of yeast that use metabolic labeling with amino acids rely on auxotrophic mutations of one or more genes on the amino acid biosynthesis pathways. These mutations affect yeast metabolism and preclude the study of some biological processes. Overcoming this limitation, it has recently been described that proteins in a yeast prototrophic strain can also be metabolically labeled with heavy amino acids. However, the temporal profiles of label incorporation under the different phases of the prototroph's growth have not been examined. Labeling trajectories are important in the study of protein turnover and dynamics, in which label incorporation into proteins is monitored across many time points. Here we monitored protein labeling trajectories for 48 h after a pulse with heavy lysine in a yeast prototrophic strain and compared them with those of a lysine auxotrophic yeast. Labeling was successful in prototroph yeast during exponential growth phase but not in stationary phase. Furthermore, we were able to determine the half-lives of more than 1700 proteins during exponential phase of growth with high accuracy and reproducibility. We found a median half-life of 2 h in both strains, which corresponds with the cellular doubling time. Nucleolar and ribosomal proteins showed short half-lives, whereas mitochondrial proteins and other energy production enzymes presented longer half-lives. Except for some proteins involved in lysine biosynthesis, we observed a high correlation in protein half-lives between prototroph and auxotroph strains. Overall, our results demonstrate the feasibility of using prototrophs for proteomic turnover studies and provide a reliable data set of protein half-lives in exponentially growing yeast.

  15. Plasma Protein Turnover Rates in Rats Using Stable Isotope Labeling, Global Proteomics, and Activity-Based Protein Profiling

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jordan N.; Tyrrell, Kimberly J.; Hansen, Joshua R.; Thomas, Dennis G.; Murphree, Taylor A.; Shukla, Anil K.; Luders, Teresa; Madden, James M.; Li, Yunying; Wright, Aaron T.; Piehowski, Paul D.

    2017-12-06

    Protein turnover is important for general health on cellular and organism scales providing a strategy to replace old, damaged, or dysfunctional proteins. Protein turnover also informs of biomarker kinetics, as a better understanding of synthesis and degradation of proteins increases the clinical utility of biomarkers. Here, turnover rates of plasma proteins in rats were measured in vivo using a pulse-chase stable isotope labeling experiment. During the pulse, rats (n=5) were fed 13C6-labeled lysine (“heavy”) feed for 23 days to label proteins. During the chase, feed was changed to an unlabeled equivalent feed (“light”), and blood was repeatedly sampled from rats over 10 time points for 28 days. Plasma samples were digested with trypsin, and analyzed with liquid chromatography-tandem mass spectrometry (LC-MS/MS). MaxQuant was used to identify peptides and proteins, and quantify heavy:light lysine ratios. A system of ordinary differential equations was used to calculate protein turnover rates. Using this approach, 273 proteins were identified, and turnover rates were quantified for 157 plasma proteins with half-lives ranging 0.3-103 days. For the ~70 most abundant proteins, variability in turnover rates among rats was low (median coefficient of variation: 0.09). Activity-based protein profiling was applied to pooled plasma samples to enrich serine hydrolases using a fluorophosphonate (FP2) activity-based probe. This enrichment resulted in turnover rates for an additional 17 proteins. This study is the first to measure global plasma protein turnover rates in rats in vivo, measure variability of protein turnover rates in any animal model, and utilize activity-based protein profiling for enhancing measurements of targeted, low-abundant proteins, such as those commonly used as biomarkers. Measured protein turnover rates will be important for understanding of the role of protein turnover in cellular and organism health as well as increasing the utility of protein

  16. Hepatitis C Virus Core Protein Decreases Lipid Droplet Turnover

    Science.gov (United States)

    Harris, Charles; Herker, Eva; Farese, Robert V.; Ott, Melanie

    2011-01-01

    Steatosis is a frequent complication of hepatitis C virus infection. In mice, this condition is recapitulated by the expression of a single viral protein, the nucleocapsid core. Core localizes to the surface of lipid droplets (LDs) in infected liver cells through a process dependent on host diacylglycerol acyltransferase 1 (DGAT1), an enzyme that synthesizes triglycerides in the endoplasmic reticulum. Whether DGAT1 also plays a role in core-induced steatosis is uncertain. Here, we show that mouse embryonic fibroblasts isolated from DGAT1−/− mice are protected from core-induced steatosis, as are livers of DGAT1−/− mice expressing core, demonstrating that the steatosis is DGAT1-dependent. Surprisingly, core expression did not increase DGAT1 activity or triglyceride synthesis, thus excluding the possibility that core activates DGAT1 to cause steatosis. Instead, we find that DGAT1-dependent localization of core to LDs is a prerequisite for the steatogenic properties of the core. Using biochemical and immunofluorescence microscopy techniques, we show that the turnover of lipids in core-coated droplets is decreased, providing a physiological mechanism for core-induced steatosis. Our results support a bipartite model in which core first requires DGAT1 to gain access to LDs, and then LD-localized core interferes with triglyceride turnover, thus stabilizing lipid droplets and leading to steatosis. PMID:21984835

  17. Protein turnover in acid maltase deficiency before and after treatment with a high protein diet.

    OpenAIRE

    Umpleby, A M; Wiles, C M; Trend, P S; Scobie, I N; Macleod, A F; Spencer, G T; Sonksen, P H

    1987-01-01

    A patient with acid maltase deficiency was treated with a high protein diet for 7 months. Protein turnover expressed in terms of lean body mass was shown to be increased in this patient before the diet but was markedly reduced following the diet. The patient improved clinically whilst on the diet both subjectively and in terms of mobility, breathing and reduced peripheral cyanosis at rest.

  18. Turnover of whole body proteins and myofibrillar proteins in middle-aged active men

    International Nuclear Information System (INIS)

    Zackin, M.; Meredith, C.; Frontera, W.; Evans, W.

    1986-01-01

    Endurance-trained older men have a higher proportion of lean tissue and greater muscle cell oxidative capacity, reversing age-related trends and suggesting major changes in protein metabolism. In this study, protein turnover was determined in 6 middle-aged (52+/-1 yr) men who were well trained (VO 2 max 55.2+/-5.0 ml O 2 /kg.min) and lean (body fat 18.9+/-2.8%, muscle mass 36.6+/-0.6%). The maintained habitual exercise while consuming 0.6, 0.9 or 1.2 g protein/kg.day for 10-day periods. N flux was measured from 15 N in urea after oral 15 N-glycine administration. Myofibrillar protein breakdown was estimated from urinary 3-methyl-histidine. Dietary protein had no effect on turnover rates, even when N balance was negative. Whole body protein synthesis was 3.60+/-0.12 g/kg.day and breakdown was 3.40+/-0.14 g/kg.day for all N intakes. Whole body protein flux, synthesis and breakdown were similar to values reported for sedentary young (SY) or sedentary old (SO) men on comparable diets. 3-me-his (3.67+/-0.14 μmol/kg.day) was similar to values reported for SY but higher (p<0.01) than for SO. Myofibrillar protein breakdown per unit muscle mass (185+/-7 μmol 3-me-his/g creatinine) was higher (p<0.01) than for SY or SO. In active middle-aged men, myofibrillar proteins may account for a greater proportion of whole body protein turnover, despite an age-related reduction in muscle mass

  19. Electron transfer in proteins

    DEFF Research Database (Denmark)

    Farver, O; Pecht, I

    1991-01-01

    Electron migration between and within proteins is one of the most prevalent forms of biological energy conversion processes. Electron transfer reactions take place between active centers such as transition metal ions or organic cofactors over considerable distances at fast rates and with remarkable...... specificity. The electron transfer is attained through weak electronic interaction between the active sites, so that considerable research efforts are centered on resolving the factors that control the rates of long-distance electron transfer reactions in proteins. These factors include (in addition......-containing proteins. These proteins serve almost exclusively in electron transfer reactions, and as it turns out, their metal coordination sites are endowed with properties uniquely optimized for their function....

  20. Protein turnover and 3-methylhistidine excretion in non-pregnant, pregnant and gestational diabetic women

    International Nuclear Information System (INIS)

    Fitch, W.L.; King, J.C.

    1986-01-01

    Protein turnover was studied in nine non-pregnant (NP) women, eight pregnant (P) and two gestational diabetic (GDM) women. Whole body protein turnover, synthesis and catabolism rates were measured using a single oral dose of 15 N-glycine followed by measurement of enrichment of urinary ammonia. Urinary 3-methylhistidine (3MH) excretion was measured for three consecutive days, including the day of the protein turnover study. Whole body protein turnover and synthesis rates did not differ between the P and NP women, although the synthesis rates tended to be higher in the P group. Gestational diabetic women appeared to have considerably higher rates of both turnover and synthesis. Pregnant women excreted significantly more urinary 3MH than did non-pregnant women. GDM women appeared to have lower 3MH excretion than the P women. Correlation between 3MH excretion and protein turnover rates was nearly significant (p = .06) in the NP women, but was poorly correlated (p = .43) in the P women, suggesting that muscles may be a less important site of whole body protein turnover in pregnancy than in the non-pregnant state

  1. Effect of thyroid hormone on the protein turnover rate of mouse pancreas

    International Nuclear Information System (INIS)

    He Xinjun; Zhou Hui; Wang Shizhen; Zhou Zhonming; Li Liangxue; Wei Huaiwei; Sun Xiaomiao; Wang Yanli

    1986-01-01

    The effects of thyroid hormone on the protein turnover of pancreas in mice were studied using labelled amino acid incorporation, double isotopic and labelled protein decay methods. After injection of L-thyroxine (100 μ g/mouse) for 5 days, the amino acid incorporation into pancreatic proteins of mice was profoundly decreased, the ratio of 3 H/ 14 C in labelled proteins and the fractional turnover rate of pancreatic proteins were also decreased, the protein half-lives being consequently prolonged. These findings suggest that large doses of thyroid hormone may reduce the trunover rate of pancreatic proteins, by inhibiting not only the synthesis but also the degradation

  2. Methyl group turnover on methyl-accepting chemotaxis proteins during chemotaxis by Bacillus subtilis

    International Nuclear Information System (INIS)

    Thoelke, M.S.; Casper, J.M.; Ordal, G.W.

    1990-01-01

    The addition of attractant to Bacillus subtilis briefly exposed to radioactive methionine causes an increase of labeling of the methyl-accepting chemotaxis proteins. The addition of attractant to cells radiolabeled for longer times shows no change in the extent of methylation. Therefore, the increase in labeling for the briefly labeled cells is due to an increased turnover of methyl groups caused by attractant. All amino acids gave enhanced turnover. This turnover lasted for a prolonged time, probably spanning the period of smooth swimming caused by the attractant addition. Repellent did not affect the turnover when added alone or simultaneously with attractant. Thus, for amino acid attractants, the turnover is probably the excitatory signal, which is seen to extend long into or throughout the adaptation period, not just at the start of it

  3. Protein Turnover Measurements in Human Serum by Serial Immunoaffinity LC-MS/MS.

    Science.gov (United States)

    Farrokhi, Vahid; Chen, Xiaoying; Neubert, Hendrik

    2018-02-01

    The half-life of target proteins is frequently an important parameter in mechanistic pharmacokinetic and pharmacodynamic (PK/PD) modeling of biotherapeutics. Clinical studies for accurate measurement of physiologically relevant protein turnover can reduce the uncertainty in PK/PD model-based predictions, for example, of the therapeutic dose and dosing regimen in first-in-human clinical trials. We used a targeted mass spectrometry work flow based on serial immunoaffinity enrichment ofmultiple human serum proteins from a [5,5,5- 2 H 3 ]-L-leucine tracer pulse-chase study in healthy volunteers. To confirm the reproducibility of turnover measurements from serial immunoaffinity enrichment, multiple aliquots from the same sample set were subjected to protein turnover analysis in varying order. Tracer incorporation was measured by multiple-reaction-monitoring mass spectrometry and target turnover was calculated using a four-compartment pharmacokinetic model. Five proteins of clinical or therapeutic relevance including soluble tumor necrosis factor receptor superfamily member 12A, tissue factor pathway inhibitor, soluble interleukin 1 receptor like 1, soluble mucosal addressin cell adhesion molecule 1, and muscle-specific creatine kinase were sequentially subjected to turnover analysis from the same human serum sample. Calculated half-lives ranged from 5-15 h; however, no tracer incorporation was observed for mucosal addressin cell adhesion molecule 1. The utility of clinical pulse-chase studies to investigate protein turnover can be extended by serial immunoaffinity enrichment of target proteins. Turnover analysis from serum and subsequently from remaining supernatants provided analytical sensitivity and reproducibility for multiple human target proteins in the same sample set, irrespective of the order of analysis. © 2017 American Association for Clinical Chemistry.

  4. Metabolic Turnover of Synaptic Proteins: Kinetics, Interdependencies and Implications for Synaptic Maintenance

    Science.gov (United States)

    Cohen, Laurie D.; Zuchman, Rina; Sorokina, Oksana; Müller, Anke; Dieterich, Daniela C.; Armstrong, J. Douglas; Ziv, Tamar; Ziv, Noam E.

    2013-01-01

    Chemical synapses contain multitudes of proteins, which in common with all proteins, have finite lifetimes and therefore need to be continuously replaced. Given the huge numbers of synaptic connections typical neurons form, the demand to maintain the protein contents of these connections might be expected to place considerable metabolic demands on each neuron. Moreover, synaptic proteostasis might differ according to distance from global protein synthesis sites, the availability of distributed protein synthesis facilities, trafficking rates and synaptic protein dynamics. To date, the turnover kinetics of synaptic proteins have not been studied or analyzed systematically, and thus metabolic demands or the aforementioned relationships remain largely unknown. In the current study we used dynamic Stable Isotope Labeling with Amino acids in Cell culture (SILAC), mass spectrometry (MS), Fluorescent Non–Canonical Amino acid Tagging (FUNCAT), quantitative immunohistochemistry and bioinformatics to systematically measure the metabolic half-lives of hundreds of synaptic proteins, examine how these depend on their pre/postsynaptic affiliation or their association with particular molecular complexes, and assess the metabolic load of synaptic proteostasis. We found that nearly all synaptic proteins identified here exhibited half-lifetimes in the range of 2–5 days. Unexpectedly, metabolic turnover rates were not significantly different for presynaptic and postsynaptic proteins, or for proteins for which mRNAs are consistently found in dendrites. Some functionally or structurally related proteins exhibited very similar turnover rates, indicating that their biogenesis and degradation might be coupled, a possibility further supported by bioinformatics-based analyses. The relatively low turnover rates measured here (∼0.7% of synaptic protein content per hour) are in good agreement with imaging-based studies of synaptic protein trafficking, yet indicate that the metabolic load

  5. Distinct responses of protein turnover regulatory pathways in hypoxia- and semistarvation-induced muscle atrophy

    NARCIS (Netherlands)

    de Theije, Chiel C.; Langen, Ramon C. J.; Lamers, Wouter H.; Schols, Annemie M. W. J.; Köhler, S. Eleonore

    2013-01-01

    The balance of muscle protein synthesis and degradation determines skeletal muscle mass. We hypothesized that hypoxia-induced muscle atrophy and alterations in the regulation of muscle protein turnover include a hypoxia-specific component, in addition to the observed effects of reduction in food

  6. Amino acid metabolism and whole-body protein turnover in lambs ...

    African Journals Online (AJOL)

    The effect of protein supplementation of a wheat straw diet on the metabolism of lysine, leucine, methionine and urea, and on whole-body protein turnover rate was investigated in lambs. The metabolism of lysine and leucine is reported elsewhere (Cronje et aI., 1992); in this paper methionine metabolism is discussed, and ...

  7. Determination of protein turnover parameters in athletes using 15N tracers

    International Nuclear Information System (INIS)

    Krumbiegel, P.; Kuehne, K.; Faust, H.; Bornhak, H.; Junghans, P.; Zerbes, H.

    1985-01-01

    In 2 adolescent female athletes engaged in technical-acrobatic sports the influence of a high protein diet on the protein turnover rate under training conditions was investigated by means of 15 N-glycine. Protein synthesis was significantly increased, whereas the utilization of nutritive nitrogen was decreased as expected. The 15 N tracer technique is well suited to determine the protein requirements under special training conditions

  8. Impact of transamination reactions and protein turnover on labeling dynamics in C-13-labeling experiments

    DEFF Research Database (Denmark)

    Grotkjær, Thomas; Åkesson, M.; Christensen, Bjarke

    2004-01-01

    A dynamic model describing carbon atom transitions in the central metabolism of Saccharomyces cerevisiae is used to investigate the influence of transamination reactions and protein turnover on the transient behavior of C-13-labeling chemostat experiments. The simulations performed suggest...... that carbon exchange due to transamination and protein turnover can significantly increase the required time needed for metabolites in the TCA cycle to reach isotopic steady state, which is in agreement with published experimental observations. On the other hand, transamination and protein turnover will speed...... behavior until after three residence times. These observations suggest that greater caution should be used while also pointing to new opportunities in the design and interpretation of C-13-labeling experiments....

  9. Stress and Protein Turnover in Lemna minor1

    Science.gov (United States)

    Cooke, Robert J.; Oliver, Jane; Davies, David D.

    1979-01-01

    Transfer of fronds of Lemna minor L. to adverse growth conditions or stress situations causes a lowering of the growth rate and a loss of soluble protein per frond, the extent of the loss being dependent on the nature of the stress. The loss or protein is due to two factors: (a) a decrease in the rate constant of protein synthesis (ks); (b) an increase in the rate constant of protein degradation (kd). In plants adapted to the stresses, protein synthesis increases and the initially rapid rate of proteolysis is reduced. Addition of abscisic acid both lowers ks and increases kd, whereas benzyladenine seems to alleviate the effects of stress on protein content by decreasing kd rather than by altering ks. Based on the measurement of enzyme activities, stress-induced protein degradation appears to be a general phenomenon, affecting many soluble proteins. The adaptive significance of stress-induced proteolysis is discussed. PMID:16661102

  10. Whole-body protein turnover of a carnivore, Felis silvestris catus.

    Science.gov (United States)

    Russell, K; Lobley, G E; Millward, D J

    2003-01-01

    The cat (Felis silvestris catus) has a higher dietary protein requirement than omnivores and herbivores, thought to be due to metabolic inflexibility. An aspect of metabolic flexibility was examined with studies of whole-body protein turnover at two levels of dietary protein energy, moderate protein (MP; 20 %) and high protein (HP; 70 %), in five adult cats in a crossover design. Following a 14 d pre-feed period, a single intravenous dose of [15N]glycine was administered and cumulative excretion of the isotope in urine and faeces determined over 48 h. N flux increased (Pwork is required to determine exactly why cats have such a high protein requirement.

  11. USP21 regulates Hippo pathway activity by mediating MARK protein turnover

    DEFF Research Database (Denmark)

    Nguyen, Thanh Hung; Kugler, Jan-Michael; Loya, Anand Chainsukh

    2017-01-01

    observed in cancer and often correlates with worse survival. The activity and stability of Hippo pathway components, including YAP/TAZ, AMOT and LATS1/2, are regulated by ubiquitin-mediated protein degradation. Aberrant expression of ubiquitin ligase complexes that regulate the turnover of Hippo components...

  12. Influence of Sex and Estrogen on Musculotendinous Protein Turnover at Rest and After Exercise

    DEFF Research Database (Denmark)

    Hansen, Mette; Kjær, Michael

    2014-01-01

    Women differ from men with regard to muscle and tendon, most likely because of sex differences in estrogen. The present experimental findings suggest the hypothesis that estrogen has an anabolic effect on muscle primarily by lowering the protein turnover and enhancing sensitivity to resistance...... training. Furthermore, estrogen may reduce the stiffness of tendons, an effect that may be modified by physical training....

  13. Effects of ractopamine and gender on protein turnover in skeletal ...

    African Journals Online (AJOL)

    p2492989

    Ractopamine significantly decreased rates of in vitro protein degradation ... with 140 mg trenbolone acetate and 14 mg estradiol (Component TE-H, Vet Life). ... samples were not used for statistical analysis, and samples collected after 15 and 29 ..... and its interaction with gender for RNA, DNA, and protein concentrations as.

  14. Cell cycle-specific UNG2 phosphorylations regulate protein turnover, activity and association with RPA

    DEFF Research Database (Denmark)

    Hagen, Lars; Kavli, Bodil; Sousa, Mirta M L

    2008-01-01

    -catalytic domain that confer distinct functional properties to UNG2. These are apparently generated by cyclin-dependent kinases through stepwise phosphorylation of S23, T60 and S64 in the cell cycle. Phosphorylation of S23 in late G1/early S confers increased association with replication protein A (RPA......) and replicating chromatin and markedly increases the catalytic turnover of UNG2. Conversely, progressive phosphorylation of T60 and S64 throughout S phase mediates reduced binding to RPA and flag UNG2 for breakdown in G2 by forming a cyclin E/c-myc-like phosphodegron. The enhanced catalytic turnover of UNG2 p-S23...

  15. Turnover-dependent inactivation of the nitrogenase MoFe-protein at high pH.

    Science.gov (United States)

    Yang, Kun-Yun; Haynes, Chad A; Spatzal, Thomas; Rees, Douglas C; Howard, James B

    2014-01-21

    Proton uptake accompanies the reduction of all known substrates by nitrogenase. As a consequence, a higher pH should limit the availability of protons as a substrate essential for turnover, thereby increasing the proportion of more highly reduced forms of the enzyme for further study. The utility of the high-pH approach would appear to be problematic in view of the observation reported by Pham and Burgess [(1993) Biochemistry 32, 13725-13731] that the MoFe-protein undergoes irreversible protein denaturation above pH 8.65. In contrast, we found by both enzyme activity and crystallographic analyses that the MoFe-protein is stable when incubated at pH 9.5. We did observe, however, that at higher pHs and under turnover conditions, the MoFe-protein is slowly inactivated. While a normal, albeit low, level of substrate reduction occurs under these conditions, the MoFe-protein undergoes a complex transformation; initially, the enzyme is reversibly inhibited for substrate reduction at pH 9.5, yet in a second, slower process, the MoFe-protein becomes irreversibly inactivated as measured by substrate reduction activity at the optimal pH of 7.8. The final inactivated MoFe-protein has an increased hydrodynamic radius compared to that of the native MoFe-protein, yet it has a full complement of iron and molybdenum. Significantly, the modified MoFe-protein retains the ability to specifically interact with its nitrogenase partner, the Fe-protein, as judged by the support of ATP hydrolysis and by formation of a tight complex with the Fe-protein in the presence of ATP and aluminum fluoride. The turnover-dependent inactivation coupled to conformational change suggests a mechanism-based transformation that may provide a new probe of nitrogenase catalysis.

  16. Effect of alcohol consumption on whole-body protein turnover in healthy adults.

    Science.gov (United States)

    Wutzke, Klaus D; Krentz, Helga; Bruns, Gerrit

    2011-03-01

    The aim of the study was to investigate the whole-body protein turnover, either before or after continuous, moderate ethanol-induced oxidative stress by red wine consumption over a relatively short period in healthy volunteers. Ten healthy adults received an individual regular diet over 20 days. After 10 days, the subjects consumed 0.4 ml ethanol kg(-1) day(-1) as red wine together with dinner over a 10-day period. After 8 and 18 days, respectively, a (15)N-labelled yeast protein was administered in a dosage of 4.2 mg kg(-1) body weight. Urine and faeces were collected over 48 h, respectively. The (15)N-enrichment was measured by isotope ratio mass spectrometry, whereas the protein flux rates were calculated by a three-compartment model. The whole-body protein turnover without/with red wine consumption amounted to 3.73±0.6 and 3.49±0.6 g kg(-1) day(-1) (not significant), respectively. Moderate alcohol consumption does not induce significant short-term changes in the whole-body protein turnover of healthy adults.

  17. Dystropathology Increases Energy Expenditure and Protein Turnover in the Mdx Mouse Model of Duchenne Muscular Dystrophy

    Science.gov (United States)

    Radley-Crabb, Hannah G.; Marini, Juan C.; Sosa, Horacio A.; Castillo, Liliana I.; Grounds, Miranda D.; Fiorotto, Marta L.

    2014-01-01

    The skeletal muscles in Duchenne muscular dystrophy and the mdx mouse model lack functional dystrophin and undergo repeated bouts of necrosis, regeneration, and growth. These processes have a high metabolic cost. However, the consequences for whole body energy and protein metabolism, and on the dietary requirements for these macronutrients at different stages of the disease, are not well-understood. This study used juvenile (4- to 5- wk-old) and adult (12- to 14-wk-old) male dystrophic C57BL/10ScSn-mdx/J and age-matched C57BL/10ScSn/J control male mice to measure total and resting energy expenditure, food intake, spontaneous activity, body composition, whole body protein turnover, and muscle protein synthesis rates. In juvenile mdx mice that have extensive muscle damage, energy expenditure, muscle protein synthesis, and whole body protein turnover rates were higher than in age-matched controls. Adaptations in food intake and decreased activity were insufficient to meet the increased energy and protein needs of juvenile mdx mice and resulted in stunted growth. In (non-growing) adult mdx mice with less severe dystropathology, energy expenditure, muscle protein synthesis, and whole body protein turnover rates were also higher than in age-matched controls. Food intake was sufficient to meet their protein and energy needs, but insufficient to result in fat deposition. These data show that dystropathology impacts the protein and energy needs of mdx mice and that tailored dietary interventions are necessary to redress this imbalance. If not met, the resultant imbalance blunts growth, and may limit the benefits of therapies designed to protect and repair dystrophic muscles. PMID:24586653

  18. Increased Protein Stability and Decreased Protein Turnover in the Caenorhabditis elegans Ins/IGF-1 daf-2 Mutant.

    Science.gov (United States)

    Depuydt, Geert; Shanmugam, Nilesh; Rasulova, Madina; Dhondt, Ineke; Braeckman, Bart P

    2016-12-01

    In Caenorhabditis elegans, cellular proteostasis is likely essential for longevity. Autophagy has been shown to be essential for lifespan extension of daf-2 insulin/IGF mutants. Therefore, it can be hypothesized that daf-2 mutants achieve this phenotype by increasing protein turnover. However, such a mechanism would exert a substantial energy cost. By using classical 35 S pulse-chase labeling, we observed that protein synthesis and degradation rates are decreased in young adults of the daf-2 insulin/IGF mutants. Although reduction of protein turnover may be energetically favorable, it may lead to accumulation and aggregation of damaged proteins. As this has been shown not to be the case in daf-2 mutants, another mechanism must exist to maintain proteostasis in this strain. We observed that proteins isolated from daf-2 mutants are more soluble in acidic conditions due to increased levels of trehalose. This suggests that trehalose may decrease the potential for protein aggregation and increases proteostasis in the daf-2 mutants. We postulate that daf-2 mutants save energy by decreasing protein turnover rates and instead stabilize their proteome by trehalose. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America.

  19. Plasma membrane microdomains regulate turnover of transport proteins in yeast

    Czech Academy of Sciences Publication Activity Database

    Grossmann, G.; Malínský, Jan; Stahlschmidt, W.; Loibl, M.; Weig-Meckl, I.; Frommer, W.B.; Opekarová, Miroslava; Tanner, W.

    2008-01-01

    Roč. 183, č. 6 (2008), s. 1075-1088 ISSN 0021-9525 R&D Projects: GA ČR GA204/06/0009; GA ČR GA204/07/0133; GA ČR GC204/08/J024 Institutional research plan: CEZ:AV0Z50390703; CEZ:AV0Z50200510 Keywords : Lithium acetate * Membrane compartment of Can1 * Monomeric red fluorescent protein Subject RIV: EA - Cell Biology Impact factor: 9.120, year: 2008

  20. In vivo measurement of myocardial protein turnover using an indicator dilution technique

    International Nuclear Information System (INIS)

    Revkin, J.H.; Young, L.H.; Stirewalt, W.S.; Dahl, D.M.; Gelfand, R.A.; Zaret, B.L.; Barrett, E.J.

    1990-01-01

    We applied a nondestructive tracer technique, previously developed for measuring skeletal muscle protein turnover, to the measurement of myocardial protein turnover in vivo. During a continuous infusion of L-[ring-2,6-3H]phenylalanine to anesthetized, overnight-fasted dogs, we measured the uptake of radiolabeled phenylalanine from plasma and the release of unlabeled phenylalanine from myocardial proteolysis using arterial and coronary sinus catheterization and analytic methods previously applied to skeletal muscle. Using these measurements, together with a model of myocardial protein synthesis that assumes rapid equilibration of tracer specific activity between myocardial phenylalanyl-tRNA and circulating phenylalanine, we estimated the rates of heart protein synthesis and degradation. The rate of heart protein synthesis was also estimated directly from the incorporation of labeled phenylalanine into tissue protein. The use of [3H]phenylalanine was compared with L-[1-14C]leucine in the measurement of heart protein turnover in dogs given simultaneous infusion of both tracers. Leucine uptake and release by the myocardium exceeded that of phenylalanine by 3.1 +/- 0.4- and 1.7 +/- 0.3-fold, respectively, consistent with leucine's 2.4-fold greater abundance in heart protein and its metabolism via other pathways. Phenylalanine is the preferred tracer for use with this method because of its limited metabolic fate in muscle. One theoretical limitation to the method, slow equilibration of circulating labeled phenylalanine with myocardial phenylalanyl-tRNA, was resolved by comparison of these specific activities after a 30-minute infusion of labeled phenylalanine in the rat. A second, empirical limitation involves precision in the measurement of the small decrements in phenylalanine specific activity that occur with each pass of blood through the coronary circulation

  1. Casein and soya-bean protein have different effects on whole body protein turnover at the same nitrogen balance

    DEFF Research Database (Denmark)

    Nielsen, K; Kondrup, J; Elsner, Petteri

    1994-01-01

    was recovered from urinary ammonia and urea during isotope steady state for measurement of protein synthesis and protein degradation. Compared with starvation the protein-free diet decreased N excretion by 75%, probably by increasing the rate of reutilization of amino acids from endogenous proteins for protein......The present study examined whether different proteins have different effects on whole-body protein turnover in adult rats. The rats were either starved, given a protein-free but energy-sufficient diet (1 MJ/kg body weight (BW) per d) or a diet containing intact casein, hydrolysed casein......, or hydrolysed soya-bean protein at a level of 9.1 g/kg BW per d. The diets, which were isoenergetic with the same carbohydrate: fat ratio, were given as a continuous intragastric infusion for at least 4 d. During the last 19 h 15N-glycine (a primed continuous infusion) was given intragastrically and 15N...

  2. Protein turnover, amino acid requirements and recommendations for athletes and active populations

    International Nuclear Information System (INIS)

    Poortmans, J.R.; Carpentier, A.; Pereira-Lancha, L.O.; Lancha, A. Jr.

    2012-01-01

    Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ( 13 C-lysine, 15 N-glycine, 2 H 5 -phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g·kg −1 ·day −1 compared to 0.8 g·kg −1 ·day −1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h

  3. Protein turnover, amino acid requirements and recommendations for athletes and active populations

    Energy Technology Data Exchange (ETDEWEB)

    Poortmans, J.R.; Carpentier, A. [Laboratory for Biometry and Sport Nutrition, Faculty of Motor Sciences, Free University of Brussels, Brussels (Belgium); Pereira-Lancha, L.O. [Departamento de Nutrição, Instituto Vita, São Paulo, SP (Brazil); Lancha, A. Jr. [Laboratório de Nutrição Aplicada à Atividade Motora, Escola de Educação Física e Esporte, Universidade de São Paulo, São Paulo, SP (Brazil)

    2012-06-08

    Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ({sup 13}C-lysine, {sup 15}N-glycine, {sup 2}H{sub 5}-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g·kg{sup −1}·day{sup −1} compared to 0.8 g·kg{sup −1}·day{sup −1} in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

  4. Protein turnover, amino acid requirements and recommendations for athletes and active populations

    Directory of Open Access Journals (Sweden)

    J.R. Poortmans

    2012-10-01

    Full Text Available Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers (13C-lysine, 15N-glycine, ²H5-phenylalanine and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes compared to resistance exercise, which induces fiber hypertrophy (myofibrils. Nitrogen balance (difference between protein intake and protein degradation for athletes is usually balanced when the intake of protein reaches 1.2 g·kg-1·day-1 compared to 0.8 g·kg-1·day-1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins and carbohydrate (± 30 g maltodextrine drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

  5. Effects of dietary protein and glycaemic index on biomarkers of bone turnover in children

    DEFF Research Database (Denmark)

    Dalskov, Stine-Mathilde; Müller, Martha; Ritz, Christian

    2014-01-01

    For decades, it has been debated whether high protein intake compromises bone mineralisation, but no long-term randomised trial has investigated this in children. In the family-based, randomised controlled trial DiOGenes (Diet, Obesity and Genes), we examined the effects of dietary protein...... and glycaemic index (GI) on biomarkers of bone turnover and height in children aged 5-18 years. In two study centres, families with overweight parents were randomly assigned to one of five ad libitum-energy, low-fat (25-30 % energy (E%)) diets for 6 months: low protein/low GI; low protein/high GI; high protein....../low GI; high protein/high GI; control. They received dietary instructions and were provided all foods for free. Children, who were eligible and willing to participate, were included in the study. In the present analyses, we included children with data on plasma osteocalcin or urinary N...

  6. Interleukin-6 markedly decreases skeletal muscle protein turnover and increases nonmuscle amino acid utilization in healthy individuals

    DEFF Research Database (Denmark)

    van Hall, Gerrit; Steensberg, Adam; Fischer, Christian

    2008-01-01

    CONTEXT: IL-6 is a key modulator of immune function and suggested to be involved in skeletal muscle wasting as seen in sepsis. OBJECTIVE: Our objective was to determine the role of IL-6 in human in vivo systemic and skeletal muscle amino acid metabolism and protein turnover. SUBJECTS AND METHODS...... synthesis was more suppressed than breakdown, causing a small increase in net muscle protein breakdown. Furthermore, rhIL-6 decreased arterial amino acid concentration with 20-40%, despite the increase net release from muscle. CONCLUSIONS: We demonstrated that IL-6 profoundly alters amino acid turnover....... A substantial decrease in plasma amino acids was observed with a concomitant 50% decrease in muscle protein turnover, however, modest increase in net muscle degradation. We hypothesize that the profound reduction in muscle protein turnover and modest increase in net degradation are primarily caused...

  7. Studies on protein turnover and energy expenditure in chronically undernourished adults during stress of infection

    International Nuclear Information System (INIS)

    Kurpad, A.V.; Shetty, P.S.; Reeds, P.J.

    1994-01-01

    Chronic undernutrition in man leads to adaptive responses which could reduce the requirements for dietary energy and protein. It is also possible that these adaptive responses, which are economical in nature, could lead to a decreased capacity for combating stress. Undernourished people are more susceptible to infections, and during these stresses, show different patterns of protein and energy metabolism from well-nourished subjects. Animal models have clearly shown a diminished response to tissue injury, in terms of the anabolic acute phase response. It is proposed to study the effect of prior nutritional status on the degree to which an infective stress stimulates the acute phase protein synthesis by the liver. In addition, the supply of amino acids to the liver in conditions of stress could come from the breakdown of body tissue proteins, particularly muscle. It is intended to study muscle protein turnover by the use of 13 C-leucine in undernourished subjects under conditions of stress. Since whole body protein turnover can be measured by two methods, using 15 N-glycine and 13 C-leucine, a comparison of these two methods will initially be made in chronically undernourished subjects. It is also intended to study daily energy expenditure in the subject by an isotopic method, i.e. the appearance of 13 CO 2 in the breath after the administration of 13 C-bicarbonate. (author). 8 refs

  8. Analytical errors in measuring radioactivity in cell proteins and their effect on estimates of protein turnover in L cells

    International Nuclear Information System (INIS)

    Silverman, J.A.; Mehta, J.; Brocher, S.; Amenta, J.S.

    1985-01-01

    Previous studies on protein turnover in 3 H-labelled L-cell cultures have shown recovery of total 3 H at the end of a three-day experiment to be always significantly in excess of the 3 H recovered at the beginning of the experiment. A number of possible sources for this error in measuring radioactivity in cell proteins has been reviewed. 3 H-labelled proteins, when dissolved in NaOH and counted for radioactivity in a liquid-scintillation spectrometer, showed losses of 30-40% of the radioactivity; neither external or internal standardization compensated for this loss. Hydrolysis of these proteins with either Pronase or concentrated HCl significantly increased the measured radioactivity. In addition, 5-10% of the cell protein is left on the plastic culture dish when cells are recovered in phosphate-buffered saline. Furthermore, this surface-adherent protein, after pulse labelling, contains proteins of high radioactivity that turn over rapidly and make a major contribution to the accumulating radioactivity in the medium. These combined errors can account for up to 60% of the total radioactivity in the cell culture. Similar analytical errors have been found in studies of other cell cultures. The effect of these analytical errors on estimates of protein turnover in cell cultures is discussed. (author)

  9. FOXO/DAF-16 Activation Slows Down Turnover of the Majority of Proteins in C. elegans

    Energy Technology Data Exchange (ETDEWEB)

    Dhondt, Ineke; Petyuk, Vladislav A.; Cai, Huaihan; Vandemeulebroucke, Lieselot; Vierstraete, Andy; Smith, Richard D.; Depuydt, Geert; Braeckman, Bart P.

    2016-09-01

    Cellular protein quality can be maintained by proteolytic elimination of damaged proteins and replacing them with newly synthesized copies, a process called protein turnover (Ward, 2000). Protein turnover rates have been estimated using SILAC (stable isotope labeling by amino acids in cell culture) in prokaryotes and eukaryotes. The last decade has witnessed a growing interest in the analysis of whole-organism proteome dynamics in metazoans using the same approach (Claydon and Beynon, 2012). In recent work, SILAC was applied to monitor protein synthesis throughout life in adult Caenorhabditis elegans (Vukoti et al., 2015) and to investigate food intake (Gomez-Amaro et al., 2015

  10. New aspects of protein stability and turnover in the regulation of genome integrity

    DEFF Research Database (Denmark)

    Gallina, Irene

    of DNA repair is the control of protein abundance, both at a global cellular level, and locally at the site of damage. This is achieved through transcriptional regulation of protein synthesis and through the control of protein stability and turnover. In this study, we investigate the role of Rad56...... sensitivity when mutant. Prior to the work presented here,all these loci have been mapped to a specific gene except RAD56. We map the rad56-1 mutation to the NAT3 gene, which encodes the catalytic subunit of the NatB N-terminal acetyltransferase in yeast. Deletion of RAD56 causes sensitivity to X-rays, methyl......-scale studies investigating factors involved in DNA metabolism, but no specific function has been assigned to Cmr1. Taking advantage of a series of high-throughput screens we characterize Cmr1 as a chromatinassociated protein, involved in the regulation of fork progression in the presence of replication stress...

  11. FOXO/DAF-16 Activation Slows Down Turnover of the Majority of Proteins in C. elegans.

    Science.gov (United States)

    Dhondt, Ineke; Petyuk, Vladislav A; Cai, Huaihan; Vandemeulebroucke, Lieselot; Vierstraete, Andy; Smith, Richard D; Depuydt, Geert; Braeckman, Bart P

    2016-09-13

    Most aging hypotheses assume the accumulation of damage, resulting in gradual physiological decline and, ultimately, death. Avoiding protein damage accumulation by enhanced turnover should slow down the aging process and extend the lifespan. However, lowering translational efficiency extends rather than shortens the lifespan in C. elegans. We studied turnover of individual proteins in the long-lived daf-2 mutant by combining SILeNCe (stable isotope labeling by nitrogen in Caenorhabditiselegans) and mass spectrometry. Intriguingly, the majority of proteins displayed prolonged half-lives in daf-2, whereas others remained unchanged, signifying that longevity is not supported by high protein turnover. This slowdown was most prominent for translation-related and mitochondrial proteins. In contrast, the high turnover of lysosomal hydrolases and very low turnover of cytoskeletal proteins remained largely unchanged. The slowdown of protein dynamics and decreased abundance of the translational machinery may point to the importance of anabolic attenuation in lifespan extension, as suggested by the hyperfunction theory. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  12. FOXO/DAF-16 Activation Slows Down Turnover of the Majority of Proteins in C. elegans

    Directory of Open Access Journals (Sweden)

    Ineke Dhondt

    2016-09-01

    Full Text Available Most aging hypotheses assume the accumulation of damage, resulting in gradual physiological decline and, ultimately, death. Avoiding protein damage accumulation by enhanced turnover should slow down the aging process and extend the lifespan. However, lowering translational efficiency extends rather than shortens the lifespan in C. elegans. We studied turnover of individual proteins in the long-lived daf-2 mutant by combining SILeNCe (stable isotope labeling by nitrogen in Caenorhabditis elegans and mass spectrometry. Intriguingly, the majority of proteins displayed prolonged half-lives in daf-2, whereas others remained unchanged, signifying that longevity is not supported by high protein turnover. This slowdown was most prominent for translation-related and mitochondrial proteins. In contrast, the high turnover of lysosomal hydrolases and very low turnover of cytoskeletal proteins remained largely unchanged. The slowdown of protein dynamics and decreased abundance of the translational machinery may point to the importance of anabolic attenuation in lifespan extension, as suggested by the hyperfunction theory.

  13. Resistance training reduces whole-body protein turnover and improves net protein retention in untrained young males.

    Science.gov (United States)

    Hartman, Joseph W; Moore, Daniel R; Phillips, Stuart M

    2006-10-01

    It is thought that resistance exercise results in an increased need for dietary protein; however, data also exists to support the opposite conclusion. The purpose of this study was to determine the impact of resistance exercise training on protein metabolism in novices with the hypothesis that resistance training would reduce protein turnover and improve whole-body protein retention. Healthy males (n = 8, 22 +/- 1 y, BMI = 25.3 +/- 1.8 kg.m(-2)) participated in a progressive whole-body split routine resistance-training program 5d/week for 12 weeks. Before (PRE) and after (POST) the training, oral [15N]-glycine ingestion was used to assess nitrogen flux (Q), protein synthesis (PS), protein breakdown (PB), and net protein balance (NPB = PS-PB). Macronutrient intake was controlled over a 5d period PRE and POST, while estimates of protein turnover and urinary nitrogen balance (N(bal) = N(in) - urine N(out)) were conducted. Bench press and leg press increased 40% and 50%, respectively (p training-induced increases in both NPB (PRE = 0.22 +/- 0.13 g.kg(-1).d(-1); POST = 0.54 +/- 0.08 g.kg(-1).d(-1)) and urinary nitrogen balance (PRE = 2.8 +/- 1.7 g N.d(-1); POST = 6.5 +/- 0.9 g N.d(-1)) were observed. A program of resistance training that induced significant muscle hypertrophy resulted in reductions of both whole-body PS and PB, but an improved NPB, which favoured the accretion of skeletal muscle protein. Urinary nitrogen balance increased after training. The reduction in PS and PB and a higher NPB in combination with an increased nitrogen balance after training suggest that dietary requirements for protein in novice resistance-trained athletes are not higher, but lower, after resistance training.

  14. Olfactory marker protein: turnover and transport in normal and regenerating neurons

    International Nuclear Information System (INIS)

    Kream, R.M.; Margolis, F.L.

    1984-01-01

    A 19,000-dalton acidic protein designated olfactory marker protein (OMP) is a cell-specific marker of mature olfactory chemosensory neurons. Intranasal irrigation of mouse olfactory epithelium with [ 35 S]methionine labeled OMP to high specific activity. Turnover and transport characteristics of 35 S-labeled OMP were compared to those of 35 S-labeled global cytosol protein in groups of young, adult, and Triton-treated adult mice. The latter contained primarily large numbers of regenerating olfactory neurons. In olfactory epithelium of young and Triton-treated mice, the specific activity of OMP was three times that of global cytosol protein, whereas in adults the two measures were equal. In all three groups, however, the rate of degradation of OMP was roughly equal to that of cytosol protein (T1/2 . 5 to 6 days). By contrast, differences in T1/2 for OMP decline in the bulb of adult, young, and Triton-treated adult mice were highly significant (T1/2's of 9.3, 6.1, and 4 to 5 days, respectively; p . 0.001). The specific activity of [35S]methionine incorporated in OMP exceeded that of the free amino acid 5-fold, indicating minimal precursor reutilization during the course of our experiments. Turnover data indicate that increased isotope incorporation into OMP in the epithelium is matched by an accelerated rate of degradation in the bulb. This may be correlated with the physiological state or developmental age of the primary neurons since in young and Triton-treated adult mice, rapidly maturing ''young'' olfactory neurons represent a larger proportion of the total population than in adults. Thus, OMP behaves as a typical, relatively slowly transported soluble protein (v . 2 to 4 mm/day, slow component b)

  15. Electron hopping through proteins

    Czech Academy of Sciences Publication Activity Database

    Warren, J. J.; Ener, M. E.; Vlček, Antonín; Winkler, J. R.; Gray, H. B.

    2012-01-01

    Roč. 256, 21-22 (2012), s. 2478-2487 ISSN 0010-8545 R&D Projects: GA MŠk(CZ) ME10124 Institutional support: RVO:61388955 Keywords : electron transfer * multistep tunneling * hopping maps Subject RIV: CG - Electrochemistry Impact factor: 11.016, year: 2012

  16. Effect of compounds astragalus extract and cysteamine on finishing pigs growth and protein turnover

    International Nuclear Information System (INIS)

    Wang Cheng; Wang Zhisheng; Zhou Anguo; Liu Guilian; Xue Bai

    2008-01-01

    32 PIC pigs, weighted 59.82±1.32 kg on average, were subjected randomly to 4 treatments for determining the effects of extrogenous metabolism-regulating agents on pig performance, protein turn-over and nitrogen retention by using isotope ( 15 N-Gly) technique and nitrogen balance trial. The 4 treatments were: (1) basal diet; (2) basal diet plus cysteamine (70mg/kg, CS group); (3) basal diet plus non-stable astragalus extracts 250mg/kg (NCAE group); (4) basal diet plus stably astragalus extracts 250mg/kg (CAE group). Astragalus extracts and cysteamine, especially NCAE, redounded to increase pig performance, especially increase average day gain (P<0.05). Both astragalus extracts and cysteamine accelerated protein aggradation rate and amino acid utilization rate, as well as biological value. Astragalus extracts helped to accelerate the synthesis rate of amino acid into body protein and reduce the excretion rate of endogenous urine nitrogen. The mechanism of increasing protein deposition of cysteamine is reducing body protein degradation rate (26.71% reduction, compared to control group), while that of astragalus extracts is bilateral, reducing protein degradation rate (24.84% and 3.66% reduction for NCAE and CAE) and accelerating protein synthesis rate (22.86% and 19.18% increase for NCAE and CAE). Both astragalus extracts and cysteamine contributed the increasing nitrogen retention, net nitrogen utilization and biological value. (authors)

  17. Turnover of amyloid precursor protein family members determines their nuclear signaling capability.

    Science.gov (United States)

    Gersbacher, Manuel T; Goodger, Zoë V; Trutzel, Annette; Bundschuh, Diana; Nitsch, Roger M; Konietzko, Uwe

    2013-01-01

    The amyloid precursor protein (APP) as well as its homologues, APP-like protein 1 and 2 (APLP1 and APLP2), are cleaved by α-, β-, and γ-secretases, resulting in the release of their intracellular domains (ICDs). We have shown that the APP intracellular domain (AICD) is transported to the nucleus by Fe65 where they jointly bind the histone acetyltransferase Tip60 and localize to spherical nuclear complexes (AFT complexes), which are thought to be sites of transcription. We have now analyzed the subcellular localization and turnover of the APP family members. Similarly to AICD, the ICD of APLP2 localizes to spherical nuclear complexes together with Fe65 and Tip60. In contrast, the ICD of APLP1, despite binding to Fe65, does not translocate to the nucleus. In addition, APLP1 predominantly localizes to the plasma membrane, whereas APP and APLP2 are detected in vesicular structures. APLP1 also demonstrates a much slower turnover of the full-length protein compared to APP and APLP2. We further show that the ICDs of all APP family members are degraded by the proteasome and that the N-terminal amino acids of ICDs determine ICD degradation rate. Together, our results suggest that different nuclear signaling capabilities of APP family members are due to different rates of full-length protein processing and ICD proteasomal degradation. Our results provide evidence in support of a common nuclear signaling function for APP and APLP2 that is absent in APLP1, but suggest that APLP1 has a regulatory role in the nuclear translocation of APP family ICDs due to the sequestration of Fe65.

  18. Associations of total, dairy, and meat protein with markers for bone turnover in healthy, prepubertal boys

    DEFF Research Database (Denmark)

    Budek, Alicja Zofia; Hoppe, Camilla; Michaelsen, Kim Fleischer

    2007-01-01

    intake was estimated from a 3-d weighed food record. sIGF-I and its binding protein-3 were assessed (immunoassay) in a subgroup of 56 boys. All statistical models included effects of age, BMI, and energy intake. Dairy protein was negatively associated with sOC (P ¼ 0.05) but not significantly associated......We previously reported that high intake of milk, but not meat, equal in protein content, increased serum insulin-like growth factor-I (sIGF-I) in prepubertal boys. sIGF-I plays a key role in bone metabolism. Therefore, the aim of this cross-sectional study was to investigate associations of total.......04) but not significantly associated with sOC and sCTX. Free sIGF-I was positively associated with total (P , 0.01) and dairy (P ¼ 0.06) protein but not with meat protein. Our results indicate that dairy and meat protein may exhibit a distinct regulatory effect on different markers for bone turnover. Future studies should...

  19. Cell viability and protein turnover in nongrowing Bacillus megaterium at sporulation suppressing temperature.

    Science.gov (United States)

    Kucerová, H; Strnadová, M; Ludvík, J; Chaloupka, J

    1999-01-01

    In Bacillus megaterium, a temperature that suppresses sporulation (43 degrees C) only slightly exceeds both the optimum growth temperature and the temperature still permitting sporulation (40-41 degrees C). Here we show that, when cells grown at 35 degrees C and transferred to a sporulation medium, were subjected to shifts between 35 degrees C and the sporulation suppressing temperature (SST, 43 degrees C), their development and proteolytic activities were deeply affected. During the reversible sporulation phase that took place at 35 degrees C for 2-3 h (T2-T3), the cells developed forespores and their protein turnover was characterized by degradation of short-lived proteins and proteins made accessible to the proteolytic attack because of starvation. During the following irreversible sporulation phase refractile heat-resistant spores appeared at T4-T5. Protein turnover rate increased again after T2 and up to T8 60-70% prelabelled proteins were degraded. The SST suppressed sporulation at its beginning; at T3 no asymmetric septa were observed and the amount of heat-resistant spores at T8 was by 4-5 orders lower than at 35 degrees C. However, the cells remained viable and were able to sporulate when transferred to a lower temperature. Protein degradation was increased up to T3 but then its velocity sharply dropped and the amount of degraded protein at T8 corresponded to slightly more than one-half of that found at 35 degrees C. The cytoplasmic proteolytic activity was enhanced but the activity in the membrane fraction was decreased. When a temperature shift to SST was applied at the beginning of the irreversible sporulation phase (T2.5), the sporulation process was impaired. A portion of forespores lyzed, the others were able to complete their development but most spores were not heat-resistant and their coats showed defects. Protein degradation increased again because an effective proteolytic system was developed during the reversible sporulation phase but the

  20. Whole-body protein turnover response to short-term high-protein diets during weight loss: a randomized controlled trial

    Science.gov (United States)

    Objective: Determine whole-body protein turnover responses to high protein diets during weight loss. Design: Thirty-nine adults (age, 21 ± 1 yr; VO2peak, 48 ± 1 ml'kg-1'min-1; body mass index, 25 ± 1 kg•m2) were randomized to diets providing protein at the recommend dietary allowance (RDA), 2X-RD...

  1. Protein turnover in malnourished patients with cystic fibrosis: Effects of elemental and nonelemental nutritional supplements

    International Nuclear Information System (INIS)

    Pelekanos, J.T.; Holt, T.L.; Ward, L.C.; Cleghorn, G.J.; Shepherd, R.W.

    1990-01-01

    To evaluate the relative efficacy of nonelemental versus semielemental enteral supplements for nutritional rehabilitation of cystic fibrosis (CF) patients, whole-body protein turnover using the [ 15 N]glycine method was studied in nine malnourished CF patients during enteral feedings, in a block design study comparing a semielemental formula (Criticare), a higher protein density but nonelemental formula (Traumacal) (T), and a nonelemental formula that had been modified to become isocaloric and isonitrogenous to the semielemental formula (modified Traumacal, MT). No significant differences in rates of protein synthesis or catabolism were observed comparing the three formulas. However, the higher protein density nonelemental formula resulted in higher net protein deposition compared to the other two formulas (T + 0.42 g kg-1 10 h-1 versus 0.33 g kg-1 10 h-1 for Criticare and -0.59 g kg-1 10 h-1 for MT), although this was significant (p less than 0.05) for the MT versus T comparison only. This study lends support to the use of less expensive nonelemental formulas for the nutritional management of malnourished patients with CF

  2. Active Gating, Molecular Pumping, and Turnover Determination in Biomimetic Lipidic Cubic Mesophases with Reconstituted Membrane Proteins.

    Science.gov (United States)

    Speziale, Chiara; Zabara, Alexandru Florian; Drummond, Calum John; Mezzenga, Raffaele

    2017-11-28

    Understanding the mechanisms controlling molecular transport in bioinspired materials is a central topic in many branches of nanotechnology. In this work, we show that biomolecules of fundamental importance in biological processes, such as glucose, can be transported in an active, controlled, and selective manner across macroscopic lipidic cubic mesophases, by correctly reconstituting within them their corresponding membrane protein transporters, such as Staphylococcus epidermidis (GlcP Se ). Importantly, by duly exploiting the symporter properties of GlcP Se of coupled glucose/H + transport, the diffusion of glucose can further be tuned by independent physiological stimuli, such as parallel or antiparallel pH gradients, offering an important model to study molecular exchange processes in cellular machinery. We finally show that by measuring the transport properties of the lipidic mesophases with and without the GlcP Se membrane protein reconstituted within, it becomes possible to determine its intrinsic conductance. We generalize these findings to other membrane proteins from the antiporters family, such as the bacterial ClC exchanger from Escherichia coli (EcClC), providing a robust method for evaluating the turnover rate of the membrane proteins in general.

  3. Studies on the possible role of thyroid hormone in altered muscle protein turnover during sepsis

    International Nuclear Information System (INIS)

    Hasselgren, P.O.; Chen, I.W.; James, J.H.; Sperling, M.; Warner, B.W.; Fischer, J.E.

    1987-01-01

    Five days after thyroidectomy (Tx) or sham-Tx in young male Sprague-Dawley rats, sepsis was induced by cecal ligation and puncture (CLP). Control animals underwent laparotomy and manipulation of the cecum without ligation or puncture. Sixteen hours after CLP or laparotomy, protein synthesis and degradation were measured in incubated extensor digitorum longus (EDL) and soleus (SOL) muscles by determining rate of 14 C-phenylalanine incorporation into protein and tyrosine release into incubation medium, respectively. Triiodothyronine (T3) was measured in serum and muscle tissue. Protein synthesis was reduced by 39% and 22% in EDL and SOL, respectively, 16 hours after CLP in sham-Tx rats. The response to sepsis of protein synthesis was abolished in Tx rats. Protein breakdown was increased by 113% and 68% in EDL and SOL, respectively, 16 hours after CLP in sham-Tx animals. The increase in muscle proteolysis during sepsis was blunted in hypothyroid animals and was 42% and 49% in EDL and SOL, respectively. T3 in serum was reduced by sepsis, both in Tx and sham-Tx rats. T3 in muscle, however, was maintained or increased during sepsis. Abolished or blunted response of muscle protein turnover after CLP in hypothyroid animals may reflect a role of thyroid hormones in altered muscle protein metabolism during sepsis. Reduced serum levels of T3, but maintained or increased muscle concentrations of the hormone, suggests that increased T3 uptake by muscle may be one mechanism of low T3 syndrome in sepsis, further supporting the concept of a role for thyroid hormone in metabolic alterations in muscle during sepsis

  4. Blood protein turnover in parasitized ruminants. The influence of host nutrition

    International Nuclear Information System (INIS)

    Dargie, J.D.

    1981-01-01

    Ruminants infected with helminth or protozoal parasites generally become anaemic and hypoalbuminaemic, as well as losing their appetite. Since feed intake plays an important part in determining blood protein levels, it is necessary, when attempting to determine the mechanisms by which parasites cause anaemia and hypoalbuminaemia, to differentiate between the effects of feed intake per se and the specific effects of the parasite on blood protein turnover. This can be done by a variety of radioisotope techniques using infected and pair-fed control animals. Additionally, animals on a poor plane of nutrition suffer more from parasitism than those which are well fed. To understand the reason for this, it is necessary to determine whether diet influences susceptibility to parasite establishment or survival, and/or susceptibility to the metabolic consequences of parasitism. Described here is the current state of knowledge on the interaction between host nutrition and susceptibility to parasitic infection and parasitic disease processes, with particular reference to anaemia and hypoalbuminaemia. It is concluded that there is little evidence that nutrition has a significant bearing on resistance or susceptibility to infection, but that it does not have a profound influence on the ability of animals to withstand the pathogenic effects of parasites. The reasons for this are discussed in detail, but the principal benefit of a good plane of nutrition is that it enables the synthetic machinery of the host to keep pace with the concurrent parasite-induced hypercatabolism of blood proteins. (author)

  5. Protein turnover in lactating mink (Mustela vison) is not affected by dietary protein supply

    DEFF Research Database (Denmark)

    Tauson, Anne-Helene; Fink, Rikke; Chwalibog, André

    2006-01-01

    The mink is a strict carnivore and may therefore serve as a model for the cat. Current recommendations for protein supply for lactating mink are based on production experiments with preweaning kit growth as a measure of dietary adequacy (1,2). Recently, nitrogen balance and substrate oxidation have...... in humans (7), growing pigs (8), and growing rats (9). In adult cats, both protein synthesis and breakdown were lower when feeding a low- than when feeding a high-protein diet [20 vs. 70% of metabolizable energy (ME)5 from protein] (10). The objectives of this study were therefore to develop a ¹5N...

  6. Electron tunneling in proteins program.

    Science.gov (United States)

    Hagras, Muhammad A; Stuchebrukhov, Alexei A

    2016-06-05

    We developed a unique integrated software package (called Electron Tunneling in Proteins Program or ETP) which provides an environment with different capabilities such as tunneling current calculation, semi-empirical quantum mechanical calculation, and molecular modeling simulation for calculation and analysis of electron transfer reactions in proteins. ETP program is developed as a cross-platform client-server program in which all the different calculations are conducted at the server side while only the client terminal displays the resulting calculation outputs in the different supported representations. ETP program is integrated with a set of well-known computational software packages including Gaussian, BALLVIEW, Dowser, pKip, and APBS. In addition, ETP program supports various visualization methods for the tunneling calculation results that assist in a more comprehensive understanding of the tunneling process. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Effects of resistance training and protein supplementation on bone turnover in young adult women

    Directory of Open Access Journals (Sweden)

    Sinning Wayne E

    2005-08-01

    Full Text Available Abstract Background The strength of aging bone depends on the balance between the resorption and formation phases of the remodeling process. The purpose of this study was to examine the interaction of two factors with the potential to exert opposing influences on bone turnover, resistance exercise training and high dietary protein intake. It was hypothesized that resistance training by young, healthy, untrained women with protein intakes near recommended levels (0.8 g·kg-1·d-1 would promote bone formation and/or inhibit bone resorption, and that subsequent supplementation to provide 2.4 g protein·kg-1·d-1 would reverse these effects. Methods Bone formation was assessed with serum bone-specific alkaline phosphatase (BAP and osteocalcin (OC, and bone resorption with urinary calcium and deoxypyridinoline (DPD. Biochemical, strength, anthropometric, dietary, and physical activity data were obtained from 24 healthy, untrained, eumenorrheic women (18–29y at baseline, after eight weeks of resistance training (3 d·wk-1, ~1 hr·d-1; 3 sets, 6–10 repetitions, 13 exercises, 75–85% maximum voluntary contraction, and after 12 weeks of resistance training and 10 days of protein/placebo supplementation. Subjects were randomized (double-blind to either a high protein (HP or training control (TC group and, during the final 10 days, consumed either enough purified whey protein to bring daily protein intake to 2.4 g·kg-1·d-1, or an equivalent dose of isoenergetic, carbohydrate placebo. Results Strength, lean tissue mass, and DPD increased significantly in both groups over time, while percent body fat and BAP decreased (repeated measures ANOVA, p ≤ 0.05, Bonferroni correction. No significant changes were observed for serum OC or urinary calcium, and no significant group (TC, HP × time (baseline, week 8, week 12 interactions emerged for any of the biochemical measures. Conclusion (1 Twelve weeks of high-intensity resistance training did not appear to

  8. Radiocarbon Dating of the Human Eye Lens Crystallines Reveal Proteins without Carbon Turnover throughout Life

    Science.gov (United States)

    Lynnerup, Niels; Kjeldsen, Henrik; Heegaard, Steffen; Jacobsen, Christina; Heinemeier, Jan

    2008-01-01

    Background Lens crystallines are special proteins in the eye lens. Because the epithelial basement membrane (lens capsule) completely encloses the lens, desquamation of aging cells is impossible, and due to the complete absence of blood vessels or transport of metabolites in this area, there is no subsequent remodelling of these fibers, nor removal of degraded lens fibers. Human tissue ultimately derives its 14C content from the atmospheric carbon dioxide. The 14C content of the lens proteins thus reflects the atmospheric content of 14C when the lens crystallines were formed. Precise radiocarbon dating is made possible by comparing the 14C content of the lens crystallines to the so-called bomb pulse, i.e. a plot of the atmospheric 14C content since the Second World War, when there was a significant increase due to nuclear-bomb testing. Since the change in concentration is significant even on a yearly basis this allows very accurate dating. Methodology/Principal Findings Our results allow us to conclude that the crystalline formation in the lens nucleus almost entirely takes place around the time of birth, with a very small, and decreasing, continuous formation throughout life. The close relationship may be further expressed as a mathematical model, which takes into account the timing of the crystalline formation. Conclusions/Significance Such a life-long permanence of human tissue has hitherto only been described for dental enamel. In confront to dental enamel it must be held in mind that the eye lens is a soft structure, subjected to almost continuous deformation, due to lens accommodation, yet its most important constituent, the lens crystalline, is never subject to turnover or remodelling once formed. The determination of the 14C content of various tissues may be used to assess turnover rates and degree of substitution (for example for brain cell DNA). Potential targets may be nervous tissues in terms of senile or pre-senile degradation, as well as other highly

  9. Radiocarbon dating of the human eye lens crystallines reveal proteins without carbon turnover throughout life.

    Directory of Open Access Journals (Sweden)

    Niels Lynnerup

    Full Text Available BACKGROUND: Lens crystallines are special proteins in the eye lens. Because the epithelial basement membrane (lens capsule completely encloses the lens, desquamation of aging cells is impossible, and due to the complete absence of blood vessels or transport of metabolites in this area, there is no subsequent remodelling of these fibers, nor removal of degraded lens fibers. Human tissue ultimately derives its (14C content from the atmospheric carbon dioxide. The (14C content of the lens proteins thus reflects the atmospheric content of (14C when the lens crystallines were formed. Precise radiocarbon dating is made possible by comparing the (14C content of the lens crystallines to the so-called bomb pulse, i.e. a plot of the atmospheric (14C content since the Second World War, when there was a significant increase due to nuclear-bomb testing. Since the change in concentration is significant even on a yearly basis this allows very accurate dating. METHODOLOGY/PRINCIPAL FINDINGS: Our results allow us to conclude that the crystalline formation in the lens nucleus almost entirely takes place around the time of birth, with a very small, and decreasing, continuous formation throughout life. The close relationship may be further expressed as a mathematical model, which takes into account the timing of the crystalline formation. CONCLUSIONS/SIGNIFICANCE: Such a life-long permanence of human tissue has hitherto only been described for dental enamel. In confront to dental enamel it must be held in mind that the eye lens is a soft structure, subjected to almost continuous deformation, due to lens accommodation, yet its most important constituent, the lens crystalline, is never subject to turnover or remodelling once formed. The determination of the (14C content of various tissues may be used to assess turnover rates and degree of substitution (for example for brain cell DNA. Potential targets may be nervous tissues in terms of senile or pre

  10. Acute moderate elevation of TNF-{alpha} does not affect systemic and skeletal muscle protein turnover in healthy humans

    DEFF Research Database (Denmark)

    Petersen, Anne Marie; Plomgaard, Peter; Fischer, Christian P

    2009-01-01

    -alpha infusion (rhTNF-alpha). We hypothesize that TNF-alpha increases human muscle protein breakdown and/or inhibit synthesis. Subjects and Methods: Using a randomized controlled, crossover design post-absorptive healthy young males (n=8) were studied 2 hours under basal conditions followed by 4 hours infusion...... with the phenylalanine 3-compartment model showed similar muscle synthesis, breakdown and net muscle degradation after 2 hours basal and after 4 hours Control or rhTNF-alpha infusion. Conclusion: This study is the first to show in humans that TNF-alpha does not affect systemic and skeletal muscle protein turnover, when......Context: Skeletal muscle wasting has been associated with elevations in circulating inflammatory cytokines, in particular TNF-alpha. Objective: In this study, we investigated whether TNF-alpha affects human systemic and skeletal muscle protein turnover, via a 4 hours recombinant human TNF...

  11. Effects of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle as measured by [14C]tyrosine infusion.

    OpenAIRE

    Carter, W J; Benjamin, W S; Faas, F H

    1982-01-01

    The effect of T3 (3,3',5-tri-iodothyronine) on protein turnover in skeletal and cardiac muscle was measured in intact rats by means of a 6 h [14C]tyrosine-infusion technique. Treatment with 25-30 micrograms of T3/100 g body wt. daily for 4-7 days increased the fractional rate of protein synthesis in skeletal muscle. Since the fractional growth rate of the muscle was decreased or unchanged, T3 treatment increased the rate of muscle protein breakdown. These findings suggest that increased prote...

  12. The HIV1 protein Vpr acts to enhance constitutive DCAF1-dependent UNG2 turnover.

    Directory of Open Access Journals (Sweden)

    Xiaoyun Wen

    Full Text Available The HIV1 protein Vpr assembles with and acts through an ubiquitin ligase complex that includes DDB1 and cullin 4 (CRL4 to cause G2 cell cycle arrest and to promote degradation of both uracil DNA glycosylase 2 (UNG2 and single-strand selective mono-functional uracil DNA glycosylase 1 (SMUG1. DCAF1, an adaptor protein, is required for Vpr-mediated G2 arrest through the ubiquitin ligase complex. In work described here, we used UNG2 as a model substrate to study how Vpr acts through the ubiquitin ligase complex. We examined whether DCAF1 is essential for Vpr-mediated degradation of UNG2 and SMUG1. We further investigated whether Vpr is required for recruiting substrates to the ubiquitin ligase or acts to enhance its function and whether this parallels Vpr-mediated G2 arrest.We found that DCAF1 plays an important role in Vpr-independent UNG2 and SMUG1 depletion. UNG2 assembled with the ubiquitin ligase complex in the absence of Vpr, but Vpr enhanced this interaction. Further, Vpr-mediated enhancement of UNG2 degradation correlated with low Vpr expression levels. Vpr concentrations exceeding a threshold blocked UNG2 depletion and enhanced its accumulation in the cell nucleus. A similar dose-dependent trend was seen for Vpr-mediated cell cycle arrest.This work identifies UNG2 and SMUG1 as novel targets for CRL4(DCAF1-mediated degradation. It further shows that Vpr enhances rather than enables the interaction between UNG2 and the ubiquitin ligase. Vpr augments CRL4(DCAF1-mediated UNG2 degradation at low concentrations but antagonizes it at high concentrations, allowing nuclear accumulation of UNG2. Further, the protein that is targeted to cause G2 arrest behaves much like UNG2. Our findings provide the basis for determining whether the CRL4(DCAF1 complex is alone responsible for cell cycle-dependent UNG2 turnover and will also aid in establishing conditions necessary for the identification of additional targets of Vpr-enhanced degradation.

  13. Dynamic Proteomics Emphasizes the Importance of Selective mRNA Translation and Protein Turnover during Arabidopsis Seed Germination*

    Science.gov (United States)

    Galland, Marc; Huguet, Romain; Arc, Erwann; Cueff, Gwendal; Job, Dominique; Rajjou, Loïc

    2014-01-01

    During seed germination, the transition from a quiescent metabolic state in a dry mature seed to a proliferative metabolic state in a vigorous seedling is crucial for plant propagation as well as for optimizing crop yield. This work provides a detailed description of the dynamics of protein synthesis during the time course of germination, demonstrating that mRNA translation is both sequential and selective during this process. The complete inhibition of the germination process in the presence of the translation inhibitor cycloheximide established that mRNA translation is critical for Arabidopsis seed germination. However, the dynamics of protein turnover and the selectivity of protein synthesis (mRNA translation) during Arabidopsis seed germination have not been addressed yet. Based on our detailed knowledge of the Arabidopsis seed proteome, we have deepened our understanding of seed mRNA translation during germination by combining two-dimensional gel-based proteomics with dynamic radiolabeled proteomics using a radiolabeled amino acid precursor, namely [35S]-methionine, in order to highlight de novo protein synthesis, stability, and turnover. Our data confirm that during early imbibition, the Arabidopsis translatome keeps reflecting an embryonic maturation program until a certain developmental checkpoint. Furthermore, by dividing the seed germination time lapse into discrete time windows, we highlight precise and specific patterns of protein synthesis. These data refine and deepen our knowledge of the three classical phases of seed germination based on seed water uptake during imbibition and reveal that selective mRNA translation is a key feature of seed germination. Beyond the quantitative control of translational activity, both the selectivity of mRNA translation and protein turnover appear as specific regulatory systems, critical for timing the molecular events leading to successful germination and seedling establishment. PMID:24198433

  14. Development of a Suitable Survey Instrument To Identify Causes Behind High Turnover Rates within the 0301 Series in the Communications Electronics Command

    Science.gov (United States)

    2017-09-01

    CAUSES BEHIND HIGH TURNOVER RATES WITHIN THE 0301 SERIES IN THE COMMUNICATIONS- ELECTRONICS COMMAND September 2017 By: Antonia U. Orjih...THE COMMUNICATIONS- ELECTRONICS COMMAND 5. FUNDING NUMBERS 6. AUTHOR(S) Antonia U. Orjih and Shamika M. Fleuranges 7. PERFORMING ORGANIZATION...AGENCY NAME(S) AND ADDRESS(ES) Communications- Electronics Command (CECOM) Aberdeen Proving Ground (APG), Maryland 10. SPONSORING / MONITORING

  15. Development of a method for the accurate measurement of protein turnover in neoplastic cells grown in culture

    International Nuclear Information System (INIS)

    Silverman, J.A.

    1984-01-01

    In this study, it was shown that standard techniques for cell recovery and sample preparation for liquid scintillation counting led to underestimation of the radioactivity present in cell proteins by 20-40%. These techniques involved labeling with 3 He leucine or 14 C leucine, scraping the cells from the dish in a buffer, TCA precipitation of the cell proteins, solubilization in NaOH and counting in a liquid scintillation counter. Hydrolysis of the proteins with HCl or Pronase significantly increased the recovery of the labeled proteins. Also, solubilization in situ with NaOH or hydrolysis in situ with Pronase recovered 5-10% additional labeled proteins. The techniques developed here allow the accurate measurement of radioactivity in cell proteins. In addition, these techniques were used to study protein turnover in rat hepatoma cells grown in culture. These cells regulated their growth rate through changes in the protein synthesis rate as opposed to changes in the protein degradation rate. These data support the hypothesis that neoplastic cells, unlike normal cells, do not regulate proteolysis in growth control; normal cells under similar conditions have been shown to activate lysosomal proteolysis as they reach confluence. The physiologic implications of this observation are discussed

  16. Electron microscopy of cyanobacterial membrane proteins

    NARCIS (Netherlands)

    Folea, Ioana Mihaela

    2008-01-01

    The main focus of this thesis is photosynthetic protein complexes, and their organization within the membrane of cyanobacteria. In cyanobacteria large proteins catalyze the light reactions of photosynthesis. One of the key proteins is photosystem II. We have found for the first time by electron

  17. The glomuvenous malformation protein Glomulin binds Rbx1 and regulates cullin RING ligase-mediated turnover of Fbw7.

    Science.gov (United States)

    Tron, Adriana E; Arai, Takehiro; Duda, David M; Kuwabara, Hiroshi; Olszewski, Jennifer L; Fujiwara, Yuko; Bahamon, Brittany N; Signoretti, Sabina; Schulman, Brenda A; DeCaprio, James A

    2012-04-13

    Fbw7, a substrate receptor for Cul1-RING-ligase (CRL1), facilitates the ubiquitination and degradation of several proteins, including Cyclin E and c-Myc. In spite of much effort, the mechanisms underlying Fbw7 regulation are mostly unknown. Here, we show that Glomulin (Glmn), a protein found mutated in the vascular disorder glomuvenous malformation (GVM), binds directly to the RING domain of Rbx1 and inhibits its E3 ubiquitin ligase activity. Loss of Glmn in a variety of cells, tissues, and GVM lesions results in decreased levels of Fbw7 and increased levels of Cyclin E and c-Myc. The increased turnover of Fbw7 is dependent on CRL and proteasome activity, indicating that Glmn modulates the E3 activity of CRL1(Fbw7). These data reveal an unexpected functional connection between Glmn and Rbx1 and demonstrate that defective regulation of Fbw7 levels contributes to GVM. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Deubiquitylating enzyme USP9x regulates hippo pathway activity by controlling angiomotin protein turnover

    DEFF Research Database (Denmark)

    Nguyen, Thanh Hung; Andrejeva, Diana; Gupta, Rajat

    2016-01-01

    /TAZ activity. We demonstrate that USPx regulates ubiquitin-mediated turnover of the YAP inhibitor, Angiomotin. USP9x acts to deubiquitylate Angiomotin at lysine 496, resulting in stabilization of Angiomotin and lower YAP/TAZ activity. USP9x mRNA levels were reduced in several cancers. Clinically, USP9x m......RNA levels were reduced in several cancers with low USPx expression correlating with poor prognosis in renal clear cell carcinoma. Our data indicate that USP9x may be a useful biomarker for renal clear cell carcinoma....

  19. Regulation of myofibrillar accumulation in chick muscle cultures - Evidence for the involvement of calcium and lysosomes in non-uniform turnover of contractile proteins

    Science.gov (United States)

    Silver, Geri; Etlinger, Joseph D.

    1985-01-01

    The effects of calcium on the synthesis and the degradation of individual myofibrillar proteins were investigated using primary chick-leg skeletal muscle cultures labeled with S-35-methionine (for protein accumulation experiments) or Ca(2+)-45 (for calcium efflux experiments). It was found that the turnover of individual contractile proteins is regulated nonuniformly by a calcium-dependent mechanism involving lysosomes. The results also indicate that contractile proteins are released from the myofibril before their breakdown to amino acids.

  20. Effects of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle as measured by [14C]tyrosine infusion.

    Science.gov (United States)

    Carter, W J; Benjamin, W S; Faas, F H

    1982-04-15

    The effect of T3 (3,3',5-tri-iodothyronine) on protein turnover in skeletal and cardiac muscle was measured in intact rats by means of a 6 h [14C]tyrosine-infusion technique. Treatment with 25-30 micrograms of T3/100 g body wt. daily for 4-7 days increased the fractional rate of protein synthesis in skeletal muscle. Since the fractional growth rate of the muscle was decreased or unchanged, T3 treatment increased the rate of muscle protein breakdown. These findings suggest that increased protein degradation is an important factor in decreasing skeletal-muscle mass in hyperthyroidism. In contrast with skeletal muscle, T3 treatment for 7 days caused an equivalent increase in the rate of cardiac muscle growth and protein synthesis. This suggests that hyperthyroidism does not increase protein breakdown in heart muscle as it does in skeletal muscle. The failure of T3 to increase proteolysis in heart muscle may be due to a different action on the cardiac myocyte or to systemic effects of T3 which increase cardiac work.

  1. Evidence for the Deregulation of Protein Turnover Pathways in Atm-Deficient Mouse Cerebellum: An Organotypic Study.

    Science.gov (United States)

    Kim, Catherine D; Reed, Ryan E; Juncker, Meredith A; Fang, Zhide; Desai, Shyamal D

    2017-07-01

    Interferon-stimulated gene 15 (ISG15), an antagonist of the ubiquitin pathway, is elevated in cells and brain tissues obtained from ataxia telangiectasia (A-T) patients. Previous studies reveal that an elevated ISG15 pathway inhibits ubiquitin-dependent protein degradation, leading to activation of basal autophagy as a compensatory mechanism for protein turnover in A-T cells. Also, genotoxic stress (ultraviolet [UV] radiation) deregulates autophagy and induces aberrant degradation of ubiquitylated proteins in A-T cells. In the current study, we show that, as in A-T cells, ISG15 protein expression is elevated in cerebellums and various other tissues obtained from Atm-compromised mice in an Atm-allele-dependent manner (Atm+/+ Atm+/- Atm-/-). Notably, in cerebellums, the brain part primarily affected in A-T, levels of ISG15 were significantly greater (3-fold higher) than cerebrums obtained from the same set of mice. Moreover, as in A-T cell culture, UV induces aberrant degradation of ubiquitylated proteins and autophagy in Atm-deficient, but not in Atm-proficient, cerebellar brain slices grown in culture. Thus, the ex vivo organotypic A-T mouse brain culture model mimics that of an A-T human cell culture model and could be useful for studying the role of ISG15-dependent proteinopathy in cerebellar neurodegeneration, a hallmark of A-T in humans. © 2017 American Association of Neuropathologists, Inc. All rights reserved.

  2. Electron image reconstruction of helical protein assemblies

    International Nuclear Information System (INIS)

    Cremers, A.F.M.

    1980-01-01

    The analysis of projections of large ordered biological systems obtained by electron microscopy of negatively stained specimens is described. The biological structures amenable to this approach are constructed from a large number of identical protein molecules, which are arranged according to helical symmetry. Electron images of these structures generally contain sufficient information in order to calculate a three-dimensional density map. (Auth.)

  3. Electron crystallography of three dimensional protein crystals

    NARCIS (Netherlands)

    Georgieva, Dilyana

    2008-01-01

    This thesis describes an investigation of the potential of electron diffraction for studying three dimensional sub-micro-crystals of proteins and pharmaceuticals. A prerequisite for using electron diffraction for structural studies is the predictable availability of tiny crystals. A method for

  4. The regulation of skeletal muscle protein turnover during the progression of cancer cachexia in the Apc(Min/+ mouse.

    Directory of Open Access Journals (Sweden)

    James P White

    Full Text Available Muscle wasting that occurs with cancer cachexia is caused by an imbalance in the rates of muscle protein synthesis and degradation. The Apc(Min/+ mouse is a model of colorectal cancer that develops cachexia that is dependent on circulating IL-6. However, the IL-6 regulation of muscle protein turnover during the initiation and progression of cachexia in the Apc(Min/+ mouse is not known. Cachexia progression was studied in Apc(Min/+ mice that were either weight stable (WS or had initial (≤5%, intermediate (6-19%, or extreme (≥20% body weight loss. The initiation of cachexia reduced %MPS 19% and a further ∼50% with additional weight loss. Muscle IGF-1 mRNA expression and mTOR targets were suppressed with the progression of body weight loss, while muscle AMPK phosphorylation (Thr 172, AMPK activity, and raptor phosphorylation (Ser 792 were not increased with the initiation of weight loss, but were induced as cachexia progressed. ATP dependent protein degradation increased during the initiation and progression of cachexia. However, ATP independent protein degradation was not increased until cachexia had progressed beyond the initial phase. IL-6 receptor antibody administration prevented body weight loss and suppressed muscle protein degradation, without any effect on muscle %MPS or IGF-1 associated signaling. In summary, the %MPS reduction during the initiation of cachexia is associated with IGF-1/mTOR signaling repression, while muscle AMPK activation and activation of ATP independent protein degradation occur later in the progression of cachexia. IL-6 receptor antibody treatment blocked cachexia progression through the suppression of muscle protein degradation, while not rescuing the suppression of muscle protein synthesis. Attenuation of IL-6 signaling was effective in blocking the progression of cachexia, but not sufficient to reverse the process.

  5. The Regulation of Skeletal Muscle Protein Turnover during the Progression of Cancer Cachexia in the ApcMin/+ Mouse

    Science.gov (United States)

    White, James P.; Baynes, John W.; Welle, Stephen L.; Kostek, Matthew C.; Matesic, Lydia E.; Sato, Shuichi; Carson, James A.

    2011-01-01

    Muscle wasting that occurs with cancer cachexia is caused by an imbalance in the rates of muscle protein synthesis and degradation. The ApcMin/+ mouse is a model of colorectal cancer that develops cachexia that is dependent on circulating IL-6. However, the IL-6 regulation of muscle protein turnover during the initiation and progression of cachexia in the ApcMin/+ mouse is not known. Cachexia progression was studied in ApcMin/+ mice that were either weight stable (WS) or had initial (≤5%), intermediate (6–19%), or extreme (≥20%) body weight loss. The initiation of cachexia reduced %MPS 19% and a further ∼50% with additional weight loss. Muscle IGF-1 mRNA expression and mTOR targets were suppressed with the progression of body weight loss, while muscle AMPK phosphorylation (Thr 172), AMPK activity, and raptor phosphorylation (Ser 792) were not increased with the initiation of weight loss, but were induced as cachexia progressed. ATP dependent protein degradation increased during the initiation and progression of cachexia. However, ATP independent protein degradation was not increased until cachexia had progressed beyond the initial phase. IL-6 receptor antibody administration prevented body weight loss and suppressed muscle protein degradation, without any effect on muscle %MPS or IGF-1 associated signaling. In summary, the %MPS reduction during the initiation of cachexia is associated with IGF-1/mTOR signaling repression, while muscle AMPK activation and activation of ATP independent protein degradation occur later in the progression of cachexia. IL-6 receptor antibody treatment blocked cachexia progression through the suppression of muscle protein degradation, while not rescuing the suppression of muscle protein synthesis. Attenuation of IL-6 signaling was effective in blocking the progression of cachexia, but not sufficient to reverse the process. PMID:21949739

  6. Regulation of Nur77 protein turnover through acetylation and deacetylation induced by p300 and HDAC1.

    Science.gov (United States)

    Kang, Shin-Ae; Na, Hyelin; Kang, Hyun-Jin; Kim, Sung-Hye; Lee, Min-Ho; Lee, Mi-Ock

    2010-09-15

    Although the roles of Nur77, an orphan member of the nuclear hormone receptor superfamily, in the control of cellular proliferation, apoptosis, inflammation, and glucose metabolism, are well recognized, the molecular mechanism regulating the activity and expression of Nur77 is not fully understood. Acetylation of transcription factors has emerged recently as a major post-translational modification that regulates protein stability and transcriptional activity. Here, we examined whether Nur77 is acetylated, and we characterized potential associated factors. First, Nur77 was found to be an acetylated protein when examined by immunoprecipitation and western blotting using acetyl protein-specific antibodies. Second, expression of p300, which possesses histone acetyltransferase activity, enhanced the acetylation and protein stability of Nur77. Treatment with a histone deacetylase (HDAC) inhibitor, trichostatin A, also increased Nur77 acetylation. Among the several types of HDACs, HDAC1 was found as the major enzyme affecting protein level of Nur77. HDAC1 decreased the acetylation level, protein level, and transcriptional activity of Nur77. Interestingly, overexpression of Nur77 induced expression of both p300 and HDAC1. Finally, the expression of Nur77 increased along with that of p300, but decreased with induction of HDAC1 after treatment with epithelial growth factor, nerve growth factor, or 6-mercaptopurine, suggesting that the self-control of the acetylation status contributes to the transient induction of Nur77 protein. Taken together, these results demonstrate that acetylation of Nur77 is modulated by p300 and HDAC1, and suggest that acetylation is an important post-translational modification for the rapid turnover of Nur77 protein. Copyright 2010 Elsevier Inc. All rights reserved.

  7. Muscle protein turnover in the elderly and its potential contribution to the development of sarcopenia.

    Science.gov (United States)

    Murton, Andrew J

    2015-11-01

    The underlying aetiology of sarcopenia appears multifaceted and not yet fully defined, but ultimately involves the gradual loss of muscle protein content over time. The present evidence suggests that the loss of lean tissue in the elderly is exacerbated by low dietary protein intake. Moreover, acute stable-isotope-based methodologies have demonstrated that the muscle anabolic response to a given amount of protein may decline with age, a phenomenon that has been termed anabolic resistance. Although the mechanism responsible for the inability of muscle to mount a satisfactory anabolic response to protein provision with increasing age is presently unknown, it does not appear due to impaired digestion or absorption of dietary protein. Rather, the issue could reside with any combination of: a diminished delivery of amino acids to peripheral tissues, impaired uptake of amino acids into muscle cells, or an inability of amino acids to elicit intracellular events pivotal for anabolism to occur. Despite the presence of anabolic resistance to dietary protein, present evidence suggests that protein supplementation may be able to overcome these issues, particularly when combined with resistance exercise programmes. As such, protein supplementation may prove to be an effective approach to delay the loss of muscle mass with age and has led to calls for the recommended daily intake of protein to be increased for the elderly population.

  8. The excretion of isotope in urea and ammonia for estimating protein turnover in man with [15N]glycine

    International Nuclear Information System (INIS)

    Fern, E.B.; Garlick, P.J.; McNurlan, M.A.; Waterlow, J.C.

    1981-01-01

    Four normal adults were given [ 15 N]-glycine in a single dose either orally or intravenously. Rates of whole-body protein turnover were estimated from the excretion of 15 N in ammonia and in urea during the following 9 h. The rate derived from urea took account of the [ 15 N]urea retained in body water. In postabsorptive subjects the rates of protein synthesis given by ammonia were equal to those from urea, when the isotope was given orally, but lower when an intravenous dose was given. In subjects receiving equal portions of food every 2 h rates of synthesis calculated from ammonia were much lower than those from urea whether an oral or intravenous isotope was given. Comparison of rates obtained during the postabsorptive and absorptive periods indicated regulation by food intake primarily of synthesis when measurements were made on urea, but regulation primarily of breakdown when measurements were made on ammonia. These inconsistencies suggest that changes in protein metabolism might be assessed better by correlating results given by different end-products, and it is suggested that the mean value given by urea and ammonia will be useful for this purpose. (author)

  9. Excretion of isotope in urea and ammonia for estimating protein turnover in man with (/sup 15/N)glycine

    Energy Technology Data Exchange (ETDEWEB)

    Fern, E B; Garlick, P J; McNurlan, M A; Waterlow, J C [London School of Hygiene and Tropical Medicine (UK)

    1981-01-01

    Four normal adults were given (/sup 15/N)-glycine in a single dose either orally or intravenously. Rates of whole-body protein turnover were estimated from the excretion of /sup 15/N in ammonia and in urea during the following 9 h. The rate derived from urea took account of the (/sup 15/N)urea retained in body water. In postabsorptive subjects the rates of protein synthesis given by ammonia were equal to those from urea, when the isotope was given orally, but lower when an intravenous dose was given. In subjects receiving equal portions of food every 2 h rates of synthesis calculated from ammonia were much lower than those from urea whether an oral or intravenous isotope was given. Comparison of rates obtained during the postabsorptive and absorptive periods indicated regulation by food intake primarily of synthesis when measurements were made on urea, but regulation primarily of breakdown when measurements were made on ammonia. These inconsistencies suggest that changes in protein metabolism might be assessed better by correlating results given by different end-products, and it is suggested that the mean value given by urea and ammonia will be useful for this purpose.

  10. Muscle protein turnover in cattle of differing genetic backgrounds as measured by urinary N tau-methylhistidine excretion

    International Nuclear Information System (INIS)

    McCarthy, F.D.; Bergen, W.G.; Hawkins, D.R.

    1983-01-01

    N tau-methylhistidine (N tau MH) was used as an index for muscle protein degradation and this index was utilized to evaluate degradation rates in young growing cattle. Initially, two Charolais crossbred heifers, 12 months of age, were used to measure the recovery of radioactivity in the urine for a 120-hour period after intravenous injection of [ 14 C]N tau MH. Of the radioactivity injected into the animals, 89.7% was recovered after 120 hours. With rate and amount of clearance as the criteria, the excretion of N tau MH in urine appears to be a valid index of muscle protein degradation in cattle. Eight steers of two genetic types were used to evaluate the effect of frame size on turnover rates of muscle proteins with N tau MH as an index. Large frame cattle (LG) excreted more N tau MH per day throughout the trial. Total daily creatinine excretion was less for small frame (SM) cattle showing an increase with time in LG and SM cattle. N tau MH-to-creatinine ratios showed a decline with time. Fractional breakdown rates (FBR) and fractional synthesis rates (FSR) appeared to parallel each other with rates tending to decrease with age. No differences were observed between LG and SM cattle for FBR, FSR or fractional growth rate

  11. Protein turnover and metabolism in the elderly intensive care unit patient

    NARCIS (Netherlands)

    Phillips, Stuart M.; Dickerson, Roland N.; Moore, Frederick A.; Paddon-Jones, Douglas; Weijs, Peter J. M.

    2017-01-01

    Many intensive care unit (ICU) patients do not achieve target protein intakes particularly in the early days following admittance. This period of iatrogenic protein undernutrition contributes to a rapid loss of lean, in particular muscle, mass in the ICU. The loss of muscle in older (aged >60 years)

  12. Dynamics in electron transfer protein complexes

    OpenAIRE

    Bashir, Qamar

    2010-01-01

    Recent studies have provided experimental evidence for the existence of an encounter complex, a transient intermediate in the formation of protein complexes. We have used paramagnetic relaxation enhancement NMR spectroscopy in combination with Monte Carlo simulations to characterize and visualize the ensemble of encounter orientations in the short-lived electron transfer complex of yeast Cc and CcP. The complete conformational space sampled by the protein molecules during the dynamic part of ...

  13. Studies on water turnover and water requirement in buffalo calves fed on different levels of energy and protein in the diet

    International Nuclear Information System (INIS)

    Verma, D.N.; Kumar, N.; Dass, R.S.; Singh, U.B.

    1980-01-01

    Experiments were conducted for measuring water turnover and water requirement in buffalo calves fed on different levels of energy and protein in the diet. There was significant difference (P<0.01) in the biological half life of tritiated water between various groups of animals. Water turnover rates were statistically (P<0.05) more in groups I and II (106.52 and 99.74 ml/kg/24 hr) than groups III and IV (93.03 and 77.09 ml/kg/24 hr). There was no significant difference in water requirement due to various treatments. (author)

  14. Naturally occurring stable isotopes reflect changes in protein turnover and growth in gilthead sea bream (Sparus aurata) juveniles under different dietary protein levels.

    Science.gov (United States)

    Martin-Perez, Miguel; Fernandez-Borras, Jaume; Ibarz, Antoni; Felip, Olga; Fontanillas, Ramon; Gutierrez, Joaquim; Blasco, Josefina

    2013-09-18

    Ideal nutritional conditions are crucial to sustainable aquaculture due to economic and environmental issues. Here we apply stable isotope analysis as an indicator of fish growth and feeding balance, to define the optimum diet for efficient growing conditions. Juveniles of gilthead sea bream were fed with six isoenergetic diets differing in protein to lipid proportion (from 41/26 to 57/20). As protein intake increased, δ¹⁵N and Δδ¹⁵N of muscle and Δδ¹⁵N and Δδ¹³C of its protein fraction decreased, indicating lower protein turnover and higher protein deposition in muscle. This is reflected in the inverse relationship found between Δδ¹⁵N and growth rate, although no differences were observed in either parameter beyond the protein/lipid proportion 47/23. Principal component analysis (PCA) also signaled 47/23 diet as the pivotal point with the highest growing efficiency, with isotopic parameters having the highest discrimination load. Thus, muscle isotope composition, especially ¹⁵N, can be used to evaluate nutritional status in farmed fish.

  15. Effect of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle.

    Science.gov (United States)

    Carter, W J; Van Der Weijden Benjamin, W S; Faas, F H

    1980-10-01

    Since experimental hyperthyroidism reduces skeletal muscle mass while simultaneously increasing cardiac muscle mass, the effect of hyperthyroidism on muscle protein degradation was compared in skeletal and cardiac muscle. Pulse-labeling studies using (3H) leucine and (14C) carboxyl labeled aspartate and glutamate were carried out. Hyperthyroidism caused a 25%-29% increase in protein breakdown in both sarcoplasmic and myofibrillar fractions of skeletal muscle. Increased muscle protein degradation may be a major factor in the development of skeletal muscle wasting and weakness in hyperthyroidism. In contrast, protein breakdown appeared to be reduced 22% in the sarcoplasmic fraction of hyperthyroid heart muscle and was unchanged in the myofibrillar fraction. Possible reasons for the contrasting effects of hyperthyroidism on skeletal and cardiac muscle include increased sensitivity of the hyperthyroid heart to catecholamines, increased cardiac work caused by the hemodynamic effects of hyperthyroidism, and a different direct effect of thyroid hormone at the nuclear level in cardiac as opposed to skeletal muscle.

  16. Efficacy of Corrected Rapid Turnover Protein Increment Index (CRII) for Early Detection of Improvement of Nutrition Status in Patients with Malnutrition

    OpenAIRE

    Suyama, Yohji; Adachi, Kyoichi; Notsu, Yoshitomo; Satoh, Emi; Nariai, Yukiko; Hashimoto, Yohko; Sumi, Asako; Kawaguchi, Mikiko; Ishimura, Norihisa

    2009-01-01

    Serum prealbumin level is useful for assessment of changes in nutritional status but it is markedly affected by the inflammation. In this study, we examined the efficacy of the corrected rapid turnover protein increment index (CRII) for prealbumin, which is calculated as [prealbumin level/C-reactive protein (CRP) level on the assessment day]/[prealbumin level/CRP level on the day of starting nutritional care], for prediction of improvement of nutritional status in patients with malnutrition. ...

  17. Casein and soya-bean protein have different effects on whole body protein turnover at the same nitrogen balance

    DEFF Research Database (Denmark)

    Nielsen, K; Kondrup, J; Elsner, Petteri

    1994-01-01

    , or hydrolysed soya-bean protein at a level of 9.1 g/kg BW per d. The diets, which were isoenergetic with the same carbohydrate: fat ratio, were given as a continuous intragastric infusion for at least 4 d. During the last 19 h 15N-glycine (a primed continuous infusion) was given intragastrically and 15N...... synthesis. The protein diets produced a positive N balance which was independent of the protein source. Intact and hydrolysed casein increased protein synthesis 2.6- and 2.0-fold respectively, compared with the protein-free diet. Protein degradation increased 1.4- and 1.2-fold respectively. Hydrolysed soya-bean...... protein did not increase protein synthesis but decreased protein degradation by 35% compared with the protein-free diet. Compared with the hydrolysed soya-bean protein, intact casein resulted in 2.2- and 2.8-fold higher rates of protein synthesis and degradation respectively. These results are not easily...

  18. Effects of intraoperative electron irradiation in the dog on cell turnover in intact and surgically-anastomosed aorta and intestine

    International Nuclear Information System (INIS)

    Sindelar, W.F.; Morrow, B.M.; Travis, E.L.; Tepper, J.; Merkel, A.B.; Kranda, K.; Terrill, R.

    1983-01-01

    Adults dogs were subjected to laparotomy and intraoperative electron irradiation after division and reanastomosis of aorta or after construction of a blind loop of small intestine having a transverse suture line and an end-to-side anastomosis. Dogs received intraoperative irradiation of both intact and anastomosed aorta or intestine in doses of 0, 2000, 3000, or 4500 rad. Animals were sacrificed at seven days or three months following treatment. At 24 hours prior to sacrifice, dogs received 5 mCi tritiated thymidine intravenously. Irradiated and non-irradiated segments of aorta and small intestine, including intact and anastomotic regions, were analyzed for tritiated thymidine incorporation and were subjected to autoradiography. Incorporation studies showed diminution in tritiated thymidine uptake by irradiated portions of aorta and small intestine, in both intact and anastomotic regions. Autoradiograms revealed that irradiated areas of intact or anastomotic aorta or intestine had diminished labeling of stromal cells, suggesting a lowered cell proliferative capacity of irradiated tissue compared to non-irradiated portions. Inflammatory cells showed similar labeling indices in irradiated and non-irradiated tissues, both intact and surgically-manipulated, suggesting that irradiation does not significantly affect a subsequent local inflammatory response. Radiation-induced decreases in tritiated thymidine incoporation in irradiated aorta and small intestine were generally more marked at seven days than at three months following irradiation, suggesting that radiation-induced depression of cell turnover rates decreases with time

  19. Muscle protein turnover in rats treated with corticosterone (CC) or/and nandrolone decanoate (ND) and fed an adequate or a low-protein diet

    Energy Technology Data Exchange (ETDEWEB)

    Santidrian, S.; Cuevillas, F.; Goena, M.; Larralde, J.

    1986-03-01

    In order to investigate the possible antagonistic effect between glucocorticoids and androgens on muscle protein turnover, the authors have measured the fractional rates of gastrocnemius muscle protein synthesis (k/sub s/) and degradation (k/sub d/) by the constant-intravenous-infusion method using L-//sup 14/C/-tyrosine in rats receiving via s.c. per 100 g b.wt. 10 mg of CC, or 2 mg of ND or CC+ND at the indicated doses, and fed either an 18% or 5% protein diets over a period of 5 days. As an additional index of protein synthesis, RNA activity (g of synthesized protein/day/g RNA) was determined as well. Results showed that as compared to vehicle-injected animals fed the adequate diet, CC-treated rats exhibited a reduction of muscle k/sub d/, while ND-treated rats had an outstanding increase of muscle k/sub s/. However, rats receiving CC+ND showed k/sub s/ and k/sub d/ values similar to those displayed by control animals. Nevertheless, when the steroids were injected to rats fed the low-protein diet, CC has a catabolic effect on muscle protein but by reducing k/sub s/, while the anabolic action of ND is still displayed but by a significant reduction of muscle k/sub d/. CC+ND given to these protein-deficient rats caused an increase in muscle k/sub s/ and a reduction in k/sub d/. These results might indicate that, at least in part, ND antagonizes the catabolic action of high doses of CC on muscle protein metabolism.

  20. Muscle protein turnover in rats treated with corticosterone (CC) or/and nandrolone decanoate (ND) and fed an adequate or a low-protein diet

    International Nuclear Information System (INIS)

    Santidrian, S.; Cuevillas, F.; Goena, M.; Larralde, J.

    1986-01-01

    In order to investigate the possible antagonistic effect between glucocorticoids and androgens on muscle protein turnover, the authors have measured the fractional rates of gastrocnemius muscle protein synthesis (k/sub s/) and degradation (k/sub d/) by the constant-intravenous-infusion method using L-/ 14 C/-tyrosine in rats receiving via s.c. per 100 g b.wt. 10 mg of CC, or 2 mg of ND or CC+ND at the indicated doses, and fed either an 18% or 5% protein diets over a period of 5 days. As an additional index of protein synthesis, RNA activity (g of synthesized protein/day/g RNA) was determined as well. Results showed that as compared to vehicle-injected animals fed the adequate diet, CC-treated rats exhibited a reduction of muscle k/sub d/, while ND-treated rats had an outstanding increase of muscle k/sub s/. However, rats receiving CC+ND showed k/sub s/ and k/sub d/ values similar to those displayed by control animals. Nevertheless, when the steroids were injected to rats fed the low-protein diet, CC has a catabolic effect on muscle protein but by reducing k/sub s/, while the anabolic action of ND is still displayed but by a significant reduction of muscle k/sub d/. CC+ND given to these protein-deficient rats caused an increase in muscle k/sub s/ and a reduction in k/sub d/. These results might indicate that, at least in part, ND antagonizes the catabolic action of high doses of CC on muscle protein metabolism

  1. Cryo-electron microscopy of membrane proteins.

    Science.gov (United States)

    Goldie, Kenneth N; Abeyrathne, Priyanka; Kebbel, Fabian; Chami, Mohamed; Ringler, Philippe; Stahlberg, Henning

    2014-01-01

    Electron crystallography is used to study membrane proteins in the form of planar, two-dimensional (2D) crystals, or other crystalline arrays such as tubular crystals. This method has been used to determine the atomic resolution structures of bacteriorhodopsin, tubulin, aquaporins, and several other membrane proteins. In addition, a large number of membrane protein structures were studied at a slightly lower resolution, whereby at least secondary structure motifs could be identified.In order to conserve the structural details of delicate crystalline arrays, cryo-electron microscopy (cryo-EM) allows imaging and/or electron diffraction of membrane proteins in their close-to-native state within a lipid bilayer membrane.To achieve ultimate high-resolution structural information of 2D crystals, meticulous sample preparation for electron crystallography is of outmost importance. Beam-induced specimen drift and lack of specimen flatness can severely affect the attainable resolution of images for tilted samples. Sample preparations that sandwich the 2D crystals between symmetrical carbon films reduce the beam-induced specimen drift, and the flatness of the preparations can be optimized by the choice of the grid material and the preparation protocol.Data collection in the cryo-electron microscope using either the imaging or the electron diffraction mode has to be performed applying low-dose procedures. Spot-scanning further reduces the effects of beam-induced drift. Data collection using automated acquisition schemes, along with improved and user-friendlier data processing software, is increasingly being used and is likely to bring the technique to a wider user base.

  2. Radiocarbon dating of the human eye lens crystallines reveal proteins without carbon turnover throughout life

    DEFF Research Database (Denmark)

    Lynnerup, Niels; Kjeldsen, Henrik; Heegaard, Steffen

    2008-01-01

    , there is no subsequent remodelling of these fibers, nor removal of degraded lens fibers. Human tissue ultimately derives its (14)C content from the atmospheric carbon dioxide. The (14)C content of the lens proteins thus reflects the atmospheric content of (14)C when the lens crystallines were formed. Precise radiocarbon...

  3. Dystropathology increases energy expenditure and protein turnover in the Mdx mouse model of Duchenne muscular dystrophy

    Science.gov (United States)

    The skeletal muscles in Duchenne muscular dystrophy and the mdx mouse model lack functional dystrophin and undergo repeated bouts of necrosis, regeneration, and growth. These processes have a high metabolic cost. However, the consequences for whole body energy and protein metabolism, and on the diet...

  4. Amino acid metabolism and whole-body protein turnover in lambs ...

    African Journals Online (AJOL)

    Department of Microbiology, Biochemistry and Nutrition, University of New England, Armidale,. NSW 2351, Australia. The effect of protein supplementation of a wheat straw ... deur byvoeding met aminosure wat teen rumenafbraak beskerm is. I Extract from a PhD thesis submitted by PBC to the University of New England.

  5. Effect of white striping myopathy on breast muscle (Pectoralis major) protein turnover and gene expression in broilers.

    Science.gov (United States)

    Vignale, Karen; Caldas, Justina V; England, Judy A; Boonsinchai, Nirun; Magnuson, Andrew; Pollock, Erik D; Dridi, Sami; Owens, Casey M; Coon, Craig N

    2017-04-01

    A study was conducted to evaluate the effect of white striping ( ) of broiler breast muscle ( Pectoralis major ) on protein turnover and gene expression of genes related to protein degradation and fatty acid synthesis. A total of 560 day-old male broiler chicks Cobb 500 were allocated in a total of 16 pens, 35 chicks per pen. A completely randomized design was conducted with a 2 × 3 factorial arrangement (2 scores: severe and normal, and 3 breast meat samples sites). At d 60, 20 birds were randomly selected, euthanized, and scored for white striping. Scoring was either normal ( , no WS) or severe ( ). Also, the same day, 17 birds (16 infused, one control) were randomly selected and infused with a solution of 15 N Phen 40% ( ). Breast muscle tissue was taken for gene expression analysis of the following genes: MuRF1, atrogin-1, IGF-1, insulin receptor ( ), fatty acid synthetase, and acetyl CoA carboxylase ( ). Each bird was humanely euthanized after 10 minutes of infusion and scored for WS (NORM or SEV). Samples of the breast muscle ( Pectoralis major ) were taken at different layers (3 samples per bird: ventral, medial, dorsal), along with a sample of excreta for 3-methylhistidine analysis. Out of the 16 breast samples taken, only 10 were selected for analysis based on the WS score (5 NORM and 5 SEV). No significant differences ( P > 0.05) were found in fractional synthesis rate ( ) between SEV WS, NORM and sample sites for breast meat. However, fractional breakdown rate ( ) was significantly higher in birds with SEV WS compared to NORM (8.2 and 4.28, respectively, P white striping are degrading more muscular protein and mobilizing more fat. © 2016 Poultry Science Association Inc.

  6. Mutational analysis of PVX TGBp3 links subcellular accumulation and protein turnover

    International Nuclear Information System (INIS)

    Ju, H.-J.; Ye, C.-M.; Verchot-Lubicz, Jeanmarie

    2008-01-01

    Potato virus X (PVX) TGBp3 is required for virus cell-to-cell transport, has an N-terminal transmembrane domain, and a C-terminal cytosolic domain. In the absence of virus infection TGBp3:GFP is seen in the cortical and perinuclear ER. In PVX infected cells the TGBp3:GFP fusion is also seen in the nucleoplasm indicating that events during PVX infection trigger entry into the nucleus. Mutational analysis failed to identify a nuclear targeting domain. Mutations inhibiting TGBp3 association with the ER and inhibiting virus movement did not block TGBp3:GFP in the nucleoplasm. A mutation disrupting the N-terminal transmembrane domain of TGBp3 caused the fusion to accumulate in the nucleus indicating that nuclear import is regulated by ER interactions. Tunicamycin, an ER-stress inducing chemical, caused lower levels of GFP and TGBp3:GFP to accumulate in virus infected protoplasts. MG115 and MG132 were used to demonstrate that wild-type and mutant TGBp3:GFP fusions were degraded by the 26S proteasome. These observations are consistent with an ER-associated protein degradation (ERAD) pathway suggesting that PVX TGBp3, similar to aberrant ER proteins, is translocate to the cytoplasm for degradation. Nuclear accumulation of mutant and wild-type TGBp3:GFP is independent of other PVX proteins and may be another feature of an ERAD pathway

  7. Whole-body protein turnover in malnourished patients with child class B and C cirrhosis on diets low to high in protein energy.

    Science.gov (United States)

    Dichi, J B; Dichi, I; Maio, R; Correa, C R; Angeleli, A Y; Bicudo, M H; Rezende, T A; Burini, R C

    2001-03-01

    The purpose of this study was to determine the rate of whole-body protein turnover in moderately and severely alcoholic, malnourished, cirrhotic patients fed with different amounts of protein or energy. Six male patients (Child classes B and C) and four age- and sex-matched healthy control subjects were studied for 18 d in fasting and feeding states; a single oral dose of [(15)N]glycine was used as a tracer and urinary ammonia was the end product. The kinetic study showed that patients had higher protein catabolism while fasting (patients: 3.14 +/- 1.2 g of lean body mass/9 h; controls: 1.8 +/- 0.3 g of lean body mass/9 h; P hyperproteic/hyperenergetic diet when compared with fasting. Nitrogen retention was consistent with the lower protein-catabolism rate; a statistically significant increase in nitrogen balance was observed when patients were fed with the hyperproteic/hyperenergetic diet compared with fasting (4.3 +/- 3.2 g of nitrogen/d and -2.2 +/- 1.9 g of nitrogen/d, respectively; P hyperproteic/hyperenergetic diet is likely needed to improve their clinical and nutritional status.

  8. Processing and turnover of the Hedgehog protein in the endoplasmic reticulum

    OpenAIRE

    Chen, Xin; Tukachinsky, Hanna; Huang, Chih-Hsiang; Jao, Cindy; Chu, Yue-Ru; Tang, Hsiang-Yun; Mueller, Britta; Schulman, Sol; Rapoport, Tom A.; Salic, Adrian

    2011-01-01

    The Hedgehog (Hh) signaling pathway has important functions during metazoan development. The Hh ligand is generated from a precursor by self-cleavage, which requires a free cysteine in the C-terminal part of the protein and results in the production of the cholesterol-modified ligand and a C-terminal fragment. In this paper, we demonstrate that these reactions occur in the endoplasmic reticulum (ER). The catalytic cysteine needs to form a disulfide bridge with a conserved cysteine, which is s...

  9. Identifying molecular effects of diet through systems biology: influence of herring diet on sterol metabolism and protein turnover in mice.

    Directory of Open Access Journals (Sweden)

    Intawat Nookaew

    Full Text Available BACKGROUND: Changes in lifestyle have resulted in an epidemic development of obesity-related diseases that challenge the healthcare systems worldwide. To develop strategies to tackle this problem the focus is on diet to prevent the development of obesity-associated diseases such as cardiovascular disease (CVD. This will require methods for linking nutrient intake with specific metabolic processes in different tissues. METHODOLOGY/PRINCIPAL FINDING: Low-density lipoprotein receptor-deficient (Ldlr -/- mice were fed a high fat/high sugar diet to mimic a westernized diet, being a major reason for development of obesity and atherosclerosis. The diets were supplemented with either beef or herring, and matched in macronutrient contents. Body composition, plasma lipids and aortic lesion areas were measured. Transcriptomes of metabolically important tissues, e.g. liver, muscle and adipose tissue were analyzed by an integrated approach with metabolic networks to directly map the metabolic effects of diet in these different tissues. Our analysis revealed a reduction in sterol metabolism and protein turnover at the transcriptional level in herring-fed mice. CONCLUSION: This study shows that an integrated analysis of transcriptome data using metabolic networks resulted in the identification of signature pathways. This could not have been achieved using standard clustering methods. In particular, this systems biology analysis could enrich the information content of biomedical or nutritional data where subtle changes in several tissues together affects body metabolism or disease progression. This could be applied to improve diets for subjects exposed to health risks associated with obesity.

  10. Processing and turnover of the Hedgehog protein in the endoplasmic reticulum.

    Science.gov (United States)

    Chen, Xin; Tukachinsky, Hanna; Huang, Chih-Hsiang; Jao, Cindy; Chu, Yue-Ru; Tang, Hsiang-Yun; Mueller, Britta; Schulman, Sol; Rapoport, Tom A; Salic, Adrian

    2011-03-07

    The Hedgehog (Hh) signaling pathway has important functions during metazoan development. The Hh ligand is generated from a precursor by self-cleavage, which requires a free cysteine in the C-terminal part of the protein and results in the production of the cholesterol-modified ligand and a C-terminal fragment. In this paper, we demonstrate that these reactions occur in the endoplasmic reticulum (ER). The catalytic cysteine needs to form a disulfide bridge with a conserved cysteine, which is subsequently reduced by protein disulfide isomerase. Generation of the C-terminal fragment is followed by its ER-associated degradation (ERAD), providing the first example of an endogenous luminal ERAD substrate that is constitutively degraded. This process requires the ubiquitin ligase Hrd1, its partner Sel1, the cytosolic adenosine triphosphatase p97, and degradation by the proteasome. Processing-defective mutants of Hh are degraded by the same ERAD components. Thus, processing of the Hh precursor competes with its rapid degradation, explaining the impaired Hh signaling of processing-defective mutants, such as those causing human holoprosencephaly.

  11. Proteome-wide analysis of protein abundance and turnover remodelling during oncogenic transformation of human breast epithelial cells [version 1; referees: 2 approved, 1 approved with reservations

    Directory of Open Access Journals (Sweden)

    Tony Ly

    2018-05-01

    Full Text Available Background: Viral oncogenes and mutated proto-oncogenes are potent drivers of cancer malignancy. Downstream of the oncogenic trigger are alterations in protein properties that give rise to cellular transformation and the acquisition of malignant cellular phenotypes. Developments in mass spectrometry enable large-scale, multidimensional characterisation of proteomes. Such techniques could provide an unprecedented, unbiased view of how oncogene activation remodels a human cell proteome. Methods: Using quantitative MS-based proteomics and cellular assays, we analysed how transformation induced by activating v-Src kinase remodels the proteome and cellular phenotypes of breast epithelial (MCF10A cells. SILAC MS was used to comprehensively characterise the MCF10A proteome and to measure v-Src-induced changes in protein abundance across seven time-points (1-72 hrs. We used pulse-SILAC MS (Boisvert et al., 2012, to compare protein synthesis and turnover in control and transformed cells. Follow-on experiments employed a combination of cellular and functional assays to characterise the roles of selected Src-responsive proteins. Results: Src-induced transformation changed the expression and/or turnover levels of ~3% of proteins, affecting ~1.5% of the total protein molecules in the cell. Transformation increased the average rate of proteome turnover and disrupted protein homeostasis. We identify distinct classes of protein kinetics in response to Src activation. We demonstrate that members of the polycomb repressive complex 1 (PRC1 are important regulators of invasion and migration in MCF10A cells. Many Src-regulated proteins are present in low abundance and some are regulated post-transcriptionally. The signature of Src-responsive proteins is highly predictive of poor patient survival across multiple cancer types. Open access to search and interactively explore all these proteomic data is provided via the EPD database (www.peptracker.com/epd. Conclusions

  12. The plant i-AAA protease controls the turnover of an essential mitochondrial protein import component.

    Science.gov (United States)

    Opalińska, Magdalena; Parys, Katarzyna; Murcha, Monika W; Jańska, Hanna

    2018-01-29

    Mitochondria are multifunctional organelles that play a central role in energy metabolism. Owing to the life-essential functions of these organelles, mitochondrial content, quality and dynamics are tightly controlled. Across the species, highly conserved ATP-dependent proteases prevent malfunction of mitochondria through versatile activities. This study focuses on a molecular function of the plant mitochondrial inner membrane-embedded AAA protease (denoted i -AAA) FTSH4, providing its first bona fide substrate. Here, we report that the abundance of the Tim17-2 protein, an essential component of the TIM17:23 translocase (Tim17-2 together with Tim50 and Tim23), is directly controlled by the proteolytic activity of FTSH4. Plants that are lacking functional FTSH4 protease are characterized by significantly enhanced capacity of preprotein import through the TIM17:23-dependent pathway. Taken together, with the observation that FTSH4 prevents accumulation of Tim17-2, our data point towards the role of this i -AAA protease in the regulation of mitochondrial biogenesis in plants. © 2018. Published by The Company of Biologists Ltd.

  13. ALDH2(E487K) mutation increases protein turnover and promotes murine hepatocarcinogenesis.

    Science.gov (United States)

    Jin, Shengfang; Chen, Jiang; Chen, Lizao; Histen, Gavin; Lin, Zhizhong; Gross, Stefan; Hixon, Jeffrey; Chen, Yue; Kung, Charles; Chen, Yiwei; Fu, Yufei; Lu, Yuxuan; Lin, Hui; Cai, Xiujun; Yang, Hua; Cairns, Rob A; Dorsch, Marion; Su, Shinsan M; Biller, Scott; Mak, Tak W; Cang, Yong

    2015-07-21

    Mitochondrial aldehyde dehydrogenase 2 (ALDH2) in the liver removes toxic aldehydes including acetaldehyde, an intermediate of ethanol metabolism. Nearly 40% of East Asians inherit an inactive ALDH2*2 variant, which has a lysine-for-glutamate substitution at position 487 (E487K), and show a characteristic alcohol flush reaction after drinking and a higher risk for gastrointestinal cancers. Here we report the characterization of knockin mice in which the ALDH2(E487K) mutation is inserted into the endogenous murine Aldh2 locus. These mutants recapitulate essentially all human phenotypes including impaired clearance of acetaldehyde, increased sensitivity to acute or chronic alcohol-induced toxicity, and reduced ALDH2 expression due to a dominant-negative effect of the mutation. When treated with a chemical carcinogen, these mutants exhibit increased DNA damage response in hepatocytes, pronounced liver injury, and accelerated development of hepatocellular carcinoma (HCC). Importantly, ALDH2 protein levels are also significantly lower in patient HCC than in peritumor or normal liver tissues. Our results reveal that ALDH2 functions as a tumor suppressor by maintaining genomic stability in the liver, and the common human ALDH2 variant would present a significant risk factor for hepatocarcinogenesis. Our study suggests that the ALDH2*2 allele-alcohol interaction may be an even greater human public health hazard than previously appreciated.

  14. In-silico assessment of protein-protein electron transfer. a case study: cytochrome c peroxidase--cytochrome c.

    Directory of Open Access Journals (Sweden)

    Frank H Wallrapp

    Full Text Available The fast development of software and hardware is notably helping in closing the gap between macroscopic and microscopic data. Using a novel theoretical strategy combining molecular dynamics simulations, conformational clustering, ab-initio quantum mechanics and electronic coupling calculations, we show how computational methodologies are mature enough to provide accurate atomistic details into the mechanism of electron transfer (ET processes in complex protein systems, known to be a significant challenge. We performed a quantitative study of the ET between Cytochrome c Peroxidase and its redox partner Cytochrome c. Our results confirm the ET mechanism as hole transfer (HT through residues Ala194, Ala193, Gly192 and Trp191 of CcP. Furthermore, our findings indicate the fine evolution of the enzyme to approach an elevated turnover rate of 5.47 × 10(6 s(-1 for the ET between Cytc and CcP through establishment of a localized bridge state in Trp191.

  15. Turnover Time

    Science.gov (United States)

    Ecosystems contain energy and materials such as carbon, nitrogen, phosphorus, and water, and are open to their flow-through. Turnover time refers to the amount of time required for replacement by flow-through of the energy or substance of interest contained in the system, and is ...

  16. Bcl-2-associated athanogene 3 (BAG3) is an enhancer of small heat shock protein turnover via activation of autophagy in the heart.

    Science.gov (United States)

    Inomata, Yui; Nagasaka, Shouta; Miyate, Kazuki; Goto, Yuta; Hino, Chizuru; Toukairin, Chihiro; Higashio, Rieko; Ishida, Kinji; Saino, Tomoyuki; Hirose, Masamichi; Tsumura, Hideki; Sanbe, Atsushi

    2018-02-19

    Bcl-2-associated athanogene 3 (BAG3) is strongly expressed in both cardiac and skeletal muscle. A recent study showed that BAG3 may play a protective role in muscles. Little is known, however, regarding the detailed role of BAG3 in cardiac muscle. To better understand the functional role of cardiac BAG3 in the heart, we generated transgenic (TG) mice that overexpress BAG3. A decrease in fractional shortening, and the induction of cardiac atrial natriuretic peptide, were observed in BAG3 TG mice. Moreover, a marked reduction in the protein level of small HSPs was detected in BAG3 TG mouse hearts. We analyzed the cardiac small HSP levels when either the ubiquitin-proteasome system (UPS) or the autophagy system (AS) was inhibited in BAG3 TG mice. The protein turnovers of small HSPs by the AS were activated in BAG3 TG mouse hearts. Thus, BAG3 is critical for the protein turnover of small HSPs via activation of autophagy in the heart. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Role of a redox-based methylation switch in mRNA life cycle ( pre- & post- transcriptional maturation and protein turnover : Implications in neurological disorders

    Directory of Open Access Journals (Sweden)

    MALAV SUCHIN TRIVEDI

    2012-06-01

    Full Text Available Homeostatic synaptic scaling in response to neuronal stimulus or activation, as well as due to changes in cellular niche, is an important phenomenon for memory consolidation, retrieval, and other similar cognitive functions. Neurological disorders and cognitive disabilities in autism, Rett syndrome, schizophrenia, dementia etc., are strongly correlated to alterations in protein expression (both synaptic and cytoplasmic. This correlation suggests that efficient temporal regulation of synaptic protein expression is important for synaptic plasticity. In addition, equilibrium between mRNA processing, protein translation and protein turnover is a critical sensor/trigger for recording synaptic information, normal cognition and behavior. Thus a regulatory switch, controlling the lifespan, maturation and processing of mRNA, might influence cognition and adaptive behavior. Here, we propose a two part novel hypothesis that methylation might act as this suggested coordinating switch to critically regulate mRNA maturation at 1.The pre-transcription level, by regulating precursor-RNA (pre-RNA processing into mRNA, via other non-coding RNAs and their influence on splicing phenomenon, and 2. the post-transcription level by modulating the regulatory functions of ribonucleoproteins (RNP and RNA binding proteins (RNABP in mRNA translation, dendritic translocation as well as protein synthesis and synaptic turnover. DNA methylation changes are well recognized and highly correlated to gene expression levels as well as, learning and memory; however, RNA methylation changes are recently characterized and yet their functional implications are not established. This review article provides some insight on the intriguing consequences of changes in methylation levels on mRNA life-cycle. We also suggest that, since methylation is under the control of glutathione antioxidant levels, the redox status of neurons might be the central regulatory switch for methylation

  18. The Influence of Dietary Habits and Meat Consumption on Plasma 3‐Methylhistidine—A Potential Marker for Muscle Protein Turnover

    Science.gov (United States)

    Kochlik, Bastian; Gerbracht, Christiana; Grune, Tilman

    2018-01-01

    Scope 3‐Methylhistidine (3‐MH) as a potential biomarker for muscle protein turnover is influenced by meat intake but data on the impact of meat on plasma 3‐MH are scarce. We determined the association of plasma 3‐MH, 1‐methylhistidine (1‐MH), and creatinine with dietary habits and assessed the impact of a single white meat intervention during a meat‐free period. Methods and results Plasma 3‐MH, 1‐MH, and creatinine concentrations of healthy young omnivores (n = 19) and vegetarians (n = 16) were analyzed together with data on anthropometry, body composition, grip strength, and nutrition. After baseline measurements omnivores adhered to a meat‐free diet for 6 days and received a defined administration of chicken breast on day four. At baseline, omnivores had higher plasma 3‐MH and 1‐MH concentrations than vegetarians. White meat administration led to a slight increase in plasma 3‐MH in omnivores. The elevated 3‐MH concentrations significantly declined within 24 h after white meat intake. Conclusion 1‐MH concentrations in plasma seem to be suitable to display (white) meat consumption and its influence on 3‐MH plasma concentration. 3‐MH in plasma may be used as a biomarker for muscle protein turnover if subjects have not consumed meat in the previous 24 h. PMID:29573154

  19. Protein turnover and cellular stress in mildly and severely affected muscles from patients with limb girdle muscular dystrophy type 2I.

    Directory of Open Access Journals (Sweden)

    Simon Hauerslev

    Full Text Available Patients with Limb girdle muscular dystrophy type 2I (LGMD2I are characterized by progressive muscle weakness and wasting primarily in the proximal muscles, while distal muscles often are spared. Our aim was to investigate if wasting could be caused by impaired regeneration in the proximal compared to distal muscles. Biopsies were simultaneously obtained from proximal and distal muscles of the same patients with LGMD2I (n = 4 and healthy subjects (n = 4. The level of past muscle regeneration was evaluated by counting internally nucleated fibers and determining actively regenerating fibers by using the developmental markers embryonic myosin heavy chain (eMHC and neural cell adhesion molecule (NCAM and also assessing satellite cell activation status by myogenin positivity. Severe muscle histopathology was occasionally observed in the proximal muscles of patients with LGMD2I whereas distal muscles were always relatively spared. No difference was found in the regeneration markers internally nucleated fibers, actively regenerating fibers or activation status of satellite cells between proximal and distal muscles. Protein turnover, both synthesis and breakdown, as well as cellular stress were highly increased in severely affected muscles compared to mildly affected muscles. Our results indicate that alterations in the protein turnover and myostatin levels could progressively impair the muscle mass maintenance and/or regeneration resulting in gradual muscular atrophy.

  20. Heterogeneous Single-Atom Catalyst for Visible-Light-Driven High-Turnover CO2 Reduction: The Role of Electron Transfer.

    Science.gov (United States)

    Gao, Chao; Chen, Shuangming; Wang, Ying; Wang, Jiawen; Zheng, Xusheng; Zhu, Junfa; Song, Li; Zhang, Wenkai; Xiong, Yujie

    2018-03-01

    Visible-light-driven conversion of CO 2 into chemical fuels is an intriguing approach to address the energy and environmental challenges. In principle, light harvesting and catalytic reactions can be both optimized by combining the merits of homogeneous and heterogeneous photocatalysts; however, the efficiency of charge transfer between light absorbers and catalytic sites is often too low to limit the overall photocatalytic performance. In this communication, it is reported that the single-atom Co sites coordinated on the partially oxidized graphene nanosheets can serve as a highly active and durable heterogeneous catalyst for CO 2 conversion, wherein the graphene bridges homogeneous light absorbers with single-atom catalytic sites for the efficient transfer of photoexcited electrons. As a result, the turnover number for CO production reaches a high value of 678 with an unprecedented turnover frequency of 3.77 min -1 , superior to those obtained with the state-of-the-art heterogeneous photocatalysts. This work provides fresh insights into the design of catalytic sites toward photocatalytic CO 2 conversion from the angle of single-atom catalysis and highlights the role of charge kinetics in bridging the gap between heterogeneous and homogeneous photocatalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Estimation of whole body protein turnover by L-[1-[sup 13]C]-leucine tracer experiment in post-viral hepatocirrhotic patients

    Energy Technology Data Exchange (ETDEWEB)

    Xinhua, Zhu; Zhenduo, Tang; Tengchang, Dai; Zongqin, Xia [Shanghai Second Medical Univ. (China)

    1993-08-01

    A constant infusion of L-[1-[sup 1]'3C]-leucine given to the subject and the plasma [sup 13]C-leucine enrichment and breath [sup 1]'3CO[sub 2] enrichment were measured with GC-MS and gas isotope ratio MS respectively. The plateau isotope enrichments reached were used to calculate the whole body protein synthesis and breakdown rates using a two pools model. 15 post-viral hepatocirrhotic patients and 6 normal adults were studied. The whole body protein synthesis and breakdown rates were both markedly increased in cirrhotic patients, with the breakdown rate higher than the synthesis rate and hence leading to a negative nitrogen balance. The changes of 7 decompensated cirrhotic patients were more severe than 8 compensated cirrhotic patients. The results suggest that the protein malnutrition and negative nitrogen balance of post-viral hepatocirrhotic patients are not simply due to low intake of protein and that the hyperactive turnover, especially the excessive breakdown of body protein might play an important role.

  2. Sucrose-phosphate synthase in tree species: light/dark regulation involves a component of protein turnover in Prosopis juliflora (SW DC).

    Science.gov (United States)

    Sinha, A K; Shirke, P A; Pathre, U; Sane, P V

    1997-10-01

    Light dependent modulation of sucrose-phosphate synthase activity (SPS; EC 2.4.1.14) was studied in a tree species, namely Prosopis juliflora. In this paper we demonstrate that cycloheximide, an inhibitor of cytoplasmic protein synthesis, when fed to detached leaves of P. juliflora through transpiration stream in the dark or in light completely prevents in vivo light activation of Vlim and Vmax activities of SPS. In case of spinach, however, cycloheximide feeding affects only Vlim activity while Vmax activity remained unchanged. In contrast, chloramphenicol, an inhibitor of protein synthesis in chloroplast has no effect on the light activation of SPS in Prosopis. The treatment with cycloheximide showed slight reduction in the rate of O2 evolution indicating that cycloheximide had very little effect on overall photosynthesis. These results indicate that short term protein turnover of the SPS protein and some other essential component(s) (e.g., a putative protein that modifies SPS activity) is one of the primary steps in a complex and unique regulatory cascade effecting the reversible light activation of SPS.

  3. Water turnover in reindeer. Some environmental implications

    International Nuclear Information System (INIS)

    Cameron, R.D.; Luick, J.R.; White, R.G.

    1982-01-01

    The nutritional and climatic effects on water turnover (determined using tritiated water) in reindeer are described. At low ambient temperatures (ca. -20 0 C) water turnover is related to protein and mineral intake, which is reflected in the relations of faecal and urinary water to nitrogen and ash excretion via these avenues. As ambient temperature increases, respiratory water, faecal water and urine flow increase, resulting in an increase in water turnover

  4. Ammonia treatment of wheat straw. 2. Efficiency of microbial protein synthesis, rumen microbial protein pool size and turnover, and small intestinal protein digestion in sheep.

    NARCIS (Netherlands)

    Oosting, S.J.; Viets, T.C.; Lammers-Wienhoven, S.C.W.; Bruchem, van J.

    1993-01-01

    Ammonia-treated wheat straw (AWS) was compared with untreated wheat straw (UWS) and untreated wheat straw supplemented with urea (SWS) in an experiment with 6 wether sheep. Microbial protein synthesis increased after ammonia treatment due to the higher intake of rumen degradable organic matter (OM).

  5. Tunneling explains efficient electron transport via protein junctions.

    Science.gov (United States)

    Fereiro, Jerry A; Yu, Xi; Pecht, Israel; Sheves, Mordechai; Cuevas, Juan Carlos; Cahen, David

    2018-05-15

    Metalloproteins, proteins containing a transition metal ion cofactor, are electron transfer agents that perform key functions in cells. Inspired by this fact, electron transport across these proteins has been widely studied in solid-state settings, triggering the interest in examining potential use of proteins as building blocks in bioelectronic devices. Here, we report results of low-temperature (10 K) electron transport measurements via monolayer junctions based on the blue copper protein azurin (Az), which strongly suggest quantum tunneling of electrons as the dominant charge transport mechanism. Specifically, we show that, weakening the protein-electrode coupling by introducing a spacer, one can switch the electron transport from off-resonant to resonant tunneling. This is a consequence of reducing the electrode's perturbation of the Cu(II)-localized electronic state, a pattern that has not been observed before in protein-based junctions. Moreover, we identify vibronic features of the Cu(II) coordination sphere in transport characteristics that show directly the active role of the metal ion in resonance tunneling. Our results illustrate how quantum mechanical effects may dominate electron transport via protein-based junctions.

  6. Accelerated extracellular matrix turnover during exacerbations of COPD

    DEFF Research Database (Denmark)

    Sand, Jannie M B; Knox, Alan J; Lange, Peter

    2015-01-01

    progression. Extracellular matrix (ECM) turnover reflects activity in tissues and consequently assessment of ECM turnover may serve as biomarkers of disease activity. We hypothesized that the turnover of lung ECM proteins were altered during exacerbations of COPD. METHODS: 69 patients with COPD hospitalised...... of circulating fragments of structural proteins, which may serve as markers of disease activity. This suggests that patients with COPD have accelerated ECM turnover during exacerbations which may be related to disease progression....

  7. Tracer kinetics: Modelling of tracer behaviour in nonlinear and nonsteady state systems exemplified by the evaluation of protein turnover in plant organs

    International Nuclear Information System (INIS)

    Winkler, E.

    1991-01-01

    If nonlinear biological processes are investigated by means of tracer experiments they can be modelled with linear kinetic equations (compartment equations) as long as the total system is in a stationary state. But if nonstationary behaviour is included considerations on the kinetics of the individual processes are necessary. Within the range of biological and agricultural investigations especially first order reactions (constant fraction processes), zero order reactions (constant amount process) and saturation reactions (Michaelis-Menten-kinetics) are to be taken into account. A rigorous treatment of data based on system theory can be preceeded by graphic-algebraic procedure which may be more or less uncertain in its results but which can easily be handled. An example is given of methodological considerations concerning the combination of evaluation procedures and the discrimination between different reaction mechanisms. It treats protein turnover in 2 different parts of growing wheat plants investigated by means of an 15 N-tracer experiment. Whereas in a stationary system (upper stalk section) linear tracer equations were sufficient irrespective of the true reaction mechanism, for protein synthesis in the upper leaf as a nonstationary system it was necessary to decide between the hypotheses of a zero order and a first order reaction. In accordance with statements in the literature the unambiguous result was a combination of protein synthesis as a zero order process and of protein degradation as a first order process. (orig.) [de

  8. Protein Turnover and Cellular Stress in Mildly and Severely Affected Muscles from Patients with Limb Girdle Muscular Dystrophy Type 2I

    DEFF Research Database (Denmark)

    Hauerslev, Simon; Sveen, Marie-Louise; Vissing, John

    2013-01-01

    Patients with Limb girdle muscular dystrophy type 2I (LGMD2I) are characterized by progressive muscle weakness and wasting primarily in the proximal muscles, while distal muscles often are spared. Our aim was to investigate if wasting could be caused by impaired regeneration in the proximal...... by using the developmental markers embryonic myosin heavy chain (eMHC) and neural cell adhesion molecule (NCAM) and also assessing satellite cell activation status by myogenin positivity. Severe muscle histopathology was occasionally observed in the proximal muscles of patients with LGMD2I whereas distal...... highly increased in severely affected muscles compared to mildly affected muscles. Our results indicate that alterations in the protein turnover and myostatin levels could progressively impair the muscle mass maintenance and/or regeneration resulting in gradual muscular atrophy....

  9. Turnover among healthcare professionals.

    Science.gov (United States)

    Wood, Ben D

    2009-01-01

    Turnover among healthcare professionals is a costly consequence. The existing body of knowledge on healthcare professional turnover is correlated with job satisfaction levels. A landmark study differentiated 2 areas of job satisfaction categories: satisfiers and dissatisfiers (intrinsic and extrinsic motivators). The aim of this article is to examine existing research on precursors of turnover, such as burnout behaviors experienced by healthcare professionals, job satisfaction levels, employee organizational commitment, health complications which precede turnover, some current strategies to reduce turnover, and some effects CEO turnover has on employee turnover intentions.

  10. Electron transfer reactions in structural units of copper proteins

    International Nuclear Information System (INIS)

    Faraggi, M.

    1975-01-01

    In previous pulse radiolysis studies it was suggested that the reduction of the Cu(II) ions in copper proteins by the hydrated electron is a multi-step electron migration process. The technique has been extended to investigate the reduction of some structural units of these proteins. These studies include: the reaction of the hydrated electron with peptides, the reaction of the disulphide bridge with formate radical ion and radicals produced by the reduction of peptides, and the reaction of Cu(II)-peptide complex with esub(aq)sup(-) and CO 2 - . Using these results the reduction mechanism of copper and other proteins will be discussed. (author)

  11. Dynamics in electron transfer protein complexes

    NARCIS (Netherlands)

    Bashir, Qamar

    2010-01-01

    Recent studies have provided experimental evidence for the existence of an encounter complex, a transient intermediate in the formation of protein complexes. We have used paramagnetic relaxation enhancement NMR spectroscopy in combination with Monte Carlo simulations to characterize and visualize

  12. Single turnover studies of oxidative halophenol dehalogenation by horseradish peroxidase reveal a mechanism involving two consecutive one electron steps: toward a functional halophenol bioremediation catalyst.

    Science.gov (United States)

    Sumithran, Suganya; Sono, Masanori; Raner, Gregory M; Dawson, John H

    2012-12-01

    Horseradish peroxidase (HRP) catalyzes the oxidative para-dechlorination of the environmental pollutant/carcinogen 2,4,6-trichlorophenol (2,4,6-TCP). A possible mechanism for this reaction is a direct oxygen atom transfer from HRP compound I (HRP I) to trichlorophenol to generate 2,6-dichloro 1,4-benzoquinone, a two-electron transfer process. An alternative mechanism involves two consecutive one-electron transfer steps in which HRP I is reduced to compound II (HRP II) and then to the ferric enzyme as first proposed by Wiese et al. [F.W. Wiese, H.C. Chang, R.V. Lloyd, J.P. Freeman, V.M. Samokyszyn, Arch. Environ. Contam. Toxicol. 34 (1998) 217-222]. To probe the mechanism of oxidative halophenol dehalogenation, the reactions between 2,4,6-TCP and HRP compounds I or II have been investigated under single turnover conditions (i.e., without excess H(2)O(2)) using rapid scan stopped-flow spectroscopy. Addition of 2,4,6-TCP to HRP I leads rapidly to HRP II and then more slowly to the ferric resting state, consistent with a mechanism involving two consecutive one-electron oxidations of the substrate via a phenoxy radical intermediate. HRP II can also directly dechlorinate 2,4,6-TCP as judged by rapid scan stopped-flow and mass spectrometry. This observation is particularly significant since HRP II can only carry out one-electron oxidations. A more detailed understanding of the mechanism of oxidative halophenol dehalogenation will facilitate the use of HRP as a halophenol bioremediation catalyst. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. The staphylococcal accessory regulator, SarA, is an RNA-binding protein that modulates the mRNA turnover properties of late-exponential and stationary phase Staphylococcus aureus cells

    Directory of Open Access Journals (Sweden)

    John M Morrison

    2012-03-01

    Full Text Available The modulation of mRNA turnover is gaining recognition as a mechanism by which Staphylococcus aureus regulates gene expression, but the factors that orchestrate alterations in transcript degradation are poorly understood. In that regard, we previously found that 138 mRNA species, including the virulence factors protein A (spa and collagen binding protein (cna, are stabilized in a sarA-dependent manner during exponential phase growth, suggesting that SarA protein may directly or indirectly effect the RNA turnover properties of these transcripts. Herein, we expanded our characterization of the effects of sarA on mRNA turnover during late exponential and stationary phases of growth. Results revealed that the locus affects the RNA degradation properties of cells during both growth phases. Further, using gel mobility shift assays and RIP-ChIP, it was found that SarA protein is capable of binding mRNA species that it stabilizes both in vitro and within bacterial cells. Taken together, these results suggest that SarA post-transcriptionally regulates S. aureus gene expression in a manner that involves binding to and consequently altering the mRNA turnover properties of target transcripts.

  14. PROTEOTRONICS: The emerging science of protein-based electronic devices

    International Nuclear Information System (INIS)

    Alfinito, Eleonora; Pousset, Jeremy; Reggiani, Lino

    2015-01-01

    Protein-mediated charge transport is of relevant importance in the design of protein based electronics and in attaining an adequate level of understanding of protein functioning. This is particularly true for the case of transmembrane proteins, like those pertaining to the G protein coupled receptors (GPCRs). These proteins are involved in a broad range of biological processes like catalysis, substance transport, etc., thus being the target of a large number of clinically used drugs. This paper briefly reviews a variety of experiments devoted to investigate charge transport in proteins and present a unified theoretical model able to relate macroscopic experimental results with the conformations of the amino acids backbone of the single protein. (paper)

  15. Standardized 15N tracer methods for the evaluation of the plasma protein turnover in clinical practice. 1

    International Nuclear Information System (INIS)

    Bornhak, H.

    1984-01-01

    Methods for quantitative isolation of plasma proteins or groups of proteins (total plasma or serum proteins, fibrin, total globulines, α, β, γ-globolines, albumin) are described based on combination of chromatography with precipitation and extraction techniques. These methods are adapted to the special requirements of 15 N analysis. They can be performed in clinic-chemical standard laboratories without special apparatuses or devices. The described procedures are the biochemico-analytical basis for the quantitative evaluation of tracer kinetics data by means of mathematic modelling. (author)

  16. The fission yeast RNA binding protein Mmi1 regulates meiotic genes by controlling intron specific splicing and polyadenylation coupled RNA turnover.

    Directory of Open Access Journals (Sweden)

    Huei-Mei Chen

    Full Text Available The polyA tails of mRNAs are monitored by the exosome as a quality control mechanism. We find that fission yeast, Schizosaccharomyces pombe, adopts this RNA quality control mechanism to regulate a group of 30 or more meiotic genes at the level of both splicing and RNA turnover. In vegetative cells the RNA binding protein Mmi1 binds to the primary transcripts of these genes. We find the novel motif U(U/C/GAAAC highly over-represented in targets of Mmi1. Mmi1 can specifically regulate the splicing of particular introns in a transcript: it inhibits the splicing of introns that are in the vicinity of putative Mmi1 binding sites, while allowing the splicing of other introns that are far from such sites. In addition, binding of Mmi1, particularly near the 3' end, alters 3' processing to promote extremely long polyA tails of up to a kilobase. The hyperadenylated transcripts are then targeted for degradation by the nuclear exonuclease Rrp6. The nuclear polyA binding protein Pab2 assists this hyperadenylation-mediated RNA decay. Rrp6 also targets other hyperadenylated transcripts, which become hyperadenylated in an unknown, but Mmi1-independent way. Thus, hyperadenylation may be a general signal for RNA degradation. In addition, binding of Mmi1 can affect the efficiency of 3' cleavage. Inactivation of Mmi1 in meiosis allows meiotic expression, through splicing and RNA stabilization, of at least 29 target genes, which are apparently constitutively transcribed.

  17. Effect of plaster cast immobilization on the turnover rates of soluble proteins and lactate dehydrogenase isoenzymes of rabbit M. soleus

    Energy Technology Data Exchange (ETDEWEB)

    Edes, I.; Dosa, E.; Sohar, I.; Guba, F. (Orvostudomanyi Egyetem, Szeged (Hungary). Biokemiai Tanszek)

    1982-01-01

    In atrophized muscle the decreases of the activity of LDH isoenzymes can be explained partly by a 15 per cent decrease of the enzyme synthesis and partly by a 25 per cent increase in catabolism. The quantities of the soluble proteins and LDH were measured after intravenously administered /sup 3/H-leucin incorporation, from the musculus soleus. LDH was isolated by means of affinity chromatography. Radioactivity was determined in a Packard Tri-Carb scintillation counter. The synthesis rate of soluble proteins barely changed during immobilization. In the atrophized muscle the decrease of the amount of soluble proteins could be almost exclusively interpreted in terms of a 25 per cent enchancement of degradative process. The accelerated catabolism is most probably due to the proteolytic enzymes activated by immobilization.

  18. First principles studies of electron tunneling in proteins

    Science.gov (United States)

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

    2014-01-01

    A first principles study of electronic tunneling along the chain of seven Fe/S clusters in respiratory complex I, a key enzyme in the respiratory electron transport chain, is described. The broken-symmetry states of the Fe/S metal clusters calculated at both DFT and semi-empirical ZINDO levels were utilized to examine both the extremely weak electronic couplings between Fe/S clusters and the tunneling pathways, which provide a detailed atomistic-level description of the charge transfer process in the protein. One-electron tunneling approximation was found to hold within a reasonable accuracy, with only a moderate induced polarization of the core electrons. The method is demonstrated to be able to calculate accurately the coupling matrix elements as small as 10−4 cm−1. A distinct signature of the wave properties of electrons is observed as quantum interferences of multiple tunneling pathways. PMID:25383312

  19. Distribution of sterol carrier protein2 (SCP2) in rat tissues and evidence for slow turnover in liver and adrenal cortex

    International Nuclear Information System (INIS)

    Kharroubi, A.; Chanderbhan, R.; Fiskum, G.; Noland, B.J.; Scallen, T.J.; Vahouny, G.V.

    1986-01-01

    Sterol carrier protein 2 (SCP 2 ) has been implicated in the regulation of the terminal stages of hepatic cholesterol biosynthesis, and in sterol utilization for adrenal steroid hormone and hepatic bile acid synthesis. In the present studies, a highly sensitive radioimmunoassay, using [ 125 I] SCP 2 , has been developed. Highest levels of SCP 2 were found in rat liver with progressively lower levels in intestinal mucosa, adrenal, kidney, lung and testis. SCP 2 levels were low or absent in heart, brain, skeletal muscle and serum. Liver SCP 2 was largely (44%) associated with the microsomal fraction, while in adrenal, 46% was associated with mitochondria, a distribution which is consistent with the proposed roles for SCP 2 in these tissues. Levels of SCP 2 in AS 30D hepatoma cells were only 5% of those in normal liver. In liver there was no indication of diurnal rhythm of SCP 2 in the cytosol and only slight variation of the microsomal SCP 2 levels. Fasting has only slight effects on SCP 2 concentration of rat liver microsomes and cytosol. Neither ACTH nor cycloheximide treatment of rats had a significant effect on SCP 2 distribution in the adrenal. In general, these findings indicate that SCP 2 has a low turn-over rate

  20. Monitoring protein turnover during phosphate starvation-dependent autophagic degradation using a photoconvertible fluorescent protein aggregate in tobacco BY-2 cells.

    Science.gov (United States)

    Tasaki, Maiko; Asatsuma, Satoru; Matsuoka, Ken

    2014-01-01

    We have developed a system for quantitative monitoring of autophagic degradation in transformed tobacco BY-2 cells using an aggregate-prone protein comprised of cytochrome b5 (Cyt b5) and a tetrameric red fluorescent protein (RFP). Unfortunately, this system is of limited use for monitoring the kinetics of autophagic degradation because the proteins synthesized before and after induction of autophagy cannot be distinguished. To overcome this problem, we developed a system using kikume green-red (KikGR), a photoconvertible and tetrameric fluorescent protein that changes its fluorescence from green to red upon irradiation with purple light. Using the fusion protein of Cyt b5 and KikGR together with a method for the bulk conversion of KikGR, which we had previously used to convert the Golgi-localized monomeric KikGR fusion protein, we were able to monitor both the growth and de novo formation of aggregates. Using this system, we found that tobacco cells do not cease protein synthesis under conditions of phosphate (Pi)-starvation. Induction of autophagy under Pi-starvation, but not under sugar- or nitrogen-starvation, was specifically inhibited by phosphite, which is an analog of Pi with a different oxidation number. Therefore, the mechanism by which BY-2 cells can sense Pi-starvation and induce autophagy does not involve sensing a general decrease in energy supply and a specific Pi sensor might be involved in the induction of autophagy under Pi-starvation.

  1. Quantum-Chemical Electron Densities of Proteins and of Selected Protein Sites from Subsystem Density Functional Theory

    NARCIS (Netherlands)

    Kiewisch, K.; Jacob, C.R.; Visscher, L.

    2013-01-01

    The ability to calculate accurate electron densities of full proteins or of selected sites in proteins is a prerequisite for a fully quantum-mechanical calculation of protein-protein and protein-ligand interaction energies. Quantum-chemical subsystem methods capable of treating proteins and other

  2. Dynamic, electronically switchable surfaces for membrane protein microarrays.

    Science.gov (United States)

    Tang, C S; Dusseiller, M; Makohliso, S; Heuschkel, M; Sharma, S; Keller, B; Vörös, J

    2006-02-01

    Microarray technology is a powerful tool that provides a high throughput of bioanalytical information within a single experiment. These miniaturized and parallelized binding assays are highly sensitive and have found widespread popularity especially during the genomic era. However, as drug diagnostics studies are often targeted at membrane proteins, the current arraying technologies are ill-equipped to handle the fragile nature of the protein molecules. In addition, to understand the complex structure and functions of proteins, different strategies to immobilize the probe molecules selectively onto a platform for protein microarray are required. We propose a novel approach to create a (membrane) protein microarray by using an indium tin oxide (ITO) microelectrode array with an electronic multiplexing capability. A polycationic, protein- and vesicle-resistant copolymer, poly(l-lysine)-grafted-poly(ethylene glycol) (PLL-g-PEG), is exposed to and adsorbed uniformly onto the microelectrode array, as a passivating adlayer. An electronic stimulation is then applied onto the individual ITO microelectrodes resulting in the localized release of the polymer thus revealing a bare ITO surface. Different polymer and biological moieties are specifically immobilized onto the activated ITO microelectrodes while the other regions remain protein-resistant as they are unaffected by the induced electrical potential. The desorption process of the PLL-g-PEG is observed to be highly selective, rapid, and reversible without compromising on the integrity and performance of the conductive ITO microelectrodes. As such, we have successfully created a stable and heterogeneous microarray of biomolecules by using selective electronic addressing on ITO microelectrodes. Both pharmaceutical diagnostics and biomedical technology are expected to benefit directly from this unique method.

  3. Platelet activation by bacterial phospholipase C involves phosphoinositide turnover and phosphorylation of 47,000 dalton but not 20,000 dalton protein

    International Nuclear Information System (INIS)

    Huzoor-Akbar; Anwer, K.

    1986-01-01

    This study was conducted to examine the role of phosphoinositides (PIns) and phosphorylation of 47,000 dalton (P47) and 20,000 dalton (P20) proteins in platelet activation by bacterial phospholipase C (PLC). PLC induced serotonin secretion (SS) and platelet aggregation (PA) in a concentration dependent manner. PLC (0.02 U/ml) caused phosphorylation of P47 in a time dependent manner (27% at 0.5 min to 378% at 7 min). PLC did not induce more than 15% phosphorylation of P20 by 7 min. Aspirin (500 μM) blocked phosphorylation of P20 but did not inhibit SS, PA or phosphorylation of P47. PLC (0.04 U/ml) decreased radioactivity (cpm) in 32 P labeled phosphatidylinositol (PI), PI-4,5-bis-PO4 (PIP2) and PI-4-PO4 (PIP) by 20%, 12% and 7.5% respectively at 15 sec. The level of PI but not that of PIP2 returned to base line in 3 min. PIP level increased above control values within one min. PLC increased phosphatidic acid level (75% at 0.5 min. to 1545% at 3 min). In other experiments PLC produced diacylglycerol (DAG) in a time and concentration dependent manner. However, no DAG was detectable in the first 60 sec. These data suggest that: (a) PIns turnover and phosphorylation of P47 but not that of P20 is involved in platelet activation by PLC; and (b) DAG production from outer membrane phospholipids is not a prerequisite for platelet activation by PLC

  4. Formation of W(3)A(1) electron-transferring flavoprotein (ETF) hydroquinone in the trimethylamine dehydrogenase x ETF protein complex.

    Science.gov (United States)

    Jang, M H; Scrutton, N S; Hille, R

    2000-04-28

    The electron-transferring flavoprotein (ETF) from Methylophilus methylotrophus (sp. W(3)A(1)) exhibits unusual oxidation-reduction properties and can only be reduced to the level of the semiquinone under most circumstances (including turnover with its physiological reductant, trimethylamine dehydrogenase (TMADH), or reaction with strong reducing reagents such as sodium dithionite). In the present study, we demonstrate that ETF can be reduced fully to its hydroquinone form both enzymatically and chemically when it is in complex with TMADH. Quantitative titration of the TMADH x ETF protein complex with sodium dithionite shows that a total of five electrons are taken up by the system, indicating that full reduction of ETF occurs within the complex. The results indicate that the oxidation-reduction properties of ETF are perturbed upon binding to TMADH, a conclusion further supported by the observation of a spectral change upon formation of the TMADH x ETF complex that is due to a change in the environment of the FAD of ETF. The results are discussed in the context of ETF undergoing a conformational change during formation of the TMADH x ETF electron transfer complex, which modulates the spectral and oxidation-reduction properties of ETF such that full reduction of the protein can take place.

  5. Nurse turnover: a literature review - an update.

    Science.gov (United States)

    Hayes, Laureen J; O'Brien-Pallas, Linda; Duffield, Christine; Shamian, Judith; Buchan, James; Hughes, Frances; Laschinger, Heather K Spence; North, Nicola

    2012-07-01

    Concerns related to the complex issue of nursing turnover continue to challenge healthcare leaders in every sector of health care. Voluntary nurse turnover is shown to be influenced by a myriad of inter-related factors, and there is increasing evidence of its negative effects on nurses, patients and health care organizations. The objectives were to conduct a comprehensive review of the related literature to examine recent findings related to the issue of nursing turnover and its causes and consequences, and to identify on methodological challenges and the implications of new evidence for future studies. A comprehensive search of the recent literature related to nursing turnover was undertaken to summarize findings published in the past six years. Electronic databases: MEDLINE, CINAHL and PubMed, reference lists of journal publications. Keyword searches were conducted for publications published 2006 or later that examined turnover or turnover intention in employee populations of registered or practical/enrolled or assistant nurses working in the hospital, long-term or community care areas. Literature findings are presented using an integrative approach and a table format to report individual studies. From about 330 citations or abstracts that were initially scanned for content relevance, 68 studies were included in this summary review. The predominance of studies continues to focus on determinants of nurse turnover in acute care settings. Recent studies offer insight into generational factors that should be considered in strategies to promote stable staffing in healthcare organizations. Nursing turnover continues to present serious challenges at all levels of health care. Longitudinal research is needed to produce new evidence of the relationships between nurse turnover and related costs, and the impact on patients and the health care team. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Regulation of endoplasmic reticulum turnover by selective autophagy

    NARCIS (Netherlands)

    Khaminets, Aliaksandr; Heinrich, Theresa; Mari, Muriel; Grumati, Paolo; Huebner, Antje K; Akutsu, Masato; Liebmann, Lutz; Stolz, Alexandra; Nietzsche, Sandor; Koch, Nicole; Mauthe, Mario; Katona, Istvan; Qualmann, Britta; Weis, Joachim; Reggiori, Fulvio; Kurth, Ingo; Hübner, Christian A; Dikic, Ivan

    2015-01-01

    The endoplasmic reticulum (ER) is the largest intracellular endomembrane system, enabling protein and lipid synthesis, ion homeostasis, quality control of newly synthesized proteins and organelle communication. Constant ER turnover and modulation is needed to meet different cellular requirements and

  7. Regulation of endoplasmic reticulum turnover by selective autophagy

    NARCIS (Netherlands)

    Khaminets, Aliaksandr; Heinrich, Theresa; Mari, Muriel; Grumati, Paolo; Huebner, Antje K.; Akutsu, Masato; Liebmann, Lutz; Stolz, Alexandra; Nietzsche, Sandor; Koch, Nicole; Mauthe, Mario; Katona, Istvan; Qualmann, Britta; Weis, Joachim; Reggiori, Fulvio; Kurth, Ingo; Huebner, Christian A.; Dikic, Ivan

    2015-01-01

    The endoplasmic reticulum (ER) is the largest intracellular endomembrane system, enabling protein and lipid synthesis, ion homeostasis, quality control of newly synthesized proteins and organelle communication(1). Constant ER turnover and modulation is needed to meet different cellular requirements

  8. Protein electron transfer: is biology (thermo)dynamic?

    International Nuclear Information System (INIS)

    Matyushov, Dmitry V

    2015-01-01

    Simple physical mechanisms are behind the flow of energy in all forms of life. Energy comes to living systems through electrons occupying high-energy states, either from food (respiratory chains) or from light (photosynthesis). This energy is transformed into the cross-membrane proton-motive force that eventually drives all biochemistry of the cell. Life’s ability to transfer electrons over large distances with nearly zero loss of free energy is puzzling and has not been accomplished in synthetic systems. The focus of this review is on how this energetic efficiency is realized. General physical mechanisms and interactions that allow proteins to fold into compact water-soluble structures are also responsible for a rugged landscape of energy states and a broad distribution of relaxation times. Specific to a protein as a fluctuating thermal bath is the protein-water interface, which is heterogeneous both dynamically and structurally. The spectrum of interfacial fluctuations is a consequence of protein’s elastic flexibility combined with a high density of surface charges polarizing water dipoles into surface nanodomains. Electrostatics is critical to the protein function and the relevant questions are: (i) What is the spectrum of interfacial electrostatic fluctuations? (ii) Does the interfacial biological water produce electrostatic signatures specific to proteins? (iii) How is protein-mediated chemistry affected by electrostatics? These questions connect the fluctuation spectrum to the dynamical control of chemical reactivity, i.e. the dependence of the activation free energy of the reaction on the dynamics of the bath. Ergodicity is often broken in protein-driven reactions and thermodynamic free energies become irrelevant. Continuous ergodicity breaking in a dense spectrum of relaxation times requires using dynamically restricted ensembles to calculate statistical averages. When applied to the calculation of the rates, this formalism leads to the nonergodic

  9. Electron-mediating Cu(A) centers in proteins

    DEFF Research Database (Denmark)

    Epel, Boris; Slutter, Claire S; Neese, Frank

    2002-01-01

    High field (W-band, 95 GHz) pulsed electron-nuclear double resonance (ENDOR) measurements were carried out on a number of proteins that contain the mixed-valence, binuclear electron-mediating Cu(A) center. These include nitrous oxide reductase (N(2)OR), the recombinant water-soluble fragment...... of subunit II of Thermus thermophilus cytochrome c oxidase (COX) ba(3) (M160T9), its M160QT0 mutant, where the weak axial methionine ligand has been replaced by a glutamine, and the engineered "purple" azurin (purpAz). The three-dimensional (3-D) structures of these proteins, apart from the mutant, are known...... indicates differences in the positions of the imidazole rings relative to the Cu(2)S(2) core. Comparison of the spectral features of the weakly coupled protons of M160QT0 with those of the other investigated proteins shows that they are very similar to those of purpAz, where the Cu(A) center is the most...

  10. Managing teacher turnover

    African Journals Online (AJOL)

    Erna Kinsey

    - ... vacant teaching posts are not filled (Pretorius & Heard, 1999; Anon., ... it reaches critical proportions. This article therefore investigates teacher turnover as a phenome- non to be managed and suggests ways of doing so. The study is based.

  11. Electron Microscopic Visualization of Protein Assemblies on Flattened DNA Origami.

    Science.gov (United States)

    Mallik, Leena; Dhakal, Soma; Nichols, Joseph; Mahoney, Jacob; Dosey, Anne M; Jiang, Shuoxing; Sunahara, Roger K; Skiniotis, Georgios; Walter, Nils G

    2015-07-28

    DNA provides an ideal substrate for the engineering of versatile nanostructures due to its reliable Watson-Crick base pairing and well-characterized conformation. One of the most promising applications of DNA nanostructures arises from the site-directed spatial arrangement with nanometer precision of guest components such as proteins, metal nanoparticles, and small molecules. Two-dimensional DNA origami architectures, in particular, offer a simple design, high yield of assembly, and large surface area for use as a nanoplatform. However, such single-layer DNA origami were recently found to be structurally polymorphous due to their high flexibility, leading to the development of conformationally restrained multilayered origami that lack some of the advantages of the single-layer designs. Here we monitored single-layer DNA origami by transmission electron microscopy (EM) and discovered that their conformational heterogeneity is dramatically reduced in the presence of a low concentration of dimethyl sulfoxide, allowing for an efficient flattening onto the carbon support of an EM grid. We further demonstrated that streptavidin and a biotinylated target protein (cocaine esterase, CocE) can be captured at predesignated sites on these flattened origami while maintaining their functional integrity. Our demonstration that protein assemblies can be constructed with high spatial precision (within ∼2 nm of their predicted position on the platforms) by using strategically flattened single-layer origami paves the way for exploiting well-defined guest molecule assemblies for biochemistry and nanotechnology applications.

  12. ANTESEDEN EMPLOYEE TURNOVER

    Directory of Open Access Journals (Sweden)

    Heryadi Fardilah

    2018-03-01

    Full Text Available This research is concerning the effect of workplace environment, job satisfaction, and  job performance on employee turnover, and the background is to get the convenience of employees condition, the satisfaction of job results, maximum performance, and keep and reduce in and out employees. The purpose of this research is to see how far the influence of workplace environment, job satisfaction, and job performance on employee turnover. Planning of this research uses primary data that is got by handing over questioners to 200 employees in Telecommunication company in East Jakarta. The analysis method which is used is double regresi.  Results of  this  research give conclusion that there's a positive and significant influence of workplace environment, job satisfaction, and job performance on employee turnover.

  13. Electron spray ionization mass spectrometry and 2D 31P NMR for monitoring 18O/16O isotope exchange and turnover rates of metabolic oligophosphates

    International Nuclear Information System (INIS)

    Nemutlu, Emirhan; Juranic, Nenad; Macura, Slobodan; Zhang, Song; Terzic, Andre; Dzeja, Petras P.; Ward, Lawrence E.; Dutta, Tumpa; Nair, K.S.

    2012-01-01

    A new method was here developed for the determination of 18 O-labeling ratios in metabolic oligophosphates, such as ATP, at different phosphoryl moieties (α-, β-, and γ-ATP) using sensitive and rapid electrospray ionization mass spectrometry (ESI-MS). The ESI-MS-based method for monitoring of 18 O/ 16 O exchange was validated with gas chromatography-mass spectrometry and 2D 31 P NMR correlation spectroscopy, the current standard methods in labeling studies. Significant correlation was found between isotopomer selective 2D 31 P NMR spectroscopy and isotopomer less selective ESI-MS method. Results demonstrate that ESI-MS provides a robust analytical platform for simultaneous determination of levels, 18 O-labeling kinetics and turnover rates of α-, β-, and γ-phosphoryls in ATP molecule. Such method is advantageous for large scale dynamic phosphometabolomic profiling of metabolic networks and acquiring information on the status of probed cellular energetic system. (orig.)

  14. Identifying the molecular functions of electron transport proteins using radial basis function networks and biochemical properties.

    Science.gov (United States)

    Le, Nguyen-Quoc-Khanh; Nguyen, Trinh-Trung-Duong; Ou, Yu-Yen

    2017-05-01

    The electron transport proteins have an important role in storing and transferring electrons in cellular respiration, which is the most proficient process through which cells gather energy from consumed food. According to the molecular functions, the electron transport chain components could be formed with five complexes with several different electron carriers and functions. Therefore, identifying the molecular functions in the electron transport chain is vital for helping biologists understand the electron transport chain process and energy production in cells. This work includes two phases for discriminating electron transport proteins from transport proteins and classifying categories of five complexes in electron transport proteins. In the first phase, the performances from PSSM with AAIndex feature set were successful in identifying electron transport proteins in transport proteins with achieved sensitivity of 73.2%, specificity of 94.1%, and accuracy of 91.3%, with MCC of 0.64 for independent data set. With the second phase, our method can approach a precise model for identifying of five complexes with different molecular functions in electron transport proteins. The PSSM with AAIndex properties in five complexes achieved MCC of 0.51, 0.47, 0.42, 0.74, and 1.00 for independent data set, respectively. We suggest that our study could be a power model for determining new proteins that belongs into which molecular function of electron transport proteins. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Costs of employee turnover

    Directory of Open Access Journals (Sweden)

    Jiří Duda

    2013-01-01

    Full Text Available The aim of this paper is to establish a general methodology for calculating the costs incurred by employee turnover. This paper deals with identification of costs incurred by the departure of an employee, and does not deal with the cost of recruitment of a new employee. Economic calculations are adjusted to the tax policy in the Czech Republic. The costs of employee turnover (according to Bliss, 2012 include the costs of substitution of the unoccupied position, costs of conducting the exit interview and termination of the contract. The cost of an executive’s time to understand the causes of leaving and costs of the leaving employee’s training were also determined. Important factors in the costs of employee turnover also include the loss of knowledge and possibly also a loss of customers. Costs of lost employee and department productiveness represent an important part of the costs of employee turnover, as well. For all of these costs there have been proposed general calculations formulas.

  16. Fast electron transfer through a single molecule natively structured redox protein

    DEFF Research Database (Denmark)

    Della Pia, Eduardo Antonio; Chi, Qijin; Macdonald, J. Emyr

    2012-01-01

    The electron transfer properties of proteins are normally measured as molecularly averaged ensembles. Through these and related measurements, proteins are widely regarded as macroscopically insulating materials. Using scanning tunnelling microscopy (STM), we present new measurements of the conduc...

  17. Peptide Level Turnover Measurements Enable the Study of Proteoform Dynamics.

    Science.gov (United States)

    Zecha, Jana; Meng, Chen; Zolg, Daniel Paul; Samaras, Patroklos; Wilhelm, Mathias; Kuster, Bernhard

    2018-05-01

    The coordination of protein synthesis and degradation regulating protein abundance is a fundamental process in cellular homeostasis. Today, mass spectrometry-based technologies allow determination of endogenous protein turnover on a proteome-wide scale. However, standard dynamic SILAC (Stable Isotope Labeling in Cell Culture) approaches can suffer from missing data across pulse time-points limiting the accuracy of such analysis. This issue is of particular relevance when studying protein stability at the level of proteoforms because often only single peptides distinguish between different protein products of the same gene. To address this shortcoming, we evaluated the merits of combining dynamic SILAC and tandem mass tag (TMT)-labeling of ten pulse time-points in a single experiment. Although the comparison to the standard dynamic SILAC method showed a high concordance of protein turnover rates, the pulsed SILAC-TMT approach yielded more comprehensive data (6000 proteins on average) without missing values. Replicate analysis further established that the same reproducibility of turnover rate determination can be obtained for peptides and proteins facilitating proteoform resolved investigation of protein stability. We provide several examples of differentially turned over splice variants and show that post-translational modifications can affect cellular protein half-lives. For example, N-terminally processed peptides exhibited both faster and slower turnover behavior compared with other peptides of the same protein. In addition, the suspected proteolytic processing of the fusion protein FAU was substantiated by measuring vastly different stabilities of the cleavage products. Furthermore, differential peptide turnover suggested a previously unknown mechanism of activity regulation by post-translational destabilization of cathepsin D as well as the DNA helicase BLM. Finally, our comprehensive data set facilitated a detailed evaluation of the impact of protein

  18. Electron paramagnetic resonance of globin proteins - a successful match between spectroscopic development and protein research

    Science.gov (United States)

    Van Doorslaer, Sabine; Cuypers, Bert

    2018-02-01

    At the start of the twenty-first century, the research into the haem-containing globins got a considerable impetus with the discovery of three new mammalian globins: neuroglobin, cytoglobin and androglobin. Globins are by now found in all kingdoms of life and, in many cases, their functions are still under debate. This revival in globin research increased the demand for adequate physico-chemical research tools to determine the structure-function relationships of these proteins. From early days onwards, electron paramagnetic resonance (EPR) has been used in globin research. In recent decades, the field of EPR has been revolutionised with the introduction of many new pulsed and high-field EPR techniques. In this review, we highlight how EPR has become an essential tool in globin research, and how globins equally provide ideal model systems to push technical developments in EPR.

  19. Effects of 2 weeks lower limb immobilization and two separate rehabilitation regimens on gastrocnemius muscle protein turnover signaling and normalization genes

    DEFF Research Database (Denmark)

    Nedergaard, Anders; Jespersen, Jakob G; Pingel, Jessica

    2012-01-01

    of resistance training and continued protein/carbohydrate supplementation (Study 2). We obtained muscle biopsies from the medial gastrocnemius prior to immobilization (PRE), post-immobilization (IMMO) and post-rehabilitation (REHAB) and measured protein expression and phosphorylation of Akt, mTOR, S6k, 4E-BP1...

  20. Protein turnover in the breast muscle of broiler chicks and studies addressing chlorine dioxide sanitation of hatching eggs, poultry leg problems and wheat middling diets for laying hens

    International Nuclear Information System (INIS)

    Patterson, P.H.

    1988-01-01

    Developmental changes occurred in breast muscle Ks measured by 14 C-tyrosine incorporation at 10, 16, 22 and 34 days of age. Protein synthesis rates decreased as the birds matures: 30 to 11.2%/d between 10 and 34 days of age. In a second study birds fed diets low in lysine or protein-energy had reduced fractional rates of protein synthesis and free tyrosine, branched chain and large neutral amino acid concentrations as compared to control birds the same body weight. Artificial weight loading and reduced dietary protein levels were used to study the effects of body weight on the severity of leg deformities in chicks and poults. Experiments investigating the practicality of wheat middlings as an alternate feedstuff for laying hens suggested that high levels in the diet will reduce egg production, feed conversion, hen livability and egg yolk color. Lastly, chlorine dioxide foam and dipping solutions were compared with formaldehyde fumigation for sanitizing hatching eggs

  1. A new technique for measuring protein turnover in the gut, liver and kidneys of lean and obese mice with [3H] glutamic acid

    International Nuclear Information System (INIS)

    Miller, B.G.; Grimble, R.F.; Taylor, T.G.

    1978-01-01

    Measurements have been made of the incorporation of an intraperitoneal injection of [ 3 H]glutamate into the protein of the gut, liver and kidney of lean and obese siblings of the genetically obese mouse. Recycling of the 3 H was minimized by using glutamate labelled at the C-2 position. Loss of label from the amino acid pool by transamination and deamination was rapid, with a half-life of 4 h. In tissue protein the amino acid showing the highest 3 H radioactivity was glutamate. The half-lives for protein synthesis and catabolism were calculated from the decay curves of both specific and total radioactivity of [ 3 H] glutamate in tissue protein. No significant differences were found between kidney, liver and gut in lean and obese mice. (author)

  2. Examination of intracellular protein turnover under the influence of glucagon exemplified by the 14C-BNPP inhibitable liver carboxylesterases of diabetic rats

    International Nuclear Information System (INIS)

    Wagenmann, F.P.

    1982-01-01

    To-date, there are but few studies on the synthesis and degradation of cell proteins under the influence of exogenically supplied-hormones. The thesis aimed at undertaking such a study using membrane-linked non-specific liver carboxyl esterases under the influence of glucagon. The method applied allows to simultaneously measure both the content and the metabolism of carboxyl esterases. Test animals were 24 male Wistar rats which were turned into diabetics using streptozotocine. Following a single i.p. application of 10mg BNPP/kg body weight, the animals received, s.c. injections of 1-1.5 mg zinc protamine glucagon/kg bodyweight daily. Esterase content per gram of microsomal protein dropped to some 50% during the 5-day observation period, whereas total protein concentration of the microsome fraction was reduced but lightly. Such a drop in the esterase concentration in the liver could not be found in a 28-amimal control group which received neither streptozotocine nor zinc protamine glucagon. Average halflife of carboxyl esterases was 43 h in these animals whereas it was 73 h in the animals treated with glucagon. A mathematical model of protein degradation allowed to prove that the supraproportional decrease of esterase content and the marked prolongation of average halflife in glucagon-treated animals was mainly due to a restriction of the de-novo synthesis of esterasis. (orig./MG) [de

  3. Salary, Performance, and Superintendent Turnover

    Science.gov (United States)

    Grissom, Jason A.; Mitani, Hajime

    2016-01-01

    Purpose: Superintendent retention is an important goal for many school districts, yet the factors contributing to superintendent turnover are poorly understood. Most prior quantitative studies of superintendent turnover have relied on small, cross-sectional samples, limiting the evidence base. Utilizing longitudinal administrative records from…

  4. Commitment Profiles and Employee Turnover

    Science.gov (United States)

    Stanley, Laura; Vandenberghe, Christian; Vandenberg, Robert; Bentein, Kathleen

    2013-01-01

    We examined how affective (AC), normative (NC), perceived sacrifice (PS), and few alternatives (FA) commitments combine to form profiles and determine turnover intention and turnover. We theorized that three mechanisms account for how profiles operate, i.e., the degree to which membership is internally regulated, the perceived desirability and…

  5. Participation of Low Molecular Weight Electron Carriers in Oxidative Protein Folding

    Directory of Open Access Journals (Sweden)

    József Mandl

    2009-03-01

    Full Text Available Oxidative protein folding is mediated by a proteinaceous electron relay system, in which the concerted action of protein disulfide isomerase and Ero1 delivers the electrons from thiol groups to the final acceptor. Oxygen appears to be the final oxidant in aerobic living organisms, although the existence of alternative electron acceptors, e.g. fumarate or nitrate, cannot be excluded. Whilst the protein components of the system are well-known, less attention has been turned to the role of low molecular weight electron carriers in the process. The function of ascorbate, tocopherol and vitamin K has been raised recently. In vitro and in vivo evidence suggests that these redox-active compounds can contribute to the functioning of oxidative folding. This review focuses on the participation of small molecular weight redox compounds in oxidative protein folding.

  6. Occupational stress and employee turnover.

    Science.gov (United States)

    Bridger, Robert S; Day, Andrea J; Morton, Kate

    2013-01-01

    Questionnaire data captured in January-March 2007 were examined in relation to turnover in males and females during the next five years. In general, most of the workplace stressors (such as role conflict or peer support) were not antecedents of turnover in any group. Junior personnel with psychological strain in 2007 had an increased risk of turnover in the next five years. Low commitment to the service in 2007 increased the odds of turnover in male and female juniors and in female officers. Female juniors with less effective skills for coping with stress and who exercised less frequently on a weekly basis were more likely to leave. An incidental finding was that the odds of turnover were three times greater in female officers with children than in female officers with no children. Stress management interventions focusing on effective coping and sports and exercise participation which are targeted appropriately may improve retention.

  7. Managing voluntary turnover through challenging assignments

    NARCIS (Netherlands)

    Preenen, P.T.Y.; de Pater, I.E.; van Vianen, A.E.M.; Keijzer, L.

    2011-01-01

    This study examines employees’ challenging assignments as manageable means to reduce turnover intentions, job search behaviors, and voluntary turnover. Results indicate that challenging assignments are negatively related to turnover intentions and job search behaviors and that these relationships

  8. Managing voluntary turnover through challenging assignments

    NARCIS (Netherlands)

    Preenen, P.T.Y.; Pater, I.E. de; Vianen, A.E.M. van; Keijzer, L.

    2011-01-01

    This study examines employees' challenging assignments as manageable means to reduce turnover intentions, job search behaviors, and voluntary turnover. Results indicate that challenging assignments are negatively related to turnover intentions and job search behaviors and that these relationships

  9. Structural investigation of membrane proteins by electron microscopy

    NARCIS (Netherlands)

    Moscicka, Katarzyna Beata

    2009-01-01

    Biological membranes are vital components of all living systems, forming the boundaries of cells and their organelles. They consist of a lipid bilayer and embedded proteins, which are nanomachines that fulfill key functions such as energy conversion, solute transport, secretion, and signal

  10. Introduction to Spin Label Electron Paramagnetic Resonance Spectroscopy of Proteins

    Science.gov (United States)

    Melanson, Michelle; Sood, Abha; Torok, Fanni; Torok, Marianna

    2013-01-01

    An undergraduate laboratory exercise is described to demonstrate the biochemical applications of electron paramagnetic resonance (EPR) spectroscopy. The beta93 cysteine residue of hemoglobin is labeled by the covalent binding of 3-maleimido-proxyl (5-MSL) and 2,2,5,5-tetramethyl-1-oxyl-3-methyl methanethiosulfonate (MTSL), respectively. The excess…

  11. Automation of specimen selection and data acquisition for protein electron crystallography

    NARCIS (Netherlands)

    Oostergetel, G.T.; Keegstra, W.; Brisson, A.D R

    A system is presented for semi-automatic specimen selection and data acquisition for protein electron crystallography, based on a slow-scan CCD camera connected to a transmission electron microscope and control from an external computer. Areas of interest on the specimen are localised at low

  12. Image processing of small protein-crystals in electron microscopy

    International Nuclear Information System (INIS)

    Feinberg, D.A.

    1978-11-01

    This electron microscope study was undertaken to determine whether high resolution reconstructed images could be obtained from statistically noisy micrographs by the super-position of several small areas of images of well-ordered crystals of biological macromolecules. Methods of rotational and translational alignment which use Fourier space data were demonstrated to be superior to methods which use Real space image data. After alignment, the addition of the diffraction patterns of four small areas did not produce higher resolution because of unexpected image distortion effects. A method was developed to determine the location of the distortion origin and the coefficients of spiral distortion and pincushion/barrel distortion in order to make future correction of distortions in electron microscope images of large area crystals

  13. A study protocol to investigate the relationship between dietary fibre intake and fermentation, colon cell turnover, global protein acetylation and early carcinogenesis: the FACT study

    International Nuclear Information System (INIS)

    Corfe, Bernard M; Williams, Elizabeth A; Bury, Jonathan P; Riley, Stuart A; Croucher, Lisa J; Lai, Daphne YL; Evans, Caroline A

    2009-01-01

    A number of studies, notably EPIC, have shown a descrease in colorectal cancer risk associated with increased fibre consumption. Whilst the underlying mechanisms are likely to be multifactorial, production of the short-chain fatty-acid butyrate fro butyratye is frequently cited as a major potential contributor to the effect. Butyrate inhibits histone deacetylases, which work on a wide range of proteins over and above histones. We therefore hypothesized that alterations in the acetylated proteome may be associated with a cancer risk phenotype in the colorectal mucosa, and that such alterations are candidate biomarkers for effectiveness of fibre interventions in cancer prevention. There are two principal arms to this study: (i) a cross-sectional study (FACT OBS) of 90 subjects recruited from gastroenterology clinics and; (ii) an intervention trial in 40 subjects with an 8 week high fibre intervention. In both studies the principal goal is to investigate a link between fibre intake, SCFA production and global protein acetylation. The primary measure is level of faecal butyrate, which it is hoped will be elevated by moving subjects to a high fibre diet. Fibre intakes will be estimated in the cross-sectional group using the EPIC Food Frequency Questionnaire. Subsidiary measures of the effect of butyrate on colon mucosal function and pre-cancerous phenotype will include measures of apoptosis, apoptotic regulators cell cycle and cell division. This study will provide a new level of mechanistic data on alterations in the functional proteome in response to the colon microenvironment which may underwrite the observed cancer preventive effect of fibre. The study may yield novel candidate biomarkers of fibre fermentation and colon mucosal function. Trial Registration Number: ISRCTN90852168

  14. A study protocol to investigate the relationship between dietary fibre intake and fermentation, colon cell turnover, global protein acetylation and early carcinogenesis: the FACT study

    Directory of Open Access Journals (Sweden)

    Croucher Lisa J

    2009-09-01

    Full Text Available Abstract Background A number of studies, notably EPIC, have shown a descrease in colorectal cancer risk associated with increased fibre consumption. Whilst the underlying mechanisms are likely to be multifactorial, production of the short-chain fatty-acid butyrate fro butyratye is frequently cited as a major potential contributor to the effect. Butyrate inhibits histone deacetylases, which work on a wide range of proteins over and above histones. We therefore hypothesized that alterations in the acetylated proteome may be associated with a cancer risk phenotype in the colorectal mucosa, and that such alterations are candidate biomarkers for effectiveness of fibre interventions in cancer prevention. Methods an design There are two principal arms to this study: (i a cross-sectional study (FACT OBS of 90 subjects recruited from gastroenterology clinics and; (ii an intervention trial in 40 subjects with an 8 week high fibre intervention. In both studies the principal goal is to investigate a link between fibre intake, SCFA production and global protein acetylation. The primary measure is level of faecal butyrate, which it is hoped will be elevated by moving subjects to a high fibre diet. Fibre intakes will be estimated in the cross-sectional group using the EPIC Food Frequency Questionnaire. Subsidiary measures of the effect of butyrate on colon mucosal function and pre-cancerous phenotype will include measures of apoptosis, apoptotic regulators cell cycle and cell division. Discussion This study will provide a new level of mechanistic data on alterations in the functional proteome in response to the colon microenvironment which may underwrite the observed cancer preventive effect of fibre. The study may yield novel candidate biomarkers of fibre fermentation and colon mucosal function. Trial Registration Trial Registration Number: ISRCTN90852168

  15. How Employee Turnover Affects Productivity

    DEFF Research Database (Denmark)

    Eriksen, Bo

    Research on employee turnover suggests that turnover results in negative organization-level outcomes. This paper provides a firm-level analysis of the impact of the in- and outflows of human resources on productivity and how the presence of organizational slack resources moderates the effects...... moderate this effect so that the negative consequences of employee turnover are less severe for larger, older and capital intensive firms. These moderating variables indicate the presence of slack resources in the firm, and thus that the accumulation of slack reduces the efficiency losses from employee...

  16. Tendon 'turnover lengthening' technique.

    Science.gov (United States)

    Cerovac, S; Miranda, B H

    2013-11-01

    Tendon defect reconstruction is amongst the most technically challenging areas in hand surgery. Tendon substance deficiency reconstruction techniques include lengthening, grafting, two-stage reconstruction and tendon transfers, however each is associated with unique challenges over and above direct repair. We describe a novel 'turnover lengthening' technique for hand tendons that has successfully been applied to the repair of several cases, including a case of attritional flexor and traumatic extensor tendon rupture in two presented patients where primary tenorrhaphy was not possible. In both cases a good post-operative outcome was achieved, as the patients were happy having returned back to normal activities of daily living such that they were discharged 12 weeks post-operatively. Our technique avoids the additional morbidity and complications associated with grafting, transfers and two stage reconstructions. It is quick, simple and reproducible for defects not exceeding 3-4 cm, provides a means of immediate one stage reconstruction, no secondary donor site morbidity and does not compromise salvage by tendon transfer and/or two-stage reconstruction in cases of failure. To our knowledge no such technique has been previously been described to reconstruct such hand tendon defects. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  17. Dissociation of bradykinin-induced prostaglandin formation from phosphatidylinositol turnover in Swiss 3T3 fibroblasts: evidence for G protein regulation of phospholipase A2

    International Nuclear Information System (INIS)

    Burch, R.M.; Axelrod, J.

    1987-01-01

    In Swiss 3T3 fibroblasts bradykinin stimulated inositol phosphate (InsP) formation and prostaglandin E 2 (PGE 2 ) synthesis. The EC 50 values for stimulation of PGE 2 synthesis and InsP formation by bradykinin were similar, 200 pM and 275 pM, respectively. Guanosine-5'-[γ-thio]triphosphate stimulated PGE 2 synthesis and InsP formation, and guanosine-5'-[β-thio]diphosphate inhibited both PGE 2 synthesis and InsP formation stimulated by bradykinin. Neither bradykinin-stimulated PGE 2 synthesis nor InsP formation was sensitive to pertussis toxin. Phorbol ester, dexamethasone, and cycloheximide distinguished between bradykinin-stimulated PGE 2 synthesis and InsP formation. Phorbol 12-myristate 13-acetate enhanced bradykinin-stimulated PGE 2 synthesis but inhibited bradykinin-stimulated InsP formation. Pretreatment of cells with dexamethasone for 24 hr inhibited bradykinin-stimulated PGE 2 synthesis but was without effect on bradykinin-stimulated InsP formation. Cycloheximide inhibited on bradykinin-stimulated InsP formation. When bradykinin was added to cells prelabeled with [ 3 H] choline, the phospholipase A 2 products lysophosphatidylcholine and glycerophosphocholine were generated. The data suggest that bradykinin receptors are coupled by GTP-binding proteins to both phospholipase C and phospholipase A 2 and that phospholipase A 2 is the enzyme that catalyzes release of arachidonate for prostaglandin synthesis

  18. Extractable proteins from electron beam (EB) irradiated natural rubber (NR) latex

    International Nuclear Information System (INIS)

    Feroza Akhtar; Fumio Yoshii; Keizo Makuuchi

    1996-01-01

    The protein assay of natural rubber latex (NRL) vulcanized by low energy electron beam (EB, 300 keV, 30 mA) has been carried out using Bicinchoninic acid (BCA) reagent. Extractable protein in irradiated latex film was determined by measuring the absorption of colored solution at 562 nm using UV spectrometer. The effect of various radiation doses on the extractable protein content of NRL was investigated. It was ,found that the quantities of extractable protein increases with radiation dose. When compared with ,gamma-ray irradiated samples the same trend was observed. Electron beam irradiated latex films are leached in 1% (ammonia water for various lengths of time. From the results it was established that within 2 hours of leaching in ammonia water most of the extractable protein (96%) were removed from rubber film

  19. First principles design of a core bioenergetic transmembrane electron-transfer protein

    Energy Technology Data Exchange (ETDEWEB)

    Goparaju, Geetha; Fry, Bryan A.; Chobot, Sarah E.; Wiedman, Gregory; Moser, Christopher C.; Leslie Dutton, P.; Discher, Bohdana M.

    2016-05-01

    Here we describe the design, Escherichia coli expression and characterization of a simplified, adaptable and functionally transparent single chain 4-α-helix transmembrane protein frame that binds multiple heme and light activatable porphyrins. Such man-made cofactor-binding oxidoreductases, designed from first principles with minimal reference to natural protein sequences, are known as maquettes. This design is an adaptable frame aiming to uncover core engineering principles governing bioenergetic transmembrane electron-transfer function and recapitulate protein archetypes proposed to represent the origins of photosynthesis. This article is part of a Special Issue entitled Biodesign for Bioenergetics — the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.

  20. Collagen turnover after tibial fractures

    DEFF Research Database (Denmark)

    Joerring, S; Krogsgaard, M; Wilbek, H

    1994-01-01

    Collagen turnover after tibial fractures was examined in 16 patients with fracture of the tibial diaphysis and in 8 patients with fracture in the tibial condyle area by measuring sequential changes in serological markers of turnover of types I and III collagen for up to 26 weeks after fracture....... The markers were the carboxy-terminal extension peptide of type I procollagen (PICP), the amino-terminal extension peptide of type III procollagen (PIIINP), and the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP). The latter is a new serum marker of degradation of type I...... collagen. A group comparison showed characteristic sequential changes in the turnover of types I and III collagen in fractures of the tibial diaphysis and tibial condyles. The turnover of type III collagen reached a maximum after 2 weeks in both groups. The synthesis of type I collagen reached a maximum...

  1. Protein oxidation and peroxidation

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan

    2016-01-01

    Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard...... to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners...... and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals...

  2. [Turnover Experience of Male Nurses].

    Science.gov (United States)

    Kim, Hyunsu; Lee, Jeongseop

    2017-02-01

    The aim of this study was to identify turnover experiences of men in nursing and to derive a substantive theory on the turnover experience of men who are nurses. Data were collected through in-depth interviews with 13 men who had worked as a nurse for 1 year or more, and had a turnover experience during that period. Collected data were analyzed on the basis of Strauss and Corbin's grounded theory. The core category in the turnover experiences of the respondents was 'seeking a stable place for me'. In the analysis of the core category, types of 'contentment', 'seeking', 'survival' and 'confusion' were identified. The sequential stages of these nurses' turnover experience were 'confrontation', 'incertitude', 'retrying' and 'realization'. However, when a problem arose in the process, they returned to the stage of confusion. Thus, these stages could occur in a circular fashion. These findings provide a deep understanding of the turnover experience of men in nursing and offers new information about how they adapt to nursing practice. The findings should be useful as foundational data for men who hope to become nurses and also for managers responsible for nurses who are men. © 2017 Korean Society of Nursing Science

  3. Electronic transport on the spatial structure of the protein: Three-dimensional lattice model

    International Nuclear Information System (INIS)

    Sarmento, R.G.; Frazão, N.F.; Macedo-Filho, A.

    2017-01-01

    Highlights: • The electronic transport on the structure of the three-dimensional lattice model of the protein is studied. • The signing of the current–voltage is directly affected by permutations of the weak bonds in the structure. • Semiconductor behave of the proteins suggest a potential application in the development of novel biosensors. - Abstract: We report a numerical analysis of the electronic transport in protein chain consisting of thirty-six standard amino acids. The protein chains studied have three-dimensional structure, which can present itself in three distinct conformations and the difference consist in the presence or absence of thirteen hydrogen-bondings. Our theoretical method uses an electronic tight-binding Hamiltonian model, appropriate to describe the protein segments modeled by the amino acid chain. We note that the presence and the permutations between weak bonds in the structure of proteins are directly related to the signing of the current–voltage. Furthermore, the electronic transport depends on the effect of temperature. In addition, we have found a semiconductor behave in the models investigated and it suggest a potential application in the development of novel biosensors for molecular diagnostics.

  4. Electronic transport on the spatial structure of the protein: Three-dimensional lattice model

    Energy Technology Data Exchange (ETDEWEB)

    Sarmento, R.G. [Departamento de Ciências Biológicas, Universidade Federal do Piauí, 64800-000 Floriano, PI (Brazil); Frazão, N.F. [Centro de Educação e Saúde, Universidade Federal de Campina Grande, 581750-000 Cuité, PB (Brazil); Macedo-Filho, A., E-mail: amfilho@gmail.com [Campus Prof. Antonio Geovanne Alves de Sousa, Universidade Estadual do Piauí, 64260-000 Piripiri, PI (Brazil)

    2017-01-30

    Highlights: • The electronic transport on the structure of the three-dimensional lattice model of the protein is studied. • The signing of the current–voltage is directly affected by permutations of the weak bonds in the structure. • Semiconductor behave of the proteins suggest a potential application in the development of novel biosensors. - Abstract: We report a numerical analysis of the electronic transport in protein chain consisting of thirty-six standard amino acids. The protein chains studied have three-dimensional structure, which can present itself in three distinct conformations and the difference consist in the presence or absence of thirteen hydrogen-bondings. Our theoretical method uses an electronic tight-binding Hamiltonian model, appropriate to describe the protein segments modeled by the amino acid chain. We note that the presence and the permutations between weak bonds in the structure of proteins are directly related to the signing of the current–voltage. Furthermore, the electronic transport depends on the effect of temperature. In addition, we have found a semiconductor behave in the models investigated and it suggest a potential application in the development of novel biosensors for molecular diagnostics.

  5. Business Ethics & Employee Turnover: CAFE Matrix

    OpenAIRE

    Sapovadia, Vrajlal; Patel, Sweta

    2013-01-01

    Abstract: Business ethics is in discussion for its importance universally, so is the employee turnover in business. Unethical practices are unwanted, so is the high employee turnover. Unethical practices and high employee turnover in business is ubiquitous. No consensus exists on defining ethics. Employee turnover is well defined, but there is no consensus on when employee turnover is disadvantageous for the company. The Golden Rule or ethic of reciprocity, a maxim states that either ...

  6. Histone turnover within nonproliferating cells

    International Nuclear Information System (INIS)

    Commerford, S.L.; Carsten, A.L.; Cronkite, E.P.

    1982-01-01

    The turnover of DNA and histones in the livers and brains of mice has been determined. These mice had been exposed to constant levels of tritiated water from conception until they were 8 months old. At this point, exposure to tritium was discontinued, and the tritium remaining in DNA and histones was measured at various intervals afterward. The half-lives calculated for these components (with 95% confidence limits given in parentheses) were 117 (85 to 188) days for liver histone, 318 (241 to 466) days for liver DNA, 159 (129 to 208) days for brain histone and 593 (376 to 1406) days for brain DNA. The difference between histone and DNA turnover is statistically significant for both tissues and indicates that histone turnover within tissues cannot be solely accounted for by cell turnover within the tissue but also must include histone turnover within living cells. The half-life of histone within cells is estimated to be 117 (88 to 178) days in liver and 223 (187 to 277) days in brain

  7. Uptake and degradation of circulating proteins by the liver.

    NARCIS (Netherlands)

    Buys, Carolus Henricus Cornelis Maria

    1976-01-01

    Circulating proteins, like all proteins in a living animal, are subject to continual replacement or turnover. This process implies both synthesis and degradation, This thesis deals with the degradative part of turnover of circulating proteins. ... Summary

  8. Probing Protein Structure and Folding in the Gas Phase by Electron Capture Dissociation

    Science.gov (United States)

    Schennach, Moritz; Breuker, Kathrin

    2015-07-01

    The established methods for the study of atom-detailed protein structure in the condensed phases, X-ray crystallography and nuclear magnetic resonance spectroscopy, have recently been complemented by new techniques by which nearly or fully desolvated protein structures are probed in gas-phase experiments. Electron capture dissociation (ECD) is unique among these as it provides residue-specific, although indirect, structural information. In this Critical Insight article, we discuss the development of ECD for the structural probing of gaseous protein ions, its potential, and limitations.

  9. Direct and Indirect Electron Emission from the Green Fluorescent Protein Chromophore

    Science.gov (United States)

    Toker, Y.; Rahbek, D. B.; Klærke, B.; Bochenkova, A. V.; Andersen, L. H.

    2012-09-01

    Photoelectron spectra of the deprotonated green fluorescent protein chromophore have been measured in the gas phase at several wavelengths within and beyond the S0-S1 photoabsorption band of the molecule. The vertical detachment energy (VDE) was determined to be 2.68±0.1eV. The data show that the first electronically excited state is bound in the Franck-Condon region, and that electron emission proceeds through an indirect (resonant) electron-emission channel within the corresponding absorption band.

  10. Metal-like transport in proteins: A new paradigm for biological electron transfer

    Science.gov (United States)

    Malvankar, Nikhil; Vargas, Madeline; Tuominen, Mark; Lovley, Derek

    2012-02-01

    Electron flow in biologically proteins generally occurs via tunneling or hopping and the possibility of electron delocalization has long been discounted. Here we report metal-like transport in protein nanofilaments, pili, of bacteria Geobacter sulfurreducens that challenges this long-standing belief [1]. Pili exhibit conductivities comparable to synthetic organic metallic nanostructures. The temperature, magnetic field and gate-voltage dependence of pili conductivity is akin to that of quasi-1D disordered metals, suggesting a metal-insulator transition. Magnetoresistance (MR) data provide evidence for quantum interference and weak localization at room temperature, as well as a temperature and field-induced crossover from negative to positive MR. Furthermore, pili can be doped with protons. Structural studies suggest the possibility of molecular pi stacking in pili, causing electron delocalization. Reducing the disorder increases the metallic nature of pili. These electronically functional proteins are a new class of electrically conductive biological proteins that can be used to generate future generation of inexpensive and environmentally-sustainable nanomaterials and nanolectronic devices such as transistors and supercapacitors. [1] Malvankar et al. Nature Nanotechnology, 6, 573-579 (2011)

  11. Job turnover and labor turnover : a taxonomy of employment dynamics

    NARCIS (Netherlands)

    Hassink, Wolter H.J.; Hamermesh, Daniel S.

    1994-01-01

    We present an organized set of stylized facts on the relations among flows of workers,changes in employment and changes in the numer of jobs at the firm level. Job turnover isusually measured by comparing stocks of employment in each firm at two points in time andadding up the absolute employment

  12. Single-particle electron microscopy in the study of membrane protein structure.

    Science.gov (United States)

    De Zorzi, Rita; Mi, Wei; Liao, Maofu; Walz, Thomas

    2016-02-01

    Single-particle electron microscopy (EM) provides the great advantage that protein structure can be studied without the need to grow crystals. However, due to technical limitations, this approach played only a minor role in the study of membrane protein structure. This situation has recently changed dramatically with the introduction of direct electron detection device cameras, which allow images of unprecedented quality to be recorded, also making software algorithms, such as three-dimensional classification and structure refinement, much more powerful. The enhanced potential of single-particle EM was impressively demonstrated by delivering the first long-sought atomic model of a member of the biomedically important transient receptor potential channel family. Structures of several more membrane proteins followed in short order. This review recounts the history of single-particle EM in the study of membrane proteins, describes the technical advances that now allow this approach to generate atomic models of membrane proteins and provides a brief overview of some of the membrane protein structures that have been studied by single-particle EM to date. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Nurse Knowledge, Work Environment, and Turnover in Highly Specialized Pediatric End-of-Life Care.

    Science.gov (United States)

    Lindley, Lisa C; Cozad, Melanie J

    2017-07-01

    To examine the relationship between nurse knowledge, work environment, and registered nurse (RN) turnover in perinatal hospice and palliative care organizations. Using nurse intellectual capital theory, a multivariate analysis was conducted with 2007 National Home and Hospice Care Survey data. Perinatal hospice and palliative care organizations experienced a 5% turnover rate. The professional experience of advanced practice nurses (APNs) was significantly related to turnover among RNs (β = -.032, P < .05). Compared to organizations with no APNs professional experience, clinical nurse specialists and nurse practitioners significantly reduced RN turnover by 3 percentage points. No other nurse knowledge or work environment variables were associated with RN turnover. Several of the control variables were also associated with RN turnover in the study; Organizations serving micropolitan (β = -.041, P < .05) and rural areas (β = -.037, P < .05) had lower RN turnover compared to urban areas. Organizations with a technology climate where nurses used electronic medical records had a higher turnover rate than those without (β = .036, P < .05). The findings revealed that advanced professional experience in the form of APNs was associated with reductions in RN turnover. This suggests that having a clinical nurse specialist or nurse practitioner on staff may provide knowledge and experience to other RNs, creating stability within the organization.

  14. Employee turnover: measuring the malady.

    Science.gov (United States)

    O'Connor, Stephen

    2002-01-01

    One measure of an organization's value to its employees is turnover. But how do you know if your employees are wondering if the grass is greener elsewhere? Scott Badler in his book What's So Funny about Looking for a Job? suggests a quick quiz to find out.

  15. Biochemical markers of bone turnover

    International Nuclear Information System (INIS)

    Kim, Deog Yoon

    1999-01-01

    Biochemical markers of bone turnover has received increasing attention over the past few years, because of the need for sensitivity and specific tool in the clinical investigation of osteoporosis. Bone markers should be unique to bone, reflect changes of bone less, and should be correlated with radiocalcium kinetics, histomorphometry, or changes in bone mass. The markers also should be useful in monitoring treatment efficacy. Although no bone marker has been established to meet all these criteria, currently osteocalcin and pyridinium crosslinks are the most efficient markers to assess the level of bone turnover in the menopausal and senile osteoporosis. Recently, N-terminal telopeptide (NTX), C-terminal telopeptide (CTX) and bone specific alkaline phosphatase are considered as new valid markers of bone turnover. Recent data suggest that CTX and free deoxypyridinoline could predict the subsequent risk of hip fracture of elderly women. Treatment of postmenopausal women with estrogen, calcitonin and bisphosphonates demonstrated rapid decrease of the levels of bone markers that correlated with the long-term increase of bone mass. Factors such as circadian rhythms, diet, age, sex, bone mass and renal function affect the results of biochemical markers and should be appropriately adjusted whenever possible. Each biochemical markers of bone turnover may have its own specific advantages and limitations. Recent advances in research will provide more sensitive and specific assays

  16. Whole-body protein turnover and energy expenditure in post-viral hepatocirrhotic patients. A study using multiple stable isotope tracers to estimate protein and energy requirements and the efficacy of a new diet therapy based on Chinese food

    International Nuclear Information System (INIS)

    Xia, Z.Q.; Dai, T.C.; Luo, W.

    1993-01-01

    L-[1- 13 C]-leucine and 15 N-glycine doubly-labelled tracer experiments revealed accelerated kinetics of leucine, glycine and whole-body protein in post-viral hepatocirrhotic patients. Together with the results of nitrogen balance measurement, the daily protein requirement of these patients was estimated to be higher than 1.2 g/kg/d. Doubly labelled water experiments and NaH 13 CO 3 experiments revealed that the freely living and basal energy expenditure of post-viral hepatocirrhotic patients was not different from that in normal subjects with comparable physical and mental activities. For those freely living in hospital, the energy requirements is estimated to be 150-160 kJ/kg/d. According to the above results, a therapeutic diet formulation based on Chinese food was designed for the patients which contained 1.5 g/kg/d of protein and 150-160 kJ/kg/d. 60-70% of the dietary protein was of vegetable origin, with a branched chain amino acid/aromatic amino acid ratio slightly but significantly higher than the common hospital diet. Patients with compensated post-viral hepatocirrhosis adapted to the diet rapidly. After two months' therapy, the negative nitrogen balance turned positive along with an increase of body weight and urinary creatinine, indicating and improvement of general nutritional status, probably with accumulation of muscle protein. The diet is relatively cheap, can be easily handled by the patients themselves, and hence is also applicable to outpatients. 54 refs, 8 tabs

  17. Antigen-driven T-cell turnover

    NARCIS (Netherlands)

    Fraser, Christophe; Ferguson, Neil M.; de Wolf, Frank; Ghani, Azra C.; Garnett, Geoff P.; Anderson, Roy M.

    2002-01-01

    A mathematical model is developed to characterize the distribution of cell turnover rates within a population of T lymphocytes. Previous models of T-cell dynamics have assumed a constant uniform turnover rate; here we consider turnover in a cell pool subject to clonal proliferation in response to

  18. How Teacher Turnover Harms Student Achievement

    Science.gov (United States)

    Ronfeldt, Matthew; Loeb, Susanna; Wyckoff, James

    2013-01-01

    Researchers and policymakers often assume that teacher turnover harms student achievement, though recent studies suggest this may not be the case. Using a unique identification strategy that employs school-by-grade level turnover and two classes of fixed-effects models, this study estimates the effects of teacher turnover on over 850,000 New York…

  19. Using Turnover as a Recruitment Strategy

    Science.gov (United States)

    Duncan, Sandra

    2009-01-01

    Teacher turnover is notoriously high in the field of early childhood education with an estimated 33% of staff exiting the workplace each year. Turnover is costly. Not only do high levels of turnover negatively impact children's growth and development, it also erodes the program's economic stability and wherewithal to provide effective operations…

  20. Measuring protein breakdown rate in individual proteins in vivo

    DEFF Research Database (Denmark)

    Holm, Lars; Kjaer, Michael

    2010-01-01

    To outline different approaches of how protein breakdown can be quantified and to present a new approach to determine the fractional breakdown rate of individual slow turnover proteins in vivo.......To outline different approaches of how protein breakdown can be quantified and to present a new approach to determine the fractional breakdown rate of individual slow turnover proteins in vivo....

  1. Cellular Assays for Ferredoxins: A Strategy for Understanding Electron Flow through Protein Carriers That Link Metabolic Pathways.

    Science.gov (United States)

    Atkinson, Joshua T; Campbell, Ian; Bennett, George N; Silberg, Jonathan J

    2016-12-27

    The ferredoxin (Fd) protein family is a structurally diverse group of iron-sulfur proteins that function as electron carriers, linking biochemical pathways important for energy transduction, nutrient assimilation, and primary metabolism. While considerable biochemical information about individual Fd protein electron carriers and their reactions has been acquired, we cannot yet anticipate the proportion of electrons shuttled between different Fd-partner proteins within cells using biochemical parameters that govern electron flow, such as holo-Fd concentration, midpoint potential (driving force), molecular interactions (affinity and kinetics), conformational changes (allostery), and off-pathway electron leakage (chemical oxidation). Herein, we describe functional and structural gaps in our Fd knowledge within the context of a sequence similarity network and phylogenetic tree, and we propose a strategy for improving our understanding of Fd sequence-function relationships. We suggest comparing the functions of divergent Fds within cells whose growth, or other measurable output, requires electron transfer between defined electron donor and acceptor proteins. By comparing Fd-mediated electron transfer with biochemical parameters that govern electron flow, we posit that models that anticipate energy flow across Fd interactomes can be built. This approach is expected to transform our ability to anticipate Fd control over electron flow in cellular settings, an obstacle to the construction of synthetic electron transfer pathways and rational optimization of existing energy-conserving pathways.

  2. Turnover and metabolism of phosphatidylglycerol acyl moieties in E. coli

    International Nuclear Information System (INIS)

    Cooper, C.L.; Rock, C.O.

    1987-01-01

    Fatty acids synthesized in mutants (plsB) blocked in de novo phospholipid biosynthesis were preferentially transferred to phosphatidylglycerol (PtdGro). The ratio of phospholipid species labeled with 32 P and [ 3 H]acetate in the absence of glycerol-3-P acyltransferase activity indicated that [ 3 H]acetate incorporation into PtdGro was due to fatty acid turnover. The magnitude of the turnover process was difficult to estimate due to a significant contraction of the acetyl-CoA pool following the inhibition of phospholipid synthesis. A possible connection between PtdGro turnover and protein acylation was investigated in an E. coli strain containing a lipoprotein expression vector. Cells were prelabeled with [ 3 H]acetate and lipoprotein expression was induced concomitant with the addition of exogenous [ 14 C]-palmitate. [ 14 C] Palmitate was assimilated into the l-position of phosphatidylethanolamine and transferred to the amino terminus of the lipoprotein. In contrast, the ester-linked lipoprotein fatty acids and PtdGro were not enriched in carbon-14 implying a metabolic relationship between these two pools. The data suggest that turnover of PtdGro acyl moieties is related to protein acylation, but a direct link between the two processes remains to be established

  3. Theoretical description of protein field effects on electronic excitations of biological chromophores

    International Nuclear Information System (INIS)

    Varsano, Daniele; Caprasecca, Stefano; Coccia, Emanuele

    2017-01-01

    Photoinitiated phenomena play a crucial role in many living organisms. Plants, algae, and bacteria absorb sunlight to perform photosynthesis, and convert water and carbon dioxide into molecular oxygen and carbohydrates, thus forming the basis for life on Earth. The vision of vertebrates is accomplished in the eye by a protein called rhodopsin, which upon photon absorption performs an ultrafast isomerisation of the retinal chromophore, triggering the signal cascade. Many other biological functions start with the photoexcitation of a protein-embedded pigment, followed by complex processes comprising, for example, electron or excitation energy transfer in photosynthetic complexes. The optical properties of chromophores in living systems are strongly dependent on the interaction with the surrounding environment (nearby protein residues, membrane, water), and the complexity of such interplay is, in most cases, at the origin of the functional diversity of the photoactive proteins. The specific interactions with the environment often lead to a significant shift of the chromophore excitation energies, compared with their absorption in solution or gas phase. The investigation of the optical response of chromophores is generally not straightforward, from both experimental and theoretical standpoints; this is due to the difficulty in understanding diverse behaviours and effects, occurring at different scales, with a single technique. In particular, the role played by ab initio calculations in assisting and guiding experiments, as well as in understanding the physics of photoactive proteins, is fundamental. At the same time, owing to the large size of the systems, more approximate strategies which take into account the environmental effects on the absorption spectra are also of paramount importance. Here we review the recent advances in the first-principle description of electronic and optical properties of biological chromophores embedded in a protein environment. We show

  4. Theoretical description of protein field effects on electronic excitations of biological chromophores

    Science.gov (United States)

    Varsano, Daniele; Caprasecca, Stefano; Coccia, Emanuele

    2017-01-01

    Photoinitiated phenomena play a crucial role in many living organisms. Plants, algae, and bacteria absorb sunlight to perform photosynthesis, and convert water and carbon dioxide into molecular oxygen and carbohydrates, thus forming the basis for life on Earth. The vision of vertebrates is accomplished in the eye by a protein called rhodopsin, which upon photon absorption performs an ultrafast isomerisation of the retinal chromophore, triggering the signal cascade. Many other biological functions start with the photoexcitation of a protein-embedded pigment, followed by complex processes comprising, for example, electron or excitation energy transfer in photosynthetic complexes. The optical properties of chromophores in living systems are strongly dependent on the interaction with the surrounding environment (nearby protein residues, membrane, water), and the complexity of such interplay is, in most cases, at the origin of the functional diversity of the photoactive proteins. The specific interactions with the environment often lead to a significant shift of the chromophore excitation energies, compared with their absorption in solution or gas phase. The investigation of the optical response of chromophores is generally not straightforward, from both experimental and theoretical standpoints; this is due to the difficulty in understanding diverse behaviours and effects, occurring at different scales, with a single technique. In particular, the role played by ab initio calculations in assisting and guiding experiments, as well as in understanding the physics of photoactive proteins, is fundamental. At the same time, owing to the large size of the systems, more approximate strategies which take into account the environmental effects on the absorption spectra are also of paramount importance. Here we review the recent advances in the first-principle description of electronic and optical properties of biological chromophores embedded in a protein environment. We show

  5. Ab Initio Calculations of the Electronic Structures and Biological Functions of Protein Molecules

    Science.gov (United States)

    Zheng, Haoping

    2003-04-01

    The self-consistent cluster-embedding (SCCE) calculation method reduces the computational effort from M3 to about M1 (M is the number of atoms in the system) with unchanged calculation precision. So the ab initio, all-electron calculation of the electronic structure and biological function of protein molecule becomes a reality, which will promote new proteomics considerably. The calculated results of two real protein molecules, the trypsin inhibitor from the seeds of squash Cucurbita maxima (CMTI-I, 436 atoms) and the Ascaris trypsin inhibitor (912 atoms, two three-dimensional structures), are presented. The reactive sites of the inhibitors are determined and explained. The precision of structure determination of inhibitors are tested theoretically.

  6. Short-Range Electron Transfer in Reduced Flavodoxin: Ultrafast Nonequilibrium Dynamics Coupled with Protein Fluctuations.

    Science.gov (United States)

    Kundu, Mainak; He, Ting-Fang; Lu, Yangyi; Wang, Lijuan; Zhong, Dongping

    2018-05-03

    Short-range electron transfer (ET) in proteins is an ultrafast process on the similar timescales as local protein-solvent fluctuations thus the two dynamics are coupled. Here, we use semiquinone flavodoxin and systematically characterized the photoinduced redox cycle with eleven mutations of different aromatic electron donors (tryptophan and tyrosine) and local residues to change redox properties. We observed the forward and backward ET dynamics in a few picoseconds, strongly following a stretched behavior resulting from a coupling between local environment relaxations and these ET processes. We further observed the hot vibrational-state formation through charge recombination and the subsequent cooling dynamics also in a few picoseconds. Combined with the ET studies in oxidized flavodoxin, these results coherently reveal the evolution of the ET dynamics from single to stretched exponential behaviors and thus elucidate critical timescales for the coupling. The observed hot vibration-state formation is robust and should be considered in all photoinduced back ET processes in flavoproteins.

  7. Nanoscale charge transfer in redox proteins and DNA: Towards biomolecular electronics

    International Nuclear Information System (INIS)

    Artés, Juan Manuel; López-Martínez, Montserrat; Díez-Pérez, Ismael; Sanz, Fausto; Gorostiza, Pau

    2014-01-01

    Understanding how charges move through and between biomolecules is a fundamental question that constitutes the basis for many biological processes. On the other hand, it has potential applications in the design of sensors based on biomolecules and single molecule devices. In this review we introduce the study of the electron transfer (ET) process in biomolecules, providing an overview of the fundamental theory behind it and the different experimental approaches. The ET in proteins is introduced by reviewing a complete electronic characterization of a redox protein (azurin) using electrochemical scanning tunnelling microscopy (ECSTM). The ET process in DNA is overviewed and results from different experimental approaches are discussed. Finally, future directions in the study of the ET process in biomolecules are introduced as well as examples of possible technological applications

  8. Quantum mechanical electronic structure calculation reveals orientation dependence of hydrogen bond energy in proteins.

    Science.gov (United States)

    Mondal, Abhisek; Datta, Saumen

    2017-06-01

    Hydrogen bond plays a unique role in governing macromolecular interactions with exquisite specificity. These interactions govern the fundamental biological processes like protein folding, enzymatic catalysis, molecular recognition. Despite extensive research work, till date there is no proper report available about the hydrogen bond's energy surface with respect to its geometric parameters, directly derived from proteins. Herein, we have deciphered the potential energy landscape of hydrogen bond directly from the macromolecular coordinates obtained from Protein Data Bank using quantum mechanical electronic structure calculations. The findings unravel the hydrogen bonding energies of proteins in parametric space. These data can be used to understand the energies of such directional interactions involved in biological molecules. Quantitative characterization has also been performed using Shannon entropic calculations for atoms participating in hydrogen bond. Collectively, our results constitute an improved way of understanding hydrogen bond energies in case of proteins and complement the knowledge-based potential. Proteins 2017; 85:1046-1055. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  9. 'Memory and molecular turnover,' 30 years after inception.

    Science.gov (United States)

    Meagher, Richard B

    2014-01-01

    In 1984 Sir Francis Crick hypothesized that memory is recorded in the brain as reversible modifications to DNA and protein, but acknowledged that most biomolecules turn over too rapidly to account for long-term memories. To accommodate this possible paradox he modeled an enzymatic mechanism to maintain modifications on hemi-modified multimeric symmetrical molecules. While studies on the turnover of chromatin modifications that may be involved in memory are in their infancy, an exploration of his model in the light of modern epigenetics produced somewhat surprising results. The molecular turnover rates for two classes of chromatin modifications believed to record and store durable memories were approximated from experiments using diverse approaches and were found to be remarkably short. The half-lives of DNA cytosine methylation and post-translationally modified nucleosomal histones are measured in hours and minutes, respectively, for a subset of sites on chromatin controlling gene expression. It appears likely that the turnover of DNA methylation in the brain and in neurons, in particular, is even more rapid than in other cell types and organs, perhaps accommodating neuronal plasticity, learning, and memory. The machinery responsible for the rapid turnover of DNA methylation and nucleosomal histone modifications is highly complex, partially redundant, and appears to act in a sequence specific manner. Molecular symmetry plays an important part in maintaining site-specific turnover, but its particular role in memory maintenance is unknown. Elucidating Crick's paradox, the contradiction between rapid molecular turnover of modified biomolecules and long-term memory storage, appears fundamental to understanding cognitive function and neurodegenerative disease.

  10. Shewanella oneidensis MR-1 chemotaxis proteins and electron-transport chain components essential for congregation near insoluble electron acceptors.

    Science.gov (United States)

    Harris, H Wayne; El-Naggar, Mohamed Y; Nealson, Kenneth H

    2012-12-01

    Shewanella oneidensis MR-1 cells utilize a behaviour response called electrokinesis to increase their speed in the vicinity of IEAs (insoluble electron acceptors), including manganese oxides, iron oxides and poised electrodes [Harris, El-Naggar, Bretschger, Ward, Romine, Obraztsova and Nealson (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 326-331]. However, it is not currently understood how bacteria remain in the vicinity of the IEA and accumulate both on the surface and in the surrounding medium. In the present paper, we provide results indicating that cells that have contacted the IEAs swim faster than those that have not recently made contact. In addition, fast-swimming cells exhibit an enhancement of swimming reversals leading to rapid non-random accumulation of cells on, and adjacent to, mineral particles. We call the observed accumulation near IEAs 'congregation'. Congregation is eliminated by the loss of a critical gene involved with EET (extracellular electron transport) (cymA, SO_4591) and is altered or eliminated in several deletion mutants of homologues of genes that are involved with chemotaxis or energy taxis in Escherichia coli. These genes include chemotactic signal transduction protein (cheA-3, SO_3207), methyl-accepting chemotaxis proteins with the Cache domain (mcp_cache, SO_2240) or the PAS (Per/Arnt/Sim) domain (mcp_pas, SO_1385). In the present paper, we report studies of S. oneidensis MR-1 that lend some insight into how microbes in this group can 'sense' the presence of a solid substrate such as a mineral surface, and maintain themselves in the vicinity of the mineral (i.e. via congregation), which may ultimately lead to attachment and biofilm formation.

  11. Analysis and control of employee turnover.

    Science.gov (United States)

    McConnell, Charles R

    2007-01-01

    Turnover is a relatively simple and easily described concept. However, considerable confusion often results when addressing turnover because of differences in how it is defined; that is, what is counted, how it is counted, and how the turnover rates are expressed. Turnover is also costly, although not enough attention is paid to its cost because so much of it is indirect, and thus, not readily visible. There are a variety of causes of turnover, some which can be corrected and some which cannot be avoided. Reducing or otherwise controlling turnover requires continuing management attention to its causes and constant recognition of what can and should be controlled and what cannot be controlled. Ongoing attention to turnover is an essential part of the department manager's role.

  12. Supervisory Turnover in Outpatient Substance Abuse Treatment

    Science.gov (United States)

    Knight, Danica K.; Broome, Kirk M.; Edwards, Jennifer R.; Flynn, Patrick M.

    2009-01-01

    Staff turnover is a significant issue within substance abuse treatment, with implications for service delivery and organizational health. This study examined factors associated with turnover among supervisors in outpatient substance abuse treatment. Turnover was conceptualized as being an individual response to organizational-level influences, and predictors represent aggregate program measures. Participants included 532 staff (including 467 counselors and 65 clinical/program directors) from 90 programs in four regions of the USA. Using logistic regression, analyses of structural factors indicated that programs affiliated with a parent organization and those providing more counseling hours to clients had higher turnover rates. When measures of job attitudes were included, only parent affiliation and collective appraisal of satisfaction were related to turnover. Subsequent analyses identified a trend toward increased supervisory turnover when satisfaction was low following the departure of a previous supervisor. These findings suggest that organizational-level factors can be influential in supervisory turnover. PMID:19949883

  13. Bone turnover in postmenopausal osteoporosis

    International Nuclear Information System (INIS)

    Thomsen, K.

    1988-02-01

    Studies of the bone turnover in postmenopausal osteoporosis are essential, because the associated bone loss is inevitably due to the relative increase of bone resorption compared with bone formation. Measurement of the bone mineral content (BMC) in normal adults is assessed - partly on the uncorrected values and partly in proportion to the body muscle mass. The whole body retention (WBR) method is presented. The WBR and alternative urinary excretion (UE) methods used by the author are characterised and compared with the retention methods described in the literature. The representativity of WBR and UE for the estimation of bone turnover in normal subjects and patients with various bone metabolic diseases is discussed. The conclusion is that the modified retention methods used by the author have a satisfactory precision and accuracy in relation to the clinical studies carried out. The author's modification of the WBR method for determination of bone turnover and the alternative urinary excretion method (UE) consists in continuous scanning in the whole body count, using a gamma camera, and with the collimator a short distance from the volunteer. This procedure has the advantage of restricting the radioactive dose to 2 mCi (72 MBa). This is smaller by a factor of 5-10 than the dose used to measure WBR with equally simple counting equipment: With the author's procedure, using frontal counting, WBR is systematically underestimated by about 4 per cent point compared to the purely dorsal count, but since the frontal position is the most comfortable, requires a smaller radioactive dose, and the error is systematic, it is the preferred counting procedure. Correction of WBR and UE for bone mineral content is in principle a new parameter of bone turnover, whose improved accuracy increases the validity of the retention determinations. 136 refs. (EG)

  14. Computational methods for constructing protein structure models from 3D electron microscopy maps.

    Science.gov (United States)

    Esquivel-Rodríguez, Juan; Kihara, Daisuke

    2013-10-01

    Protein structure determination by cryo-electron microscopy (EM) has made significant progress in the past decades. Resolutions of EM maps have been improving as evidenced by recently reported structures that are solved at high resolutions close to 3Å. Computational methods play a key role in interpreting EM data. Among many computational procedures applied to an EM map to obtain protein structure information, in this article we focus on reviewing computational methods that model protein three-dimensional (3D) structures from a 3D EM density map that is constructed from two-dimensional (2D) maps. The computational methods we discuss range from de novo methods, which identify structural elements in an EM map, to structure fitting methods, where known high resolution structures are fit into a low-resolution EM map. A list of available computational tools is also provided. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Difficulties in applying pure Kohn-Sham density functional theory electronic structure methods to protein molecules

    Science.gov (United States)

    Rudberg, Elias

    2012-02-01

    Self-consistency-based Kohn-Sham density functional theory (KS-DFT) electronic structure calculations with Gaussian basis sets are reported for a set of 17 protein-like molecules with geometries obtained from the Protein Data Bank. It is found that in many cases such calculations do not converge due to vanishing HOMO-LUMO gaps. A sequence of polyproline I helix molecules is also studied and it is found that self-consistency calculations using pure functionals fail to converge for helices longer than six proline units. Since the computed gap is strongly correlated to the fraction of Hartree-Fock exchange, test calculations using both pure and hybrid density functionals are reported. The tested methods include the pure functionals BLYP, PBE and LDA, as well as Hartree-Fock and the hybrid functionals BHandHLYP, B3LYP and PBE0. The effect of including solvent molecules in the calculations is studied, and it is found that the inclusion of explicit solvent molecules around the protein fragment in many cases gives a larger gap, but that convergence problems due to vanishing gaps still occur in calculations with pure functionals. In order to achieve converged results, some modeling of the charge distribution of solvent water molecules outside the electronic structure calculation is needed. Representing solvent water molecules by a simple point charge distribution is found to give non-vanishing HOMO-LUMO gaps for the tested protein-like systems also for pure functionals.

  16. Ultrafast quenching of tryptophan fluorescence in proteins: Interresidue and intrahelical electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Weihong; Li Tanping; Zhang Luyuan; Yang Yi; Kao Yating; Wang Lijuan [Department of Physics, Chemistry, and Biochemistry, Program of Biophysics, Chemical Physics, and Biochemistry, Ohio State University, Columbus, OH 43210 (United States); Zhong Dongping [Department of Physics, Chemistry, and Biochemistry, Program of Biophysics, Chemical Physics, and Biochemistry, Ohio State University, Columbus, OH 43210 (United States)], E-mail: dongping@mps.ohio-state.edu

    2008-06-23

    Quenching of tryptophan fluorescence in proteins has been critical to the understanding of protein dynamics and enzyme reactions using tryptophan as a molecular optical probe. We report here our systematic examinations of potential quenching residues with more than 40 proteins. With site-directed mutation, we placed tryptophan to desired positions or altered its neighboring residues to screen quenching groups among 20 amino acid residues and of peptide backbones. With femtosecond resolution, we observed the ultrafast quenching dynamics within 100 ps and identified two ultrafast quenching groups, the carbonyl- and sulfur-containing residues. The former is glutamine and glutamate residues and the later is disulfide bond and cysteine residue. The quenching by the peptide-bond carbonyl group as well as other potential residues mostly occurs in longer than 100 ps. These ultrafast quenching dynamics occur at van der Waals distances through intraprotein electron transfer with high directionality. Following optimal molecular orbital overlap, electron jumps from the benzene ring of the indole moiety in a vertical orientation to the LUMO of acceptor quenching residues. Molecular dynamics simulations were invoked to elucidate various correlations of quenching dynamics with separation distances, relative orientations, local fluctuations and reaction heterogeneity. These unique ultrafast quenching pairs, as recently found to extensively occur in high-resolution protein structures, may have significant biological implications.

  17. Difficulties in applying pure Kohn-Sham density functional theory electronic structure methods to protein molecules

    International Nuclear Information System (INIS)

    Rudberg, Elias

    2012-01-01

    Self-consistency-based Kohn-Sham density functional theory (KS-DFT) electronic structure calculations with Gaussian basis sets are reported for a set of 17 protein-like molecules with geometries obtained from the Protein Data Bank. It is found that in many cases such calculations do not converge due to vanishing HOMO-LUMO gaps. A sequence of polyproline I helix molecules is also studied and it is found that self-consistency calculations using pure functionals fail to converge for helices longer than six proline units. Since the computed gap is strongly correlated to the fraction of Hartree-Fock exchange, test calculations using both pure and hybrid density functionals are reported. The tested methods include the pure functionals BLYP, PBE and LDA, as well as Hartree-Fock and the hybrid functionals BHandHLYP, B3LYP and PBE0. The effect of including solvent molecules in the calculations is studied, and it is found that the inclusion of explicit solvent molecules around the protein fragment in many cases gives a larger gap, but that convergence problems due to vanishing gaps still occur in calculations with pure functionals. In order to achieve converged results, some modeling of the charge distribution of solvent water molecules outside the electronic structure calculation is needed. Representing solvent water molecules by a simple point charge distribution is found to give non-vanishing HOMO-LUMO gaps for the tested protein-like systems also for pure functionals. (fast track communication)

  18. Time-resolved protein nano-crystallography using an X-ray free-electron laser

    International Nuclear Information System (INIS)

    Aquila, Andrew; Hunter, Mark S.; Fromme, Petra; Fromme, Raimund; Grotjohann, Ingo; Doak, R. Bruce; Kirian, Richard A.; Schmidt, Kevin E.; Wang, Xiaoyu; Weierstall, Uwe; Spence, John C.H.; White, Thomas A.; Caleman, Carl; DePonte, Daniel P.; Fleckenstein, Holger; Gumprecht, Lars; Liang, Mengning; Martin, Andrew V.; Schulz, Joachim; Stellato, Francesco; Stern, Stephan; Barty, Anton; Andreasson, Jakob; Davidsson, Jan; Hajdu, Janos; Maia, Filipe R.N.C.; Seibert, M. Marvin; Timneanu, Nicusor; Arnlund, David; Johansson, Linda; Malmerberg, Erik; Neutze, Richard; Bajt, Sasa; Barthelmess, Miriam; Graafsma, Heinz; Hirsemann, Helmut; Wunderer, Cornelia; Barends, Thomas R.M.; Foucar, Lutz; Krasniqi, Faton; Lomb, Lukas; Rolles, Daniel; Schlichting, Ilme; Schmidt, Carlo; Bogan, Michael J.; Hampton, Christina Y.; Sierra, Raymond; Starodub, Dmitri; Bostedt, Christoph; Bozek, John D.; Messerschmidt, Marc; Williams, Garth J.; Bottin, Herve

    2012-01-01

    We demonstrate the use of an X-ray free electron laser synchronized with an optical pump laser to obtain X-ray diffraction snapshots from the photo-activated states of large membrane protein complexes in the form of nano-crystals flowing in a liquid jet. Light-induced changes of Photosystem I-Ferredoxin co-crystals were observed at time delays of 5 to 10 μs after excitation. The result correlates with the microsecond kinetics of electron transfer from Photosystem I to ferredoxin. The undocking process that follows the electron transfer leads to large rearrangements in the crystals that will terminally lead to the disintegration of the crystals. We describe the experimental setup and obtain the first time resolved femtosecond serial X-ray crystallography results from an irreversible photo-chemical reaction at the Linac Coherent Light Source. This technique opens the door to time-resolved structural studies of reaction dynamics in biological systems. (authors)

  19. Dual pathways for ribonucleic acid turnover in WI-38 but not in I-cell human diploid fibroblasts

    International Nuclear Information System (INIS)

    Sameshima, M.; Liebhaber, S.A.; Schlessinger, D.

    1981-01-01

    The turnover rates of /sup 3/H-labeled 18S ribosomal ribonucleic acid (RNA), 28S ribsomal RNA, transfer RNA, and total cytoplasmic RNA were very similar in growing WI-38 diploid fibroblasts. The rate of turnover was at least twofold greater when cell growth stopped due to cell confluence, /sup 3/H irradiation, or treatment with 20 mM NaN/sub 3/ or 2 mM NaF. In contrast, the rate of total /sup 3/H-protein turnover was the same in growing and nongrowing cells. Both RNA and protein turnovers were accelerated at least twofold in WI-38 cells deprived of serum, and this increase in turnover was inhibited by NH/sub 4/Cl. These results are consistent with two pathways for RNA turnover, oe of them being nonlysosomal and the other being lyosome mediated (NH/sub 4/Cl sensitive), as has been suggested for protein turnover. Also consistent with the notion of two pathways for RNA turnover were findings with I-cells, which are deficient for many lysosomal enzymes, and in which all RNA turnover were nonlysosomal (NH/sub 4/Cl resistant)

  20. KECENDERUNGAN KEPUASAN KERJA SEBAGAI TRIGGER TURNOVER

    Directory of Open Access Journals (Sweden)

    Raditya Adi Saputra

    2017-06-01

    Full Text Available The purpose of this study are: (1 To determine the effect of job satisfaction on turnover intention; (2 To determine the effect of work stress on turnover intention; (3 To determine the effect of compensation on turnover intention; (4 To determine the effect of organizational climate on turnover intention; and (5 To determine the stress of work, compensation, organizational climate and job satisfaction effect on turnover intention. The population in this study are employees of the Cooperative KOKAPURA AVIA totaling 180 people, while employees who have worked more than three years as many as 128 people. Samples were taken 97 people. The technique of collecting data using questionnaires. The analysis used is multiple regression analysis and path analysis using PLS 3.0 Smart program. Based on the results of the study concluded that: (1 Job satisfaction significantly influence employee turnover intention; (2 Work stress significantly influence employee turnover intention; (3 Compensation incentives significantly influence employee turnover intention; (4 organizational climate significantly influence employee turnover intention; and (5 Work stress, incentive compensation, organizational climate and job satisfaction simultaneously significantly influence employee turnover intention.

  1. NMR of proteins (4Fe-4S): structural properties and intramolecular electron transfer

    International Nuclear Information System (INIS)

    Huber, J.G.

    1996-01-01

    NMR started to be applied to Fe-S proteins in the seventies. Its use has recently been enlarged as the problems arising from the paramagnetic polymetallic clusters ware overcome. Applications to [4Fe-4S] are presented herein. The information derived thereof deepens the understanding of the redox properties of these proteins which play a central role in the metabolism of bacterial cells. The secondary structure elements and the overall folding of Chromatium vinosum ferredoxin (Cv Fd) in solution have been established by NMR. The unique features of this sequence have been shown to fold as an α helix at the C-terminus and as a loop between two cysteines ligand of one cluster: these two parts localize in close proximity from one another. The interaction between nuclear and electronic spins is a source of additional structural information for (4Fe-AS] proteins. The conformation of the cysteine-ligands, as revealed by the Fe-(S γ -C β -H β )Cys dihedral angles, is related to the chemical shifts of the signals associated with the protons of these residues. The longitudinal relaxation times of the protons depend on their distance to the cluster. A quantitative relationship has been established and used to show that the solution structure of the high-potential ferredoxin from Cv differs significantly from the crystal structure around Phe-48. Both parameters (chemical shifts and longitudinal relaxation times) give also insight into the electronic and magnetic properties of the [4Fe-4S] clusters. The rate of intramolecular electron transfer between the two [4FE-4S] clusters of ferredoxins has been measured by NMR. It is far slower in the case of Cv Fd than for shorter ferredoxins. The difference may be associated with changes in the magnetic and/or electronic properties of one cluster. The strong paramagnetism of the [4Fe-4S] clusters, which originally limited the applicability of NMR to proteins containing these cofactors, has been proven instrumental in affording new

  2. Collagen turnover in normal and degenerate human intervertebral discs as determined by the racemization of aspartic acid

    NARCIS (Netherlands)

    Sivan, S.-S.; Wachtel, E.; Tsitron, E.; Sakkee, N.; Ham, F. van der; Groot, J.de; Roberts, S.; Maroudas, A.

    2008-01-01

    Knowledge of rates of protein turnover is important for a quantitative understanding of tissue synthesis and catabolism. In this work, we have used the racemization of aspartic acid as a marker for the turnover of collagen obtained from healthy and pathological human intervertebral disc matrices. We

  3. An electronic channel switching-based aptasensor for ultrasensitive protein detection

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongbo; Wang Cui [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Wu Zaisheng, E-mail: wuzaisheng@163.com [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Lu Limin; Qiu Liping; Zhou Hui; Shen Guoli [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Yu Ruqin, E-mail: rqyu@hnu.edu.cn [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-01-03

    Highlights: Black-Right-Pointing-Pointer Target IgE is successfully designed to serve as a barrier to separate enzyme from its substrate. Black-Right-Pointing-Pointer This sensing platform of electronic channel switching-based aptasensor can be simply manipulated. Black-Right-Pointing-Pointer The stable hairpin structure of anti-IgE aptamer is utilized to detect target IgE. Black-Right-Pointing-Pointer The sensor is ultrasensitive sensitivity, excellent selectivity and small volume of sample. Black-Right-Pointing-Pointer It is a powerful platform to be further expanded to detect more kinds of proteins and even cells. - Abstract: Due to the ubiquity and essential of the proteins in all living organisms, the identification and quantification of disease-specific proteins are particularly important. Because the conformational change of aptamer upon its target or probe/target/probe sandwich often is the primary prerequisite for the design of an electrochemical aptameric assay system, it is extremely difficult to construct the electrochemical aptasensor for protein assay because the corresponding aptamers cannot often meet the requirement. To circumvent the obstacles mentioned, an electronic channel switching-based (ECS) aptasensor for ultrasensitive protein detection is developed. The essential achievement made is that an innovative sensing concept is proposed: the hairpin structure of aptamer is designed to pull electroactive species toward electrode surface and makes the surface-immobilized IgE serve as a barrier that separates enzyme from its substrate. It seemingly ensures that the ECS aptasensor exhibits most excellent assay features, such as, a detection limit of 4.44 Multiplication-Sign 10{sup -6} {mu}g mL{sup -1} (22.7 fM, 220 zmol in 10-{mu}L sample) (demonstrating a 5 orders of magnitude improvement in detection sensitivity compared with classical electronic aptasensors) and dynamic response range from 4.44 Multiplication-Sign 10{sup -6} to 4.44 Multiplication

  4. Coupling of kinesin ATP turnover to translocation and microtubule regulation: one engine, many machines.

    Science.gov (United States)

    Friel, Claire T; Howard, Jonathon

    2012-12-01

    The cycle of ATP turnover is integral to the action of motor proteins. Here we discuss how variation in this cycle leads to variation of function observed amongst members of the kinesin superfamily of microtubule associated motor proteins. Variation in the ATP turnover cycle among superfamily members can tune the characteristic kinesin motor to one of the range of microtubule-based functions performed by kinesins. The speed at which ATP is hydrolysed affects the speed of translocation. The ratio of rate constants of ATP turnover in relation to association and dissociation from the microtubule influence the processivity of translocation. Variation in the rate-limiting step of the cycle can reverse the way in which the motor domain interacts with the microtubule producing non-motile kinesins. Because the ATP turnover cycle is not fully understood for the majority of kinesins, much work remains to show how the kinesin engine functions in such a wide variety of molecular machines.

  5. Tritium turnover in succulent plants

    International Nuclear Information System (INIS)

    Krishnamoorthy, T.M.; Gogate, S.S.; Soman, S.D.

    1977-01-01

    Measurements of turnover rates for tissue free water tritium (TFWT) and tissue bound tritium (TBT) were carried out in three succulent plants, Opuntia sp., E. Trigona and E. Mili using tritiated water as tracer. The estimated half-times were 52, 57.5 and 80 days for TFWT and 212, 318 and 132 days for TBT in the stems of the above plants respectively. Opuntia sp. showed significant incorporation of TBT, 10% of TFWT on weight basis, while the other two plants showed lesser incorporation, 2-3% of TFWT. However, the leaves of E. Mili indicated the same level of fixation of TBT as the stem of Opuntia sp. (author)

  6. The effect of driving force on intramolecular electron transfer in proteins. Studies on single-site mutated azurins

    DEFF Research Database (Denmark)

    Farver, O; Skov, L K; van de Kamp, M

    1992-01-01

    -6972]. To further investigate the nature of this long-range electron transfer (LRET) proceeding within the protein matrix, we have now investigated it in two azurins where amino acids have been substituted by single-site mutation of the wild-type Pseudomonas aeruginosa azurin. In one mutated protein, a methionine...... the reorganization energy, lambda and electronic coupling factor, beta. The calculated values fit very well with a through-bond LRET mechanism....

  7. Potential application of electronic nose in processed animal proteins (PAP detection in feedstuffs

    Directory of Open Access Journals (Sweden)

    Dell'Orto V.

    2004-01-01

    Full Text Available Electronic nose and olfactometry techniques represent a modern analytical approach in food industry since they could potentially improve quality and safety of food processing. The aim of this study was to evaluate possible application of electronic nose in PA P detection and recognition in feed. For this purpose 6 reference feedstuffs (CRA-W / UE STRAT F E E D Project were used. The basis of the test samples was a compound feed for bovine fortified with processed animal proteins ( PAP consisting of meat and bone meal (MBM and/or fish meal at different concentrations. Each feed sample was tested in glass vials and the odour profile was determined by the ten MOS (metal oxide semi-conductor sensors of the electronic nose. Ten different descriptors, representing each ten sensors of electronic nose, were used to characterise the odour of each sample. In the present study, electronic nose was able to discriminate the blank sample from all other samples containing PA P ( M B M , fish meal or both. Samples containing either 0.5% of MBM or 5% of fish meal were identified, while samples containing a high fish meal content (5% associated with a low MBM content (0.5% were not discriminated from samples containing solely fish meal at that same high level (5%. This latter indicates that probably the high fish meal level, in samples containing both MBM and fish meal, tended to mask MBM odour. It was also evident that two odour descriptors were enough to explain 72.12% of total variability in odour pattern. In view of these results, it could be suggested that electronic nose and olfactometry techniques can provide an interesting approach for screening raw materials in feed industry, even though further studies using a wider set of samples are needed.

  8. Fitting multimeric protein complexes into electron microscopy maps using 3D Zernike descriptors.

    Science.gov (United States)

    Esquivel-Rodríguez, Juan; Kihara, Daisuke

    2012-06-14

    A novel computational method for fitting high-resolution structures of multiple proteins into a cryoelectron microscopy map is presented. The method named EMLZerD generates a pool of candidate multiple protein docking conformations of component proteins, which are later compared with a provided electron microscopy (EM) density map to select the ones that fit well into the EM map. The comparison of docking conformations and the EM map is performed using the 3D Zernike descriptor (3DZD), a mathematical series expansion of three-dimensional functions. The 3DZD provides a unified representation of the surface shape of multimeric protein complex models and EM maps, which allows a convenient, fast quantitative comparison of the three-dimensional structural data. Out of 19 multimeric complexes tested, near native complex structures with a root-mean-square deviation of less than 2.5 Å were obtained for 14 cases while medium range resolution structures with correct topology were computed for the additional 5 cases.

  9. The costs of turnover in nursing homes

    Science.gov (United States)

    Mukamel, Dana B.; Spector, William D.; Limcangco, Rhona; Wang, Ying; Feng, Zhanlian; Mor, Vincent

    2009-01-01

    Background Turnover rates in nursing homes have been persistently high for decades, ranging upwards of 100%. Objectives To estimate the net costs associated with turnover of direct care staff in nursing homes. Data and sample 902 nursing homes in California in 2005. Data included Medicaid cost reports, the Minimum Data Set (MDS), Medicare enrollment files, Census and Area Resource File (ARF). Research Design We estimated total cost functions, which included in addition to exogenous outputs and wages, the facility turnover rate. Instrumental variable (IV) limited information maximum likelihood techniques were used for estimation to deal with the endogeneity of turnover and costs. Results The cost functions exhibited the expected behavior, with initially increasing and then decreasing returns to scale. The ordinary least square estimate did not show a significant association between costs and turnover. The IV estimate of turnover costs was negative and significant (p=0.039). The marginal cost savings associated with a 10 percentage point increase in turnover for an average facility was $167,063 or 2.9% of annual total costs. Conclusion The net savings associated with turnover offer an explanation for the persistence of this phenomenon over the last decades, despite the many policy initiatives to reduce it. Future policy efforts need to recognize the complex relationship between turnover and costs. PMID:19648834

  10. The costs of turnover in nursing homes.

    Science.gov (United States)

    Mukamel, Dana B; Spector, William D; Limcangco, Rhona; Wang, Ying; Feng, Zhanlian; Mor, Vincent

    2009-10-01

    Turnover rates in nursing homes have been persistently high for decades, ranging upwards of 100%. To estimate the net costs associated with turnover of direct care staff in nursing homes. DATA AND SAMPLE: Nine hundred two nursing homes in California in 2005. Data included Medicaid cost reports, the Minimum Data Set, Medicare enrollment files, Census, and Area Resource File. We estimated total cost functions, which included in addition to exogenous outputs and wages, the facility turnover rate. Instrumental variable limited information maximum likelihood techniques were used for estimation to deal with the endogeneity of turnover and costs. The cost functions exhibited the expected behavior, with initially increasing and then decreasing returns to scale. The ordinary least square estimate did not show a significant association between costs and turnover. The instrumental variable estimate of turnover costs was negative and significant (P = 0.039). The marginal cost savings associated with a 10% point increase in turnover for an average facility was $167,063 or 2.9% of annual total costs. The net savings associated with turnover offer an explanation for the persistence of this phenomenon over the last decades, despite the many policy initiatives to reduce it. Future policy efforts need to recognize the complex relationship between turnover and costs.

  11. [New nurse turnover intention and influencing factors].

    Science.gov (United States)

    Han, Sang Sook; Sohn, In Soon; Kim, Nam Eun

    2009-12-01

    The study was done to identify turnover intention in new nurses according to characteristics of the nurses and other factors affecting turnover and to provide data to set up a strategy to reduce the turnover. Data were collected from 1,077 new nurses who had less than 12 months employment experience and worked in one of 188 hospitals. Eight research instruments were used. Data analysis was done using SPSS WIN 15.0 program. Several factors influence new nurse turnover intention. The average score for turnover intention was 2.12. The scores for subscales were self efficacy, 3.76, nursing performance, 3.90, job satisfaction, 2.09, organization commitment, 1.28, stress, 1.32, burnout, 2.82 and nursing organizational culture, 3.29. Turnover intention was related to self efficacy, nursing performance, job satisfaction, organization commitment, stress, burnout, nursing organizational culture, duration of in-class training, duration of on the job training, number of hospital beds, length of employment and duration of employment in current workplace. The predicting factors for turnover intention were burnout, stress, duration of employment in the current workplace, self efficacy and nursing performance. Those factors explained 51.6% of turnover intention. New nurse turnover intention can be reduced by mitigating the factors affecting this intention.

  12. Final technical brief / DOE grant DE-FG03-96 ER 62219. Computational study of electron tunneling in proteins

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey J. Regan

    1999-03-03

    Electron transfer (ET) processes in proteins are characterized by the motion of a single electron between centers of localization (such as the chlorophyll dimer in photosynthetic reaction centers). An electronic donor state D is created by the injection of an electron or by photo-excitation, after which the system makes a radiationless transition to an acceptor state A., resulting in the effective transfer of an electron over several angstroms. The experimental and theoretical understanding of the rate of this process has been the focus of much attention in physics, chemistry and biology.

  13. Comparing the photophysics of the two forms of the Orange Carotenoid Protein using 2D electronic spectroscopy

    Directory of Open Access Journals (Sweden)

    Mathies R.A.

    2013-03-01

    Full Text Available Broadband two-dimensional electronic spectroscopy is applied to investigate the photophysics of the photoactive orange carotenoid protein, which is involved in nonphotochemical quenching in cyanobacteria. Differences in dynamics between the light and dark forms arise from the different structure of the carotenoid in the protein pocket, with consequences for the biological role of the two forms.

  14. Sequential Proton Loss Electron Transfer in Deactivation of Iron(IV) Binding Protein by Tyrosine Based Food Components

    DEFF Research Database (Denmark)

    Tang, Ning; Skibsted, Leif Horsfelt

    2017-01-01

    The iron(IV) binding protein ferrylmyoglobin, MbFe(IV)=O, was found to be reduced by tyrosine based food components in aqueous solution through a sequential proton loss electron transfer reaction mechanism without binding to the protein as confirmed by isothermal titration calorimetry. Dopamine a...

  15. Employee Turnover among Full-time Public Librarians.

    Science.gov (United States)

    Rubin, Richard

    1989-01-01

    A study of employee turnover in 31 public libraries in the American Midwest established baseline turnover rates and examined the relationship of gender to turnover behavior. Findings showed that: turnover rates are low compared to other occupations; and turnover rates of males and females are similar. (28 references) (Author/MES)

  16. Electron paramagnetic resonance study of lipid and protein membrane components of erythrocytes oxidized with hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Mendanha, S.A.; Anjos, J.L.V.; Silva, A.H.M.; Alonso, A. [Instituto de Física, Universidade Federal de Goiás, Goiânia, GO (Brazil)

    2012-04-05

    Electron paramagnetic resonance (EPR) spectroscopy of spin labels was used to monitor membrane dynamic changes in erythrocytes subjected to oxidative stress with hydrogen peroxide (H{sub 2}O{sub 2}). The lipid spin label, 5-doxyl stearic acid, responded to dramatic reductions in membrane fluidity, which was correlated with increases in the protein content of the membrane. Membrane rigidity, associated with the binding of hemoglobin (Hb) to the erythrocyte membrane, was also indicated by a spin-labeled maleimide, 5-MSL, covalently bound to the sulfhydryl groups of membrane proteins. At 2% hematocrit, these alterations in membrane occurred at very low concentrations of H{sub 2}O{sub 2} (50 µM) after only 5 min of incubation at 37°C in azide phosphate buffer, pH 7.4. Lipid peroxidation, suggested by oxidative hemolysis and malondialdehyde formation, started at 300 µM H{sub 2}O{sub 2} (for incubation of 3 h), which is a concentration about six times higher than those detected with the probes. Ascorbic acid and α-tocopherol protected the membrane against lipoperoxidation, but did not prevent the binding of proteins to the erythrocyte membrane. Moreover, the antioxidant (+)-catechin, which also failed to prevent the cross-linking of cytoskeletal proteins with Hb, was very effective in protecting erythrocyte ghosts from lipid peroxidation induced by the Fenton reaction. This study also showed that EPR spectroscopy can be useful to assess the molecular dynamics of red blood cell membranes in both the lipid and protein domains and examine oxidation processes in a system that is so vulnerable to oxidation.

  17. Reversible assembly of protein-DNA nanostructures triggered by mediated electron transfer

    International Nuclear Information System (INIS)

    Vogt, Stephan; Wenderhold-Reeb, Sabine; Nöll, Gilbert

    2017-01-01

    Stable protein-DNA nanostructures have been assembled by reconstitution of the multi-ligand binding flavoprotein dodecin on top of flavin-terminated dsDNA monolayers on gold electrodes. These structures could be disassembled by electrochemical flavin reduction via mediated electron transfer. For this purpose a negative potential was applied at the Au working electrode in the presence of the redox mediator bis-(ammoniumethyl)-4,4′-bipyridinium tetrabromide. The stepwise formation of the flavin-terminated dsDNA monolayers as well as the binding and electrochemically triggered release of apododecin were monitored by surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) measurements. The assembly and disassembly of the protein-DNA nanostructures were fully reversible processes, which could be carried out multiple times at the same flavin-dsDNA modified surface. When a negative potential was applied in the absence of a redox mediator apododecin could not be released, i.e. direct electron transfer was not possible. As alternative redox mediators also methylene blue and phenosafranine were studied, but in the presence of these molecules apododecin was released without applying a potential, probably because the tricyclic aromatic compounds are able to replace the flavins at the binding sites.

  18. A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals

    Energy Technology Data Exchange (ETDEWEB)

    Nederlof, Igor; Genderen, Eric van; Li, Yao-Wang; Abrahams, Jan Pieter, E-mail: abrahams@chem.leidenuniv.nl [Leiden University, Einsteinweg 55, 2333 CC Leiden (Netherlands)

    2013-07-01

    An ultrasensitive Medipix2 detector allowed the collection of rotation electron-diffraction data from single three-dimensional protein nanocrystals for the first time. The data could be analysed using the standard X-ray crystallography programs MOSFLM and SCALA. When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e{sup −} Å{sup −2}), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins.

  19. A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals

    International Nuclear Information System (INIS)

    Nederlof, Igor; Genderen, Eric van; Li, Yao-Wang; Abrahams, Jan Pieter

    2013-01-01

    An ultrasensitive Medipix2 detector allowed the collection of rotation electron-diffraction data from single three-dimensional protein nanocrystals for the first time. The data could be analysed using the standard X-ray crystallography programs MOSFLM and SCALA. When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e − Å −2 ), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins

  20. Electron Microscopic, Genetic and Protein Expression Analyses of Helicobacter acinonychis Strains from a Bengal Tiger

    Science.gov (United States)

    Tegtmeyer, Nicole; Rivas Traverso, Francisco; Rohde, Manfred; Oyarzabal, Omar A.; Lehn, Norbert; Schneider-Brachert, Wulf; Ferrero, Richard L.; Fox, James G.; Berg, Douglas E.; Backert, Steffen

    2013-01-01

    Colonization by Helicobacter species is commonly noted in many mammals. These infections often remain unrecognized, but can cause severe health complications or more subtle host immune perturbations. The aim of this study was to isolate and characterize putative novel Helicobacter spp. from Bengal tigers in Thailand. Morphological investigation (Gram-staining and electron microscopy) and genetic studies (16SrRNA, 23SrRNA, flagellin, urease and prophage gene analyses, RAPD DNA fingerprinting and restriction fragment polymorphisms) as well as Western blotting were used to characterize the isolated Helicobacters. Electron microscopy revealed spiral-shaped bacteria, which varied in length (2.5–6 µm) and contained up to four monopolar sheathed flagella. The 16SrRNA, 23SrRNA, sequencing and protein expression analyses identified novel H. acinonychis isolates closely related to H. pylori. These Asian isolates are genetically very similar to H. acinonychis strains of other big cats (cheetahs, lions, lion-tiger hybrid and other tigers) from North America and Europe, which is remarkable in the context of the great genetic diversity among worldwide H. pylori strains. We also found by immunoblotting that the Bengal tiger isolates express UreaseA/B, flagellin, BabA adhesin, neutrophil-activating protein NapA, HtrA protease, γ-glutamyl-transpeptidase GGT, Slt lytic transglycosylase and two DNA transfer relaxase orthologs that were known from H. pylori, but not the cag pathogenicity island, nor CagA, VacA, SabA, DupA or OipA proteins. These results give fresh insights into H. acinonychis genetics and the expression of potential pathogenicity-associated factors and their possible pathophysiological relevance in related gastric infections. PMID:23940723

  1. Importance of dispersion and electron correlation in ab initio protein folding.

    Science.gov (United States)

    He, Xiao; Fusti-Molnar, Laszlo; Cui, Guanglei; Merz, Kenneth M

    2009-04-16

    Dispersion is well-known to be important in biological systems, but the effect of electron correlation in such systems remains unclear. In order to assess the relationship between the structure of a protein and its electron correlation energy, we employed both full system Hartree-Fock (HF) and second-order Møller-Plesset perturbation (MP2) calculations in conjunction with the Polarizable Continuum Model (PCM) on the native structures of two proteins and their corresponding computer-generated decoy sets. Because of the expense of the MP2 calculation, we have utilized the fragment molecular orbital method (FMO) in this study. We show that the sum of the Hartree-Fock (HF) energy and force field (LJ6)-derived dispersion energy (HF + LJ6) is well correlated with the energies obtained using second-order Møller-Plesset perturbation (MP2) theory. In one of the two examples studied, the correlation energy as well as the empirical dispersive energy term was able to discriminate between native and decoy structures. On the other hand, for the second protein we studied, neither the correlation energy nor dispersion energy showed discrimination capabilities; however, the ab initio MP2 energy and the HF+LJ6 both ranked the native structure correctly. Furthermore, when we randomly scrambled the Lennard-Jones parameters, the correlation between the MP2 energy and the sum of the HF energy and dispersive energy (HF+LJ6) significantly drops, which indicates that the choice of Lennard-Jones parameters is important.

  2. Electron microscopic, genetic and protein expression analyses of Helicobacter acinonychis strains from a Bengal tiger.

    Directory of Open Access Journals (Sweden)

    Nicole Tegtmeyer

    Full Text Available Colonization by Helicobacter species is commonly noted in many mammals. These infections often remain unrecognized, but can cause severe health complications or more subtle host immune perturbations. The aim of this study was to isolate and characterize putative novel Helicobacter spp. from Bengal tigers in Thailand. Morphological investigation (Gram-staining and electron microscopy and genetic studies (16SrRNA, 23SrRNA, flagellin, urease and prophage gene analyses, RAPD DNA fingerprinting and restriction fragment polymorphisms as well as Western blotting were used to characterize the isolated Helicobacters. Electron microscopy revealed spiral-shaped bacteria, which varied in length (2.5-6 µm and contained up to four monopolar sheathed flagella. The 16SrRNA, 23SrRNA, sequencing and protein expression analyses identified novel H. acinonychis isolates closely related to H. pylori. These Asian isolates are genetically very similar to H. acinonychis strains of other big cats (cheetahs, lions, lion-tiger hybrid and other tigers from North America and Europe, which is remarkable in the context of the great genetic diversity among worldwide H. pylori strains. We also found by immunoblotting that the Bengal tiger isolates express UreaseA/B, flagellin, BabA adhesin, neutrophil-activating protein NapA, HtrA protease, γ-glutamyl-transpeptidase GGT, Slt lytic transglycosylase and two DNA transfer relaxase orthologs that were known from H. pylori, but not the cag pathogenicity island, nor CagA, VacA, SabA, DupA or OipA proteins. These results give fresh insights into H. acinonychis genetics and the expression of potential pathogenicity-associated factors and their possible pathophysiological relevance in related gastric infections.

  3. Electron microscopic, genetic and protein expression analyses of Helicobacter acinonychis strains from a Bengal tiger.

    Science.gov (United States)

    Tegtmeyer, Nicole; Rivas Traverso, Francisco; Rohde, Manfred; Oyarzabal, Omar A; Lehn, Norbert; Schneider-Brachert, Wulf; Ferrero, Richard L; Fox, James G; Berg, Douglas E; Backert, Steffen

    2013-01-01

    Colonization by Helicobacter species is commonly noted in many mammals. These infections often remain unrecognized, but can cause severe health complications or more subtle host immune perturbations. The aim of this study was to isolate and characterize putative novel Helicobacter spp. from Bengal tigers in Thailand. Morphological investigation (Gram-staining and electron microscopy) and genetic studies (16SrRNA, 23SrRNA, flagellin, urease and prophage gene analyses, RAPD DNA fingerprinting and restriction fragment polymorphisms) as well as Western blotting were used to characterize the isolated Helicobacters. Electron microscopy revealed spiral-shaped bacteria, which varied in length (2.5-6 µm) and contained up to four monopolar sheathed flagella. The 16SrRNA, 23SrRNA, sequencing and protein expression analyses identified novel H. acinonychis isolates closely related to H. pylori. These Asian isolates are genetically very similar to H. acinonychis strains of other big cats (cheetahs, lions, lion-tiger hybrid and other tigers) from North America and Europe, which is remarkable in the context of the great genetic diversity among worldwide H. pylori strains. We also found by immunoblotting that the Bengal tiger isolates express UreaseA/B, flagellin, BabA adhesin, neutrophil-activating protein NapA, HtrA protease, γ-glutamyl-transpeptidase GGT, Slt lytic transglycosylase and two DNA transfer relaxase orthologs that were known from H. pylori, but not the cag pathogenicity island, nor CagA, VacA, SabA, DupA or OipA proteins. These results give fresh insights into H. acinonychis genetics and the expression of potential pathogenicity-associated factors and their possible pathophysiological relevance in related gastric infections.

  4. Serum biomarker profile associated with high bone turnover and BMD in postmenopausal women.

    Science.gov (United States)

    Bhattacharyya, Sudeepa; Siegel, Eric R; Achenbach, Sara J; Khosla, Sundeep; Suva, Larry J

    2008-07-01

    Early diagnosis of the onset of osteoporosis is key to the delivery of effective therapy. Biochemical markers of bone turnover provide a means of evaluating skeletal dynamics that complements static measurements of BMD by DXA. Conventional clinical measurements of bone turnover, primarily the estimation of collagen and its breakdown products in the blood or urine, lack both sensitivity and specificity as a reliable diagnostic tool. As a result, improved tests are needed to augment the use of BMD measurements as the principle diagnostic modality. In this study, the serum proteome of 58 postmenopausal women with high or low/normal bone turnover (training set) was analyzed by surface enhanced laser-desorption/ionization time-of-flight mass spectrometry, and a diagnostic fingerprint was identified using a variety of statistical and machine learning tools. The diagnostic fingerprint was validated in a separate distinct test set, consisting of serum samples from an additional 59 postmenopausal women obtained from the same Mayo cohort, with a gap of 2 yr. Specific protein peaks that discriminate between postmenopausal patients with high or low/normal bone turnover were identified and validated. Multiple supervised learning approaches were able to classify the level of bone turnover in the training set with 80% sensitivity and 100% specificity. In addition, the individual protein peaks were also significantly correlated with BMD measurements in these patients. Four of the major discriminatory peaks in the diagnostic profile were identified as fragments of interalpha-trypsin-inhibitor heavy chain H4 precursor (ITIH4), a plasma kallikrein-sensitive glycoprotein that is a component of the host response system. These data suggest that these serum protein fragments are the serum-borne reflection of the increased osteoclast activity, leading to the increased bone turnover that is associated with decreasing BMD and presumably an increased risk of fracture. In conjunction with the

  5. Employee Turnover: Evidence from a Case Study.

    Science.gov (United States)

    Borland, Jeff

    1997-01-01

    Patterns of employee turnover from a medium-sized law firm in Australia were examined in regard to theories of worker mobility (matching, sectoral shift, and incentive). Results support a role for matching effects, but personnel practices affect the timing of turnover. Matching and incentive-based theories do not explain the high rates of turnover…

  6. Predicting Employee Turnover from Communication Networks.

    Science.gov (United States)

    Feeley, Thomas H.; Barnett, George A.

    1997-01-01

    Investigates three social network models of employee turnover: a structural equivalence model, a social influence model, and an erosion model. Administers a communication network questionnaire to all 170 employees of an organization. Finds support for all three models of turnover, with the erosion model explaining more of the variance than do the…

  7. Employee Turnover: An Empirical and Methodological Assessment.

    Science.gov (United States)

    Muchinsky, Paul M.; Tuttle, Mark L.

    1979-01-01

    Reviews research on the prediction of employee turnover. Groups predictor variables into five general categories: attitudinal (job satisfaction), biodata, work-related, personal, and test-score predictors. Consistent relationships between common predictor variables and turnover were found for four categories. Eight methodological problems/issues…

  8. University Lecturers' Professional Empowerment and Turnover in ...

    African Journals Online (AJOL)

    Many universities in Uganda are grappling with the challenge of academic staff turnover. While research conducted so far has established different factors explaining the problems of turnover, many of which have been addressed, this challenge has not been resolved. Hitherto, attention has not been paid to whether ...

  9. Relationship between Job Satisfaction and Turnover Intention ...

    African Journals Online (AJOL)

    This study explores the association between job satisfaction and turnover intentions among lecturers in three public universities in Tanzania. It had three objectives: (1) to determine the level of perceived job satisfaction among lecturers; (2) to determine the association between job satisfaction and turnover intention; and (3) ...

  10. Global turnover of histone post-translational modifications and variants in human cells

    Directory of Open Access Journals (Sweden)

    Zee Barry M

    2010-12-01

    Full Text Available Abstract Background Post-translational modifications (PTMs on the N-terminal tails of histones and histone variants regulate distinct transcriptional states and nuclear events. Whereas the functional effects of specific PTMs are the current subject of intense investigation, most studies characterize histone PTMs/variants in a non-temporal fashion and very few studies have reported kinetic information about these histone forms. Previous studies have used radiolabeling, fluorescence microscopy and chromatin immunoprecipitation to determine rates of histone turnover, and have found interesting correlations between increased turnover and increased gene expression. Therefore, histone turnover is an understudied yet potentially important parameter that may contribute to epigenetic regulation. Understanding turnover in the context of histone modifications and sequence variants could provide valuable additional insight into the function of histone replacement. Results In this study, we measured the metabolic rate of labeled isotope incorporation into the histone proteins of HeLa cells by combining stable isotope labeling of amino acids in cell culture (SILAC pulse experiments with quantitative mass spectrometry-based proteomics. In general, we found that most core histones have similar turnover rates, with the exception of the H2A variants, which exhibit a wider range of rates, potentially consistent with their epigenetic function. In addition, acetylated histones have a significantly faster turnover compared with general histone protein and methylated histones, although these rates vary considerably, depending on the site and overall degree of methylation. Histones containing transcriptionally active marks have been consistently found to have faster turnover rates than histones containing silent marks. Interestingly, the presence of both active and silent marks on the same peptide resulted in a slower turnover rate than either mark alone on that same

  11. Communication: Microsecond dynamics of the protein and water affect electron transfer in a bacterial bc1 complex

    Science.gov (United States)

    Martin, Daniel R.; Matyushov, Dmitry V.

    2015-04-01

    Cross-membrane electron transport between cofactors localized in proteins of mitochondrial respiration and bacterial photosynthesis is the source of all biological energy. The statistics and dynamics of nuclear fluctuations in these protein/membrane/water heterogeneous systems are critical for their energetic efficiency. The results of 13 μs of atomistic molecular dynamics simulations of the membrane-bound bc1 bacterial complex are analyzed here. The reaction is affected by a broad spectrum of nuclear modes, with the slowest dynamics in the range of time-scales ˜0.1-1.6 μs contributing half of the reaction reorganization energy. Two reorganization energies are required to describe protein electron transfer due to dynamical arrest of protein conformations on the observation window. This mechanistic distinction allows significant lowering of activation barriers for reactions in proteins.

  12. Communication: Microsecond dynamics of the protein and water affect electron transfer in a bacterial bc1 complex

    International Nuclear Information System (INIS)

    Martin, Daniel R.; Matyushov, Dmitry V.

    2015-01-01

    Cross-membrane electron transport between cofactors localized in proteins of mitochondrial respiration and bacterial photosynthesis is the source of all biological energy. The statistics and dynamics of nuclear fluctuations in these protein/membrane/water heterogeneous systems are critical for their energetic efficiency. The results of 13 μs of atomistic molecular dynamics simulations of the membrane-bound bc 1 bacterial complex are analyzed here. The reaction is affected by a broad spectrum of nuclear modes, with the slowest dynamics in the range of time-scales ∼0.1-1.6 μs contributing half of the reaction reorganization energy. Two reorganization energies are required to describe protein electron transfer due to dynamical arrest of protein conformations on the observation window. This mechanistic distinction allows significant lowering of activation barriers for reactions in proteins

  13. Communication: Microsecond dynamics of the protein and water affect electron transfer in a bacterial bc{sub 1} complex

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Daniel R.; Matyushov, Dmitry V., E-mail: dmitrym@asu.edu [Department of Physics and Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287 (United States)

    2015-04-28

    Cross-membrane electron transport between cofactors localized in proteins of mitochondrial respiration and bacterial photosynthesis is the source of all biological energy. The statistics and dynamics of nuclear fluctuations in these protein/membrane/water heterogeneous systems are critical for their energetic efficiency. The results of 13 μs of atomistic molecular dynamics simulations of the membrane-bound bc{sub 1} bacterial complex are analyzed here. The reaction is affected by a broad spectrum of nuclear modes, with the slowest dynamics in the range of time-scales ∼0.1-1.6 μs contributing half of the reaction reorganization energy. Two reorganization energies are required to describe protein electron transfer due to dynamical arrest of protein conformations on the observation window. This mechanistic distinction allows significant lowering of activation barriers for reactions in proteins.

  14. Chronic Teacher Turnover in Urban Elementary Schools

    Directory of Open Access Journals (Sweden)

    Kacey Guin

    2004-08-01

    Full Text Available This study examines the characteristics of elementary schools that experience chronic teacher turnover and the impacts of turnover on a school’s working climate and ability to effectively function. Based on evidence from staff climate surveys and case studies, it is clear that high turnover schools face significant organizational challenges. Schools with high teacher turnover rates have difficulty planning and implementing a coherent curriculum and sustaining positive working relationships among teachers. The reality of these organizational challenges is particularly alarming, given that high turnover schools are more likely to serve low-income and minority students. The negative relationship between teacher turnover and school functioning, and the fact that turbulent schools are disproportionately likely to serve lowincome and minority students have important implications for both district and school-level policies. Specifically: Teacher turnover rates are one indicator of school health, which school districts should consider when focusing on school improvements. Districts need to begin by developing the means to identify individual schools that experience high levels of teacher turnover. Current district policies in implementing professional development for teachers in low-performing schools are inefficient when teachers do not remain in the schools in which they are trained. In order for low-performing schools to improve, districts need to consider providing incentive programs so that high quality teachers apply for, and remain in, these schools. Future research is needed to address the causal link between turnover, organizational functioning and student outcomes. Additionally, there is a need for research examining district policies that may facilitate teacher turnover within a district, including how districts place and transfer teachers, as well as how teachers’ salaries are budgeted.

  15. Identification of a multi-protein reductive dehalogenase complex in Dehalococcoides mccartyi strain CBDB1 suggests a protein-dependent respiratory electron transport chain obviating quinone involvement

    DEFF Research Database (Denmark)

    Kublik, Anja; Deobald, Darja; Hartwig, Stefanie

    2016-01-01

    electrophoresis (BN-PAGE), gel filtration and ultrafiltration an active dehalogenating protein complex with a molecular mass of 250–270 kDa was identified. The active subunit of reductive dehalogenase (RdhA) colocalised with a complex iron-sulfur molybdoenzyme (CISM) subunit (CbdbA195) and an iron-sulfur cluster...... of the dehalogenating complex prior to membrane solubilisation. Taken together, the identification of the respiratory dehalogenase protein complex and the absence of indications for quinone participation in the respiration suggest a quinone-independent protein-based respiratory electron transfer chain in D. mccartyi....

  16. Determination of anisotropy constants of protein encapsulated iron oxide nanoparticles by electron magnetic resonance

    International Nuclear Information System (INIS)

    Li Hongyan; Klem, Michael T.; Sebby, Karl B.; Singel, David J.; Young, Mark; Douglas, Trevor; Idzerda, Yves U.

    2009-01-01

    Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19 nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1 T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles' easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size

  17. Determination of anisotropy constants of protein encapsulated iron oxide nanoparticles by electron magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongyan [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Klem, Michael T.; Sebby, Karl B.; Singel, David J. [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Young, Mark [Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Douglas, Trevor [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Idzerda, Yves U. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States)], E-mail: Idzerda@montana.edu

    2009-02-15

    Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19 nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1 T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles' easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size.

  18. Temperature dependence of Q-band electron paramagnetic resonance spectra of nitrosyl heme proteins

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Marco; Wajnberg, Eliane; Bemski, George

    1997-11-01

    The Q-band (35 GHz) electron paramagnetic resonance (EPR) spectra of nitrosyl hemoglobin (Hb N O) and nitrosyl myoglobin (Mb NO) were studied as a function of temperature between 19 K and 200 K. The spectra of both heme proteins show classes of variations as a function of temperature. The first one has previously been associated with the existence of two paramagnetic species, one with rhombic and the other with axial symmetry. The second one manifests itself in changes in the g-factors and linewidths of each species. These changes are correlated with the conformational substates model and associate the variations of g-values with changes in the angle of the N(his)-Fe-N (NO) bond in the rhombic species and with changes in the distance between Fe and N of the proximal (F8) histidine in the axial species. (author) 24 refs., 6 figs.

  19. AN ECONOMETRIC APPROACH ABOUT VOLUNTARY TURNOVER

    Directory of Open Access Journals (Sweden)

    ADALET EREN

    2013-06-01

    Full Text Available This study analyzes individual and organizational variables that affect voluntary turnover are determined in the special defence and security companies. A binomial logistic regression model is used to estimate voluntary turnover.  Binomial Logistic regression, reliability test (scale alfa, variance (ANOVA, Post-hoc/Tukey, correlation (Pearson and other basic statistical techniques  with SPSS 13 statistical packet program was used in the analyzes ofresearch data. The study finds that; situation of suppose working, number of child, number of death child, number of home’s moving, support of rent, total monthly income of household, last work’s region, number of prizes, affect voluntary turnover are determined.

  20. The validation of the turnover intention scale

    Directory of Open Access Journals (Sweden)

    Chris F.C. Bothma

    2013-04-01

    Full Text Available Orientation: Turnover intention as a construct has attracted increased research attention in the recent past, but there are seemingly not many valid and reliable scales around to measure turnover intention. Research purpose: This study focused on the validation of a shortened, six-item version of the turnover intention scale (TIS-6. Motivation for the study: The research question of whether the TIS-6 is a reliable and a valid scale for measuring turnover intention and for predicting actual turnover was addressed in this study. Research design, approach and method: The study was based on a census-based sample (n= 2429 of employees in an information, communication and technology (ICT sector company (N= 23 134 where the TIS-6 was used as one of the criterion variables. The leavers (those who left the company in this sample were compared with the stayers (those who remained in the employ of the company in this sample in respect of different variables used in the study. Main findings: It was established that the TIS-6 could measure turnover intentions reliably (α= 0.80. The TIS-6 could significantly distinguish between leavers and stayers (actual turnover, thereby confirming its criterion-predictive validity. The scale also established statistically significant differences between leavers and stayers in respect of a number of the remaining theoretical variables used in the study, thereby also confirming its differential validity. These comparisons were conducted for both the 4-month and the 4-year period after the survey was conducted. Practical/managerial implications: Turnover intention is related to a number of variables in the study which necessitates a reappraisal and a reconceptualisation of existing turnover intention models. Contribution/value-add: The TIS-6 can be used as a reliable and valid scale to assess turnover intentions and can therefore be used in research to validly and reliably assess turnover intentions or to

  1. Specific, sensitive, high-resolution detection of protein molecules in eukaryotic cells using metal-tagging transmission electron microscopy

    Science.gov (United States)

    Risco, Cristina; Sanmartín-Conesa, Eva; Tzeng, Wen-Pin; Frey, Teryl K.; Seybold, Volker; de Groot, Raoul J.

    2012-01-01

    Summary More than any other methodology, transmission electron microscopy (TEM) has contributed to our understanding of the architecture and organization of cells. With current detection limits approaching atomic resolution, it will ultimately become possible to ultrastructurally image intracellular macromolecular assemblies in situ. Presently, however, methods to unambiguously identify proteins within the crowded environment of the cell’s interior are lagging behind. We describe a novel approach, metal-tagging TEM (METTEM) that allows detection of intracellular proteins in mammalian cells with high specificity, exceptional sensitivity and at molecular scale resolution. In live cells treated with gold salts, proteins bearing a small metal-binding tag will form 1-nm gold nanoclusters, readily detectable in electron micrographs. The applicability and strength of METTEM is demonstrated by a study of Rubella virus replicase and capsid proteins, which revealed virus-induced cell structures not seen before. PMID:22579245

  2. Incorporating deep learning with convolutional neural networks and position specific scoring matrices for identifying electron transport proteins.

    Science.gov (United States)

    Le, Nguyen-Quoc-Khanh; Ho, Quang-Thai; Ou, Yu-Yen

    2017-09-05

    In several years, deep learning is a modern machine learning technique using in a variety of fields with state-of-the-art performance. Therefore, utilization of deep learning to enhance performance is also an important solution for current bioinformatics field. In this study, we try to use deep learning via convolutional neural networks and position specific scoring matrices to identify electron transport proteins, which is an important molecular function in transmembrane proteins. Our deep learning method can approach a precise model for identifying of electron transport proteins with achieved sensitivity of 80.3%, specificity of 94.4%, and accuracy of 92.3%, with MCC of 0.71 for independent dataset. The proposed technique can serve as a powerful tool for identifying electron transport proteins and can help biologists understand the function of the electron transport proteins. Moreover, this study provides a basis for further research that can enrich a field of applying deep learning in bioinformatics. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. The longitudinal study of turnover and the cost of turnover in emergency medical services.

    Science.gov (United States)

    Patterson, P Daniel; Jones, Cheryl B; Hubble, Michael W; Carr, Matthew; Weaver, Matthew D; Engberg, John; Castle, Nicholas

    2010-01-01

    Few studies have examined employee turnover and associated costs in emergency medical services (EMS). To quantify the mean annual rate of turnover, total median cost of turnover, and median cost per termination in a diverse sample of EMS agencies. A convenience sample of 40 EMS agencies was followed over a six-month period. Internet, telephone, and on-site data-collection methods were used to document terminations, new hires, open positions, and costs associated with turnover. The cost associated with turnover was calculated based on a modified version of the Nursing Turnover Cost Calculation Methodology (NTCCM). The NTCCM identified direct and indirect costs through a series of questions that agency administrators answered monthly during the study period. A previously tested measure of turnover to calculate the mean annual rate of turnover was used. All calculations were weighted by the size of the EMS agency roster. The mean annual rate of turnover, total median cost of turnover, and median cost per termination were determined for three categories of agency staff mix: all-paid staff, mix of paid and volunteer (mixed) staff, and all-volunteer staff. The overall weighted mean annual rate of turnover was 10.7%. This rate varied slightly across agency staffing mix (all-paid = 10.2%, mixed = 12.3%, all-volunteer = 12.4%). Among agencies that experienced turnover (n = 25), the weighted median cost of turnover was $71,613.75, which varied across agency staffing mix (all-paid = $86,452.05, mixed = $9,766.65, and all-volunteer = $0). The weighted median cost per termination was $6,871.51 and varied across agency staffing mix (all-paid = $7,161.38, mixed = $1,409.64, and all-volunteer = $0). Annual rates of turnover and costs associated with turnover vary widely across types of EMS agencies. The study's mean annual rate of turnover was lower than expected based on information appearing in the news media and EMS trade magazines. Findings provide estimates of two key

  4. The longitudinal study of turnover and the cost of turnover in EMS

    Science.gov (United States)

    Patterson, P. Daniel; Jones, Cheryl B.; Hubble, Michael W.; Carr, Matthew; Weaver, Matthew D.; Engberg, John; Castle, Nicholas

    2010-01-01

    Purpose Few studies have examined employee turnover and associated costs in emergency medical services (EMS). The purpose of this study was to quantify the mean annual rate of turnover, total median cost of turnover, and median cost per termination in a diverse sample of EMS agencies. Methods A convenience sample of 40 EMS agencies was followed over a 6 month period. Internet, telephone, and on-site data collection methods were used to document terminations, new hires, open positions, and costs associated with turnover. The cost associated with turnover was calculated based on a modified version of the Nursing Turnover Cost Calculation Methodology (NTCCM). The NTCCM identified direct and indirect costs through a series of questions that agency administrators answered monthly during the study period. A previously tested measure of turnover to calculate the mean annual rate of turnover was used. All calculations were weighted by the size of the EMS agency roster. The mean annual rate of turnover, total median cost of turnover, and median cost per termination were determined for 3 categories of agency staff mix: all paid staff, mix of paid and volunteer (mixed), and all-volunteer. Results The overall weighted mean annual rate of turnover was 10.7%. This rate varied slightly across agency staffing mix: (all-paid=10.2%, mixed=12.3%, all-volunteer=12.4%). Among agencies that experienced turnover (n=25), the weighted median cost of turnover was $71,613.75, which varied across agency staffing mix: (all-paid=$86,452.05, mixed=$9,766.65, and all-volunteer=$0). The weighted median cost per termination was $6,871.51 and varied across agency staffing mix: (all-paid=$7,161.38, mixed=$1,409.64, and all-volunteer=$0). Conclusions Annual rates of turnover and costs associated with turnover vary widely across types of EMS agencies. The study’s mean annual rate of turnover was lower than expected based on information appearing in the news media and EMS trade magazines. Findings

  5. Elucidating the design principles of photosynthetic electron-transfer proteins by site-directed spin labeling EPR spectroscopy.

    Science.gov (United States)

    Ishara Silva, K; Jagannathan, Bharat; Golbeck, John H; Lakshmi, K V

    2016-05-01

    Site-directed spin labeling electron paramagnetic resonance (SDSL EPR) spectroscopy is a powerful tool to determine solvent accessibility, side-chain dynamics, and inter-spin distances at specific sites in biological macromolecules. This information provides important insights into the structure and dynamics of both natural and designed proteins and protein complexes. Here, we discuss the application of SDSL EPR spectroscopy in probing the charge-transfer cofactors in photosynthetic reaction centers (RC) such as photosystem I (PSI) and the bacterial reaction center (bRC). Photosynthetic RCs are large multi-subunit proteins (molecular weight≥300 kDa) that perform light-driven charge transfer reactions in photosynthesis. These reactions are carried out by cofactors that are paramagnetic in one of their oxidation states. This renders the RCs unsuitable for conventional nuclear magnetic resonance spectroscopy investigations. However, the presence of native paramagnetic centers and the ability to covalently attach site-directed spin labels in RCs makes them ideally suited for the application of SDSL EPR spectroscopy. The paramagnetic centers serve as probes of conformational changes, dynamics of subunit assembly, and the relative motion of cofactors and peptide subunits. In this review, we describe novel applications of SDSL EPR spectroscopy for elucidating the effects of local structure and dynamics on the electron-transfer cofactors of photosynthetic RCs. Because SDSL EPR Spectroscopy is uniquely suited to provide dynamic information on protein motion, it is a particularly useful method in the engineering and analysis of designed electron transfer proteins and protein networks. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson. Copyright © 2016. Published by Elsevier B.V.

  6. Small angle X-ray scattering and transmission electron microscopy study of the Lactobacillus brevis S-layer protein

    Energy Technology Data Exchange (ETDEWEB)

    Jaeaeskelaeinen, Pentti [Department of Biomedical Engineering and Computational Science, PO Box 2200, FI-02015 Aalto University School of Science and Technology (Finland); Engelhardt, Peter [Haartman Institute, Department of Pathology, PO Box 21, FIN-00014 University of Helsinki (Finland); Hynoenen, Ulla; Palva, Airi [Department of Basic Veterinary Sciences, Division of Microbiology, FIN-00014 University of Helsinki (Finland); Torkkeli, Mika; Serimaa, Ritva, E-mail: ritva.serimaa@helsinki.f [Department of Physics, POB 64, 00014 University of Helsinki (Finland)

    2010-10-01

    The structure of self-assembly domain containing recombinant truncation mutants of Lactobacillus brevis surface layer protein SlpA in aqueous solution was studied using small-angle X-ray scattering and transmission electron microscopy. The proteins were found out to interact with each other forming stable globular oligomers of about 10 monomers. The maximum diameter of the oligomers varied between 75 A and 435 A.

  7. Crystallization and preliminary electron diffraction study to 3. 7 A of DNA helix-destabilizing protein gp32*I

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, W; Hosoda, J

    1978-01-01

    A two-dimensionally large and thin crystal has been obtained from gp32*I, a proteolytically digested product of a DNA helix-destabilizing protein coded by gene 32 in bacteriophage T4. High-resolution electron diffraction patterns (approx. 3.7 A) are recorded from both unstained and stained protein crystals embedded in glucose. The crystal is of orthorhombic space group with a = 62.9 A and b = 47.3 A.

  8. Organisational Commitment, Job Satisfaction and Turnover ...

    African Journals Online (AJOL)

    This study investigated organisational commitment, job satisfaction and turnover intentions among records management personnel in Ondo State Civil Service, Akure, Nigeria. Simple random sampling technique was used to draw 240 subjects from a population size of 275 records management personnel.

  9. Rethinking Teacher Turnover: Longitudinal Measures of Instability in Schools

    Science.gov (United States)

    Holme, Jennifer Jellison; Jabbar, Huriya; Germain, Emily; Dinning, John

    2018-01-01

    While there is a robust literature examining the patterns and causes of teacher turnover, few articles to date have critically examined the measures of turnover used in these studies. Yet, an assessment of the way turnover is measured is important, as the measures become the means by which the "problem" of turnover becomes defined and…

  10. Gold nanoparticle assisted assembly of a heme protein for enhancement of long-range interfacial electron transfer

    DEFF Research Database (Denmark)

    Jensen, Palle Skovhus; Chi, Qijin; Grumsen, Flemming Bjerg

    2007-01-01

    and characterization of water-soluble gold nanoparticles (AuNPs) with core diameter 3-4 nm and their application for the enhancement of long-range interfacial ET of a heme protein. Gold nanoparticles were electrostatically conjugated with cyt c to form nanoparticle-protein hybrid ET systems with well...... and the protein molecule. When the nanoparticle-protein conjugates are assembled on Au(111) surfaces, long-range interfacial ET across a physical distance of over 50 A via the nanoparticle becomes feasible. Moreover, significant enhancement of the interfacial ET rate by more than an order of magnitude compared...... with that of cyt c in the absence of AuNPs is observed. AuNPs appear to serve as excellent ET relays, most likely by facilitating the electronic coupling between the protein redox center and the electrode surface....

  11. Altered expression of mitochondrial electron transport chain proteins and improved myocardial energetic state during late ischemic preconditioning

    NARCIS (Netherlands)

    J.A. Cabrera (Jesús); E.A. Ziemba (Elizabeth); L.H. Colbert (Lisa); L.B. Anderson (Lorraine); W.J. Sluiter (Wim); D.J.G.M. Duncker (Dirk); T.A. Butterick (Tammy); J. Sikora (Joseph); H.B. Ward (Herbert B.); R.F. Kelly (Rosemary); E.O. McFalls (Edward)

    2012-01-01

    textabstractAltered expression of mitochondrial electron transport proteins has been shown in early preconditioned myocardial tissue. We wished to determine whether these alterations persist in the Second Window of Protection (SWOP) and if so, whether a favorable energetic state is facilitated

  12. Electron microscopic visualization of the RecA protein-mediated pairing and branch migration phases of DNA strand exchange

    DEFF Research Database (Denmark)

    Register, JC; Christiansen, Gunna; Griffith, J

    1987-01-01

    examined by electron microscopy: supertwisted double-stranded (ds) DNA and linear single-stranded (ss) DNA, linear dsDNA and circular ssDNA, and linear dsDNA and colinear ssDNA. Several major observations were: (i) with RecA protein bound to the DNA, plectonemic joints were ultrastructurally...

  13. Visualizing a protein quake with time-resolved X-ray scattering at a free-electron laser

    DEFF Research Database (Denmark)

    Arnlund, David; Johansson, Linda C.; Wickstrand, Cecilia

    2014-01-01

    We describe a method to measure ultrafast protein structural changes using time-resolved wide-angle X-ray scattering at an X-ray free-electron laser. We demonstrated this approach using multiphoton excitation of the Blastochloris viridis photosynthetic reaction center, observing an ultrafast glob...

  14. Addressing employee turnover and retention: keeping your valued performers.

    Science.gov (United States)

    McConnell, Charles R

    2011-01-01

    Employee turnover and employee retention are inextricably linked; to control turnover is to enhance retention. Turnover is a relatively simple concept; however, considerable confusion often results when addressing turnover because of differences in how it is defined; that is, what is counted, how it is counted, and how the turnover rates are expressed. Turnover is also costly, although not enough attention is paid to its cost because so much of it is indirect and thus not readily visible. There are a variety of causes of turnover, some that can be corrected and some that cannot be avoided. Reducing or otherwise controlling turnover requires continuing management attention to its causes and constant recognition of what can and should be controlled and what cannot be controlled. Ongoing attention to turnover is an essential part of the department manager's role; every improvement in turnover is a direct improvement in retention, with eventual positive effects on the bottom line.

  15. Galectin-3 binding protein links circulating microparticles with electron dense glomerular deposits in lupus nephritis.

    Science.gov (United States)

    Nielsen, C T; Østergaard, O; Rekvig, O P; Sturfelt, G; Jacobsen, S; Heegaard, N H H

    2015-10-01

    A high level of galectin-3-binding protein (G3BP) appears to distinguish circulating cell-derived microparticles in systemic lupus erythematosus (SLE). The aim of this study is to characterize the population of G3BP-positive microparticles from SLE patients compared to healthy controls, explore putative clinical correlates, and examine if G3BP is present in immune complex deposits in kidney biopsies from patients with lupus nephritis. Numbers of annexin V-binding and G3BP-exposing plasma microparticles from 56 SLE patients and 36 healthy controls were determined by flow cytometry. Quantitation of microparticle-associated G3BP, C1q and immunoglobulins was obtained by liquid chromatography tandem mass spectrometry (LC-MS/MS). Correlations between microparticle-G3BP data and clinical parameters were analyzed. Co-localization of G3BP with in vivo-bound IgG was examined in kidney biopsies from one non-SLE control and from patients with class IV (n = 2) and class V (n = 1) lupus nephritis using co-localization immune electron microscopy. Microparticle-G3BP, microparticle-C1q and microparticle-immunoglobulins were significantly (P microparticle populations could be discerned by flow cytometry, including two subpopulations that were significantly increased in SLE samples (P = 0.01 and P = 0.0002, respectively). No associations of G3BP-positive microparticles with clinical manifestations or disease activity were found. Immune electron microscopy showed co-localization of G3BP with in vivo-bound IgG in glomerular electron dense immune complex deposits in all lupus nephritis biopsies. Both circulating microparticle-G3BP numbers as well as G3BP expression are increased in SLE patients corroborating G3BP being a feature of SLE microparticles. By demonstrating G3BP co-localized with deposited immune complexes in lupus nephritis, the study supports cell-derived microparticles as a major autoantigen source and provides a new understanding of the origin of

  16. Electronic damage in S atoms in a native protein crystal induced by an intense X-ray free-electron laser pulse

    Directory of Open Access Journals (Sweden)

    L. Galli

    2015-07-01

    Full Text Available Current hard X-ray free-electron laser (XFEL sources can deliver doses to biological macromolecules well exceeding 1 GGy, in timescales of a few tens of femtoseconds. During the pulse, photoionization can reach the point of saturation in which certain atomic species in the sample lose most of their electrons. This electronic radiation damage causes the atomic scattering factors to change, affecting, in particular, the heavy atoms, due to their higher photoabsorption cross sections. Here, it is shown that experimental serial femtosecond crystallography data collected with an extremely bright XFEL source exhibit a reduction of the effective scattering power of the sulfur atoms in a native protein. Quantitative methods are developed to retrieve information on the effective ionization of the damaged atomic species from experimental data, and the implications of utilizing new phasing methods which can take advantage of this localized radiation damage are discussed.

  17. Effect of Electron Beam Irradiation on Degradability Coefficients and Ruminalpostruminal Digestibility of Dry Matter and Crude Protein of some Plant Protein Sources

    Directory of Open Access Journals (Sweden)

    gasem tahan

    2016-06-01

    Full Text Available Effect of electron beam irradiation on degradability coefficients and ruminal- postruminal digestibility of dry matter and crude protein of soybean meal, canola meal and Lathyrus sativus seed, irradiated at doses of 50, 100 and 150 kGy was investigated. Ruminal degradability of dry matter and crude protein was determined by in situ method using two cannulated Holstein heifers. Ruminal- postruminal digestibility of dry matter and crude protein was determined by in situ (nylon bag-in vitro (daisy digestor techniques. Data analyzed using SAS software as randomized completely design and the treatment means were compared using Tukey test. The results indicated that irradiation had no effect on dry matter, ether extract and ash content of feeds. In soybean meal, washout fraction and potentially degradable fraction of dry matter and crude protein was higher and lower at dose of 150 kGy irradiation than other treatments, respectively, and degradation rate constant and ruminal effective degradability of dry matter and crude protein was lower at all doses of irradiation than untreated soybean meal. In canola meal, irradiation at doses of 50 and 100 kGy decreased washout fraction and increased potentially degradable fraction of crude protein compared with untreated canola meal. In Lathyrus sativus seed, only potentially degradable fraction of dry matter and crude protein was lower at dose of 150 kGy irradiation than untreated Lathyrus sativus seed. Ruminal digestibility of crude protein decreased in soybean meal at doses of 100 and 150 kGy irradiation and for canola meal at all doses of irradiation than untreated samples. Total tract digestibility of crude protein decreased in soybean meal at dose of 150 kGy irradiation and for canola meal at all doses of irradiation than untreated samples. In Lathyrus sativus seed, ruminal-postruminal digestibility and total tract digestibility of dry matter increased at doses of 100 and 150 kGy irradiation than untreated

  18. KORELASI ANTARA EMPLOYEES INVOLVEMENT, TURNOVER SERTA PENGARUHNYA TERHADAP PRODUKTIVITAS

    Directory of Open Access Journals (Sweden)

    Purnawan Adi Wicaksono

    2012-02-01

    Full Text Available Praktek yang berkembang menyatakan bahwa employee involvement memiliki efek positif terhadap kinerja organisasi. Perubahan pada kultur organisasi dapat menimbulkan dampak berkurangnya absen, turnover, pengambilan keputusan yang lebih baik dan sebagainya. Sehingga menarik untuk diteliti apakah ada korelasi antara aplikasi perubahan organisasi yaitu employee involvement, turnover serta produktivitas Berdasarkan studi literatur didapatkan hubungan antara employee involvement dengan level turnover, serta hubungan turnover dengan produktivitas. Sehingga employee involvement dapat digunakan sebagai salah satu aspek menghitung produktivitas Keyword : employee involvement, turnover, produktivitas

  19. Predictors of Staff Turnover and Turnover Intentions within Addiction Treatment Settings: Change Over Time Matters.

    Science.gov (United States)

    Garner, Bryan R; Hunter, Brooke D

    2014-01-01

    This study examined the extent to which changes over time in clinicians' responses to measures of work attitude (eg, job satisfaction) and psychological climate (eg, supervisor support) could predict actual turnover and turnover intentions above and beyond absolute levels of these respective measures. Longitudinal data for this study were collected from a sample of clinicians (N = 96) being trained to implement an evidence-based treatment for adolescent substance use disorders. Supporting findings from a recent staff turnover study, we found job satisfaction change was able to predict actual turnover above and beyond average levels of job satisfaction. Representing new contributions to the staff turnover literature, we also found that change over time in several other key measures (eg, job satisfaction, role manageability, role clarity) explained a significant amount of variance in turnover intentions above and beyond the absolute level of each respective measure. A key implication of the current study is that organizations seeking to improve their ability to assess risk for staff turnover may want to consider assessing staff at multiple points in time in order to identify systematic changes in key employee attitudes like turnover intentions and job satisfaction.

  20. Predictors of Staff Turnover and Turnover Intentions within Addiction Treatment Settings: Change over Time Matters

    Directory of Open Access Journals (Sweden)

    Bryan R. Garner

    2014-01-01

    Full Text Available This study examined the extent to which changes over time in clinicians’ responses to measures of work attitude (eg, job satisfaction and psychological climate (eg, supervisor support could predict actual turnover and turnover intentions above and beyond absolute levels of these respective measures. Longitudinal data for this study were collected from a sample of clinicians ( N = 96 being trained to implement an evidence-based treatment for adolescent substance use disorders. Supporting findings from a recent staff turnover study, we found job satisfaction change was able to predict actual turnover above and beyond average levels of job satisfaction. Representing new contributions to the staff turnover literature, we also found that change over time in several other key measures (eg, job satisfaction, role manageability, role clarity explained a significant amount of variance in turnover intentions above and beyond the absolute level of each respective measure. A key implication of the current study is that organizations seeking to improve their ability to assess risk for staff turnover may want to consider assessing staff at multiple points in time in order to identify systematic changes in key employee attitudes like turnover intentions and job satisfaction.

  1. A Dual Role of Upper Zone of Growth Plate and Cartilage Matrix-Associated Protein in Human and Mouse Osteoarthritic Cartilage: Inhibition of Aggrecanases and Promotion of Bone Turnover

    NARCIS (Netherlands)

    Stock, M.; Menges, S.; Eitzinger, N.; Gesslein, M.; Botschner, R.; Wormser, L.; Distler, A.; Schlotzer-Schrehardt, U.; Dietel, K.; Distler, J.; Beyer, C.; Gelse, K.; Engelke, K.; Koenders, M.I.; Berg, W.B. van den; Mark, K. von der; Schett, G.

    2017-01-01

    OBJECTIVE: Cartilage damage and subchondral bone changes are closely connected in osteoarthritis. Nevertheless, how these processes are interlinked is, to date, incompletely understood. This study was undertaken to investigate the mechanistic role of a cartilage-derived protein, upper zone of growth

  2. High Turnover of Tissue Factor Enables Efficient Intracellular Delivery of Antibody-Drug Conjugates

    DEFF Research Database (Denmark)

    de Goeij, Bart E.C.G.; Satijn, D.; Freitag, C. M.

    2015-01-01

    specificities. TF-ADC demonstrated effective killing against tumor cell lines with variable levels of target expression. In xenograft models, TF-ADC was relatively potent in reducing tumor growth compared with EGFR-and HER2-ADCs. We hypothesize that the constant turnover of TF on tumor cells makes this protein...

  3. Glutathione turnover in 14 rat tissues

    International Nuclear Information System (INIS)

    Potter, D.W.; Tran, T.

    1990-01-01

    GSH is a tripeptide found in all tissues and is important in maintaining cellular redox status. First-order rate constants for GSH turnover were determined for various tissues of Fischer male rats. Animals were administered [ 35 S]Cys by tail vein injection and GSH turnover was estimated by the decrease in GSH specific activity following incorporation of Cys, 1-102 hr after administration. Tissue nonprotein sulfhydryls (NPSH) were detected by Ellman's assay and compared with GSH and Cys concentrations determined by HPLC with electrochemical detection. [ 35 S]GSH was analyzed by HPLC equipped with a flow-through radioactivity detector. Although total GSH and Cys were usually slightly lower than NPSH concentrations for the tissues examined, both assay systems gave comparable results. An exception was the glandular stomach which had approximately 2-fold higher NPSH. Liver and kidney had rapid turnover rates with GSH half-lives between 2-5 hr, while heart and skeletal muscle tissue had half-lives of 80-90 hr. Turnover in the blood was slowest, with a half-life of 170 hr. Gastrointestinal tract tissues were shown to have intermediate turnover rates of the following order: glandular stomach > duodenum = small intestine = caecum = large intestine = colon > forestomach. GSH half-life in lung and skin was approximately 45 hr. These studies indicate that tissues utilize GSH at markedly different rates

  4. Nurse turnover: the mediating role of burnout.

    Science.gov (United States)

    Leiter, Michael P; Maslach, Christina

    2009-04-01

    This study tested whether the mediation model of burnout could predict nurses' turnover intentions. A better understanding of what factors support a commitment to a nursing career could inform both policies and workplace practices. The mediation model of burnout provides a way of linking the quality of a nurse's worklife to various outcomes, such as turnover. Data on areas of worklife, burnout, and turnover intentions were collected by surveying 667 Canadian nurses in the Atlantic Provinces. The findings supported the mediation model of burnout, in which areas of worklife predicted burnout, which in turn predicted turnover intentions. Cynicism was the key burnout dimension for turnover, and the most critical areas of worklife were value conflicts and inadequate rewards. The results of this study provide some new insights into how the intention of nurses to leave their job is related to particular aspects of their worklife and to burnout. These results suggest what may be the most appropriate areas to target for interventions to reduce the risk of nurses exiting early from their chosen career.

  5. VALSARTAN REGULATES MYOCARDIAL AUTOPHAGY AND MITOCHONDRIAL TURNOVER IN EXPERIMENTAL HYPERTENSION

    Science.gov (United States)

    Zhang, Xin; Li, Zi-Lun; Crane, John A.; Jordan, Kyra L.; Pawar, Aditya S.; Textor, Stephen C.; Lerman, Amir; Lerman, Lilach O.

    2014-01-01

    Renovascular hypertension alters cardiac structure and function. Autophagy is activated during left ventricular hypertrophy and linked to adverse cardiac function. The Angiotensin II receptor blocker Valsartan lowers blood pressure and is cardioprotective, but whether it modulates autophagy in the myocardium is unclear. We hypothesized that Valsartan would alleviate autophagy and improve left ventricular myocardial mitochondrial turnover in swine renovascular hypertension. Domestic pigs were randomized to control, unilateral renovascular hypertension, and renovascular hypertension treated with Valsartan (320 mg/day) or conventional triple therapy (Reserpine+hydralazine+hydrochlorothiazide) for 4 weeks post 6-weeks of renovascular hypertension (n=7 each group). Left ventricular remodeling, function and myocardial oxygenation and microcirculation were assessed by multi-detector computer tomography, blood-oxygen-level-dependent magnetic resonance imaging and microcomputer tomography. Myocardial autophagy, markers for mitochondrial degradation and biogenesis, and mitochondrial respiratory-chain proteins were examined ex vivo. Renovascular hypertension induced left ventricular hypertrophy and myocardial hypoxia, enhanced cellular autophagy and mitochondrial degradation, and suppressed mitochondrial biogenesis. Valsartan and triple therapy similarly decreased blood pressure, but Valsartan solely alleviated left ventricular hypertrophy, ameliorated myocardial autophagy and mitophagy, and increased mitochondrial biogenesis. In contrast, triple therapy only slightly attenuated autophagy and preserved mitochondrial proteins, but elicited no improvement in mitophagy. These data suggest a novel potential role of Valsartan in modulating myocardial autophagy and mitochondrial turnover in renovascular hypertension-induced hypertensive heart disease, which may possibly bolster cardiac repair via a blood pressure-independent manner. PMID:24752430

  6. Electron microscopy of the complexes of ribulose-1,5-bisphosphate carboxylase (Rubisco) and Rubisco subunit-binding protein from pea leaves

    NARCIS (Netherlands)

    Tsuprun, V.L.; Boekema, E.J.; Samsonidze, T.G.; Pushkin, A.V.

    1991-01-01

    The structure of ribulose-1,5-bisphosphate carboxylase (Rubisco) subunit-binding protein and its interaction with pea leaf chloroplast Rubisco were studied by electron microscopy and image analysis. Electron-microscopic evidence for the association of Rubisco subunit-binding protein, consisting of

  7. Electron beam irradiation induces abnormal development and the stabilization of p53 protein of American serpentine leafminer, Liriomyza trifolii (Burgess)

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Hyun-Na; Yun, Seung-Hwan; Yoon, Changmann [Department of Plant Medicine, College of Agriculture, Life and Environment Sciences, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Kim, Gil-Hah, E-mail: khkim@chungbuk.ac.kr [Department of Plant Medicine, College of Agriculture, Life and Environment Sciences, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)

    2012-01-15

    The American serpentine leafminer fly, Liriomyza trifolii (Burgess), is one of the most destructive polyphagous pests worldwide. In this study, we determined electron beam doses for inhibition of normal development of the leaf miner and investigated the effect of electron beam irradiation on DNA damage and p53 stability. Eggs (0-24 h old), larvae (2nd instar), puparia (0-24 h old after pupariation) and adults (24 h after emergence) were irradiated with increasing doses of electron beam irradiation (six levels between 30 and 200 Gy). At 150 Gy, the number of adults that developed from irradiated eggs, larvae and puparia was lower than in the untreated control. Fecundity and egg hatchability decreased depending on the doses applied. Reciprocal crosses between irradiated and unirradiated flies demonstrated that males were more radiotolerant than females. Adult longevity was not affected in all stages. The levels of DNA damage in L. trifolii adults were evaluated using the alkaline comet assay. Our results indicate that electron beam irradiation increased levels of DNA damage in a dose-dependent manner. Moreover, low doses of electron beam irradiation led to the rapid appearance of p53 protein within 6 h; however, it decreased after exposure to high doses (150 Gy and 200 Gy). These results suggest that electron beam irradiation induced not only abnormal development and reproduction but also p53 stability caused by DNA damage in L. trifolii. We conclude that a minimum dose of 150 Gy should be sufficient for female sterilization of L. trifolii. - Highlights: > Electron beam irradiation inhibited normal development of the leaf miner. > Electron beam irradiation inhibited normal reproduction of the leaf miner. > Electron beam irradiation increased levels of DNA damage. > Electron beam irradiation induced p53 stability.

  8. Does Judge Turnover Affect Judicial Performance?

    DEFF Research Database (Denmark)

    Guerra, Alice; Tagliapietra, Claudio

    2017-01-01

    office to another after three years of mandate, and the law prescribes their transfer after ten years to guarantee their independence. Flaws in the process managing the backlog of outbound judges and the existence of asynchrony between outbound and inbound transfers produce a chain of delays...... to the disposition of court cases. Using a novel dataset on Court of Appeal Districts in Italy (2008–2012), we provide evidence of a strong negative relation between high turnover rates and judicial performance. We find that marginal increases in judge turnover rates lead to a statistically significant decrease...... in judicial performance over two years of time...

  9. The rate and cost of nurse turnover in Australia.

    Science.gov (United States)

    Roche, Michael A; Duffield, Christine M; Homer, Caroline; Buchan, James; Dimitrelis, Sofia

    2015-01-01

    Nurse turnover is a critical issue facing workforce planners across the globe, particularly in light of protracted and continuing workforce shortages. An ageing population coupled with the rise in complex and chronic diseases, have contributed to increased demands placed on the health system and importantly, nurses who themselves are ageing. Costs associated with nurse turnover are attracting more attention; however, existing measurements of turnover show inconsistent findings, which can be attributed to differences in study design, metrics used to calculate turnover and variations in definitions for turnover. This paper will report the rates and costs of nurse turnover across three States in Australia.

  10. Short range photoinduced electron transfer in proteins: QM-MM simulations of tryptophan and flavin fluorescence quenching in proteins

    International Nuclear Information System (INIS)

    Callis, Patrik R.; Liu Tiqing

    2006-01-01

    Hybrid quantum mechanical-molecular mechanics (dynamics) were performed on flavin reductase (Fre) and flavodoxin reductase (Fdr), both from Escherichia coli. Each was complexed with riboflavin (Rbf) or flavin mononucleotide (FMN). During 50 ps trajectories, the relative energies of the fluorescing state (S 1 ) of the isoalloxazine ring and the lowest charge transfer state (CT) were assessed to aid prediction of fluorescence lifetimes that are shortened due to quenching by electron transfer from tyrosine. The simulations for the four cases display a wide range in CT-S 1 energy gap caused by the presence of phosphate, other charged and polar residues, water, and by intermolecular separation between donor and acceptor. This suggests that the Gibbs energy change (ΔG 0 ) and reorganization energy (λ) for the electron transfer may differ in different flavoproteins

  11. NMR of proteins (4Fe-4S): structural properties and intramolecular electron transfer; RMN de proteines (4Fe-4S): proprietes structurales et transfert electronique intramoleculaire

    Energy Technology Data Exchange (ETDEWEB)

    Huber, J G

    1996-10-17

    NMR started to be applied to Fe-S proteins in the seventies. Its use has recently been enlarged as the problems arising from the paramagnetic polymetallic clusters ware overcome. Applications to [4Fe-4S] are presented herein. The information derived thereof deepens the understanding of the redox properties of these proteins which play a central role in the metabolism of bacterial cells. The secondary structure elements and the overall folding of Chromatium vinosum ferredoxin (Cv Fd) in solution have been established by NMR. The unique features of this sequence have been shown to fold as an {alpha} helix at the C-terminus and as a loop between two cysteines ligand of one cluster: these two parts localize in close proximity from one another. The interaction between nuclear and electronic spins is a source of additional structural information for (4Fe-AS] proteins. The conformation of the cysteine-ligands, as revealed by the Fe-(S{sub {gamma}}-C{sub {beta}}-H{sub {beta}})Cys dihedral angles, is related to the chemical shifts of the signals associated with the protons of these residues. The longitudinal relaxation times of the protons depend on their distance to the cluster. A quantitative relationship has been established and used to show that the solution structure of the high-potential ferredoxin from Cv differs significantly from the crystal structure around Phe-48. Both parameters (chemical shifts and longitudinal relaxation times) give also insight into the electronic and magnetic properties of the [4Fe-4S] clusters. The rate of intramolecular electron transfer between the two [4FE-4S] clusters of ferredoxins has been measured by NMR. It is far slower in the case of Cv Fd than for shorter ferredoxins. The difference may be associated with changes in the magnetic and/or electronic properties of one cluster. The strong paramagnetism of the [4Fe-4S] clusters, which originally limited the applicability of NMR to proteins containing these cofactors, has been proven

  12. Insights into the Structural Changes Occurring upon Photoconversion in the Orange Carotenoid Protein from Broadband Two-Dimensional Electronic Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    De Re, Eleonora; Schlau-Cohen, Gabriela S.; Leverenz, Ryan L.; Huxter, Vanessa M.; Oliver, Thomas A. A.; Mathies, Richard A.; Fleming, Graham R.

    2014-05-22

    Carotenoids play an essential role in photoprotection, interacting with other pigments to safely dissipate excess absorbed energy as heat. In cyanobacteria, the short time scale photoprotective mechanisms involve the photoactive orange carotenoid protein (OCP), which binds a single carbonyl carotenoid. Blue-green light induces the photoswitching of OCP from its ground state form (OCPO) to a metastable photoproduct (OCPR). OCPR can bind to the phycobilisome antenna and induce fluorescence quenching. The photoswitching is accompanied by structural and functional changes at the level of the protein and of the bound carotenoid. In this study, we use broadband two-dimensional electronic spectroscopy to look at the differences in excited state dynamics of the carotenoid in the two forms of OCP. Our results provide insight into the origin of the pronounced vibrational lineshape and oscillatory dynamics observed in linear absorption and 2D electronic spectroscopy of OCPO and the large inhomogeneous broadening in OCPR, with consequences for the chemical function of the two forms.

  13. A novel bi-protein bio-interphase of cytochrome c and glucose oxidase: Electron transfer and electrocatalysis

    International Nuclear Information System (INIS)

    Song, Yonghai; Liu, Hongyu; Wang, Yu; Wang, Li

    2013-01-01

    Graphical abstract: Glucose oxidase (GOD) and cytochrome c (Cyt c) were co-entrapped in the poly(diallyldimethylammonium chloride)–graphene nanosheets–gold nanoparticles (PDDA–Gp–AuNPs) nanocomposites modified glassy carbon electrode. Electron transfer and electrocatalysis of the novel bi-protein bio-interphase were investigated. The bio-interphase developed here not only successfully achieved DET of GOD, but also showed great potential for the fabrication of novel glucose biosensors with linear response up to 18 mM. Highlights: ► A bio-interphase composed of cytochrome c and glucose oxidase was developed. ► The electron transfer in the bio-interphase was investigated. ► Electrocatalytic performances of bio-interphase were explored. ► The bio-interphase exhibited good electrocatalytic response glucose. - Abstract: Glucose oxidase (GOD) and cytochrome c (Cyt c) were co-entrapped in the poly(diallyldimethylammonium chloride)–graphene nanosheets–gold nanoparticles (PDDA–Gp–AuNPs) hybrid nanocomposites modified glassy carbon electrode to prepare a novel bi-protein bio-interphase. Electron transfer and electrocatalysis of the bi-protein bio-interphase were investigated in detail. The results showed that the PDDA–Gp–AuNPs nanocomposites accelerated the electron transfer between proteins and electrode. The bi-protein exhibited effective direct electron transfer (DET) reaction with an apparent rate constant (k s ) of 2.36 s −1 . The optimal molar ratio and total amount of Cyt c and GOD in the bio-interphase for DET of GOD was estimated to be about 3:1 and 1.40 nmol, respectively. The bi-protein bio-interphase could be used to detect glucose based on the consumption of O 2 with the oxidation of glucose catalyzed by GOD. The resulted biosensor exhibits wide linear range from 2.0 to 18.0 mM. Thus, this study not only successfully achieved DET of GOD, but also constructed a novel biosensor for glucose detection

  14. Electronic transport in single-helical protein molecules: Effects of multiple charge conduction pathways and helical symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Sourav, E-mail: sourav.kunduphy@gmail.com; Karmakar, S.N.

    2016-07-15

    We propose a tight-binding model to investigate electronic transport properties of single helical protein molecules incorporating both the helical symmetry and the possibility of multiple charge transfer pathways. Our study reveals that due to existence of both the multiple charge transfer pathways and helical symmetry, the transport properties are quite rigid under influence of environmental fluctuations which indicates that these biomolecules can serve as better alternatives in nanoelectronic devices than its other biological counterparts e.g., single-stranded DNA.

  15. Enhancing Protein Disulfide Bond Cleavage by UV Excitation and Electron Capture Dissociation for Top-Down Mass Spectrometry

    OpenAIRE

    Wongkongkathep, Piriya; Li, Huilin; Zhang, Xing; Loo, Rachel R. Ogorzalek; Julian, Ryan R.; Loo, Joseph A.

    2015-01-01

    The application of ion pre-activation with 266 nm ultraviolet (UV) laser irradiation combined with electron capture dissociation (ECD) is demonstrated to enhance top-down mass spectrometry sequence coverage of disulfide bond containing proteins. UV-based activation can homolytically cleave a disulfide bond to yield two separated thiol radicals. Activated ECD experiments of insulin and ribonuclease A containing three and four disulfide bonds, respectively, were performed. UV-activation in comb...

  16. Changes in alanine turnover rate due to nutritional and genetic obesity in the rat.

    Science.gov (United States)

    Yebras, M; Salvadó, J; Arola, L; Remesar, X; Segués, T

    1994-08-01

    The changes in alanine turnover were determined in Zucker rats, which were either genetically obese (fa/fa) or rendered obese by dietary treatment (cafeteria fed). The whole body rate of alanine turnover was higher in genetically obese rats than in rats in which obesity was induced by diet (cafeteria). This is possibly due to variations in the rate of the amino acid incorporation into proteins, since the rate of whole body alanine degradation is the same for both groups. Thus, the different pattern followed by alanine turnover rate in these types of obese animals reflects the differences in the nitrogen economy of these animals, pointing to a higher alanine utilization in the genetically obese animals and a conservative management of alanine in the cafeteria-fed animals.

  17. Effect of Gamma Radiation and Electron Beam on Microbiological Quality and Protein Patterns of 4 Selected Beans

    International Nuclear Information System (INIS)

    Chookaew, S.; Eamsir, J.; Pewlong, W.; Sajjabut, S.

    2014-01-01

    The aim of the present study was to evaluate the effect of gamma ray and electron beam on microbiological quality and protein pattern of four selected beans: mung beans, soy beans, peanuts and black beans. All beans samples were exposed to irradiation at doses of 0, 0.5, 1, and 2 kGy before evaluated for their microbiological quality using AOAC method and protein analysis by gel electrophoresis. Results showed that the amount of bacteria, yeast and mold of irradiated mung beans and peanuts were reduced, whereas these microbiological quality values remained relatively the same for irradiated soy beans and black beans compared to non-irradiated samples. In terms of protein analysis, the protein patterns of the irradiated beans were of the same quality as the non-irradiated samples. To further tested the effect of irradiation on the bean's protein at higher doses, all four selected beans were exposed to gamma ray at 10, 50, 100, 150 and 200 kGy. We found that the protein patterns of mung beans, peanuts and black beans were altered at doses above 50 kGy.

  18. The use of the exit interview to reduce turnover amongst healthcare professionals.

    Science.gov (United States)

    Flint, Anndrea; Webster, Joan

    2011-01-19

    Exit interviews are widely used in healthcare organisations to identify reasons for staff attrition, yet their usefulness in limiting turnover is unclear. To determine the effectiveness of various exit interview strategies in decreasing turnover rates amongst healthcare professionals. We used a comprehensive search strategy including an electronic search of the following databases: DARE, CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO, ERIC (search date: 7 September 2010) and EPOC Specialised Register (search date: 30 September 2009). We also screened the reference lists of included studies and relevant reviews. Randomised controlled trials, controlled clinical trials, controlled before and after studies and interrupted time series studies comparing turnover rates between healthcare professionals who had undergone one form of exit interview with another form of exit interview or with no interview. Two review authors independently assessed trial quality and extracted data. The search identified 1560 citations of which we considered 19 potentially relevant. The two authors independently reviewed the abstracts of these studies and retrieved the full texts of eight studies. We excluded all eight following independent assessment. They were either interviews, commentaries on how to do an exit interview or descriptive studies about reasons for leaving. We found no trials that matched our inclusion criteria. Evidence about the effectiveness of exit interviews to reduce turnover is currently not available. However, exit interviews may provide useful information about the work environment which, in turn, may be useful in the development of interventions to reduce turnover.

  19. Loss of job-related right to healthcare associated with employment turnover: challenges for the Mexican health system.

    Science.gov (United States)

    Guerra, Germán; Gutiérrez-Calderón, Emilio; Salgado de Snyder, Nelly; Borja-Aburto, Víctor Hugo; Martínez-Valle, Adolfo; González-Block, Miguel Ángel

    2018-06-15

    The Mexican health system segments access and right to healthcare according to worker position in the labour market. In this contribution we analyse how access and continuity of healthcare gets interrupted by employment turnover in the labour market, including its formal and informal sectors, as experienced by affiliates to the Mexican Institute of Social Security (IMSS) at national level, and of workers with type 2 diabetes (T2DM) in Mexico City. Using data from the National Employment and Occupation Survey, 2014, and from IMSS electronic medical records for workers in Mexico City, we estimated annual employment turnover rates to measure the loss of healthcare access due to labour market dynamics. We fitted a binary logistic regression model to analyse the association between sociodemographic variables and employment turnover. Lastly we analysed job-related access to health care in relation to employment turnover events. At national level, 38.3% of IMSS affiliates experienced employment turnover at least once, thus losing the right to access to healthcare. The turnover rate for T2DM patients was 22.5%. Employment turnover was more frequent at ages 20-39 (38.6% national level; 28% T2DM) and among the elderly (62.4% national level; 26% T2DM). At the national level, higher educational levels (upper-middle, OR = 0.761; upper, OR = 0.835) and income (5 minimum wages or more, OR = 0.726) were associated with lower turnover. Being single and younger were associated with higher turnover (OR = 1.413). T2DM patients aged 40-59 (OR = 0.655) and with 5 minimum wages or more (OR = 0.401) experienced less turnover. Being a T2DM male patient increased the risk of experiencing turnover (OR = 1.166). Up to 89% of workers losing IMSS affiliation and moving on to other jobs failed to gain job-related access to health services. Only 9% gained access to the federal workers social security institute (ISSSTE). Turnover across labour market sectors is

  20. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  1. Cytochrome b 6 f function and localization, phosphorylation state of thylakoid membrane proteins and consequences on cyclic electron flow.

    Science.gov (United States)

    Dumas, Louis; Chazaux, Marie; Peltier, Gilles; Johnson, Xenie; Alric, Jean

    2016-09-01

    Both the structure and the protein composition of thylakoid membranes have an impact on light harvesting and electron transfer in the photosynthetic chain. Thylakoid membranes form stacks and lamellae where photosystem II and photosystem I localize, respectively. Light-harvesting complexes II can be associated to either PSII or PSI depending on the redox state of the plastoquinone pool, and their distribution is governed by state transitions. Upon state transitions, the thylakoid ultrastructure and lateral distribution of proteins along the membrane are subject to significant rearrangements. In addition, quinone diffusion is limited to membrane microdomains and the cytochrome b 6 f complex localizes either to PSII-containing grana stacks or PSI-containing stroma lamellae. Here, we discuss possible similarities or differences between green algae and C3 plants on the functional consequences of such heterogeneities in the photosynthetic electron transport chain and propose a model in which quinones, accepting electrons either from PSII (linear flow) or NDH/PGR pathways (cyclic flow), represent a crucial control point. Our aim is to give an integrated description of these processes and discuss their potential roles in the balance between linear and cyclic electron flows.

  2. The quantum Kramers' turnover. IT-23

    Energy Technology Data Exchange (ETDEWEB)

    Barik, Debashis; Shankar Ray, Deb [Indian Association for the Cultivation of Science, Jadavpur, Kolkata (India)

    2004-12-01

    The key result of Kramers' dynamical theory of reaction rate is that the rate varies linearly in the weak dissipative regime and inversely in the high dissipative regime with friction of the reaction medium. That is in between the energy diffusion and spatial diffusion limited regime the rate constant as a function of friction exhibits a bell-shaped curve known as Kramers' turnover.

  3. The quantum Kramers' turnover. IT-23

    International Nuclear Information System (INIS)

    Barik, Debashis; Shankar Ray, Deb

    2004-01-01

    The key result of Kramers' dynamical theory of reaction rate is that the rate varies linearly in the weak dissipative regime and inversely in the high dissipative regime with friction of the reaction medium. That is in between the energy diffusion and spatial diffusion limited regime the rate constant as a function of friction exhibits a bell-shaped curve known as Kramers' turnover

  4. Employee Development and Turnover Intention: Theory Validation

    Science.gov (United States)

    Rahman, Wali; Nas, Zekeriya

    2013-01-01

    Purpose: This study aims to examine the pattern of behavior of turnover intentions in developing countries "vis-a-vis" the one in advanced countries through the empirical data from public universities in Khyber Pakhtunkhwa, Pakistan. The study provides empirical evidence from academia in Pakistan, thereby enriching the understanding of…

  5. A Turnover Model for the Mexican Maquiladoras.

    Science.gov (United States)

    Maertz, Carl P.; Stevens, Michael J.; Campion, Michael A.

    2003-01-01

    From interviews with 47 Mexican maquiladora workers, a model of voluntary turnover was created and compared with models from the United States, Canada, England, and Australia. Despite similarities, the cultural and economic environment affected the precise content of antecedents in the Mexican model. (Contains 63 references.) (SK)

  6. Health care workplace discrimination and physician turnover.

    Science.gov (United States)

    Nunez-Smith, Marcella; Pilgrim, Nanlesta; Wynia, Matthew; Desai, Mayur M; Bright, Cedric; Krumholz, Harlan M; Bradley, Elizabeth H

    2009-12-01

    To examine the association between physician race/ ethnicity, workplace discrimination, and physician job turnover. Cross-sectional, national survey conducted in 2006-2007 of practicing physicians (n = 529) randomly identified via the American Medical Association Masterfile and the National Medical Association membership roster. We assessed the relationships between career racial/ethnic discrimination at work and several career-related dependent variables, including 2 measures of physician turnover, career satisfaction, and contemplation of career change. We used standard frequency analyses, odds ratios and chi2 statistics, and multivariate logistic regression modeling to evaluate these associations. Physicians who self-identified as nonmajority were significantly more likely to have left at least 1 job because of workplace discrimination (black, 29%; Asian, 24%; other race, 21%; Hispanic/Latino, 20%; white, 9%). In multivariate models, having experienced racial/ethnic discrimination at work was associated with high job turnover (adjusted odds ratio, 2.7; 95% CI, 1.4-4.9). Among physicians who experienced workplace discrimination, only 45% of physicians were satisfied with their careers (vs 88% among those who had not experienced workplace discrimination, p value workplace discrimination, p value Workplace discrimination is associated with physician job turnover, career dissatisfaction, and contemplation of career change. These findings underscore the importance of monitoring for workplace discrimination and responding when opportunities for intervention and retention still exist.

  7. Biochemical Markers of Joint Tissue Turnover

    DEFF Research Database (Denmark)

    Bay-Jensen, Anne-Christine; Sondergaard, Bodil Cecilie; Christiansen, Claus

    2009-01-01

    available for the study of tissue turnover in each of the three compartments of the articular joint, that is the bone, the cartilage, and the synovium. Finally, we provide some perspective to future developments in biomarker discovery and discuss the potential impact such technologies could have on the drug...

  8. Turnover of Public School Superintendents in Arizona

    Science.gov (United States)

    Meyer, Joyce Ntsoaki

    2013-01-01

    This study used a descriptive qualitative design utilizing a phenomenological approach to determine and examine the reasons behind the voluntary or involuntary turnover of Arizona school superintendents. Open-ended questions were used to interview five superintendents who had left their districts between 2008 and 2013 about their perceptions on…

  9. Teacher Turnover in Charter Schools. Research Brief

    Science.gov (United States)

    Stuit, David; Smith, Thomas M.

    2010-01-01

    The current study aimed to contribute to a deeper understanding of the organizational conditions of charter schools by examining teacher turnover. Using data from the National Center for Education Statistics (NCES) 2003-04 Schools and Staffing Survey (SASS) and the Teacher Follow-Up Survey (TFS), researchers from the National Center on School…

  10. Director Turnover: An Australian Academic Development Study

    Science.gov (United States)

    Fraser, Kym; Ryan, Yoni

    2012-01-01

    Although it can be argued that directors of central academic development units (ADUs) are critical to the implementation of university teaching and learning strategies, it would appear there is a high director turnover rate. While research in the USA, the UK, and Australia illustrates that ADUs are frequently closed or restructured, that research…

  11. Antecedents of Norwegian Beginning Teachers' Turnover Intentions

    Science.gov (United States)

    Tiplic, Dijana; Brandmo, Christian; Elstad, Eyvind

    2015-01-01

    This study aims at exploring several individual, organizational, and contextual factors that may affect beginning teachers' turnover intentions during their first years of practice. The sample consists of 227 beginning teachers (69% female and 31% male) from 133 schools in Norway. The results show four important antecedents of beginning teachers'…

  12. Turnover among Community Mental Health Workers in Ohio.

    Science.gov (United States)

    Bukach, Ashley M; Ejaz, Farida K; Dawson, Nicole; Gitter, Robert J

    2017-01-01

    This study examined turnover of community mental health workers in 42 randomly selected mental health agencies in Ohio. The turnover rate in 2011 was 26 %. A regression analysis indicated that agencies with lower turnover offered higher maximum pay and were smaller in size, while those offering career advancement opportunities, such as career ladder programs, had higher turnover. The findings suggest that improving wages for workers is likely to reduce turnover. It is also possible that smaller agencies have lower turnover due to stronger relationships with workers and/or more successful hiring practices. Furthermore, turnover that occurs as a result of career advancement could have positive effects and should be examined separate from other types of turnover in the future.

  13. Work-life balance, job satisfaction and turnover intention amongst ...

    African Journals Online (AJOL)

    Work-life balance, job satisfaction and turnover intention amongst ... Employee turnover has signifi cant costs and negative consequences for ... However, no interaction effect was observed between overall work-life balance and job ...

  14. Turnover of grain legume N rhizodeposits and effect of rhizodeposition on the turnover of crop residues

    DEFF Research Database (Denmark)

    Mayer, J.; Buegger, F.; Jensen, E.S.

    2004-01-01

    The turnover of N derived from rhizodeposition of faba bean (Vicia faba L.), pea (Pisum sativum L.) and white lupin (Lupinus albus L.) and the effects of the rhizodeposition on the subsequent C and N turnover of its crop residues were investigated in an incubation experiment (168 days, 15 degrees....... In the experiment the turnover of C and N was compared in soils with and without previous growth of three legumes and with and without incorporation of crop residues. After 168 days, 21% (lupin), 26% (faba bean) and 27% (pea) of rhizodeposition N was mineralised in the treatments without crop residues. A smaller...... amount of 15-17% was present as microbial biomass and between 30 and 55% of mineralised rhizodeposition N was present as microbial residue pool, which consists of microbial exoenzymes, mucous substances and dead microbial biomass. The effect of rhizodeposition on the C and N turnover of crop residues...

  15. Electron transfer patterns of the di-heme protein cytochrome c(4) from Pseudomonas stutzeri

    DEFF Research Database (Denmark)

    Raffalt, Anders Christer; Schmidt, L.; Christensen, Hans Erik Mølager

    2009-01-01

    protein structural mobility in the overall two-ET process. We suggest that conformational protein mobility blocks intramolecular interheme ET in bulk homogeneous solution but triggers opening of this gated ET channel in the electrochemical environment or in the membrane environment of natural respiratory...

  16. Earnings Management Surrounding CEO Turnover: Evidence from Korea

    OpenAIRE

    JONG-SEO CHOI; YOUNG-MIN KWAK; CHONGWOO CHOE

    2012-01-01

    This article examines the empirical relation between CEO turnover and earnings management in Korea using a sample of 317 CEO turnovers and 634 non-turnover control firms during the period of 2001-2008. We classify CEO turnovers into four types depending on whether the departure of outgoing CEO is peaceful or forced and the incoming CEO is promoted from within or recruited from outside the firm. We measure earnings management by both discretionary accruals and real activities management. We al...

  17. A Ministudy of employee turnover in US hospitals.

    Science.gov (United States)

    Collins, Sandra K; McKinnies, Richard C; Matthews, Eric P; Collins, Kevin S

    2015-01-01

    A ministudy was conducted to collect self-reported employee turnover rates in US hospitals. The results indicate many hospitals are struggling with high employee turnover rates. Widespread variances in ratings were observed across hospitals, which may be due to lack of consistency in how they each calculate their employee turnover. This makes benchmarking for the purposes of performance improvement challenging.

  18. Salary and Ranking and Teacher Turnover: A Statewide Study

    Science.gov (United States)

    Garcia, Cynthia Martinez; Slate, John R.; Delgado, Carmen Tejeda

    2009-01-01

    This study examined three years of data obtained from the Academic Excellence Indicator System of the State of Texas regarding teacher turnover rate and teacher salary. Across all public school districts, teacher salary was consistently negatively related to teacher turnover; that is, where salary was lower, turnover rate was higher When data were…

  19. Investing in Leadership: The District's Role in Managing Principal Turnover

    Science.gov (United States)

    Mascall, Blair; Leithwood, Kenneth

    2010-01-01

    This article presents the results of research into the impact of principal turnover on schools, and the ability of schools to mitigate the negative effects of frequent turnover by distributing leadership in the schools. The findings from this qualitative and quantitative analysis show that rapid principal turnover does indeed have a negative…

  20. Superintendent Turnover in Kentucky. Issues & Answers. REL 2011-No. 113

    Science.gov (United States)

    Johnson, Jerry; Huffman, Tyler; Madden, Karen; Shope, Shane

    2011-01-01

    This study examines superintendent turnover in Kentucky public school districts for 1998/99-2007/08, looking at how turnover varies by rural status, Appalachian and non-Appalachian region, and 2007/08 school district characteristics. Key findings include: (1) Kentucky school districts averaged one superintendent turnover during 1998/99-2007/08;…

  1. High School Band Students' Perspectives of Teacher Turnover

    Science.gov (United States)

    Kloss, Thomas E.

    2013-01-01

    Teacher turnover remains an important issue in education. The least researched perspectives, though, are those of the students who experience teacher turnover. The purpose of this study was to examine how high school band students experience teacher turnover. A total of twelve students were interviewed, representing three schools that experienced…

  2. 41 CFR 109-27.5002 - Stores inventory turnover ratio.

    Science.gov (United States)

    2010-07-01

    ... turnover ratio. 109-27.5002 Section 109-27.5002 Public Contracts and Property Management Federal Property....5002 Stores inventory turnover ratio. Comparison of investment in stores inventories to annual issues... comparison may be expressed either as a turnover ratio (dollar value of issues divided by dollar value of...

  3. Turnover of regulated nurses in long-term care facilities.

    Science.gov (United States)

    Chu, Charlene H; Wodchis, Walter P; McGilton, Katherine S

    2014-07-01

    To describe the relationship between nursing staff turnover in long-term care (LTC) homes and organisational factors consisting of leadership practices and behaviours, supervisory support, burnout, job satisfaction and work environment satisfaction. The turnover of regulated nursing staff [Registered Nurses (RNs) and Registered Practical Nurses (RPNs)] in LTC facilities is a pervasive problem, but there is a scarcity of research examining this issue in Canada. The study was conceptualized using a Stress Process model. Distinct surveys were distributed to administrators to measure organisational factors and to regulated nurses to measure personal and job-related sources of stress and workplace support. In total, 324 surveys were used in the linear regression analysis to examine factors associated with high turnover rates. Higher leadership practice scores were associated with lower nursing turnover; a one score increase in leadership correlated with a 49% decrease in nursing turnover. A significant inverse relationship between leadership turnover and nurse turnover was found: the higher the administrator turnover the lower the nurse turnover rate. Leadership practices and administrator turnover are significant in influencing regulated nurse turnover in LTC. Long-term care facilities may want to focus on building good leadership and communication as an upstream method to minimize nurse turnover. © 2013 John Wiley & Sons Ltd.

  4. Modification of quinone electrochemistry by the proteins in the biological electron transfer chains: examples from photosynthetic reaction centers

    Science.gov (United States)

    Gunner, M. R.; Madeo, Jennifer; Zhu, Zhenyu

    2009-01-01

    Quinones such as ubiquinone are the lipid soluble electron and proton carriers in the membranes of mitochondria, chloroplasts and oxygenic bacteria. Quinones undergo controlled redox reactions bound to specific sites in integral membrane proteins such as the cytochrome bc1 oxidoreductase. The quinone reactions in bacterial photosynthesis are amongst the best characterized, presenting a model to understand how proteins modulate cofactor chemistry. The free energy of ubiquinone redox reactions in aqueous solution and in the QA and QB sites of the bacterial photosynthetic reaction centers (RCs) are compared. In the primary QA site ubiquinone is reduced only to the anionic semiquinone (Q•−) while in the secondary QB site the product is the doubly reduced, doubly protonated quinol (QH2). The ways in which the protein modifies the relative energy of each reduced and protonated intermediate are described. For example, the protein stabilizes Q•− while destabilizing Q= relative to aqueous solution through electrostatic interactions. In addition, kinetic and thermodynamic mechanisms for stabilizing the intermediate semiquinones are compared. Evidence for the protein sequestering anionic compounds by slowing both on and off rates as well as by binding the anion more tightly is reviewed. PMID:18979192

  5. Literature review of labour turnover and absenteeism costs in the coal mining industry

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, A.

    1977-01-01

    This paper includes labor turnover formulae, turnover costs, and turnover rates for the mining industry. Few meaningful studies or reports on absenteeism costs and labour turnover in mining were retrieved.

  6. Spectral methods for study of the G-protein-coupled receptor rhodopsin: I. Vibrational and electronic spectroscopy

    Science.gov (United States)

    Struts, A. V.; Barmasov, A. V.; Brown, M. F.

    2015-05-01

    Here we review the application of modern spectral methods for the study of G-protein-coupled receptors (GPCRs) using rhodopsin as a prototype. Because X-ray analysis gives us immobile snapshots of protein conformations, it is imperative to apply spectroscopic methods for elucidating their function: vibrational (Raman, FTIR), electronic (UV-visible absorption, fluorescence) spectroscopies, and magnetic resonance (electron paramagnetic resonance, EPR), and nuclear magnetic resonance (NMR). In the first of the two companion articles, we discuss the application of optical spectroscopy for studying rhodopsin in a membrane environment. Information is obtained regarding the time-ordered sequence of events in rhodopsin activation. Isomerization of the chromophore and deprotonation of the retinal Schiff base leads to a structural change of the protein involving the motion of helices H5 and H6 in a pH-dependent process. Information is obtained that is unavailable from X-ray crystallography, which can be combined with spectroscopic studies to achieve a more complete understanding of GPCR function.

  7. l-Tryptophan Radical Cation Electron Spin Resonance Studies: Connecting Solution-derived Hyperfine Coupling Constants with Protein Spectral Interpretations

    Science.gov (United States)

    Connor, Henry D.; Sturgeon, Bradley E.; Mottley, Carolyn; Sipe, Herbert J.; Mason, Ronald P.

    2009-01-01

    Fast-flow electron spin resonance (ESR) spectroscopy has been used to detect a free radical formed from the reaction of l-tryptophan with Ce4+ in an acidic aqueous environment. Computer simulations of the ESR spectra from l-tryptophan and several isotopically modified forms strongly support the conclusion that the l-tryptophan radical cation has been detected by ESR for the first time. The hyperfine coupling constants (HFCs) determined from the well-resolved isotropic ESR spectra support experimental and computational efforts to understand l-tryptophan's role in protein catalysis of oxidation-reduction processes. l-tryptophan HFCs facilitated the simulation of fast-flow ESR spectra of free radicals from two related compounds, tryptamine and 3-methylindole. Analysis of these three compounds' β-methylene hydrogen HFC data along with equivalent l-tyrosine data has led to a new computational method that can distinguish between these two amino acid free radicals in proteins without dependence on isotope labeling, electron nuclear double resonance or high-field ESR. This approach also produces geometric parameters (dihedral angles for the β-methylene hydrogens) which should facilitate protein site assignment of observed l-tryptophan radicals as has been done for l-tyrosine radicals. PMID:18433127

  8. PERAN STRES KERJA DAN KEPUASAN KERJA UNTUK MENGURANGI TURNOVER INTENTION

    Directory of Open Access Journals (Sweden)

    Syarifah Nazenin

    2014-09-01

    Full Text Available Tujuan penelitian ini untuk menguji pengaruh variabel stres kerja dan kepuasan kerja pada turnover intention karyawan tetap bagian produksi. Sampel penelitian ini adalah 86 responden, menggunakan metode Slovin dengan teknik probability sampling dengan jenis proportionate random sampling. Berdasarkan hasil penelitian, menunjukkan bahwa stres kerja berpengaruh positif signifikan pada turnover intention. Kemudian, kepuasan kerja berpengaruh negatif signifikan. Penelitian ini menyimpulkan, bahwa stres kerja berpengaruh positif dan signifikan pada turnover intention karyawan dan kepuasan kerja berpengaruh negatif dan signifikan terhadap turnover intention karyawan. Implikasi manajerial yang bisa dilakukan adalah dengan pengurangan tingkat stres karyawan dan membuat program untuk tujuan menekan turnover intention, seperti kesempatan promosi dan meningkatkan reward karyawan. The purpose of this study conducted to examine the effect of work stress and job satisfaction on turnover intention of employee in production department. The sample was 86 respondent, using Slovin method with proportionate random sampling technique. The result showed that job stress has a positive effect on turnover intention while job satisfaction has a negative effect on turnover intention. This study conclude that job stress has positive and significant impact on employee turnover intention and job satisfaction significantly and negatively related to turnover intention of employees. Therefore, it is recommended to managerial level people to reduce stress levels in employees and to create a program for pressing turnover intention, such as promotional opportunities and improve employee rewards.

  9. Sequencing Larger Intact Proteins (30-70 kDa) with Activated Ion Electron Transfer Dissociation

    Science.gov (United States)

    Riley, Nicholas M.; Westphall, Michael S.; Coon, Joshua J.

    2018-01-01

    The analysis of intact proteins via mass spectrometry can offer several benefits to proteome characterization, although the majority of top-down experiments focus on proteoforms in a relatively low mass range (AI-ETD) to proteins in the 30-70 kDa range. AI-ETD leverages infrared photo-activation concurrent to ETD reactions to improve sequence-informative product ion generation. This method generates more product ions and greater sequence coverage than conventional ETD, higher-energy collisional dissociation (HCD), and ETD combined with supplemental HCD activation (EThcD). Importantly, AI-ETD provides the most thorough protein characterization for every precursor ion charge state investigated in this study, making it suitable as a universal fragmentation method in top-down experiments. Additionally, we highlight several acquisition strategies that can benefit characterization of larger proteins with AI-ETD, including combination of spectra from multiple ETD reaction times for a given precursor ion, multiple spectral acquisitions of the same precursor ion, and combination of spectra from two different dissociation methods (e.g., AI-ETD and HCD). In all, AI-ETD shows great promise as a method for dissociating larger intact protein ions as top-down proteomics continues to advance into larger mass ranges. [Figure not available: see fulltext.

  10. How Wage Compression Affects Job Turnover

    OpenAIRE

    Heyman, Fredrik

    2008-01-01

    I use Swedish establishment-level panel data to test Bertola and Rogerson’s (1997) hypothesis of a positive relation between the degree of wage compression and job reallocation. Results indicate that the effect of wage compression on job turnover is positive and significant in the manufacturing sector. The wage compression effect is stronger on job destruction than on job creation, consistent with downward wage rigidity. Further results include a strong positive relationship between the fract...

  11. Measuring temporal turnover in ecological communities

    OpenAIRE

    Shimadzu, Hideyasu; Dornelas, Maria; Magurran, Anne

    2015-01-01

    The authors acknowledge support from the European Research Council (project BioTIME 250189) and the Royal Society. MD acknowledges funding from the Marine Alliance for Science and Technology Scotland (MASTS). MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. 1.Range migrations in response to climate change, invasive species and the emergence of novel ecosystems highlight the importance of temporal turnover in community composition as a...

  12. Stock Option Compensation and Managerial Turnover

    OpenAIRE

    Raluca Georgiana NASTASESCU

    2009-01-01

    This study examines the association between managerial turnover and equity-based compensation. I investigate whether stock options act to bond executives to their firms and whether retention of managers is a motivation of companies in designing CEO incentive contracts. The results show that stock options do negatively influence the probability of a CEO leaving the company. The monetary cost of losing the value of equity-based compensation package keeps the manager with his company. I also fin...

  13. High bone turnover in Irish professional jockeys.

    LENUS (Irish Health Repository)

    Waldron-Lynch, F

    2012-02-01

    SUMMARY: Professional jockeys are routinely exposed to high impact trauma and sustain fractures frequently. We found that jockeys restrict their caloric intake in order to maintain regulation weights, and that bone turnover is high. There are significant health and safety implications for the racing industry. INTRODUCTION: Professional jockeys routinely sustain fractures from high impact falls. Jockeys maintain a low percentage body fat and a low body mass index (BMI) to achieve low weight targets in order to race. We evaluated dietary habits and bone metabolism in jockeys. METHODS: Bone mineral density (BMD) was measured in 27 male jockeys of the 144 jockeys licensed in Ireland. Fourteen (52%) had BMD T score below -1.0, of whom 12 consented to clinical review, nutritional survey, endocrine studies, and bone turnover markers (BTM). BTM were compared to age- and sex-matched controls (n = 16). RESULTS: BMI was 20.6 +\\/- 1.7 kg\\/m(2); previous fracture frequency was 3.2 +\\/- 2.0 per rider. All had normal endocrine axes. The jockeys\\' diet as determined by a 7-day dietary recall was deficient in energy, calcium, and vitamin D intake. Compared with the control group, the jockey group had evidence of increased bone turnover. CONCLUSIONS: A substantial proportion of the professional jockeys in Ireland have low-normal BMD, low BMI, and high bone turnover that may result from weight and dietary restrictions. These factors seem to have a deleterious effect on their bone health and predispose the jockeys to a high fracture risk that should be remediated.

  14. Bone mass and turnover in fibromyalgia

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Gam, A; Egsmose, C

    1993-01-01

    Physical inactivity accelerates bone loss. Since patients with fibromyalgia are relatively physically inactive, bone mass and markers of bone metabolism were determined in 12 premenopausal women with fibromyalgia and in healthy age matched female control subjects. No differences were found in lum.......01. This was linked to lower urinary creatinine excretion (p = 0.02) probably reflecting lower physical activity in the patients with fibromyalgia. We conclude that bone mass and turnover are generally not affected in premenopausal women with fibromyalgia....

  15. UV lithography-based protein patterning on silicon: Towards the integration of bioactive surfaces and CMOS electronics

    Energy Technology Data Exchange (ETDEWEB)

    Lenci, S., E-mail: silvia.lenci@iet.unipi.it [Dipartimento di Ingegneria dell' Informazione, via G.Caruso 16, Pisa I-56122 (Italy); Tedeschi, L. [Istituto di Fisiologia Clinica - CNR, via G. Moruzzi 1, Pisa I-56124 (Italy); Pieri, F. [Dipartimento di Ingegneria dell' Informazione, via G.Caruso 16, Pisa I-56122 (Italy); Domenici, C. [Istituto di Fisiologia Clinica - CNR, via G. Moruzzi 1, Pisa I-56124 (Italy)

    2011-08-01

    A simple and fast methodology for protein patterning on silicon substrates is presented, providing an insight into possible issues related to the interaction between biological and microelectronic technologies. The method makes use of standard photoresist lithography and is oriented towards the implementation of biosensors containing Complementary Metal-Oxide-Semiconductor (CMOS) conditioning circuitry. Silicon surfaces with photoresist patterns were prepared and hydroxylated by means of resist- and CMOS backend-compatible solutions. Subsequent aminosilane deposition and resist lift-off in organic solvents resulted into well-controlled amino-terminated geometries. The discussion is focused on resist- and CMOS-compatibility problems related to the used chemicals. Some samples underwent gold nanoparticle (Au NP) labeling and Scanning Electron Microscopy (SEM) observation, in order to investigate the quality of the silane layer. Antibodies were immobilized on other samples, which were subsequently exposed to a fluorescently labeled antigen. Fluorescence microscopy observation showed that this method provides spatially selective immobilization of protein layers onto APTES-patterned silicon samples, while preserving protein reactivity inside the desired areas and low non-specific adsorption elsewhere. Strong covalent biomolecule binding was achieved, giving stable protein layers, which allows stringent binding conditions and a good binding specificity, really useful for biosensing.

  16. Protein sequences and redox titrations indicate that the electron acceptors in reaction centers from heliobacteria are similar to Photosystem I

    Science.gov (United States)

    Trost, J. T.; Brune, D. C.; Blankenship, R. E.

    1992-01-01

    Photosynthetic reaction centers isolated from Heliobacillus mobilis exhibit a single major protein on SDS-PAGE of 47 000 Mr. Attempts to sequence the reaction center polypeptide indicated that the N-terminus is blocked. After enzymatic and chemical cleavage, four peptide fragments were sequenced from the Heliobacillus mobilis apoprotein. Only one of these sequences showed significant specific similarity to any of the protein and deduced protein sequences in the GenBank data base. This fragment is identical with 56% of the residues, including both cysteines, found in highly conserved region that is proposed to bind iron-sulfur center Fx in the Photosystem I reaction center peptide that is the psaB gene product. The similarity to the psaA gene product in this region is 48%. Redox titrations of laser-flash-induced photobleaching with millisecond decay kinetics on isolated reaction centers from Heliobacterium gestii indicate a midpoint potential of -414 mV with n = 2 titration behavior. In membranes, the behavior is intermediate between n = 1 and n = 2, and the apparent midpoint potential is -444 mV. This is compared to the behavior in Photosystem I, where the intermediate electron acceptor A1, thought to be a phylloquinone molecule, has been proposed to undergo a double reduction at low redox potentials in the presence of viologen redox mediators. These results strongly suggest that the acceptor side electron transfer system in reaction centers from heliobacteria is indeed analogous to that found in Photosystem I. The sequence similarities indicate that the divergence of the heliobacteria from the Photosystem I line occurred before the gene duplication and subsequent divergence that lead to the heterodimeric protein core of the Photosystem I reaction center.

  17. Protein hydrogen exchange measured at single-residue resolution by electron transfer dissociation mass spectrometry

    DEFF Research Database (Denmark)

    Rand, Kasper D; Zehl, Martin; Jensen, Ole Nørregaard

    2009-01-01

    Because of unparalleled sensitivity and tolerance to protein size, mass spectrometry (MS) has become a popular method for measuring the solution hydrogen (1H/2H) exchange (HX) of biologically relevant protein states. While incorporated deuterium can be localized to different regions by pepsin....... The deuterium labeling pattern of beta2-microglobulin is retained in the gaseous fragment ions by employing mild declustering conditions for electrospray ionization. A recently developed model peptide is used to arrive at such ion source declustering conditions that prevent the occurrence of intramolecular gas...

  18. A new software routine that automates the fitting of protein X-ray crystallographic electron-density maps.

    Science.gov (United States)

    Levitt, D G

    2001-07-01

    The classical approach to building the amino-acid residues into the initial electron-density map requires days to weeks of a skilled investigator's time. Automating this procedure should not only save time, but has the potential to provide a more accurate starting model for input to refinement programs. The new software routine MAID builds the protein structure into the electron-density map in a series of sequential steps. The first step is the fitting of the secondary alpha-helix and beta-sheet structures. These 'fits' are then used to determine the local amino-acid sequence assignment. These assigned fits are then extended through the loop regions and fused with the neighboring sheet or helix. The program was tested on the unaveraged 2.5 A selenomethionine multiple-wavelength anomalous dispersion (SMAD) electron-density map that was originally used to solve the structure of the 291-residue protein human heart short-chain L-3-hydroxyacyl-CoA dehydrogenase (SHAD). Inputting just the map density and the amino-acid sequence, MAID fitted 80% of the residues with an r.m.s.d. error of 0.43 A for the main-chain atoms and 1.0 A for all atoms without any user intervention. When tested on a higher quality 1.9 A SMAD map, MAID correctly fitted 100% (418) of the residues. A major advantage of the MAID fitting procedure is that it maintains ideal bond lengths and angles and constrains phi/psi angles to the appropriate Ramachandran regions. Recycling the output of this new routine through a partial structure-refinement program may have the potential to completely automate the fitting of electron-density maps.

  19. Web-based computational chemistry education with CHARMMing III: Reduction potentials of electron transfer proteins.

    Directory of Open Access Journals (Sweden)

    B Scott Perrin

    2014-07-01

    Full Text Available A module for fast determination of reduction potentials, E°, of redox-active proteins has been implemented in the CHARMM INterface and Graphics (CHARMMing web portal (www.charmming.org. The free energy of reduction, which is proportional to E°, is composed of an intrinsic contribution due to the redox site and an environmental contribution due to the protein and solvent. Here, the intrinsic contribution is selected from a library of pre-calculated density functional theory values for each type of redox site and redox couple, while the environmental contribution is calculated from a crystal structure of the protein using Poisson-Boltzmann continuum electrostatics. An accompanying lesson demonstrates a calculation of E°. In this lesson, an ionizable residue in a [4Fe-4S]-protein that causes a pH-dependent E° is identified, and the E° of a mutant that would test the identification is predicted. This demonstration is valuable to both computational chemistry students and researchers interested in predicting sequence determinants of E° for mutagenesis.

  20. Treatment staff turnover in organizations implementing evidence-based practices: Turnover rates and their association with client outcomes

    Science.gov (United States)

    Garner, Bryan R.; Hunter, Brooke D.; Modisette, Kathryn C.; Ihnes, Pamela C.; Godley, Susan H.

    2011-01-01

    High staff turnover has been described as a problem for the substance use disorder treatment field. This assertion is based primarily on the assumption that staff turnover adversely impacts treatment delivery and effectiveness. This assumption, however, has not been empirically tested. In this study, we computed annualized rates of turnover for treatment staff (n=249) participating in an evidence-based practice implementation initiative and examined the association between organizational-level rates of staff turnover and client-level outcomes. Annualized rates of staff turnover were 31% for clinicians and 19% for clinical supervisors. Additionally, multilevel analyses did not reveal the expected relationship between staff turnover and poorer client-level outcomes. Rather, organizational-level rates of staff turnover were found to have a significant positive association with two measures of treatment effectiveness: less involvement in illegal activity and lower social risk. Possible explanations for these findings are discussed. PMID:22154040

  1. Glucosamine but not ibuprofen alters cartilage turnover in osteoarthritis patients in response to physical training

    DEFF Research Database (Denmark)

    Petersen, Susanne Germann; Saxne, T; Heinegard, D

    2010-01-01

    OBJECTIVE: To investigate changes in levels of serum cartilage oligomeric matrix protein (COMP) and urine c-telopeptide of type-2 collagen (CTX-II) as markers for cartilage turnover in patients with osteoarthritis (OA) of the knee, in response to muscle strength training in combination with treat......OBJECTIVE: To investigate changes in levels of serum cartilage oligomeric matrix protein (COMP) and urine c-telopeptide of type-2 collagen (CTX-II) as markers for cartilage turnover in patients with osteoarthritis (OA) of the knee, in response to muscle strength training in combination......). RESULTS: All three groups increased their muscle strength following 12 weeks of strength training (Preduced in the glucosamine-treated group after the training period (P=0.012), whereas they did not change in the two other groups. Glucosamine reduced COMP statistically...

  2. Turnover in health care: the mediating effects of employee engagement.

    Science.gov (United States)

    Collini, Stevie A; Guidroz, Ashley M; Perez, Lisa M

    2015-03-01

    This study aimed to understand the interaction between interpersonal respect, diversity climate, mission fulfilment and engagement to better predict turnover in health care. Registered nurse turnover has averaged 14% and current nursing shortages are expected to spread. Few studies have studied employee engagement as a mediator between organisational context and turnover. Study participants were employees working within 185 departments across ten hospitals within a large healthcare organisation in the USA. Although a total of 5443 employees work in these departments, employee opinion survey responses were aggregated by department before being linked to turnover rates gathered from company records. Engagement fully mediated the relationship between respect and turnover and the relationship between mission fulfilment and turnover. Diversity climate was not related to turnover. Turnover in health care poses a significant threat to the mission of creating a healing environment for patients and these results demonstrate that workplace respect and connection to the mission affect turnover by decreasing engagement. The findings demonstrated that to increase engagement, and improve turnover rates in health care, it would be beneficial for organisations, and nurse management to focus on improving mission fulfilment and interpersonal relationships. © 2013 John Wiley & Sons Ltd.

  3. Workforce turnover at local health departments: nature, characteristics, and implications.

    Science.gov (United States)

    Newman, Sarah J; Ye, Jiali; Leep, Carolyn J

    2014-11-01

    Employee turnover, defined as total separations from employment, is expensive, can result in lost capacity, and can limit local health departments' (LHDs') ability to respond to public health needs. Despite the importance of workforce capacity in public health, little is known about workforce turnover in LHDs. To examine the extent to which LHDs experience turnover and identify LHD characteristics that are associated with turnover. A cross-sectional data set of employee turnover and LHD characteristics from the 2013 National Profile of LHDs was analyzed. Descriptive statistics and bivariate analyses were conducted in 2014 on turnover rates. The effect of the following LHD characteristics on turnover rates were examined: population size, governance type, degree of urbanization, top executive experience level, expenditures per capita, and LHD budget cuts. In 2013, LHDs experienced a mean turnover rate of 9.88%; approximately one third of turnover was due to retirements. LHDs with shared state and local governance experienced a higher turnover rate than LHDs with exclusive state or local governance. LHDs that are units of state agencies had a significantly higher retirement rate than those governed by local authorities. Top executive experience level, per capita expenditures, and LHD budget cuts were also related to turnover rates. LHDs experienced a lower overall turnover rate than state health departments in 2011 and lower than all local and state government agencies in 2012. Strengthening leadership skills of new top executives and ensuring adequate funding may reduce turnover in LHDs. Copyright © 2014 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  4. Resolving Electronic Transitions in Synthetic Fluorescent Protein Chromophores by Magnetic Circular Dichroism

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, P.; Cowie, T. Y.; Šafařík, Martin; Šebestík, Jaroslav; Pohl, Radek; Bouř, Petr

    2016-01-01

    Roč. 17, č. 15 (2016), s. 2348-2354 ISSN 1439-4235 R&D Projects: GA ČR GA13-03978S; GA ČR(CZ) GA16-05935S Institutional support: RVO:61388963 Keywords : density functional calculations * fluorescence protein chromophores * magnetic circular dichroism * organic synthesis * spectral simulations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.075, year: 2016

  5. Bioinformatic evidence for a widely distributed, ribosomally produced electron carrier precursor, its maturation proteins, and its nicotinoprotein redox partners

    Directory of Open Access Journals (Sweden)

    Haft Daniel H

    2011-01-01

    Full Text Available Abstract Background Enzymes in the radical SAM (rSAM domain family serve in a wide variety of biological processes, including RNA modification, enzyme activation, bacteriocin core peptide maturation, and cofactor biosynthesis. Evolutionary pressures and relationships to other cellular constituents impose recognizable grammars on each class of rSAM-containing system, shaping patterns in results obtained through various comparative genomics analyses. Results An uncharacterized gene cluster found in many Actinobacteria and sporadically in Firmicutes, Chloroflexi, Deltaproteobacteria, and one Archaeal plasmid contains a PqqE-like rSAM protein family that includes Rv0693 from Mycobacterium tuberculosis. Members occur clustered with a strikingly well-conserved small polypeptide we designate "mycofactocin," similar in size to bacteriocins and PqqA, precursor of pyrroloquinoline quinone (PQQ. Partial Phylogenetic Profiling (PPP based on the distribution of these markers identifies the mycofactocin cluster, but also a second tier of high-scoring proteins. This tier, strikingly, is filled with up to thirty-one members per genome from three variant subfamilies that occur, one each, in three unrelated classes of nicotinoproteins. The pattern suggests these variant enzymes require not only NAD(P, but also the novel gene cluster. Further study was conducted using SIMBAL, a PPP-like tool, to search these nicotinoproteins for subsequences best correlated across multiple genomes to the presence of mycofactocin. For both the short chain dehydrogenase/reductase (SDR and iron-containing dehydrogenase families, aligning SIMBAL's top-scoring sequences to homologous solved crystal structures shows signals centered over NAD(P-binding sites rather than over substrate-binding or active site residues. Previous studies on some of these proteins have revealed a non-exchangeable NAD cofactor, such that enzymatic activity in vitro requires an artificial electron acceptor such

  6. Redox activity distinguishes solid-state electron transport from solution-based electron transfer in a natural and artificial protein: cytochrome C and hemin-doped human serum albumin.

    Science.gov (United States)

    Amdursky, Nadav; Ferber, Doron; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2013-10-28

    Integrating proteins in molecular electronic devices requires control over their solid-state electronic transport behavior. Unlike "traditional" electron transfer (ET) measurements of proteins that involve liquid environments and a redox cycle, no redox cofactor is needed for solid-state electron transport (ETp) across the protein. Here we show the fundamental difference between these two approaches by macroscopic area measurements, which allow measuring ETp temperature dependence down to cryogenic temperatures, via cytochrome C (Cyt C), an ET protein with a heme (Fe-porphyrin) prosthetic group as a redox centre. We compare the ETp to electrochemical ET measurements, and do so also for the protein without the Fe (with metal-free porphyrin) and without porphyrin. As removing the porphyrin irreversibly alters the protein's conformation, we repeat these measurements with human serum albumin (HSA), 'doped' (by non-covalent binding) with a single hemin equivalent, i.e., these natural and artificial proteins share a common prosthetic group. ETp via Cyt C and HSA-hemin are very similar in terms of current magnitude and temperature dependence, which suggests similar ETp mechanisms via these two systems, thermally activated hopping (with ~0.1 eV activation energy) >190 K and tunneling by superexchange Fe(3+) + e(-)), measured by electrochemistry of HSA-hemin are only 4 times lower than those for Cyt C. However, while removing the Fe redox centre from the porphyrin ring markedly affects the ET rate, it hardly changes the ETp currents through these proteins, while removing the macrocycle (from HSA, which retains its conformation) significantly reduces ETp efficiency. These results show that solid-state ETp across proteins does not require the presence of a redox cofactor, and that while for ET the Fe ion is the main electron mediator, for ETp the porphyrin ring has this function.

  7. Norepinephrine turnover in brown adipose tissue is stimulated by a single meal

    International Nuclear Information System (INIS)

    Glick, Z.; Raum, W.J.

    1986-01-01

    A single meal stimulates brown adipose tissue (BAT) thermogenesis in rats. In the present study the role of norepinephrine in this thermogenic response was assessed from the rate of its turnover in BAT after a single test meal. For comparison, norepinephrine turnover was determined in the heart and spleen. A total of 48 male Wistar rats (200 g) were trained to eat during two feeding sessions per day. On the experimental day, one group (n = 24) was meal deprived and the other (n = 24) was given a low-protein high-carbohydrate test meal for 2 h. The synthesis inhibition method with α-methyl-p-tyrosine was employed to determine norepinephrine turnover from its concentration at four hourly time points after the meal. Tissue concentrations of norepinephrine were determined by radioimmunoassay. Norepinephrine concentration and turnover rate were increased more than threefold in BAT of the meal-fed compared with the meal-deprived rats. Neither were significantly altered by the meal in the heart or spleen. The data suggest that norepinephrine mediates a portion of the thermic effect of meals that originate in BAT

  8. Trial production of low protein irradiated natural rubber latex by low energy electron beam in pilot scale

    International Nuclear Information System (INIS)

    Utama, Marga; Yoshii, F.; Kume, T.

    2006-01-01

    Three importance factors for producing low protein by low energy electron beam (250 keV/10 mA) irradiation in pilot scale (20 liters per bath) with 1,9-nonediol diacrylate (NDA) namely: maturation time of natural rubber latex before irradiation, treatment of irradiated natural rubber latex (INRL) before and after centrifugation, and standard irradiation method has been carried out. The results showed that the optimum irradiation time for producing INRL with 5 phr (part hundred ratio of rubber) of NDA as sensitize agent, and with the rotation speed of agitation 210 rpm (rotation per minutes) was between 20-30 minutes. By using this condition tensile strength of the INRL film was 26 MPa. The maturation of natural rubber latex before irradiation is the key for driving the quality of INRL. Water extractable protein content of INRL after leaching in 1% ammonia solution for 30 minutes at room temperature was around 47 μ/g, and after adding with 1 phr of PVA (poly vinyl alcohol) or 0.1 phr CMC (carboxy methyl cellulose) the water extractable protein content decrease less than 6 μ/g. (author)

  9. Discriminating aging and protein-to-fat ratio in Cheddar cheese using sensory analysis and a potentiometric electronic tongue.

    Science.gov (United States)

    Lipkowitz, Jackie B; Ross, Carolyn F; Diako, Charles; Smith, Denise M

    2018-03-01

    The objectives of this study were to evaluate the flavor and taste attributes of full-fat Cheddar cheeses with different protein-to-fat ratios (PFR) over aging time using a descriptive sensory analysis panel and a consumer panel, and to correlate these attributes with instrumental parameters obtained by the potentiometric electronic tongue. Three Cheddar cheese formulations (PFR of 0.74, 0.85, and 1.01) were produced in triplicate and composition was verified. Cheese was aged at 7.2°C and evaluated at 2, 5, 8, 10, 11, and 12 mo by a trained panel (n = 10) for 8 flavor and 5 taste attributes and using an electronic tongue for 7 nonvolatile taste attributes. Cheese aged for 12 mo was also evaluated by a consumer sensory panel for liking and intensity attributes. Principal component analysis was performed to discriminate cheese based on aging time and PFR, whereas correlation between sensory and instrumental attributes was assessed using partial least squares regression. Descriptive sensory analysis of flavor and taste attributes differentiated Cheddar cheeses over aging time, but not among PFR formulations. The electronic tongue distinguished changes among cheese samples due to PFR formulation and aging time. The electronic tongue proved successful in characterizing the nonvolatile flavor components in Cheddar cheese and correlated with taste perceptions measured by descriptive sensory analysis. Consumer evaluations showed distinctive attribute profiles for the 3 PFR Cheddar cheese formulations. Overall, higher fat content was associated with increased flavor intensities in Cheddar cheese and drove consumer acceptability and purchase intent ratings. The electronic tongue detected smaller changes in tastes (bitter, metallic, salty, sour, spicy, sweet, and umami) of the 3 PFR formulations over time when compared with the trained panelists, who detected no differences, suggesting that the electronic tongue may be more sensitive to tastants than humans and may have the

  10. Protein synthesis and antioxidant capacity in aging mice : Effects of long-term voluntary exercise

    NARCIS (Netherlands)

    Vaanholt, Lobke M.; Speakman, John R.; Garland, Theodore; Lobley, Gerald E.; Visser, G. Henk

    2008-01-01

    Exercise increases metabolic rate and the production of reactive oxygen species (ROS) but also elevates protein turnover. ROS cause damage to macromolecules (e. g., proteins) and thereby contribute to aging. Protein turnover removes and replaces damaged proteins. The balance between these two

  11. Role of PufX protein in photosynthetic growth of Rhodobacter sphaeroides. 1. PufX is required for efficient light-driven electron transfer and photophosphorylation under anaerobic conditions.

    Science.gov (United States)

    Barz, W P; Francia, F; Venturoli, G; Melandri, B A; Verméglio, A; Oesterhelt, D

    1995-11-21

    The pufX gene is essential for photoheterotrophic growth of the purple bacterium Rhodobacter sphaeroides. In order to analyze the molecular function of the PufX membrane protein, we constructed a chromosomal pufX deletion mutant and phenotypically compared it to a pufX+ control strain and to two suppressor mutants which are able to grow photosynthetically in the absence of pufX. Using this genetic background, we confirmed that PufX is required for photoheterotrophic growth under anaerobic conditions, although all components of the photosynthetic apparatus were present in similar amounts in all strains investigated. We show that the deletion of PufX is not lethal for illuminated pufX- cells, suggesting that PufX is required for photosynthetic cell division. Since chromatophores isolated from the pufX- mutant were found to be unsealed vesicles, the role of PufX in photosynthetic energy transduction was studied in vivo. We show that PufX is essential for light-induced ATP synthesis (photophosphorylation) in anaerobically incubated cells. Measurements of absorption changes induced by a single turnover flash demonstrated that PufX is not required for electron flow through the reaction center and the cytochrome bc1 complex under anaerobic conditions. During prolonged illumination, however, PufX is essential for the generation of a sufficiently large membrane potential to allow photosynthetic growth. These in vivo results demonstrate that under anaerobic conditions PufX plays an essential role in facilitating effective interaction of the components of the photosynthetic apparatus.

  12. Sclerostin as a novel marker of bone turnover in athletes

    Directory of Open Access Journals (Sweden)

    A Zagrodna

    2016-02-01

    Full Text Available Sclerostin is a protein secreted by osteocytes that acts as an inhibitor of bone formation. It has been shown that physical activity affects sclerostin concentration and thus bone remodelling. The aim of the study was to evaluate serum concentrations of sclerostin, selected bone turnover markers (PTH, P1NP, 25(OH D3 and the intake of calcium and vitamin D in physically active versus sedentary men. A total of 59 healthy men aged 17-37 were enrolled in the study (43 athletes and 16 non-athletes. The mean sclerostin concentration in the group of athletes (A was significantly higher than in non-athletes (NA (35.3±8.9 vs 28.0±5.6 pmol• l-1, p= 0.004. A compared with NA had higher concentrations of P1NP (145.6±77.5 vs 61.2±22.3 ng• ml-1, p= <0.0001 and 25(OHD3 (16.9±8.4 vs 10.3±4.3 ng • ml-1, p= 0.004 and lower concentrations of PTH (25.8±8.3 vs 38.2±11.5 pg• ml-1, p= <0.0001. Vitamin D deficiency was found in 77% of A and 100% of NA. A and NA had similar daily energy intake. They did not differ as to the intake of calcium and vitamin D. We observed a negative correlation between the serum concentrations of sclerostin and calcium in the studied subjects. Our results suggest that regular, long-lasting physical training may be associated with higher concentration of sclerostin. It seems that increased sclerostin is not related to other bone turnover markers (PTH, P1NP.

  13. PENGARUH KEPUASAN KERJA DAN KOMITMEN ORGANISASI TERHADAP TURNOVER INTENTION

    Directory of Open Access Journals (Sweden)

    V. Mardi Widyadmono

    2017-04-01

    Full Text Available This study assesses the influence of job satisfaction and organizational commitment on Turnover Intention. Futhermore, the study identify the mediation role of organizational commitment in the relationship between job satifaction and Turnover Intention. The participants of the study are 98 employees working in private companies operated in Yogyakarta, (36 men and 62 women. Respondents complete questionnaire containing questions on job satisfaction variable, questions on organizational commitment and questions on Turnover Intention. The statistics tools applied are regression analysis to assess the relation between variables and Sobel test to measure the mediation role of organizational commitment. The results of the investigation revealed that job satisfication and organizational commitment influence negatively and significantly Turnover Intention. The higher the job satisfication and the organizational commitment of employees lead to the lower Turnover Intention. The organizational commitment does not play mediation role in the relationship between job satisfication and Turnover Intention

  14. Mentor program boosts new nurses' satisfaction and lowers turnover rate.

    Science.gov (United States)

    Fox, Kathy C

    2010-07-01

    In 2004, the turnover rate among first-year registered nurses (RNs) at St. Francis Hospital and Health Centers had mushroomed to 31%. Based on research, in 2006, the hospital embarked on a journey to implement an RN mentor program to improve satisfaction and reduce turnover. A pilot program was initiated, including 12 RN mentors and 12 RN protégés from select nursing units. The results showed a 0% turnover rate during the 1-year pilot program. Based on these findings, the mentor program was expanded to include RNs working in inpatient nursing units and surgery and emergency departments. Each year, the RN turnover rate has decreased. In 2009, the turnover rate was 10.3%. Because of the success of the program, it has been expanded in scope to include other professionals experiencing high turnover in targeted departments, including radiological technicians, respiratory therapists, pharmacists, and physical therapists.

  15. Turnover of circulating hematopoietic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Dorie, M J; Maloney, M A; Patt, H M

    1979-10-01

    Short-term parabiosis of male and female CBA/CaJ mice was used to investigate the turnover of circulating hematopoietic stem cells. The change and subsequent disappearance of donor stem cells were monitored by spleen colony assay and chromosome analysis of individual colonies. The results revealed an exponential disappearance of pluripotent stem cells from blood with a characteristic half time of 1.7 h. Blood-borne stem cells were shown to be equilibrated with a subpopulation of marrow stem cells exhibiting a disappearance half time of 9.5 h. Splenectomy did not change the apparent rate of stem cell removal from the blood.

  16. Endogenous Turnover of Cyanogenic Glycosides in Plants

    DEFF Research Database (Denmark)

    Picmanova, Martina

    , there is strong evidence that CNglcs serve a no less significant purpose as a transport and storage form of reduced nitrogen which may be remobilized and recycled to balance the needs of primary metabolism during certain developmental events. Reduced nitrogen from CNglcs may be recovered either via HCN refixation...... revealed the formation of glycosides of amides, carboxylic acids and "anitriles", including their di- and triglycosides, evidently derived from CNglcs. Based on results common to the three phylogenetically unrelated plant species, a recycling endogenous turnover pathway for CNglcs was suggested in which...

  17. Protein 3D Structure and Electron Microscopy Map Retrieval Using 3D-SURFER2.0 and EM-SURFER.

    Science.gov (United States)

    Han, Xusi; Wei, Qing; Kihara, Daisuke

    2017-12-08

    With the rapid growth in the number of solved protein structures stored in the Protein Data Bank (PDB) and the Electron Microscopy Data Bank (EMDB), it is essential to develop tools to perform real-time structure similarity searches against the entire structure database. Since conventional structure alignment methods need to sample different orientations of proteins in the three-dimensional space, they are time consuming and unsuitable for rapid, real-time database searches. To this end, we have developed 3D-SURFER and EM-SURFER, which utilize 3D Zernike descriptors (3DZD) to conduct high-throughput protein structure comparison, visualization, and analysis. Taking an atomic structure or an electron microscopy map of a protein or a protein complex as input, the 3DZD of a query protein is computed and compared with the 3DZD of all other proteins in PDB or EMDB. In addition, local geometrical characteristics of a query protein can be analyzed using VisGrid and LIGSITE CSC in 3D-SURFER. This article describes how to use 3D-SURFER and EM-SURFER to carry out protein surface shape similarity searches, local geometric feature analysis, and interpretation of the search results. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  18. Submolecular Gates Self-Assemble for Hot-Electron Transfer in Proteins.

    Science.gov (United States)

    Filip-Granit, Neta; Goldberg, Eran; Samish, Ilan; Ashur, Idan; van der Boom, Milko E; Cohen, Hagai; Scherz, Avigdor

    2017-07-27

    Redox reactions play key roles in fundamental biological processes. The related spatial organization of donors and acceptors is assumed to undergo evolutionary optimization facilitating charge mobilization within the relevant biological context. Experimental information from submolecular functional sites is needed to understand the organization strategies and driving forces involved in the self-development of structure-function relationships. Here we exploit chemically resolved electrical measurements (CREM) to probe the atom-specific electrostatic potentials (ESPs) in artificial arrays of bacteriochlorophyll (BChl) derivatives that provide model systems for photoexcited (hot) electron donation and withdrawal. On the basis of computations we show that native BChl's in the photosynthetic reaction center (RC) self-assemble at their ground-state as aligned gates for functional charge transfer. The combined computational and experimental results further reveal how site-specific polarizability perpendicular to the molecular plane enhances the hot-electron transport. Maximal transport efficiency is predicted for a specific, ∼5 Å, distance above the center of the metalized BChl, which is in remarkably close agreement with the distance and mutual orientation of corresponding native cofactors. These findings provide new metrics and guidelines for analysis of biological redox centers and for designing charge mobilizing machines such as artificial photosynthesis.

  19. The phase model of burnout and employee turnover.

    Science.gov (United States)

    Goodman, Eric A; Boss, R Wayne

    2002-01-01

    This study explores the phase model of burnout and investigates its relationship to actual turnover in a hospital. The results indicate that employees who turnover have significantly higher burnout phase scores that those who stay in the organization. A further comparison of voluntary and involuntary turnover demonstrates that there is no significant differences on burnout phase scores. The findings lend support to the usefulness of the phase model of burnout.

  20. Job and industry turnover for registered and licensed vocational nurses.

    Science.gov (United States)

    Spetz, Joanne; Rickles, Jordan; Chapman, Susan; Ong, Paul M

    2008-09-01

    Most studies of nurse turnover focus on job turnover, which could reflect nurse advancement and thus not be detrimental to the workforce. The authors discuss findings from a study that involved 2 cohorts of graduates from registered nursing and licensed vocational nursing community college programs in California. The duration of employment in the healthcare industry, as well as with specific employers, is tracked, lending a more thorough analysis of nursing job and industry turnover than found in other studies.

  1. The Impact of Human Resource Management Practices on Employee Turnover

    OpenAIRE

    Ozoliņa-Ozola, I

    2014-01-01

    The aim of this research was to identify the human resource management practices that are effective for employee turnover reducing. For this purpose the methods of document analysis and expert survey were used. On the basis of analysis of the scientific literature retrieved from academic databases the human resource management practices, which were mentioned in connection with employee turnover, were detected and described its effect on employee turnover. By conducting two separate expert sur...

  2. Does public service performance affect top management turnover?

    OpenAIRE

    Boyne, George A.; James, Oliver; John, Peter; Petrovsky, Nicolai

    2010-01-01

    Political and organizational theories suggest that the turnover of chief executives and other members of senior management teams are likely to be influenced by public service performance. We use a panel data set of 148 English local governments over 4 years to test this proposition. The empirical results show that performance has a negative effect on turnover, but that this effect is weaker for chief executives than for members of their senior management teams. In addition, top team turnover ...

  3. Explaining turnover intention in Korean public community hospitals: occupational differences.

    Science.gov (United States)

    Hwang, Jee-In; Chang, Hyejung

    2008-01-01

    Personnel in public hospitals had relatively low job satisfaction despite of tenure employment. High turnover rates degrade hospital image and incur additional costs related to recruitment and training. The purposes of this study were to describe the occupational differences and to identify factors affecting turnover intention among public hospital personnel. A questionnaire survey was conducted as part of Administrative Services Quality Evaluation Program by Seoul metropolitan municipality from 1 November to 1 December in 2003. The subjects were 1251 entire hospital personnel in four hospitals. The questionnaire was designed to measure job satisfaction, organizational commitment, turnover intention, and demographic characteristics. Logistic regression analysis was performed to determine factors influencing turnover intention. There were significant differences in job satisfaction, organizational commitment, and turnover intention according to the occupations. The turnover intention rates were highest among physicians, followed by paramedicals and nursing staffs and then administrators. The significant factors affecting turnover intention were involvement and loyalty among physicians, hospital type, satisfaction with systems and loyalty among nursing staffs, satisfaction with relationship and loyalty among administrators, and loyalty among paramedicals. There were different moderators that influence turnover intentions of hospital personnel. Loyalty had the most important effect upon turnover intention in all occupations. 2007 John Wiley & Sons, Ltd

  4. Scale dependence in species turnover reflects variance in species occupancy.

    Science.gov (United States)

    McGlinn, Daniel J; Hurlbert, Allen H

    2012-02-01

    Patterns of species turnover may reflect the processes driving community dynamics across scales. While the majority of studies on species turnover have examined pairwise comparison metrics (e.g., the average Jaccard dissimilarity), it has been proposed that the species-area relationship (SAR) also offers insight into patterns of species turnover because these two patterns may be analytically linked. However, these previous links only apply in a special case where turnover is scale invariant, and we demonstrate across three different plant communities that over 90% of the pairwise turnover values are larger than expected based on scale-invariant predictions from the SAR. Furthermore, the degree of scale dependence in turnover was negatively related to the degree of variance in the occupancy frequency distribution (OFD). These findings suggest that species turnover diverges from scale invariance, and as such pairwise turnover and the slope of the SAR are not redundant. Furthermore, models developed to explain the OFD should be linked with those developed to explain species turnover to achieve a more unified understanding of community structure.

  5. Preservation of high resolution protein structure by cryo-electron microscopy of vitreous sections

    International Nuclear Information System (INIS)

    Sader, Kasim; Studer, Daniel; Zuber, Benoit; Gnaegi, Helmut; Trinick, John

    2009-01-01

    We have quantitated the degree of structural preservation in cryo-sections of a vitrified biological specimen. Previous studies have used sections of periodic specimens to assess the resolution present, but preservation before sectioning was not assessed and so the damage due particularly to cutting was not clear. In this study large single crystals of lysozyme were vitrified and from these X-ray diffraction patterns extending to better than 2.1 A were obtained. The crystals were high pressure frozen in 30% dextran, and cryo-sectioned using a diamond knife. In the best case, preservation to a resolution of 7.9 A was shown by electron diffraction, the first observation of sub-nanometre structural preservation in a vitreous section.

  6. Dynamics of Adipocyte Turnover in Humans

    Energy Technology Data Exchange (ETDEWEB)

    Spalding, K; Arner, E; Westermark, P; Bernard, S; Buchholz, B; Bergmann, O; Blomqvist, L; Hoffstedt, J; Naslund, E; Britton, T; Concha, H; Hassan, M; Ryden, M; Frisen, J; Arner, P

    2007-07-16

    Obesity is increasing in an epidemic fashion in most countries and constitutes a public health problem by enhancing the risk for cardiovascular disease and metabolic disorders such as type 2 diabetes. Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time in recent history. The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells is thought to be most important. We show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese and even under extreme conditions, indicating that the number of adipocytes is set during childhood and adolescence. To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analyzing the integration of {sup 14}C derived from nuclear bomb tests in genomic DNA. Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. Neither adipocyte death nor generation rate is altered in obesity, suggesting a tight regulation of fat cell number that is independent of metabolic profile in adulthood. The high turnover of adipocytes establishes a new therapeutic target for pharmacological intervention in obesity.

  7. Towards first-principles calculation of electronic excitations in the ring of the protein-bound bacteriochlorophylls

    Science.gov (United States)

    Polyakov, Igor V.; Khrenova, Maria G.; Moskovsky, Alexander A.; Shabanov, Boris M.; Nemukhin, Alexander V.

    2018-04-01

    Modeling electronic excitation of bacteriochlorophyll (BChl) molecules in light-harvesting (LH) antennae from photosynthetic centers presents a challenge for the quantum theory. We report on a quantum chemical study of the ring of 32 BChl molecules from the bacterial core complex LH1-RC. Diagonal and off-diagonal elements of the excitonic Hamiltonian matrices are estimated in quantum chemical calculations of relevant fragments using the TD-DFT and CIS approaches. The deviation of the computed excitation energy of this BChl system from the experimental data related to the Qy band maximum of this LH1-RC complex is about 0.2 eV. We demonstrate that corrections due to improvement in modeling of an individual BChl molecule and due to contributions from the protein environment are in the range of the obtained discrepancy between theory and experiment. Differences between results of the excitonic model and direct quantum chemical calculations of BChl aggregates fall in the same range.

  8. Application of mid-infrared free-electron laser tuned to amide bands for dissociation of aggregate structure of protein.

    Science.gov (United States)

    Kawasaki, Takayasu; Yaji, Toyonari; Ohta, Toshiaki; Tsukiyama, Koichi

    2016-01-01

    A mid-infrared free-electron laser (FEL) is a linearly polarized, high-peak powered pulse laser with tunable wavelength within the mid-infrared absorption region. It was recently found that pathogenic amyloid fibrils could be partially dissociated to the monomer form by the irradiation of the FEL targeting the amide I band (C=O stretching vibration), amide II band (N-H bending vibration) and amide III band (C-N stretching vibration). In this study, the irradiation effect of the FEL on keratin aggregate was tested as another model to demonstrate an applicability of the FEL for dissociation of protein aggregates. Synchrotron radiation infrared microscopy analysis showed that the α-helix content in the aggregate structure decreased to almost the same level as that in the monomer state after FEL irradiation tuned to 6.06 µm (amide I band). Both irradiations at 6.51 µm (amide II band) and 8.06 µm (amide III band) also decreased the content of the aggregate but to a lesser extent than for the irradiation at the amide I band. On the contrary, the irradiation tuned to 5.6 µm (non-absorbance region) changed little the secondary structure of the aggregate. Scanning-electron microscopy observation at the submicrometer order showed that the angular solid of the aggregate was converted to non-ordered fragments by the irradiation at each amide band, while the aggregate was hardly deformed by the irradiation at 5.6 µm. These results demonstrate that the amide-specific irradiation by the FEL was effective for dissociation of the protein aggregate to the monomer form.

  9. Effect of Solvation on Electron Detachment and Excitation Energies of a Green Fluorescent Protein Chromophore Variant.

    Science.gov (United States)

    Bose, Samik; Chakrabarty, Suman; Ghosh, Debashree

    2016-05-19

    Hybrid quantum mechanics/molecular mechanics (QM/MM) is applied to the fluorinated green fluorescent protein (GFP) chromophore (DFHBDI) in its deprotonated form to understand the solvatochromic shifts in its vertical detachment energy (VDE) and vertical excitation energy (VEE). This variant of the GFP chromophore becomes fluorescent in an RNA environment and has a wide range of applications in biomedical and biochemical fields. From microsolvation studies, we benchmark (with respect to full QM) the accuracy of our QM/MM calculations with effective fragment potential (EFP) as the MM method of choice. We show that while the solvatochromic shift in the VEE is minimal (0.1 eV blue shift) and its polarization component is only 0.03 eV, the effect of the solvent on the VDE is quite large (3.85 eV). We also show by accurate calculations on the solvatochromic shift of the VDE that polarization accounts for ∼0.23 eV and therefore cannot be neglected. The effect of the counterions on the VDE of the deprotonated chromophore in solvation is studied in detail, and a charge-smearing scheme is suggested for charged chromophores.

  10. Enhancing Protein Disulfide Bond Cleavage by UV Excitation and Electron Capture Dissociation for Top-Down Mass Spectrometry.

    Science.gov (United States)

    Wongkongkathep, Piriya; Li, Huilin; Zhang, Xing; Loo, Rachel R Ogorzalek; Julian, Ryan R; Loo, Joseph A

    2015-11-15

    The application of ion pre-activation with 266 nm ultraviolet (UV) laser irradiation combined with electron capture dissociation (ECD) is demonstrated to enhance top-down mass spectrometry sequence coverage of disulfide bond containing proteins. UV-based activation can homolytically cleave a disulfide bond to yield two separated thiol radicals. Activated ECD experiments of insulin and ribonuclease A containing three and four disulfide bonds, respectively, were performed. UV-activation in combination with ECD allowed the three disulfide bonds of insulin to be cleaved and the overall sequence coverage to be increased. For the larger sized ribonuclease A with four disulfide bonds, irradiation from an infrared laser (10.6 µm) to disrupt non-covalent interactions was combined with UV-activation to facilitate the cleavage of up to three disulfide bonds. Preferences for disulfide bond cleavage are dependent on protein structure and sequence. Disulfide bonds can reform if the generated radicals remain in close proximity. By varying the time delay between the UV-activation and the ECD events, it was determined that disulfide bonds reform within 10-100 msec after their UV-homolytic cleavage.

  11. Immunoassay of C-reactive protein by hot electron induced electrochemiluminescence using integrated electrodes with hydrophobic sample confinement

    Energy Technology Data Exchange (ETDEWEB)

    Ylinen-Hinkka, T., E-mail: tiina.ylinen-hinkka@aalto.fi [Laboratory of Analytical Chemistry, Aalto University School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto (Finland); Niskanen, A.J.; Franssila, S. [Department of Materials Science and Engineering, Aalto University School of Chemical Technology, P.O. Box 16200, FI-00076 Aalto (Finland); Kulmala, S. [Laboratory of Analytical Chemistry, Aalto University School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto (Finland)

    2011-09-19

    Highlights: {center_dot} C-reactive protein has been determined in the concentration range 0.01-10 mg L{sup -1} using an electrochemiluminescence microchip which employs integrated electrodes with hydrophobic sample confinement. {center_dot} This arrangement enables very simple and fast CRP analysis amenable to point-of-care applications. - Abstract: C-reactive protein (CRP) was determined in the concentration range 0.01-10 mg L{sup -1} using hot electron induced electrochemiluminescence (HECL) with devices combining both working and counter electrodes and sample confinement on a single chip. The sample area on the electrodes was defined by a hydrophobic ring, which enabled dispensing the reagents and the analyte directly on the electrode. Immunoassay of CRP by HECL using integrated electrodes is a good candidate for a high-sensitivity point-of-care CRP-test, because the concentration range is suitable, miniaturisation of the measurement system has been demonstrated and the assay method with integrated electrodes is easy to use. High-sensitivity CRP tests can be used to monitor the current state of cardiovascular disease and also to predict future cardiovascular problems in apparently healthy people.

  12. Effects of electron beam irradiation on chemical composition, antinutritional factors, ruminal degradation and in vitro protein digestibility of canola meal

    International Nuclear Information System (INIS)

    Taghinejad-Roudbaneh, M.; Ebrahimi, S.R.; Azizi, S.; Shawrang, P.

    2010-01-01

    The aim of the present study was to determine the impact of electron beam (EB) irradiation at doses of 15, 30 and 45 kGy on the nutritional value of canola meal. The phytic acid and total glucosinolate content of EB-irradiated canola meal decreased as irradiation doses increased (P<0.01). From in situ results, irradiation of canola meal at doses of 45 kGy decreased (P<0.05) the effective degradibility of crude protein (CP) by 14%, compared with an untreated sample. In vitro CP digestibility of EB-irradiated canola meal at doses of 15 and 30 kGy was improved (P<0.05). Electrophoresis results showed that napin and cruciferin sub-units of 30 and 45 kGy EB-irradiated canola meal were more resistant to degradation, compared with an untreated sample. Electron beam irradiation was effective in protecting CP from ruminal degradation and reducing antinutritional factors of irradiated canola meal.

  13. Effects of electron beam irradiation on chemical composition, antinutritional factors, ruminal degradation and in vitro protein digestibility of canola meal

    Energy Technology Data Exchange (ETDEWEB)

    Taghinejad-Roudbaneh, M., E-mail: mtaghinejad@iaut.ac.i [Department of Animal Science, Faculty of Agriculture, Islamic Azad University, Tabriz Branch, P.O. Box 51589, Tabriz (Iran, Islamic Republic of); Ebrahimi, S.R. [Department of Animal Science, Faculty of Agriculture, Shahr-e-Qods Branch, Islamic Azad University, P.O. Box 37515-374, Shahr-e-Qods (Iran, Islamic Republic of); Azizi, S. [Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, P.O. Box 57155-1177, Urmia (Iran, Islamic Republic of); Shawrang, P. [Nuclear Science and Technology Research Institute, Agricultural, Medical and Industrial Research School, Atomic Energy Organization of Iran, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of)

    2010-12-15

    The aim of the present study was to determine the impact of electron beam (EB) irradiation at doses of 15, 30 and 45 kGy on the nutritional value of canola meal. The phytic acid and total glucosinolate content of EB-irradiated canola meal decreased as irradiation doses increased (P<0.01). From in situ results, irradiation of canola meal at doses of 45 kGy decreased (P<0.05) the effective degradibility of crude protein (CP) by 14%, compared with an untreated sample. In vitro CP digestibility of EB-irradiated canola meal at doses of 15 and 30 kGy was improved (P<0.05). Electrophoresis results showed that napin and cruciferin sub-units of 30 and 45 kGy EB-irradiated canola meal were more resistant to degradation, compared with an untreated sample. Electron beam irradiation was effective in protecting CP from ruminal degradation and reducing antinutritional factors of irradiated canola meal.

  14. Site-Specific Protein Labeling Utilizing Lipoic Acid Ligase (LplA) and Bioorthogonal Inverse Electron Demand Diels-Alder Reaction.

    Science.gov (United States)

    Baalmann, Mathis; Best, Marcel; Wombacher, Richard

    2018-01-01

    Here, we describe a two-step protocol for selective protein labeling based on enzyme-mediated peptide labeling utilizing lipoic acid ligase (LplA) and bioorthogonal chemistry. The method can be applied to purified proteins, protein in cell lysates, as well as living cells. In a first step a W37V mutant of the lipoic acid ligase (LplA W37V ) from Escherichia coli is utilized to ligate a synthetic chemical handle site-specifically to a lysine residue in a 13 amino acid peptide motif-a short sequence that can be genetically expressed as a fusion with any protein of interest. In a second step, a molecular probe can be attached to the chemical handle in a bioorthogonal Diels-Alder reaction with inverse electron demand (DA inv ). This method is a complementary approach to protein labeling using genetic code expansion and circumvents larger protein tags while maintaining label specificity, providing experimental flexibility and straightforwardness.

  15. An Electron microscopic, radioautographic study of protein synthesis in vitro in the palatal mucosa of the rat

    International Nuclear Information System (INIS)

    Kim, Hyun Joo

    1987-01-01

    The incorporation of 3H-proline by epithelial and connective tissue elements of rat palatal mucosa was studied in order to investigate the relative levels of protein synthesis by the epithelium and underlying connective tissue cells. Following a sixty minutes incorporation of the radioactive tracer in vitro, it was found that the suprabasal cells had most grains per unit area. Furthermore, the grains were more concentrated over the cytoplasm than the nucleus. This was in contrast with the labeling of basal cells which had twice as many grains over the nucleoplasm than that over the cytoplasm. In intermediate cells; i.e., the spinous layer, the number of silver grains per unit area was decreased from that of the surprabasal cells. In area where desmosomes were more prominent, many grains were in touch with such desmosomes. However, the labeling appeared to be reduced as soon as the cells became flattened. Moreover, the epidermal keratohyalin granules were relatively free of grains. Except for certain intercellular surfaces the keratinized cells were generally free of grains. On the connective tissue side, silver grains were primarily localized over the fibroblasts with occasional grains over collagenous fibers were found over palatal muscle cells, neural elements and so on. Most grains over collagenous fibers were found in relation to mature collagen fibrils. Thus, protein synthesis in isolated mucosas of the rat palate apparent take place both in epithelial and connective elements. There were no apparent tissue alterations caused by the in vitro incorporation procedure utilized under conditions of this study. Key words: Electron microscopy, Radioautography, Protein synthesis, In vitro, Rat, Palate, 3H-poline

  16. Sequential Proton Loss Electron Transfer in Deactivation of Iron(IV) Binding Protein by Tyrosine Based Food Components.

    Science.gov (United States)

    Tang, Ning; Skibsted, Leif H

    2017-08-02

    The iron(IV) binding protein ferrylmyoglobin, MbFe(IV)═O, was found to be reduced by tyrosine based food components in aqueous solution through a sequential proton loss electron transfer reaction mechanism without binding to the protein as confirmed by isothermal titration calorimetry. Dopamine and epinephrine are the most efficient food components reducing ferrylmyoglobin to oxymyoglobin, MbFe(II)O 2 , and metmyoglobin, MbFe(III), as revealed by multivariate curve resolution alternating least-squares with second order rate constants of 33.6 ± 2.3 L/mol/s (ΔH ⧧ of 19 ± 5 kJ/mol, ΔS ⧧ of -136 ± 18 J/mol K) and 228.9 ± 13.3 L/mol/s (ΔH ⧧ of 110 ± 7 kJ/mol, ΔS ⧧ of 131 ± 25 J/mol K), respectively, at pH 7.4 and 25 °C. The other tyrosine based food components were found to reduce ferrylmyoglobin to metmyoglobin with similar reduction rates at pH 7.4 and 25 °C. These reduction reactions were enhanced by protonation of ferrylmyoglobin and facilitated proton transfer at acidic conditions. Enthalpy-entropy compensation effects were observed for the activation parameters (ΔH ⧧ and ΔS ⧧ ), indicating the common reaction mechanism. Moreover, principal component analysis combined with heat map were performed to understand the relationship between density functional theory calculated molecular descriptors and kinetic data, which was further modeled by partial least squares for quantitative structure-activity relationship analysis. In addition, a three tyrosine residue containing protein, lysozyme, was also found to be able to reduce ferrylmyoglobin with a second order rate constant of 66 ± 28 L/mol/s as determined by a competitive kinetic method.

  17. Static and dynamic protein impact on electronic properties of light-harvesting complex LH2.

    Science.gov (United States)

    Zerlauskiene, O; Trinkunas, G; Gall, A; Robert, B; Urboniene, V; Valkunas, L

    2008-12-11

    A comparative analysis of the temperature dependence of the absorption spectra of the LH2 complexes from different species of photosynthetic bacteria, i.e., Rhodobacter sphaeroides, Rhodoblastus acidophilus, and Phaeospirillum molischianum, was performed in the temperature range from 4 to 300 K. Qualitatively, the temperature dependence is similar for all of the species studied. The spectral bandwidths of both B800 and B850 bands increases with temperature while the band positions shift in opposite directions: the B800 band shifts slightly to the red while the B850 band to the blue. These results were analyzed using the modified Redfield theory based on the exciton model. The main conclusion drawn from the analysis was that the spectral density function (SDF) is the main factor underlying the strength of the temperature dependence of the bandwidths for the B800 and B850 electronic transitions, while the bandwidths themselves are defined by the corresponding inhomogeneous distribution function (IDF). Slight variation of the slope of the temperature dependence of the bandwidths between species can be attributed to the changes of the values of the reorganization energies and characteristic frequencies determining the SDF. To explain the shift of the B850 band position with temperature, which is unusual for the conventional exciton model, a temperature dependence of the IDF must be postulated. This dependence can be achieved within the framework of the modified (dichotomous) exciton model. The slope of the temperature dependence of the B850 bandwidth is then defined by the value of the reorganization energy and by the difference between the transition energies of the dichotomous states of the pigment molecules. The equilibration factor between these dichotomous states mainly determines the temperature dependence of the peak shift.

  18. Histone H4 hyperacetylation and rapid turnover of its acetyl groups in transcriptionally inactive rooster testis spermatids.

    Science.gov (United States)

    Oliva, R; Mezquita, C

    1982-01-01

    In order to study the relationship between acetylation of histones, chromatin structure and gene activity, the distribution and turnover of acetyl groups among nucleosomal core histones and the extent of histone H4 acetylation were examined in rooster testis cell nuclei at different stages of spermatogenesis. Histone H4 was the predominant acetylated histone in mature testes. Hyperacetylation of H4 and rapid turnover of its acetyl groups are not univocally correlated with transcriptional activity since they were detected in both genetically active testicular cells and genetically inactive elongated spermatids. During the transition from nucleohistone to nucleoprotamine in elongated spermatids the chromatin undergoes dramatic structural changes with exposition of binding sites on DNA (1). Hyperacetylation of H4 and rapid turnover of its acetyl groups could be correlated with the particular conformation of chromatin in elongated spermatids and might represent a necessary condition for binding of chromosomal proteins to DNA. Images PMID:7162988

  19. Turnover of Biogenic Amines in the Hypothalamus of Rats during Pyrogen Fever

    Science.gov (United States)

    Penn, P. E.; Williams, B. A.

    1979-01-01

    Many pharmacological studies have implicated the biogenic amines in the hypothalamus as playing a role in the production of fever, but few investigations of endogenous neurochemicals have been made during fever. Turnover rates of transmitters utilizing radioactive precursors may be one of the most accurate measurements of activity in brain regions. The present study was designed to measure the turnover of 5-hydroxytryptamine (5-HT) norepinephrine (NE) and dopamine (DA) in the hypothalamus of rats during pyrogen fever. Salmonella typhosa (Wyeth, 8 units) was previously found in our laboratory to produce a significant hyperthermia in most rats by 2.5 hours. This pyrogen (N = l2) or saline control (N = 8) was injected intraperitoneally and the rats killed 2.75 hours later. Rectal temperatures (Tr) were monitored continuously with thermocouples taped to the tail and recorded automatically every 3 minutes. Half of each group received an injection of radioactive precursors, (3)H-tryptophan (0.5 mCi) and (3)H-tryptophan (1.0 mCi), via an indwelling jugular catheter 60 minutes before killing, and the other half at 90 minutes. The rats were killed by near freezing in liquid nitrogen and the brains dissected in the cold. Turnover was measured by the method of Lane (Life Sci 21, 1101, 1977). At the time of killing most of the pyrogen group showed a significant (p pyrogen and saline groups. A significant difference was found in the specific activity of NE between the 60 minute pyrogen and saline groups (4.41 +/- 0.41 vs 2.6 +/- 0.51 dpm/pmole) but no change in turnover. This suggests an increased accumulation of (3)H-NE in the pyrogen group, but no change in utilization. An increased turnover of DA for the pyrogen group (44.5 vs 19.2 pmole/mg protein/hr) was found. However, DA is mainly a precursor in the hypothalamus and measurement was near the limit of sensitivity for the assay; these limitations Must be considered in interpreting this data. The most significant finding was

  20. Organisational commitment and turnover intentions in humanitarian organisations

    NARCIS (Netherlands)

    Wijnmaalen, Julia; Heyse, Liesbet; Voordijk, Johannes T.

    2016-01-01

    Unwanted staff turnover is a prominent HRM problem in humanitarian organisations. In the profit sector, HRM tools such as pay, benefits, socialisation and training have proven to be effective in increasing organisational commitment and decreasing staff turnover. This study explores whether such

  1. How Multiple Interventions Influenced Employee Turnover: A Case Study.

    Science.gov (United States)

    Hatcher, Timothy

    1999-01-01

    A 3-year study of 46 textile industry workers identified causes of employee turnover (supervision, training, organizational communication) using performance analysis. A study of multiple interventions based on the analysis resulted in changes in orientation procedures, organizational leadership, and climate, reducing turnover by 24%. (SK)

  2. Survey of pay satisfaction, job satisfaction and employee turnover in ...

    African Journals Online (AJOL)

    Survey of pay satisfaction, job satisfaction and employee turnover in selected business organisations in Lagos, Nigeria. ... Global Journal of Social Sciences ... The study was an attempt at investigating the relatedness of pay satisfaction, job satisfaction and employee turnover in business organizations in Lagos Nigeria.

  3. Performance and turnover intentions: a social exchange perspective

    NARCIS (Netherlands)

    Biron, M.; Boon, C.

    2013-01-01

    Purpose - Prior research has yielded mixed results regarding the relationship between performance and turnover intentions. Drawing from social exchange theory, the purpose of this paper is to propose that the performance-turnover intentions association may be contingent upon individuals' exchange

  4. Telaah Hubungan Kepuasan Kerja Dan Komitmen Organisasional Terhadap Turnover Intention

    OpenAIRE

    Ali Amran; Acep Rohendi

    2017-01-01

    ABSTRAK Karyawan merupakan elemen yang sangat penting bagi perusahaan. Karyawan sebagai sumber daya manusia adalah penggerak utama berjalannya roda perusahaan sehingga perusahaan harus menjaga kepuasan kerja dan komitmen organisasional agar karyawan tidak berkeinginan untuk berpindah ke perusahaan lain (turnover intention). Hal ini perlu dikaji pengaruh kepuasan kerja dan komitmen organisasional terhadap turnover intention sehingga dapat bermanfaat untuk mengetahui nilai penting dari kepu...

  5. A Review of the Literature on Principal Turnover

    Science.gov (United States)

    Snodgrass Rangel, Virginia

    2018-01-01

    Among the many challenges facing public schools are high levels of principal turnover. Given the important role that principals play and are expected to play in the improvement process, concerns about principal turnover have resulted in a growing body of research on its causes and consequences. The purpose of this review is to take stock of what…

  6. Health workforce acquisition, retention and turnover in southwest ...

    African Journals Online (AJOL)

    Background: Skill mix of health professionals, staff acquisition and turnover rate are among the major challenges for the delivery of quality health care. This study assessed the health workforce acquisition, retention, turnover rate and their intention to leave. Methods: A cross-sectional survey with quantitative and qualitative ...

  7. The Link between Training Satisfaction, Work Engagement and Turnover Intention

    Science.gov (United States)

    Memon, Mumtaz Ali; Salleh, Rohani; Baharom, Mohamed Noor Rosli

    2016-01-01

    Purpose: The purpose of this paper is to examine the casual relationship between training satisfaction, work engagement (WE) and turnover intention and the mediating role of WE between training satisfaction and turnover intention. Design/methodology/approach: Data were collected from 409 oil and gas professionals using an email survey…

  8. Estimating Cause: Teacher Turnover and School Effectiveness in Michigan

    Science.gov (United States)

    Keesler, Venessa; Schneider, Barbara

    2010-01-01

    The purpose of this paper is investigate issues related to within-school teacher supply and school-specific teacher turnover within the state of Michigan using state administrative data on Michigan's teaching force. This paper 1) investigates the key predictors of teacher turnover and mobility, 2) develops a profile of schools that are likely to…

  9. Efficacy of 22Na turnover in ecopbysiological studies of carnivores

    African Journals Online (AJOL)

    Efficacy of 22Na turnover in ecopbysiological studies of carnivores. loS. Wilkinson and J.D. Skinner*. Mammal Research Institute, University of Pretoria, Pretoria, 0002 Republic of South Africa. Received 8 December 1986; accepted 11 August 1987. 22Na turnover rates gave overestimates of mean 23Na intake in both ...

  10. ON THE TURNOVER OF THE TULLY-FISHER RELATION

    NARCIS (Netherlands)

    RHEE, MH; PELETIER, RF; VANALBADA, TS

    1995-01-01

    The observed turnover at the high linewidth end of the infrared Tully-Fisher relation can be explained by the stellar population differences among galaxies. When the IRAS 60 mu m fluxes are added to the Tully-Fisher relation as a second parameter, the turnover disappears and the scatter becomes

  11. Below the Surface of Special Education Administrator Turnover

    Science.gov (United States)

    Meeks, Amy

    2016-01-01

    The field of special education administration has experienced a shortage of high quality special education leadership candidates for several decades. If school districts are to effectively address the turnover of educational leaders, they must know what is happening that affects turnover of their leadership team. The intent of this study was to…

  12. Current Proteomic Methods to Investigate the Dynamics of Histone Turnover in the Central Nervous System.

    Science.gov (United States)

    Farrelly, L A; Dill, B D; Molina, H; Birtwistle, M R; Maze, I

    2016-01-01

    Characterizing the dynamic behavior of nucleosomes in the central nervous system is vital to our understanding of brain-specific chromatin-templated processes and their roles in transcriptional plasticity. Histone turnover-the complete loss of old, and replacement by new, nucleosomal histones-is one such phenomenon that has recently been shown to be critical for cell-type-specific transcription in brain, synaptic plasticity, and cognition. Such revelations that histones, long believed to static proteins in postmitotic cells, are highly dynamic in neurons were only possible owing to significant advances in analytical chemistry-based techniques, which now provide a platform for investigations of histone dynamics in both healthy and diseased tissues. Here, we discuss both past and present proteomic methods (eg, mass spectrometry, human "bomb pulse labeling") for investigating histone turnover in brain with the hope that such information may stimulate future investigations of both adaptive and aberrant forms of "neuroepigenetic" plasticity. © 2016 Elsevier Inc. All rights reserved.

  13. Water turnover rate and its metabolism in defaunated, refaunated and faunated male buffalo calves

    International Nuclear Information System (INIS)

    Chaudhary, L.C.; Srivastava, Arun

    1993-01-01

    In tropical countries like India, environment climatic conditions are variable throughout the year ranging from favourable to very hostile. The high temperature and humidity and often limited supply of water causes low productivity of livestock even when good quality of feed is supplied in required quantity. The turnover rate of water is related to environmental temperature, feed supply, protein or electrolyte content of the diet and also on physiological status of the animals.In the present experiment tritiated water dilution technique was used in an attempt to study the effect of removing ciliate protozoa from the rumen (defaunation) on water metabolism and its turnover rate in buffalo calves given wheat straw and concentrate mixture. (author). 18 refs., 2 tabs

  14. Combined effects of positive and negative affectivity and job satisfaction on job performance and turnover intentions.

    Science.gov (United States)

    Bouckenooghe, Dave; Raja, Usman; Butt, Arif Nazir

    2013-01-01

    Capturing data from employee-supervisor dyads (N = 321) from eight organizations in Pakistan, including human service organizations, an electronics assembly plant, a packaging material manufacturing company, and a small food processing plant, we used moderated regression analysis to examine whether the relationships between trait affect (positive affectivity [PA] and negative affectivity [NA]) and two key work outcome variables (job performance and turnover) are contingent upon the level of job satisfaction. We applied the Trait Activation Theory to explain the moderating effect of job satisfaction on the relationship between affect and performance and between affect and turnover. Overall, the data supported our hypotheses. Positive and negative affectivity influenced performance and the intention to quit, and job satisfaction moderated these relationships. We discuss in detail the results of these findings and their implications for research and practice.

  15. Bone mass and turnover in fibromyalgia

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Gam, A; Egsmose, C

    1993-01-01

    Physical inactivity accelerates bone loss. Since patients with fibromyalgia are relatively physically inactive, bone mass and markers of bone metabolism were determined in 12 premenopausal women with fibromyalgia and in healthy age matched female control subjects. No differences were found...... in lumbar bone mineral density, femoral neck bone mineral density, serum levels of alkaline phosphatase, osteocalcin, ionized calcium and phosphate. The urinary excretion of both hydroxyproline and calcium relative to urinary creatinine excretion was significantly higher in patients with fibromyalgia, p = 0.......01. This was linked to lower urinary creatinine excretion (p = 0.02) probably reflecting lower physical activity in the patients with fibromyalgia. We conclude that bone mass and turnover are generally not affected in premenopausal women with fibromyalgia....

  16. Prediction of FAD binding sites in electron transport proteins according to efficient radial basis function networks and significant amino acid pairs.

    Science.gov (United States)

    Le, Nguyen-Quoc-Khanh; Ou, Yu-Yen

    2016-07-30

    Cellular respiration is a catabolic pathway for producing adenosine triphosphate (ATP) and is the most efficient process through which cells harvest energy from consumed food. When cells undergo cellular respiration, they require a pathway to keep and transfer electrons (i.e., the electron transport chain). Due to oxidation-reduction reactions, the electron transport chain produces a transmembrane proton electrochemical gradient. In case protons flow back through this membrane, this mechanical energy is converted into chemical energy by ATP synthase. The convert process is involved in producing ATP which provides energy in a lot of cellular processes. In the electron transport chain process, flavin adenine dinucleotide (FAD) is one of the most vital molecules for carrying and transferring electrons. Therefore, predicting FAD binding sites in the electron transport chain is vital for helping biologists understand the electron transport chain process and energy production in cells. We used an independent data set to evaluate the performance of the proposed method, which had an accuracy of 69.84 %. We compared the performance of the proposed method in analyzing two newly discovered electron transport protein sequences with that of the general FAD binding predictor presented by Mishra and Raghava and determined that the accuracy of the proposed method improved by 9-45 % and its Matthew's correlation coefficient was 0.14-0.5. Furthermore, the proposed method enabled reducing the number of false positives significantly and can provide useful information for biologists. We developed a method that is based on PSSM profiles and SAAPs for identifying FAD binding sites in newly discovered electron transport protein sequences. This approach achieved a significant improvement after we added SAAPs to PSSM features to analyze FAD binding proteins in the electron transport chain. The proposed method can serve as an effective tool for predicting FAD binding sites in electron

  17. One hundred years of employee turnover theory and research.

    Science.gov (United States)

    Hom, Peter W; Lee, Thomas W; Shaw, Jason D; Hausknecht, John P

    2017-03-01

    We review seminal publications on employee turnover during the 100-year existence of the Journal of Applied Psychology . Along with classic articles from this journal, we expand our review to include other publications that yielded key theoretical and methodological contributions to the turnover literature. We first describe how the earliest papers examined practical methods for turnover reduction or control and then explain how theory development and testing began in the mid-20th century and dominated the academic literature until the turn of the century. We then track 21st century interest in the psychology of staying (rather than leaving) and attitudinal trajectories in predicting turnover. Finally, we discuss the rising scholarship on collective turnover given the centrality of human capital flight to practitioners and to the field of human resource management strategy. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  18. PENGARUH KEPUASAN KERJA TERHADAP KOMITMEN ORGANISASI DAN TURNOVER INTENTION

    Directory of Open Access Journals (Sweden)

    Agi Syarif Hidayat

    2018-03-01

    Full Text Available The high level of employee turnover in the marketing department at PT. Toyamilindo indicates low organizational commitment and high turnover intention. The purpose of this study is to determine the effect of job satisfaction on organizational commitment and turnover intention. Quantitative methods are used in this study. Population is the  employees of marketing department at PT. Toyamilindo with 50 people. Sampling technique used is sampling saturated with the number of samples of 50 people. Data collection technique uses questionnaires and regression analysis. Finding on the research results shows that there are positive and significant influence of job satisfaction on organizational commitment and negative and significant influence of job satisfaction on turnover intention, and also the influence of organizational commitment on work satisfaction to turnover intention. The managerial implications of corporate leaders must improve employee work satisfaction, especially in terms of salary.

  19. Pitfalls in quantifying species turnover: the residency effect

    Directory of Open Access Journals (Sweden)

    Kevin Chase Burns

    2014-03-01

    Full Text Available The composition of ecological communities changes continuously through time and space. Understanding this turnover in species composition is a central goal in biogeography, but quantifying species turnover can be problematic. Here, I describe an underappreciated source of bias in quantifying species turnover, namely ‘the residency effect’, which occurs when the contiguous distributions of species across sampling domains are small relative to census intervals. I present the results of a simulation model that illustrates the problem theoretically and then I demonstrate the problem empirically using a long-term dataset of plant species turnover on islands. Results from both exercises indicate that empirical estimates of species turnover may be susceptible to significant observer bias, which may potentially cloud a better understanding of how the composition of ecological communities changes through time.

  20. Perceptions of hospital CEOs about the effects of CEO turnover.

    Science.gov (United States)

    Khaliq, Amir A; Thompson, David M; Walston, Stephen L

    2006-01-01

    Empirical evidence is scarce on chief executive officer (CEO) turnover in U.S. hospitals, with potentially serious implications for many of these organizations. This study, based on a nationwide survey of CEOs at non-federal general surgical and medical community hospitals conducted in the spring of 2004, reports the perceptions of hospital CEOs regarding the circumstances and impact of CEO turnover on U.S. hospitals. In the opinion of the respondents, the impact includes competitors taking advantage of turnover by luring employees and physicians away from the target hospital, significantly increasing the likelihood of other senior executives leaving the hospital, and many of the important strategic activities being delayed or cancelled altogether. Interestingly, the perceptions of CEOs regarding the effects of turnover do not seem to differ regardless of voluntary or involuntary circumstances of turnover. However, there is a notable bias in emphasizing the perceived negative implications of respondents' own departures and allegedly positive effects of their predecessors' departures.

  1. How Serious of a Problem is Staff Turnover in Substance Abuse Treatment? A Longitudinal Study of Actual Turnover1

    Science.gov (United States)

    Eby, Lillian T.; Burk, Hannah; Maher, Charleen P.

    2010-01-01

    In the substance abuse treatment field, the annual turnover rate is cited as being anywhere between 19 and 50 percent (Johnson & Roman, 2002; Gallon, Gabriel, & Knudsen, 2003; Knudsen et al., 2003; McLellan et al., 2003). However, no research to date has evaluated these claims by tracking turnover longitudinally using organizational turnover data from substance abuse treatment centers. This research presents the results of a longitudinal study designed to systematically examine actual turnover among counselors and clinical supervisors. Twenty-seven geographically dispersed treatment organizations, serving a wide range of clients in the public and private sector, provided data for the study over a two year time span (2008–2009). The annual turnover rate was 33.2% for counselors and 23.4% for clinical supervisors. For both groups the majority of turnover was voluntary (employee-initiated). Specific reasons for turnover were largely consistent across the two groups, with the most common reason being a new job or new opportunity. The findings are discussed in terms of the unique employment context of substance abuse treatment. Practical recommendations are also discussed to help stem the tide of turnover in the field of substance abuse treatment. PMID:20675097

  2. How serious of a problem is staff turnover in substance abuse treatment? A longitudinal study of actual turnover.

    Science.gov (United States)

    Eby, Lillian T; Burk, Hannah; Maher, Charleen P

    2010-10-01

    In the substance abuse treatment field, the annual turnover rate is cited as being anywhere between 19% and 50% (J.A. Johnson & P.M. Roman, 2002; S.L. Gallon, R.M. Gabriel, J.R.W. Knudsen, 2003; H.K. Knudsen, J.A. Johnson, & P.M. Roman, 2003; A.T. McLellan, D. Carise, & H.D. Kleber, 2003). However, no research to date has evaluated these claims by tracking turnover longitudinally using organizational turnover data from substance abuse treatment centers. This research presents the results of a longitudinal study designed to systematically examine actual turnover among counselors and clinical supervisors. Twenty-seven geographically dispersed treatment organizations, serving a wide range of clients in the public and private sector, provided data for the study over a 2-year time span (2008-2009). The annual turnover rate was 33.2% for counselors and 23.4% for clinical supervisors. For both groups, the majority of turnover was voluntary (employee-initiated). Specific reasons for turnover were largely consistent across the two groups, with the most common reason being a new job or new opportunity. The findings are discussed in terms of the unique employment context of substance abuse treatment. Practical recommendations are also discussed to help stem the tide of turnover in the field of substance abuse treatment. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  3. A novel Geobacteraceae-specific outer membrane protein J (OmpJ is essential for electron transport to Fe (III and Mn (IV oxides in Geobacter sulfurreducens

    Directory of Open Access Journals (Sweden)

    Schiffer Marianne

    2005-07-01

    Full Text Available Abstract Background Metal reduction is thought to take place at or near the bacterial outer membrane and, thus, outer membrane proteins in the model dissimilatory metal-reducing organism Geobacter sulfurreducens are of interest to understand the mechanisms of Fe(III reduction in the Geobacter species that are the predominant Fe(III reducers in many environments. Previous studies have implicated periplasmic and outer membrane cytochromes in electron transfer to metals. Here we show that the most abundant outer membrane protein of G. sulfurreducens, OmpJ, is not a cytochrome yet it is required for metal respiration. Results When outer membrane proteins of G. sulfurreducens were separated via SDS-PAGE, one protein, designated OmpJ (outer membrane protein J, was particularly abundant. The encoding gene, which was identified from mass spectrometry analysis of peptide fragments, is present in other Geobacteraceae, but not in organisms outside this family. The predicted localization and structure of the OmpJ protein suggested that it was a porin. Deletion of the ompJ gene in G. sulfurreducens produced a strain that grew as well as the wild-type strain with fumarate as the electron acceptor but could not grow with metals, such as soluble or insoluble Fe (III and insoluble Mn (IV oxide, as the electron acceptor. The heme c content in the mutant strain was ca. 50% of the wild-type and there was a widespread loss of multiple cytochromes from soluble and membrane fractions. Transmission electron microscopy analyses of mutant cells revealed an unusually enlarged periplasm, which is likely to trigger extracytoplasmic stress response mechanisms leading to the degradation of periplasmic and/or outer membrane proteins, such as cytochromes, required for metal reduction. Thus, the loss of the capacity for extracellular electron transport in the mutant could be due to the missing c-type cytochromes, or some more direct, but as yet unknown, role of OmpJ in metal

  4. Age-related collagen turnover of the interstitial matrix and basement membrane: Implications of age- and sex-dependent remodeling of the extracellular matrix

    DEFF Research Database (Denmark)

    Kehlet, Stephanie N.; Willumsen, Nicholas; Armbrecht, Gabriele

    2018-01-01

    The extracellular matrix (ECM) plays a vital role in maintaining normal tissue function. Collagens are major components of the ECM and there is a tight equilibrium between degradation and formation of these proteins ensuring tissue health and homeostasis. As a consequence of tissue turnover, small...... collagen fragments are released into the circulation, which act as important biomarkers in the study of certain tissue-related remodeling factors in health and disease. The aim of this study was to establish an age-related collagen turnover profile of the main collagens of the interstitial matrix (type I...... an increased turnover. In summary, collagen turnover is affected by age and sex with the interstitial matrix and the basement membrane being differently regulated. The observed changes needs to be accounted for when measuring ECM related biomarkers in clinical studies....

  5. Staff turnover in statewide implementation of ACT: relationship with ACT fidelity and other team characteristics

    OpenAIRE

    Rollins, Angela L.; Salyers, Michelle P.; Tsai, Jack; Lydick, Jennifer M.

    2010-01-01

    Staff turnover on assertive community treatment (ACT) teams is a poorly understood phenomenon. This study examined annual turnover and fidelity data collected in a statewide implementation of ACT over a 5-year period. Mean annual staff turnover across all observations was 30.0%. Turnover was negatively correlated with overall fidelity at Year 1 and 3. The team approach fidelity item was negatively correlated with staff turnover at Year 3. For 13 teams with 3 years of follow-up data, turnover ...

  6. Differential challenge stressor-hindrance stressor relationships with job attitudes, turnover intentions, turnover, and withdrawal behavior: a meta-analysis.

    Science.gov (United States)

    Podsakoff, Nathan P; LePine, Jeffery A; LePine, Marcie A

    2007-03-01

    In this article, a 2-dimensional work stressor framework is used to explain inconsistencies in past research with respect to stressor relationships with retention-related criteria. Results of meta-analyses of 183 independent samples indicated that whereas hindrance stressors had dysfunctional relationships with these criteria (negative relationships with job satisfaction and organizational commitment and positive relationships with turnover intentions, turnover, and withdrawal behavior), relationships with challenge stressors were generally the opposite (positive relationships with job satisfaction and organizational commitment and negative relationships with turnover intentions and turnover). Results also suggested that the differential relationships between challenge stressors and hindrance stressors and the more distal criteria (withdrawal behavior and turnover) were due, in part, to the mediating effects of job attitudes. (c) 2007 APA, all rights reserved.

  7. An Analysis of the Effects of Deployment on Turnover in the United States Army Reserve

    National Research Council Canada - National Science Library

    McCloskey, Michele

    1999-01-01

    .... Survey questions were developed using motivation and turnover theories, and a Integrated Turnover Model relating a Reservist's deployment experience to the presence or absence of six major factors...

  8. Staff turnover in statewide implementation of ACT: relationship with ACT fidelity and other team characteristics.

    Science.gov (United States)

    Rollins, Angela L; Salyers, Michelle P; Tsai, Jack; Lydick, Jennifer M

    2010-09-01

    Staff turnover on assertive community treatment (ACT) teams is a poorly understood phenomenon. This study examined annual turnover and fidelity data collected in a statewide implementation of ACT over a 5-year period. Mean annual staff turnover across all observations was 30.0%. Turnover was negatively correlated with overall fidelity at Year 1 and 3. The team approach fidelity item was negatively correlated with staff turnover at Year 3. For 13 teams with 3 years of follow-up data, turnover rates did not change over time. Most ACT staff turnover rates were comparable or better than other turnover rates reported in the mental health and substance abuse literature.

  9. Electron microscopy and image analysis of the GroEL-like protein and its complexes with glutamine synthetase from pea leaves

    NARCIS (Netherlands)

    Tsuprun, Vladimir L.; Boekema, Egbert J.; Pushkin, Alexander V.; Tagunova, Irina V.

    1992-01-01

    The molecular structure of groEL-like protein from pea leaves has been studied by electron microscopy and image analysis of negatively stained particles. Over 1500 molecular projections were selected and classified by multivariate statistical analysis. It was shown that the molecule consists of 14

  10. Understanding the factors that determine registered nurses' turnover intentions.

    Science.gov (United States)

    Osuji, Joseph; Uzoka, Faith-Michael; Aladi, Flora; El-Hussein, Mohammed

    2014-01-01

    Turnover among registered nurses (RNs) produces a negative impact on the health outcomes of any health care organization. It is also recognized universally as a problem in the nursing profession. Little is known about the turnover intentions and career orientations of RNs working in Calgary, Alberta, Canada. The aim of this study is to contribute to the knowledge of and to advance the discussion on the turnover of nursing professionals. The study population consisted of RNs employed in the five major hospitals in Calgary. There were 193 surveys returned, representing a response rate of 77.2%. The results show that age and education have a negative effect on turnover intention. Education was found to have a significant negative effect on career satisfaction but not on job satisfaction and organizational commitment. Length of service has a significant negative effect on turnover intention. Role ambiguity has significant highly negative effect on career satisfaction. Growth opportunity and supervisor support have a very significant positive effect on job satisfaction, career satisfaction, and organizational commitment. External career opportunities and organizational commitment do not seem to have a significant effect on turnover intention. Career satisfaction, on the other hand, had negative significant effects on turnover intention.

  11. Estimating Population Turnover Rates by Relative Quantification Methods Reveals Microbial Dynamics in Marine Sediment.

    Science.gov (United States)

    Kevorkian, Richard; Bird, Jordan T; Shumaker, Alexander; Lloyd, Karen G

    2018-01-01

    The difficulty involved in quantifying biogeochemically significant microbes in marine sediments limits our ability to assess interspecific interactions, population turnover times, and niches of uncultured taxa. We incubated surface sediments from Cape Lookout Bight, North Carolina, USA, anoxically at 21°C for 122 days. Sulfate decreased until day 68, after which methane increased, with hydrogen concentrations consistent with the predicted values of an electron donor exerting thermodynamic control. We measured turnover times using two relative quantification methods, quantitative PCR (qPCR) and the product of 16S gene read abundance and total cell abundance (FRAxC, which stands for "fraction of read abundance times cells"), to estimate the population turnover rates of uncultured clades. Most 16S rRNA reads were from deeply branching uncultured groups, and ∼98% of 16S rRNA genes did not abruptly shift in relative abundance when sulfate reduction gave way to methanogenesis. Uncultured Methanomicrobiales and Methanosarcinales increased at the onset of methanogenesis with population turnover times estimated from qPCR at 9.7 ± 3.9 and 12.6 ± 4.1 days, respectively. These were consistent with FRAxC turnover times of 9.4 ± 5.8 and 9.2 ± 3.5 days, respectively. Uncultured Syntrophaceae , which are possibly fermentative syntrophs of methanogens, and uncultured Kazan-3A-21 archaea also increased at the onset of methanogenesis, with FRAxC turnover times of 14.7 ± 6.9 and 10.6 ± 3.6 days. Kazan-3A-21 may therefore either perform methanogenesis or form a fermentative syntrophy with methanogens. Three genera of sulfate-reducing bacteria, Desulfovibrio , Desulfobacter , and Desulfobacterium , increased in the first 19 days before declining rapidly during sulfate reduction. We conclude that population turnover times on the order of days can be measured robustly in organic-rich marine sediment, and the transition from sulfate-reducing to methanogenic conditions stimulates

  12. Correlation of sensory bitterness in dairy protein hydrolysates: Comparison of prediction models built using sensory, chromatographic and electronic tongue data.

    Science.gov (United States)

    Newman, J; Egan, T; Harbourne, N; O'Riordan, D; Jacquier, J C; O'Sullivan, M

    2014-08-01

    Sensory evaluation can be problematic for ingredients with a bitter taste during research and development phase of new food products. In this study, 19 dairy protein hydrolysates (DPH) were analysed by an electronic tongue and their physicochemical characteristics, the data obtained from these methods were correlated with their bitterness intensity as scored by a trained sensory panel and each model was also assessed by its predictive capabilities. The physiochemical characteristics of the DPHs investigated were degree of hydrolysis (DH%), and data relating to peptide size and relative hydrophobicity from size exclusion chromatography (SEC) and reverse phase (RP) HPLC. Partial least square regression (PLS) was used to construct the prediction models. All PLS regressions had good correlations (0.78 to 0.93) with the strongest being the combination of data obtained from SEC and RP HPLC. However, the PLS with the strongest predictive power was based on the e-tongue which had the PLS regression with the lowest root mean predicted residual error sum of squares (PRESS) in the study. The results show that the PLS models constructed with the e-tongue and the combination of SEC and RP-HPLC has potential to be used for prediction of bitterness and thus reducing the reliance on sensory analysis in DPHs for future food research. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. The homeobox protein CEH-23 mediates prolonged longevity in response to impaired mitochondrial electron transport chain in C. elegans.

    Directory of Open Access Journals (Sweden)

    Ludivine Walter

    2011-06-01

    Full Text Available Recent findings indicate that perturbations of the mitochondrial electron transport chain (METC can cause extended longevity in evolutionarily diverse organisms. To uncover the molecular basis of how altered METC increases lifespan in C. elegans, we performed an RNAi screen and revealed that three predicted transcription factors are specifically required for the extended longevity of mitochondrial mutants. In particular, we demonstrated that the nuclear homeobox protein CEH-23 uniquely mediates the longevity but not the slow development, reduced brood size, or resistance to oxidative stress associated with mitochondrial mutations. Furthermore, we showed that ceh-23 expression levels are responsive to altered METC, and enforced overexpression of ceh-23 is sufficient to extend lifespan in wild-type background. Our data point to mitochondria-to-nucleus communications to be key for longevity determination and highlight CEH-23 as a novel longevity factor capable of responding to mitochondrial perturbations. These findings provide a new paradigm for how mitochondria impact aging and age-dependent diseases.

  14. Characterization of a nuclear compartment shared by nuclear bodies applying ectopic protein expression and correlative light and electron microscopy

    International Nuclear Information System (INIS)

    Richter, Karsten; Reichenzeller, Michaela; Goerisch, Sabine M.; Schmidt, Ute; Scheuermann, Markus O.; Herrmann, Harald; Lichter, Peter

    2005-01-01

    To investigate the accessibility of interphase nuclei for nuclear body-sized particles, we analyzed in cultured cells from human origin by correlative fluorescence and electron microscopy (EM) the bundle-formation of Xenopus-vimentin targeted to the nucleus via a nuclear localization signal (NLS). Moreover, we investigated the spatial relationship of speckles, Cajal bodies, and crystalline particles formed by Mx1 fused to yellow fluorescent protein (YFP), with respect to these bundle arrays. At 37 deg C, the nucleus-targeted, temperature-sensitive Xenopus vimentin was deposited in focal accumulations. Upon shift to 28 deg C, polymerization was induced and filament arrays became visible. Within 2 h after temperature shift, arrays were found to be composed of filaments loosely embedded in the nucleoplasm. The filaments were restricted to limited areas of the nucleus between focal accumulations. Upon incubation at 28 deg C for several hours, NLS vimentin filaments formed bundles looping throughout the nuclei. Speckles and Cajal bodies frequently localized in direct neighborhood to vimentin bundles. Similarly, small crystalline particles formed by YFP-tagged Mx1 also located next to vimentin bundles. Taking into account that nuclear targeted vimentin locates in the interchromosomal domain (ICD), we conclude that nuclear body-sized particles share a common nuclear space which is controlled by higher order chromatin organization

  15. Employee turnover and productivity among small business entities in Nigeria

    Directory of Open Access Journals (Sweden)

    John N. N. Ugoani

    2016-12-01

    Full Text Available This study was designed to evaluate the problems of employee turnover on productivity among small business entities in Nigeria, and recommend remedial actions. Employee turnover is the separation of employees from employers and replacement with other employees. Productive manpower is a critical element for the economic survival of any small business entity. The survey research design was used for the study. The sample comprised of 320 respondents. Data generated were analyzed by using descriptive, and Z-test statistical techniques. It was found that employee turnover adversely affects productivity in small business entities.

  16. Turnover and employment in the German wind energy industry

    International Nuclear Information System (INIS)

    Keuper, A.

    1995-01-01

    Results of the fast growing wind energy market in 1994 are the turnover reaching more than 800 million DM, and the number of employees to about 3,700. In 1995 the manufacturers expect to need less than 4 employees to build and to install 1 MW rated power and to decrease the ratio of manufacturer's turnover per installed power unit to about 1900 DM/kW. In spite of this development it is expected that the turnover and the number of employees will increase due to the still fast growing market. (orig.)

  17. The curvilinear effect of work engagement on employees' turnover intentions.

    Science.gov (United States)

    Caesens, Gaëtane; Stinglhamber, Florence; Marmier, Virginie

    2016-04-01

    Numerous studies have shown the positive consequences of work engagement for both organisations and employees experiencing it. For instance, research has demonstrated that work-engaged employees have lower levels of turnover intentions than non-engaged employees. However, in this research, we examined whether there is a dark side of work engagement. More precisely, we investigated whether the relationship between work engagement and employees' turnover intentions might be non-linear. Based on two different samples, our results indicated that the relationship between work engagement and employees' turnover intentions is curvilinear. The theoretical and practical implications of these results are discussed. © 2014 International Union of Psychological Science.

  18. Rapid phospho-turnover by receptor tyrosine kinases impacts downstream signaling and drug binding.

    Science.gov (United States)

    Kleiman, Laura B; Maiwald, Thomas; Conzelmann, Holger; Lauffenburger, Douglas A; Sorger, Peter K

    2011-09-02

    Epidermal growth factor receptors (ErbB1-4) are oncogenic receptor tyrosine kinases (RTKs) that regulate diverse cellular processes. In this study, we combine measurement and mathematical modeling to quantify phospho-turnover at ErbB receptors in human cells and to determine the consequences for signaling and drug binding. We find that phosphotyrosine residues on ErbB1 have half-lives of a few seconds and therefore turn over 100-1000 times in the course of a typical immediate-early response to ligand. Rapid phospho-turnover is also observed for EGF-activated ErbB2 and ErbB3, unrelated RTKs, and multiple intracellular adaptor proteins and signaling kinases. Thus, the complexes formed on the cytoplasmic tail of active receptors and the downstream signaling kinases they control are highly dynamic and antagonized by potent phosphatases. We develop a kinetic scheme for binding of anti-ErbB1 drugs to receptors and show that rapid phospho-turnover significantly impacts their mechanisms of action. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Effects of immobilization and whole-body vibration on rat serum Type I collagen turnover.

    Science.gov (United States)

    Dönmez, Gürhan; Doral, Mahmut Nedim; Suljevic, Şenay; Sargon, Mustafa Fevzi; Bilgili, Hasan; Demirel, Haydar Ali

    2016-08-01

    The aim of this study was to investigate the effects of short-term, high-magnitude whole-body vibration (WBV) on serum type I collagen turnover in immobilized rats. Thirty Wistar albino rats were randomly divided into the following 5 groups: immobilization (IS), immobilization + remobilization (IR), immobilization + WBV (IV), control (C), and WBV control (CV). Immobilization was achieved by casting from the crista iliaca anterior superior to the lower part of the foot for 2 weeks. The applied WBV protocol involved a frequency of 45 Hz and amplitude of 3 mm for 7 days starting a day after the end of the immobilization period. Serum type I collagen turnover markers were measured by using ELISA kits. Serum NH2-terminal propeptide of type I collagen (PINP) levels were significantly lower in the immobilization groups (p immobilization groups. Similarly, serum COOH-terminal telopeptide of type I collagen (CTX) levels were higher in the WBV controls than their own controls (p Immobilization led to deterioration of tendon tissue, as observed by histopathological analysis with a transmission electron microscope. Although 1 week of WBV had a positive effect on type I collagen turnover in controls, it is not an efficient method for repairing tissue damage in the early stage following immobilization. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

  20. Sildenafil Stimulates Aqueous Humor Turnover in Rabbits

    Science.gov (United States)

    Alvarez, Lawrence J.; Zamudio, Aldo C.; Candia, Oscar A.

    2013-01-01

    Sildenafil citrate increases ocular blood flow and accelerates the rate of anterior chamber refilling after paracentesis. The latter effect could have resulted from a reduction in outflow facility or from an increase in aqueous humor (AH) production. In this study, we used scanning ocular fluorophotometry to examine the effects of sildenafil on AH turnover, and thus, AH production in eyes of live normal rabbits. For this, the rate of aqueous humor flow (AHF) was quantified with a commercially available fluorophotometer that measured the rate of fluorescein clearance from the anterior segment, which predominantly occurs via the trabecular meshwork. After ≈ 2 hrs of control scans to determine the baseline rate of AHF, the rabbits were fed 33 mg of sildenafil and allowed ≈ 45 min for the drug to enter the systemic circulation. Thereafter, fluorescence scans were retaken for an additional 90–120 min. Sildenafil ingestion increased AHF by about 36%, from 2.31 μL/min to 3.14 μL/min (PViagra, Revatio), stimulates AHF in rabbits. Our results seem consistent with reports indicating that the drug dilates intraocular arteries and augments intraocular vascular flow. These physiological responses to the agent apparently led to increased fluid entry into the anterior chamber. As such, the drug might have utility in patients with ocular hypotony resulting from insufficient AH formation. PMID:23562660

  1. Schistosoma mansoni; relationship between membrane turnover rates and susceptibility to immune damage. Part of a coordinated programme on preparation of irradiated vaccines against some human diseases

    International Nuclear Information System (INIS)

    Pereira Tavares, C.A.

    1983-11-01

    It is known that the schistosomulum of Schistosoma mansoni become refractory to damage by antibody and complement in vitro in the presence of serum, or Concanavalin A (Con A), or after contact with host tissues, presumably due to intrinsic changes in the surface membrane. This project studied the effect of dialysed fetal calf serum (DFCS) and Con A on the synthesis and turnover of individual proteins in the surface membrane using the incorporation of 14 C- and 3 H-labelled Arginine and the separation of the membrane proteins in SDS-PAGE. The results indicate that during the period in which schistosomules become resistant to immune attack, no qualitative alterations in electrophoretic patterns of surface proteins were observed. There was, however, a marked heterogeneity in synthesis and degradation among constituent proteins. In addition, Con A which had been shown to be effective in stimulating loss of susceptibility to immune attack, caused a slight decrease in the synthesis and turnover rate of high molecular weight proteins, whilst DFCS increased synthesis and turnover of low molecular weight proteins. This suggests that at least two processes occur in the membrane which may be related to the development of protection against immune attack. Serum might stimulate the loss of crucial antigens by accelerating their turnover making antibody attachment difficult, and Con A could be stabilizing the membrane by crosslinking large macromolecules. It is possible that in vivo both mechanisms occur to make the schistosomule surface refractory to damage

  2. Synthesis of P-protein in mature phloem of Cucurbita maxima.

    Science.gov (United States)

    Nuske, J; Eschrich, W

    1976-01-01

    Cotyledons of Cucurbita maxima Duch. seedlings were provided with (14)C-labeled amino acids for 12 h. Besides the bulk of labeled amino acids the sieve-tube exudate also carried labeled proteins. 80% of the incorporated radioactivity was found in the P-protein, 20% in a neutral protein, and traces were found in acidic proteins after fractionation on diethyl-aminoethyl cellulose columns. The radioactive elutes were characterized by autoradiographs of both disc- and sodium dodecyl sulfate-gelelectropherograms, and by isoelectric focusing. The P-protein fraction appeared with the void volume from the diethylaminoethyl-cellulose column. Obviously, this is the protein that gels when oxidized and that is reversibly precipitable giving rise to filaments when processed for electron microscopy. Its main component has a molecular weight of 115,000 Dalton. By isoelectric focusing this fraction separated into 3 proteins with isoelectric points of 9.8, 9.4, and 9.2. The isoelectric point 9.2-protein probably is identical with an oligomer of a 30,000 Dalton protein with neutral isoelectric point, which keeps 20% of the incorporated label. Microautoradiographs suggest that the labeled proteins were synthesized in companion cells. The results indicate that P-protein of Cucurbita maxima is synthesized continuously in mature phloem. It can be assumed that P-protein has a relatively high turn-over rate. Therefore it seems unlikely that P-protein is a "structural" protein.

  3. A Comprehensive Model of the Employee's Turnover Decision Process

    National Research Council Canada - National Science Library

    Donnelly, David

    2002-01-01

    .... In any environment in which retention is a primary goal, an essential first step in controlling attrition is the development of an in-depth understanding of the employee turnover decision process...

  4. Wind energy industry in Germany. Turnover and employment

    International Nuclear Information System (INIS)

    Keuper, A.; Schmidt, A.

    1994-01-01

    As a consequence of the growing wind energy market in Germany the importance of the industry in this business are has grown. In 1994 the turnover will go beyond 500 million DM, and the number of employees will reach 2,900. The turnover and the number of employees are increasing in spite of the higher efficiency. In 1994 only 5 employees are needed by a manufacturer to install 1 MW rated power instead of 15 in 1989, and the ratio of installed power to manufacturer's turnover has risen from 0,25 W/DM in 1988 to 0,455 W/DM in 1994. On the other hand the turnover of the manufacturers per employee has increased from 80,000 DM in 1988 to 440,000 DM in 1994. Economic development has considerably been advanced by subsidies for the application of wind energy technology. (orig.)

  5. SOME FEATURES OF CONTROL STAFF TURNOVER IN PERSONNEL MANAGEMENT

    Directory of Open Access Journals (Sweden)

    S. N. Kaznacheeva

    2015-01-01

    Full Text Available The author refers to the decision of the actual problem of staff turnover in the transformation of the Russian economy. In light of the problem of the effectiveness of human resources management the author indicates the most frequent problems faced by the company and focus on the problem of staff turnover. The author presents a different interpretation, defining "Marketing personnel" as a kind of administrative activity aimed at ensuring the long-term organization of human resources (identifying staffing needs, and these needs, that is, covering the organization's needs for personnel. It highlights the main features and distinctive features of marketing staff. We consider the objective (external and subjective reasons (internal reasons for staff turnover. The author proposes a number of measures to help identify the causes of turnover.

  6. Bone turnover and oxidative stress markers in estrogen- deficient ...

    African Journals Online (AJOL)

    Bone turnover and oxidative stress markers in estrogen- ... reproduction in any medium, provided the original work is properly credited. ..... Institute for Laboratory Animal Research: Guide for the ... American Veterinary Medical Association.

  7. Autoradiographic imaging of phosphoinositide turnover in the brain

    International Nuclear Information System (INIS)

    Hwang, P.M.; Bredt, D.S.; Snyder, S.H.

    1990-01-01

    With [ 3 H]cytidine as a precursor, phosphoinositide turnover can be localized in brain slices by selective autoradiography of the product [ 3 H]cytidine diphosphate diacylglycerol, which is membrane-bound. In the cerebellum, glutamatergic stimulation elicits an increase of phosphoinositide turnover only in Purkinje cells and the molecular layer. In the hippocampus, both glutamatergic and muscarinic cholinergic stimulation increase phosphoinositide turnover, but with distinct localizations. Cholinergic stimulation affects CA1, CA3, CA4, and subiculum, whereas glutamatergic effects are restricted to the subiculum and CA3. Imaging phosphoinositide turnover in brain slices, which are amenable to electrophysiologic studies, will permit a dynamic localized analysis of regulation of this second messenger in response to synaptic stimulation of specific neuronal pathways

  8. survey of pay satisfaction, job satisfaction and employee turnover

    African Journals Online (AJOL)

    employee turnover in business organizations in Lagos Nigeria. Data were .... to be making more money than them were more dissatisfied with ... postulates that an employee is a rational decision maker, hence, he makes efforts that lead to a ...

  9. Report: Remedial Project Manager Turnover at Superfund Sites

    Science.gov (United States)

    Report #2001-M-000015, June 15, 2001. We determined that EPA Region III did not have formal procedures in place to mitigate continuity problems caused by turnover of EPA personnel in the Superfund program.

  10. Rationale for the evaluation of trabecular bone turnover

    International Nuclear Information System (INIS)

    Kimmel, D.B.; Jee, W.S.S.

    1976-01-01

    A procedure for the morphometric evaluation of trabecular bone is identified. Its scrupulous use allows total identification of bone formation and resorption rates, items necessary for the direct histologic analysis of bone turnover

  11. Structure analysis of OmpC, one of the major proteins in the outer membrane of E. coli, by high resolution electron microscopy

    International Nuclear Information System (INIS)

    Chang, C.F.

    1983-07-01

    This dissertation is concerned with the structure analysis of a pore-forming membrane protein, OmpC, which is one of the major proteins in the outer membrane of Escherichia coli. In order to obtain structural information it was necessary to develop a suitable technique for preparing two-dimensional crystalline arrays of this membrane protein in an unfixed, unstained and hydrated condition. Electron micrographs were recorded at exposures of less than 5 electrons/A 2 in order to avoid severe radiation damage. The resulting images were crystallographically averaged, in order to overcome the statistical limitations associated with the low electron exposures. The resulting images, which extend to a resolution of approx. 13.5 A, lend themselves to a natural interpretation that is consistent with the mass density of protein, water and lipid, prior data from 2-D and 3-D structure studies of negatively stained specimens at approx. = 20 A resolution, and published spectroscopic data on the peptide chain secondary structure

  12. Employee motivation development opportunities seeking to reduce employee turnover

    OpenAIRE

    Pilukienė, Laura; Kšivickaitė, Gertūda

    2014-01-01

    In this article, the authors analyse one of the main nowadays human resources problem – growing employee turnover. Employee motivation process is analysed as a key competitive advantage in employee retention that leads to the growth of the business company’s productivity and competitive stability. The main goal of the article is to analyse the employee motivation and employee turnover relationship and its development possibilities in Lithuania’s business sector.

  13. Liquid Crystal Gel Reduces Age Spots by Promoting Skin Turnover

    OpenAIRE

    Mina Musashi; Ariella Coler-Reilly; Teruaki Nagasawa; Yoshiki Kubota; Satomi Kato; Yoko Yamaguchi

    2014-01-01

    Studies have shown that liquid crystals structurally resembling the intercellular lipids in the stratum corneum can beneficially affect the skin when applied topically by stimulating the skin’s natural regenerative functions and accelerating epidermal turnover. In the present study, the effects of applying low concentrations of a liquid crystal gel of our own creation were evaluated using epidermal thickening in mouse skin as an assay for effective stimulation of epidermal turnover. A liquid ...

  14. Turnover rate of hypoxic cells in solid tumors

    International Nuclear Information System (INIS)

    Ljungkvist, A.S.E.; Bussink, J.; Rijken, P.F.J.W.; Van Der Kogel, A.J.

    2003-01-01

    Most solid tumors contain hypoxic cells, and both the amount and duration of tumor hypoxia has been shown to influence the effect of radiation treatment negatively. It is important to understand the dynamic processes within the hypoxic cell population in non-treated tumors, and the effect of different treatment modalities on the kinetics of hypoxic cells to be able to design optimal combined modality treatments. The turnover rate of hypoxic cells was analyzed in three different solid tumor models with a double bio-reductive hypoxic marker assay with sequential injection of the two hypoxic markers. Previously it was shown that this assay could be used to detect both a decrease and an increase of tumor hypoxia in relation to the tumor vasculature with high spatial resolution. In this study the first hypoxic marker, pimonidazole, was administered at variable times relative to tumor harvest, and the second hypoxic marker, CCI-103F, was injected at a fixed time before harvest. The hypoxic cell turnover rate was calculated as the loss of pimonidazole positive cells relative to CCI-103F. The murine C38 line had the fastest hypoxic turnover rate of 60% /24h and the human xenograft line SCCNij3 had the slowest hypoxic turnover rate of 30% /24 h. The hypoxic turnover rate was most heterogeneous in the SCCNij3 line that even contained viable groups of cells that had been hypoxic for at least 5 days. The human xenograft line MEC82 fell in between with a hypoxic turnover rate of 50% /24 h. The hypoxic cell turnover was related to the potential tumor volume doubling time (Tpot) with a Tpot of 26h in C38 and 103h in SCCNij3. The dynamics of hypoxic cells, quantified with a double hypoxic marker method, showed large differences in hypoxic cell turnover rate and were related to Tpot

  15. Physician and staff turnover in community primary care practice.

    Science.gov (United States)

    Ruhe, Mary; Gotler, Robin S; Goodwin, Meredith A; Stange, Kurt C

    2004-01-01

    The effect of a rapidly changing healthcare system on personnel turnover in community family practices has not been analyzed. We describe physician and staff turnover and examine its association with practice characteristics and patient outcomes. A cross-sectional evaluation of length of employment of 150 physicians and 762 staff in 77 community family practices in northeast Ohio was conducted. Research nurses collected data using practice genograms, key informant interviews, staff lists, practice environment checklists, medical record reviews, and patient questionnaires. The association of physician and staff turnover with practice characteristics, patient satisfaction, and preventive service data was tested. During a 2-year period, practices averaged a 53% turnover rate of staff. The mean length of duration of work at the current practice location was 9.1 years for physicians and 4.1 years for staff. Longevity varied by position, with a mean of 3.4 years for business employees, 4.0 years for clinical employees, and 7.8 years for office managers. Network-affiliated practices experienced higher turnover than did independent practices. Physician longevity was associated with a practice focus on managing chronic illness, keeping on schedule, and responding to insurers' requests. No association was found between turnover and patient satisfaction or preventive service delivery rates. Personnel turnover is pervasive in community primary care practices and is associated with employee role, practice network affiliation, and practice focus. The potentially disruptive effect of personnel turnover on practice functioning, finances, and longitudinal relationships with patients deserves further study despite the reassuring lack of association with patient satisfaction and preventive service delivery rates.

  16. Corporate governance mechanisms in family firms: Evidence from CEO turnovers

    OpenAIRE

    González, Maximiliano; Guzmán, Alexander; Pombo, Carlos; Trujillo, María Andréa

    2013-01-01

    Research Question/Issue: How sensitive is CEO turnover to firm performance in the context of family firms? Research Findings/Insights: Using a detailed database of mostly non-listed Colombian firms, we found that family ownership (direct and indirect through pyramidal structures) reduces the probability of CEO turnover when financial performance has been poor; however, we found that the opposite effect is true when families participate actively on the board of directors. These results hold tr...

  17. The Modern Technologies to Reduce Turnover of Company Staff

    OpenAIRE

    Zaiko Tetiana O.; Poplavska Oksana M.

    2017-01-01

    The article is aimed at analyzing and substantiating the use in practice of modern technologies to reduce turnover of staff, which do not bear significant financial costs for the company. The authors have proved that non-material measures to reduce staff turnover in companies are becoming predominant nowadays. Among them as the most important are indicated: introduction of flexible schedule (mode) of work, transition to the remote form of employment, and distribution of internal shares, in pa...

  18. Prediction of Employee Turnover in Organizations using Machine Learning Algorithms

    OpenAIRE

    Rohit Punnoose; Pankaj Ajit

    2016-01-01

    Employee turnover has been identified as a key issue for organizations because of its adverse impact on work place productivity and long term growth strategies. To solve this problem, organizations use machine learning techniques to predict employee turnover. Accurate predictions enable organizations to take action for retention or succession planning of employees. However, the data for this modeling problem comes from HR Information Systems (HRIS); these are typically under-funded compared t...

  19. Kramers Turnover Theory for a Triple Well Potential

    International Nuclear Information System (INIS)

    Pollak, E.; Talkner, P.

    2001-01-01

    Kramers turnover theory is solved for a particle in a symmetric triple well potential for temperatures above the crossover temperature between tunneling and activated barrier crossing. Comparison with the turnover theory for a double well potential shows that the presence of the intermediate well always leads to a decrease of the reaction rate. At most though, the rate is a factor of two smaller than in the case of a double well potential. (author)

  20. Modeling and computations of the intramolecular electron transfer process in the two-heme protein cytochrome em>c>4

    DEFF Research Database (Denmark)

    Natzmutdinov, Renat R.; Bronshtein, Michael D.; Zinkicheva, Tamara T.

    2012-01-01

    force were determined using dielectric continuum models. We then calculated the electronic transmission coefficient of the intramolecular ET rate using perturbation theory combined with the electronic wave functions determined by the DFT calculations for different heme group orientations and Fe...

  1. Telaah Hubungan Kepuasan Kerja Dan Komitmen Organisasional Terhadap Turnover Intention

    Directory of Open Access Journals (Sweden)

    Ali Amran

    2017-04-01

    ABSTRACT       Employees are the most important resources of company. They are human resources to do and move all of the activities of company. Therefore, company needs to keep and maintain their job satisfaction and organizational commitment in order to reduce the intention to leave the company (turnover intention. It is necessary to study the relationship among job satisfaction, organizational commitment and turnover intention. This will give benefit to determine the important values of employees’ job satisfaction and organizational commitment and its influences on turnover intention. The research methods are descriptive survey and verificative survey that is used to assess the performance of independent variables: those are job satisfaction and organizational commitment,  and dependent variable: that is turnover intention with doing observation to employees of PT. Alexindo Bekasi. The result of this research is there is influence of job satisfaction and organizational commitment on turnover intention. This research is the improvement of existing researches which can be applied in the other companies specially for the human resource or employee behavior field.   Keywords: Job Satisfaction, Organizational Commitment, Turnover Intention

  2. The tear turnover and tear clearance tests - a review.

    Science.gov (United States)

    Garaszczuk, Izabela K; Montes Mico, Robert; Iskander, D Robert; Expósito, Alejandro Cerviño

    2018-03-01

    The aim is to provide a summary of methods available for the assessment of tear turnover and tear clearance rates. The review defines tear clearance and tear turnover and describes their implication for ocular surface health. Additionally, it describes main types of techniques for measuring tear turnover, including fluorescein tear clearance tests, techniques utilizing electromagnetic spectrum and tracer molecule and novel experimental techniques utilizing optical coherence tomography and fluorescein profilometry. Areas covered: Internet databases (PubMed, Science Direct, Google Scholar) and most frequently cited references were used as a principal resource of information on tear turnover rate and tear clearance rate, presenting methodologies and equipment, as well as their definition and implications for the anterior eye surface health and function. Keywords used for data-search were as follows: tear turnover, tear clearance, fluorescein clearance, scintigraphy, fluorophotometry, tear flow, drainage, tear meniscus dynamics, Krehbiel flow and lacrimal functional unit. Expert commentary: After decades, the topic of tear turnover assessment has been reintroduced. Recently, new techniques have been developed to propose less invasive, less time consuming and simpler methodologies for the assessment of tear dynamics that have the potential to be utilized in clinical practice.

  3. Turnover intention among intensive care unit nurses in Alexandria, Egypt.

    Science.gov (United States)

    Mosallam, Rasha; Hamidi, Samer; Elrefaay, Manal

    2015-06-01

    Given the difficulty in recruiting new nurses, it is imperative to retain those already in the profession. This cross-sectional study explored the relationship of demographic and work-related factors, burnout, conflict management and relationship between nurses and physicians on turnover intentions among ICU nurses in eight major hospitals in Alexandria, Egypt. Data on burnout, conflict management, nurse-physician communication, and turnover intention were collected by surveying 100 nurses in eight hospitals in Alexandria governorate. All nurses at the ICU of selected hospitals were approached (n=100) and a 47-item Likert scale questionnaire was administered to explore the factors affecting the turnover intention of ICU nurses in Alexandria. ICU nurses exhibited a mean score for turnover intention of 3.23 (mean score percentage 65.0%). There was a moderately positive statistically significant correlation between turnover intention and emotional exhaustion (r=0.29, Pturnover intention were emotional exhaustion and age. Nurses turnover intention at the ICU of the selected hospitals is high and is significantly associated with nurses' emotional exhaustion, poor nurse-physician communication, and nurses age.

  4. Stable isotopic constraints on global soil organic carbon turnover

    Science.gov (United States)

    Wang, Chao; Houlton, Benjamin Z.; Liu, Dongwei; Hou, Jianfeng; Cheng, Weixin; Bai, Edith

    2018-02-01

    Carbon dioxide release during soil organic carbon (SOC) turnover is a pivotal component of atmospheric CO2 concentrations and global climate change. However, reliably measuring SOC turnover rates on large spatial and temporal scales remains challenging. Here we use a natural carbon isotope approach, defined as beta (β), which was quantified from the δ13C of vegetation and soil reported in the literature (176 separate soil profiles), to examine large-scale controls of climate, soil physical properties and nutrients over patterns of SOC turnover across terrestrial biomes worldwide. We report a significant relationship between β and calculated soil C turnover rates (k), which were estimated by dividing soil heterotrophic respiration rates by SOC pools. ln( - β) exhibits a significant linear relationship with mean annual temperature, but a more complex polynomial relationship with mean annual precipitation, implying strong-feedbacks of SOC turnover to climate changes. Soil nitrogen (N) and clay content correlate strongly and positively with ln( - β), revealing the additional influence of nutrients and physical soil properties on SOC decomposition rates. Furthermore, a strong (R2 = 0.76; p turnover and thereby improving predictions of multiple global change influences over terrestrial C-climate feedback.

  5. Turnover intention of graduate nurses in South Korea.

    Science.gov (United States)

    Lee, Haejung; Lim, Yeonjung; Jung, Hee Young; Shin, Youn-Wha

    2012-06-01

    The purpose of this study was to identify the turnover intention of graduate nurses in South Korea and to explore the correlates of turnover intention. A descriptive, correlational design was used. The participants comprised 225 female nurses who were working at 13 general hospitals and who had accumulated turnover intention was 7.51. Turnover intention was found to be related to the number of beds in the hospital, workplace, and duration of job orientation (theory and practice), instruction by a preceptor, job stress, clinical competence, self-efficacy, and the practice environment. In the multivariate approach, the practice environment, job stress, and the workplace were found to be significantly related to turnover intention and accounted for 36% of the said intention in the studied graduate nurses. The results support that the characteristics of magnet hospitals that improve the practice environment could play a critical role in retaining nurses in hospitals. Managerial interventions that enhance the practice environment, reduce job stress, and place graduate nurses in nursing units with a single specialty could benefit the hospitals employing such nurses. Further research to explore the effects of managerial strategies on graduate nurses' turnover intention is warranted. © 2011 The Authors; Japan Journal of Nursing Science © 2011 Japan Academy of Nursing Science.

  6. Factors influencing turnover intention among registered nurses in Samar Philippines.

    Science.gov (United States)

    Labrague, Leodoro J; Gloe, Donna; McEnroe, Denise M; Konstantinos, Kostas; Colet, Paolo

    2018-02-01

    Despite the massive nurse migration and turnover of nurses in the Philippines, there remains a lack of studies describing factors influencing the migration of Filipino nurses. This study explored the effects of nurses' characteristics, work satisfaction, and work stress with the intent to leave an organization among registered nurses in the Philippines. This study utilized a descriptive, cross-sectional approach. One hundred sixty six (166) nurses participated in the study during the months of September 2015 to December 2015. Three standardized instruments were used in the study: Job Satisfaction Index (JSI), Job Stress Scale (JSS), and Turnover Intention Inventory Scale (TIIS). Data were analyzed using descriptive and inferential statistical tools. Nurses' ages were found to significantly influence their turnover intentions. Job satisfaction (β=-0.47, p=0.001) and job stress (β=0.23, p=0.001) strongly predicted turnover intentions in the nurses. The mean values for the job satisfaction scale, job stress scale, and turnover intention inventory scale were 3.13 (SD=0.60), 2.74 (SD=0.71), and 2.43 (SD=0.67) respectively. Several predictors of turnover intentions were determined in this study through nurses' age, job satisfaction, and job stress as being the most influential factors. Efforts to increase nurses' job satisfaction and reduce job stress should be implemented to halt further loss of these skilled groups of healthcare professionals. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Organisational commitment and turnover intentions: evidence from Nigerian paramilitary organisation

    Directory of Open Access Journals (Sweden)

    Dotun Olaleye Faloye

    2014-09-01

    Full Text Available This study explores the empirical link between different dimensions of organizational commitment and turnover intentions on Nigeria paramilitary organisation. A literature review of organizational commitment and employee turnover provides the basis for the research hypotheses. Four research hypotheses were formulated and tested at 95% and 99% confidence level. The study adopted a survey research design. A self-administered questionnaire was used, involving 144 respondents from selected paramilitary organisation in Akure, Nigeria to collect data and testing the existing theory. Data collected were analysed using both descriptive and inferential statistical techniques. In contrary to theory, the study revealed a weak positive relationship between organizational commitment dimensions (affective, continuance and normative and turnover intentions. The relationships are statistically significant expect the one between turnover intention and normative commitment which is statistically insignificant. The study concluded that the commitment of an employee to organisational goals, missions, and values is not enough to predict his/her stay in the organisation. There are other variables apart from organisational commitment that are predictor of employees’ intentions to quit. Thus, organisations should look beyond forces in their internal environment, when considering reduction in employee’s turnover intentions and the actual employee’s turnover.

  8. Reviewing Employee Turnover: Focusing on Proximal Withdrawal States and an Expanded Criterion

    Science.gov (United States)

    Hom, Peter W.; Mitchell, Terence R.; Lee, Thomas W.; Griffeth, Rodger W.

    2012-01-01

    We reconceptualize employee turnover to promote researchers' understanding and prediction of why employees quit or stay in employing institutions. A literature review identifies shortcomings with prevailing turnover dimensions. In response, we expand the conceptual domain of the turnover criterion to include multiple types of turnover (notably,…

  9. Explaining the Gap in Charter and Traditional Public School Teacher Turnover Rates

    Science.gov (United States)

    Stuit, David A.; Smith, Thomas M.

    2012-01-01

    This study uses national survey data to examine why charter school teachers are more likely to turnover than their traditional public school counterparts. We test whether the turnover gap is explained by different distributions of factors that are empirically and theoretically linked to turnover risk. We find that the turnover rate of charter…

  10. The interaction domain of the redox protein adrenodoxin is mandatory for binding of the electron acceptor CYP11A1, but is not required for binding of the electron donor adrenodoxin reductase

    International Nuclear Information System (INIS)

    Heinz, Achim; Hannemann, Frank; Mueller, Juergen J.; Heinemann, Udo; Bernhardt, Rita

    2005-01-01

    Adrenodoxin (Adx) is a [2Fe-2S] ferredoxin involved in electron transfer reactions in the steroid hormone biosynthesis of mammals. In this study, we deleted the sequence coding for the complete interaction domain in the Adx cDNA. The expressed recombinant protein consists of the amino acids 1-60, followed by the residues 89-128, and represents only the core domain of Adx (Adx-cd) but still incorporates the [2Fe-2S] cluster. Adx-cd accepts electrons from its natural redox partner, adrenodoxin reductase (AdR), and forms an individual complex with this NADPH-dependent flavoprotein. In contrast, formation of a complex with the natural electron acceptor, CYP11A1, as well as electron transfer to this steroid hydroxylase is prevented. By an electrostatic and van der Waals energy minimization procedure, complexes between AdR and Adx-cd have been proposed which have binding areas different from the native complex. Electron transport remains possible, despite longer electron transfer pathways

  11. Photoinduced electron transfer for an eosin-tyrosine conjugate. Activity of the tyrosinate anion in long-range electron transfer in a protein-like polymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G. II; Feng, Z.; Oh, C. [Boston Univ., MA (United States)

    1995-03-23

    The Xanthene dye eosin Y has been modified via a thiohydantoin link to the amine terminus of the amino acid L-tyrosine. Photochemical electron transfer involving the singlet state of the dye and the attached phenol-containing residue led to a reduction in eosin fluorescence quantum yield and lifetime for aqueous solutions at elevated pH. The conjugate provided an electron transfer product of relatively long lifetime (1 {mu}s range) observed by flash photolysis of solutions at pH 12.0, conditions under which the tyrosine moiety is ionized. The effects of binding of the conjugate in the polymer poly(vinylpyrrolidone) (PVP) on the rates of electron transfer of species of different charge type were examined. 30 refs., 5 figs., 1 tab.

  12. Expression and characterization of truncated human heme oxygenase (hHO-1) and a fusion protein of hHO-1 with human cytochrome P450 reductase.

    Science.gov (United States)

    Wilks, A; Black, S M; Miller, W L; Ortiz de Montellano, P R

    1995-04-04

    A human heme oxygenase (hHO-1) gene without the sequence coding for the last 23 amino acids has been expressed in Escherichia coli behind the pho A promoter. The truncated enzyme is obtained in high yields as a soluble, catalytically-active protein, making it available for the first time for detailed mechanistic studies. The purified, truncated hHO-1/heme complex is spectroscopically indistinguishable from that of the rat enzyme and converts heme to biliverdin when reconstituted with rat liver cytochrome P450 reductase. A self-sufficient heme oxygenase system has been obtained by fusing the truncated hHO-1 gene to the gene for human cytochrome P450 reductase without the sequence coding for the 20 amino acid membrane binding domain. Expression of the fusion protein in pCWori+ yields a protein that only requires NADPH for catalytic turnover. The failure of exogenous cytochrome P450 reductase to stimulate turnover and the insensitivity of the catalytic rate toward changes in ionic strength establish that electrons are transferred intramolecularly between the reductase and heme oxygenase domains of the fusion protein. The Vmax for the fusion protein is 2.5 times higher than that for the reconstituted system. Therefore, either the covalent tether does not interfere with normal docking and electron transfer between the flavin and heme domains or alternative but equally efficient electron transfer pathways are available that do not require specific docking.

  13. Calculation of X-ray scattering curves and electron distance distribution functions of biological macromolecules in solution using the PROTEIN DATA BANK

    International Nuclear Information System (INIS)

    Mueller, J.J.; Friedrichowicz, E.; Nothnagel, A.; Wunderlich, T.; Ziehlsdorf, E.; Damaschun, G.

    1983-01-01

    The wide angle X-ray scattering curve, the electron distance distribution function and the solvent excluded volume of a macromolecule in solution are calculated from the atomic coordinates contained in the PROTEIN DATA BANK. The structures and the projections of the excluded volumes are depicted using molecule graphic routines. The described computer programs are used to determine the three-dimensional structure of macromolecules in solution from wide angle X-ray scattering data. (author)

  14. Turnover of registered nurses in Israel: characteristics and predictors.

    Science.gov (United States)

    Toren, Orly; Zelker, Revital; Lipschuetz, Michal; Riba, Shoshana; Reicher, Sima; Nirel, Nurit

    2012-05-01

    In an era of global and local nursing shortages, nursing turnover has negative consequences in terms of diminished quality of care, increased costs and economic losses and decreased job satisfaction. To examine the turnover rate of registered nurses in Israel by assessing the varying degree of turnover between economic sectors, between hospital and community facilities, and/or between types of hospitals; and by examining potential predicting factors of turnover among registered nurses. A national phone survey was undertaken in Israel consisting of a random sampling of registered nurses of working age (up to age 60). The subjects comprised 10% of a national database of 32,000 registered nurses. The turnover rate among working nurses in Israel currently stands at 23%. In addition, 13% of employed nurses have taken a temporary leave of absence for a period greater than 6 months in the past 10 years, most up to 1 year. While job satisfaction rates were relatively high (72%), Professional satisfaction rates were 60% with no significant difference between hospital and community nurses. The turnover rate of registered nurses from a hospital setting to the community was significantly higher (pcommunity registered nurses to hospitals. Predicting factors of turnover were found to be: young age, part-time work, lack of advanced professional education, academic education and low satisfaction with the nursing profession. The shift of nursing workforce is mainly from hospitals to community health settings. There is a need to monitor and understand the characteristics of job and professional satisfaction among hospital nurses in order to implement crucial organizational interventions and retain hospital nursing staffs. Since young nurses, nurses working part time and nurses with no advanced professional and academic education, tend to move more than others, efforts should be targeted at these specific groups. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  15. A case study into labour turnover within an NHS Trust.

    Science.gov (United States)

    Bamford, David; Hall, Catherine

    2007-02-01

    This paper investigates turnover in a British NHS Trust, to find out why staff left and whether factors identified in the literature with regards to improving turnover were pertinent to the organization. The research also investigated staff groups with high turnover--staff with less than 12 months service, and the unqualified nursing staff group--to ascertain whether there were any reasons for leaving or areas of dissatisfaction particular to these groups. The outcomes of the research complied with much of the published research with some interesting differences. The main reasons for leaving were identified as moving house, promotion or career development and taking up education and training opportunities elsewhere. There was no evidence of 'level of pay', commonly given as a significant influence behind turnover, as a reason for leaving. It was also found that the retention strategies identified in the published research were mainly applicable to the research, with evidence to support the improvement of line management skills, training and development, career development, appraisal, communications and induction in order to reduce turnover. There was less evidence for introducing work-life balance policies, improving communications, pay and working relationships as retention strategies. Recommendations for future management of labour turnover within the NHS Trust and elsewhere are made, with observations about the validity of some existing models. The core contribution of this research is in adding to the body of knowledge about labour turnover issues. This is of value to those working in the UK health-care and wider public sector. Specific recommendations for future research are made.

  16. Degradation of protein translation machinery by amino acid starvation-induced macroautophagy

    DEFF Research Database (Denmark)

    Gretzmeier, Christine; Eiselein, Sven; Johnson, Gregory R.

    2017-01-01

    , unbiased approaches relying on quantitative mass spectrometry-based proteomics. Macroautophagy is induced by rapamycin treatment, and by amino acid and glucose starvation in differentially, metabolically labeled cells. Protein dynamics are linked to image-based models of autophagosome turnover. Depending...... on the inducing stimulus, protein as well as organelle turnover differ. Amino acid starvation-induced macroautophagy leads to selective degradation of proteins important for protein translation. Thus, protein dynamics reflect cellular conditions in the respective treatment indicating stimulus-specific pathways...

  17. Changes in Inflammatory and Bone Turnover Markers After Periodontal Disease Treatment in Patients With Diabetes.

    Science.gov (United States)

    Izuora, Kenneth E; Ezeanolue, Echezona E; Neubauer, Michael F; Gewelber, Civon L; Allenback, Gayle L; Shan, Guogen; Umpierrez, Guillermo E

    2016-06-01

    The underlying mechanisms for increased osteopenia and fracture rates in patients with diabetes are not well understood, but may relate to chronic systemic inflammation. We assessed the effect of treating periodontal disease (POD), a cause of chronic inflammation, on inflammatory and bone turnover markers in patients with diabetes. Using an investigator-administered questionnaire, we screened a cross-section of patients presenting for routine outpatient diabetes care. We recruited 22 subjects with POD. Inflammatory and bone turnover markers were measured at baseline and 3 months following POD treatment (scaling, root planing and subantimicrobial dose doxycycline). There were nonsignificant reductions in high-sensitivity C-reactive protein (6.34-5.52mg/L, P = 0.626) and tumor necrosis factor-alpha (10.37-10.01pg/mL, P = 0.617). There were nonsignificant increases in urinary C-terminal telopeptide (85.50-90.23pg/mL, P = 0.684) and bone-specific alkaline phosphatase (7.45-8.79pg/mL, P = 0.074). Patients with >90% adherence with doxycycline were 6.4 times more likely to experience reduction in tumor necrosis factor-alpha (P = 0.021) and 2.8 times more likely to experience reductions in high-sensitivity C-reactive protein (P = 0.133). Treatment of POD in patients with diabetes resulted in nonsignificant lowering of inflammatory markers and nonsignificant increase in bone turnover markers. However, adherence to doxycycline therapy resulted in better treatment effects. Copyright © 2016 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.

  18. A role for PERK in the mechanism underlying fluoride-induced bone turnover

    International Nuclear Information System (INIS)

    Sun, Fei; Li, Xining; Yang, Chen; Lv, Peng; Li, Guangsheng; Xu, Hui

    2014-01-01

    While it has been well-documented that excessive fluoride exposure caused the skeletal disease and osteoblasts played a critical role in the advanced skeletal fluorosis, the underlying mechanism that mediated these effects remain poorly understood. The present study was undertaken to examine the effect of fluoride on bone of rats and MC3T3-E1 cells in vitro. Herein we found pathological features of high bone turnover in fluoride-treated rats, which was supported by an increase of osteogenic and osteoclastogenic genes expression in different stages of fluoride exposure. The skeletal toxicity of fluoride was accompanied by activation of endoplasmic reticulum (ER) stress and subsequent unfolded protein response (UPR). A novel finding of this study was that expression of PKR-like endoplasmic reticulum kinase (PERK) was the same trend with receptor activator for nuclear factor-κ B ligand (RANKL), and NF-E2 p45-related factor 2 (Nrf2) was the same trend with Runt-related transcription factor 2 (Runx2) in bones of rats exposed to varied fluoride condition. Based on these data, we hypothesized that up-regulation of PERK probably played a role in mediating bone turnover induced by fluoride. Action of fluoride on MC3T3-E1 cells differentiation was demonstrated through analysis of alkaline phosphatase (ALP) activity and mineralized nodules formation. Meantime, an increase of binding immunoglobulin protein (BiP) expression indicated the active ER stress in cells exposed to various dose of fluoride. Blocking PERK expression using siRNA showed the obvious decrease of osteogenic and osteoclastogenic factors expression in MC3T3-E1 cells exposed to certain dose of fluoride that could positively stimulate osteoblastic viability. In conclusion these findings underscore the importance of PERK in modulating fluoride induced bone formation and bone resorption. Understanding the link between PERK and bone turnover could probe into the mechanism underlying different bone lesion of

  19. Human adenosine deaminase: properties and turnover in cultured T and B lymphoblasts

    International Nuclear Information System (INIS)

    Daddona, P.E.

    1981-01-01

    In this study, the properties and rate of turnover of adenosine deaminase are compared in cultured human T and B lymphoblast cell lines. 1) Relative to B lymphoblasts, the level of adenosine deaminase activity in extracts of T lymphoblast cell lines (MOLT-4, RPMI-8402, CCRF-CEM, and CCRF-HSB-2) is elevated 7-14-fold and differs by 2-fold between the C cell lines. 2) In both T and B lymphoblast extracts, the enzyme is apparently identical, based on K/sub m/ for adenosine and deoxyadenosine, K/sub i/ for inosine, V/sub max/ for adenosine, /sub S20,w/, isoelectric pH, and heat stability. Furthermore, by radioimmunoassay, the quantity of adenosine deaminase-immunocreative protein is proportional to the level of enzyme activity in all cell lines studies. 3) Using a purification and selective immunoprecipitation technique, the enzyme turnover could be assessed in cell lines labeled with [ 35 S]methionine. The apparent rate of adenosine deaminase synthesis, relative to total protein, is 2-fold faster in both T cell lines (RPMI-8402 and CCRF-CEM) than in the B cell lines (MGL-8 and GM-130). The apparent half-life (tsub1/2) for the enzyme degradation is 19 and 39 h, respectively, in CCFR-CEM and RPMI-8402, while the tsub1/2 in both B cell lines is 7-9 h. From the net rate of synthesis and degradation, the T cell lines, respectively, exhibit approximately a 6- and 12-fold difference in adenosine deaminase turnover relative to B cells, consistent with the observed differences in enzyme activity. This study suggests that while adenosine deaminase is apparently identical in both T and B lymphoblast cell lines, alterations in both the rate of enzyme synthesis and degradation contribute to its high steady state level in T cells

  20. Heterogeneous electron transfer of a two-centered heme protein: redox and electrocatalytic properties of surface-immobilized cytochrome C(4).

    Science.gov (United States)

    Monari, Stefano; Battistuzzi, Gianantonio; Borsari, Marco; Di Rocco, Giulia; Martini, Laura; Ranieri, Antonio; Sola, Marco

    2009-10-15

    The recombinant diheme cytochrome c(4) from the psycrophilic bacterium Pseudoalteromonas haloplanktis TAC 125 and its Met64Ala and Met164Ala variants, which feature a hydroxide ion axially bound to the heme iron at the N- and C-terminal domains, respectively, were found to exchange electrons efficiently with a gold electrode coated with a SAM of 11-mercapto-1-undecanoic acid. The mutation-induced removal of the redox equivalence of the two heme groups and changes in the net charge of the protein lobes yield two-centered protein systems with unprecedented properties in the electrode-immobilized state. The heterogeneous and intraheme electron transfer processes were characterized for these species in which the high- and low-potential heme groups are swapped over in the bilobal protein framework and experience a constrained (M64A) and unconstrained (M164A) orientation toward the electrode. The reduction thermodynamics for the native and mutated hemes were measured for the first time for a diheme cytochrome c. In the diffusing regime, they reproduce closely those for the corresponding centers in single-heme class-I cytochromes c, despite the low sequence identity. Larger differences are observed in the thermodynamics of the immobilized species and in the heterogeneous electron transfer rate constants. T-dependent kinetic measurements show that the proteins are positioned approximately 7 A from the HOOC-terminated SAM-coated electrode. Protein-electrode orientation and efficient intraheme ET enable the His,OH(-)-ligated heme A of the immobilized Met64Ala variant to carry out the reductive electrocatalysis of molecular oxygen. This system therefore constitutes a novel two-centered heme-based biocatalytic interface to be exploited for "third-generation" amperometric biosensing.

  1. Energy filtering transmission electron microscopy immunocytochemistry and antigen retrieval of surface layer proteins from Tannerella forsythensis using microwave or autoclave heating with citraconic anhydride

    Science.gov (United States)

    2012-01-01

    Tannerella forsythensis (Bacteroides forsythus), an anaerobic Gram-negative species of bacteria that plays a role in the progression of periodontal disease, has a unique bacterial protein profile. It is characterized by two unique protein bands with molecular weights of more than 200 kDa. It also is known to have a typical surface layer (S-layer) consisting of regularly arrayed subunits outside the outer membrane. We examined the relationship between high molecular weight proteins and the S-layer using electron microscopic immunolabeling with chemical fixation and an antigen retrieval procedure consisting of heating in a microwave oven or autoclave with citraconic anhydride. Immunogold particles were localized clearly at the outermost cell surface. We also used energy-filtering transmission electron microscopy (EFTEM) to visualize 3, 3′-diaminobenzidine tetrahydrochloride (DAB) reaction products after microwave antigen retrieval with 1% citraconic anhydride. The three-window method for electron spectroscopic images (ESI) of nitrogen by the EFTEM reflected the presence of moieties demonstrated by the DAB reaction with horseradish peroxidase (HRP)-conjugated secondary antibodies instead of immunogold particles. The mapping patterns of net nitrogen were restricted to the outermost cell surface. PMID:22984898

  2. Depth profiles of pulmonary surfactant protein B in phosphatidylcholine bilayers, studied by fluorescence and electron spin resonance spectroscopy

    DEFF Research Database (Denmark)

    Cruz, A; Casals, C; Plasencia, I

    1998-01-01

    Pulmonary surfactant-associated protein B (SP-B) has been isolated from porcine lungs and reconstituted in bilayers of dipalmitoylphosphatidylcholine (DPPC) or egg yolk phosphatidylcholine (PC) to characterize the extent of insertion of the protein into phospholipid bilayers. The parameters...... for the interaction of SP-B with DPPC or PC using different reconstitution protocols have been estimated from the changes induced in the fluorescence emission spectrum of the single protein tryptophan. All the different reconstituted SP-B-phospholipid preparations studied had similar Kd values for the binding...... that there are significant differences in the extent of insertion of the protein, depending on the method of reconstitution. SP-B reconstituted from lipid/protein mixtures in organic solvents is inserted more deeply in PC or DPPC bilayers than the protein reconstituted by addition to preformed phospholipid vesicles...

  3. Existence of life-time stable proteins in mature rats-Dating of proteins' age by repeated short-term exposure to labeled amino acids throughout age

    DEFF Research Database (Denmark)

    Bechshøft, Cecilie Leidesdorff; Schjerling, Peter; Bornø, Andreas

    2017-01-01

    In vivo turnover rates of proteins covering the processes of protein synthesis and breakdown rates have been measured in many tissues and protein pools using various techniques. Connective tissue and collagen protein turnover is of specific interest since existing results are rather diverging. Th...... living days, indicating very slow turnover. The data support the hypothesis that some proteins synthesized during the early development and growth still exist much later in life of animals and hence has a very slow turnover rate.......In vivo turnover rates of proteins covering the processes of protein synthesis and breakdown rates have been measured in many tissues and protein pools using various techniques. Connective tissue and collagen protein turnover is of specific interest since existing results are rather diverging....... The aim of this study is to investigate whether we can verify the presence of protein pools within the same tissue with very distinct turnover rates over the life-span of rats with special focus on connective tissue. Male and female Lewis rats (n = 35) were injected with five different isotopically...

  4. Analysis of protein incorporation of radioactive isotopes in the Chinese hamster ovary cell cycle by electronic sorting and gel microelectrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Pipkin, J.L.; Anson, J.F.; Hinson, W.G.; Schol, H.; Burns, E.R.; Casciano, D.A.

    1986-03-01

    The patterns of (3H)-leucine and (32P)-phosphate incorporation of proteins extracted with varying molarities of sodium chloride were analyzed from nuclei physically sorted from six fluorescence windows after propidium iodine staining of the G0 + G1 and G2 + M phases of the Chinese hamster ovary (CHO) cell cycle. Eight hundred nanograms of protein were used in each electrophoretic analysis obtained from 200,000 nuclei, a portion of the sample, from each window. Autoradiography was performed in a two-dimensional polyacrylamide gel ultra-microelectrophoresis apparatus (UMEA) designed and fabricated in this laboratory. There was a net reduction and/or loss of (3H)-leucine- and (32P)-phosphate-labeled protein regions from the autoradiographs occurring primarily in the G2 + M phase. Two phosphorylated proteins that were stage specific were observed in partitions of the G2 + M phase. The use of isolated proteins and the coelectrophoresis of these markers demonstrated the similarity in mobility of a number of proteins seen in the autoradiographs of proteins extracted with high and low salt molarities and implied they are synonymous. Coelectrophoresis indicated that a substantial number of high molecular weight proteins that decreased or disappeared at late stages of G2 + M and early mitosis were composed, in part, of nucleolar proteins.

  5. Investigating the adequacy of the Competence-Turnover Intention Model: how does nursing competence affect nurses' turnover intention?

    Science.gov (United States)

    Takase, Miyuki; Teraoka, Sachiko; Kousuke, Yabase

    2015-03-01

    The aim of this study was to test the adequacy of the Competence-Turnover Intention Model, which was developed to identify how nursing competence could affect nurses' turnover intention (nurses' intention to voluntarily leave an organisation). Recent studies have suggested that the level of nursing competence is negatively related to nurses' intention to leave their jobs, suggesting that a lack of competence threatens both the quality and quantity of the nursing workforce. However, the mechanism of how nursing competence affects nurses' turnover intention has not been explored previously. A cross-sectional survey design was used. Surveys were distributed to 1337 Japanese registered nurses/midwives in October, 2013. The adequacy of the model was analysed using structural equation modelling. In total, 766 questionnaires were returned, with a return rate of 57%. The model fitted well with the data. The results showed that the level of nursing competence was related positively to the quantity of organisational rewards they felt they had received, and negatively related to the level of exhaustion they experienced. Moreover, the perceived organisational rewards and exhaustion were correlated with nurses' turnover intention through affective commitment. The Competence-Turnover Intention Model is useful for explaining how nursing competence impacts on their turnover intention. Clinical implications derived from the findings are that: promoting nursing competence is key to improving not only the quality of care provided by nurses, but also to retaining the nursing workforce, and the model can be used to develop strategies that would mitigate their turnover intention. © 2014 John Wiley & Sons Ltd.

  6. Type VI collagen turnover-related peptides—novel serological biomarkers of muscle mass and anabolic response to loading in young men

    DEFF Research Database (Denmark)

    Nedergaard, Anders; Sun, Shu; Karsdal, Morten A

    2013-01-01

    Immobilization-induced loss of muscle mass is a complex phenomenon with several parallels to sarcopenic and cachectic muscle loss. Muscle is a large organ with a protein turnover that is orders of magnitude larger than most other tissues. Thus, we hypothesize that muscle loss and regain is reflec...

  7. Health insurance, cost expectations, and adverse job turnover.

    Science.gov (United States)

    Ellis, Randall P; Albert Ma, Ching-To

    2011-01-01

    Because less healthy employees value health insurance more than the healthy ones, when health insurance is newly offered job turnover rates for healthier employees decline less than turnover rates for the less healthy. We call this adverse job turnover, and it implies that a firm's expected health costs will increase when health insurance is first offered. Health insurance premiums may fail to adjust sufficiently fast because state regulations restrict annual premium changes, or insurers are reluctant to change premiums rapidly. Even with premiums set at the long run expected costs, some firms may be charged premiums higher than their current expected costs and choose not to offer insurance. High administrative costs at small firms exacerbate this dynamic selection problem. Using 1998-1999 MEDSTAT MarketScan and 1997 Employer Health Insurance Survey data, we find that expected employee health expenditures at firms that offer insurance have lower within-firm and higher between-firm variance than at firms that do not. Turnover rates are systematically higher in industries in which firms are less likely to offer insurance. Simulations of the offer decision capturing between-firm health-cost heterogeneity and expected turnover rates match the observed pattern across firm sizes well. 2010 John Wiley & Sons, Ltd.

  8. [Cost of nursing turnover in a Teaching Hospital].

    Science.gov (United States)

    Ruiz, Paula Buck de Oliveira; Perroca, Marcia Galan; Jericó, Marli de Carvalho

    2016-02-01

    To map the sub processes related to turnover of nursing staff and to investigate and measure the nursing turnover cost. This is a descriptive-exploratory study, classified as case study, conducted in a teaching hospital in the southeastern, Brazil, in the period from May to November 2013. The population was composed by the nursing staff, using Nursing Turnover Cost Calculation Methodology. The total cost of turnover was R$314.605,62, and ranged from R$2.221,42 to R$3.073,23 per employee. The costs of pre-hire totaled R$101.004,60 (32,1%), and the hiring process consumed R$92.743,60 (91.8%) The costs of post-hire totaled R$213.601,02 (67,9%), for the sub process decreased productivity, R$199.982,40 (93.6%). The study identified the importance of managing the cost of staff turnover and the financial impact of the cost of the employee termination, which represented three times the average salary of the nursing staff.

  9. Quality of working life: an antecedent to employee turnover intention.

    Science.gov (United States)

    Mosadeghrad, Ali Mohammad

    2013-06-01

    The purpose of this study was to measure the level of quality of work life (QWL) among hospital employees in Iran. Additionally, it aimed to identify the factors that are critical to employees' QWL. It also aimed to test a theoretical model of the relationship between employees' QWL and their intention to leave the organization. A survey study was conducted based on a sample of 608 hospital employees using a validated questionnaire. Face, content and construct validity were conducted on the survey instrument. Hospital employees reported low QWL. Employees were least satisfied with pay, benefits, job promotion, and management support. The most important predictor of QWL was management support, followed by job proud, job security and job stress. An inverse relationship was found between employees QWL and their turnover intention. This study empirically examined the relationships between employees' QWL and their turnover intention. Managers can take appropriate actions to improve employees' QWL and subsequently reduce employees' turnover.

  10. Estimation of Employee Turnover with Competing Risks Models

    Directory of Open Access Journals (Sweden)

    Grzenda Wioletta

    2015-12-01

    Full Text Available Employee turnover accompanies every business organization, regardless of the industry and size. Nowadays, many companies struggle with problems related to the lack of sufficient information about the nature of employee turnover processes. Therefore, comprehensive analysis of these processes is necessary. This article aims to examine the turnover of employees from a big manufacturing company using competing risks models with covariates and without covariates. This technique allows to incorporate the information about the type of employment contract termination. Moreover, Cox proportional hazard model enables the researcher to analyse simultaneously multiple factors that affect employment duration. One of the major observations is that employee remuneration level differentiates most strongly the risk of job resignation.

  11. PENGARUH JOB SATISFACTION TERHADAP OCB DAN TURNOVER INTENTION

    Directory of Open Access Journals (Sweden)

    Febru Rida Ningsih

    2015-06-01

    Full Text Available This article aims to provide the impact of job satisfaction to OCB and turnover intention. This study used a quantitative method with a statistical analysis. Simple analysis regression used to test each hypotheses. The object of this research is a branch of national bank. Population in this research are entire employees of a brach of national bank that is e non frontliner employees. Non-probability sampling is used of this reseach. The measurement of job satiafaction and turnover intention variables used likert scale that developed by Rinaldi (2008 and measurement of OCB variable adopted from  Organ (1988.  The result of this research has shown that hypotheses one is rejected and hypotheses two is accepted. Eventually, through this article, an understanding that job satisfaction does not significantly influence to OCB but job satisfaction has significant influence to turnover intention.

  12. No turnover in lens lipids for the entire human lifespan.

    Science.gov (United States)

    Hughes, Jessica R; Levchenko, Vladimir A; Blanksby, Stephen J; Mitchell, Todd W; Williams, Alan; Truscott, Roger J W

    2015-03-11

    Lipids are critical to cellular function and it is generally accepted that lipid turnover is rapid and dysregulation in turnover results in disease (Dawidowicz 1987; Phillips et al., 2009; Liu et al., 2013). In this study, we present an intriguing counter-example by demonstrating that in the center of the human ocular lens, there is no lipid turnover in fiber cells during the entire human lifespan. This discovery, combined with prior demonstration of pronounced changes in the lens lipid composition over a lifetime (Hughes et al., 2012), suggests that some lipid classes break down in the body over several decades, whereas others are stable. Such substantial changes in lens cell membranes may play a role in the genesis of age-related eye disorders. Whether long-lived lipids are present in other tissues is not yet known, but this may prove to be important in understanding the development of age-related diseases.

  13. Cogema in 1996: increasing turnover and stable net results

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    This short article gives some financial informations about the Cogema group for 1996. The net result for 1996 reached 977 millions of French Francs (FF) with respect to 973 for the previous year. The turnover reached 34.427 billions of FF in 1996 and 30.611 in 1995, which represents a 12.5% growth. In the mining sector, the turnover has decreased to 2.853 billions of FF with respect to 3.238 in 1995. In the engineering and industry services sector the turnover of the overall companies, with the exception of Cogema, has considerably progressed (2.199 billions of FF in 1996, 1.738 in 1995). (J.S.)

  14. DNA turnover and strand breaks in Escherichia coli

    International Nuclear Information System (INIS)

    Hanawalt, P.; Grivell, A.; Nakayama, H.

    1975-01-01

    The extent of DNA turnover has been measured in a dnaB mutant of Escherichia coli, temperature sensitive for semiconservative DNA replication. At the nonpermissive temperature about 0.02 percent of the deoxynucleotides in DNA are exchanged per generation period. This turnover rate is markedly depressed in the presence of rifampicin. During thymine starvation strand breaks accumulate in the DNA of E. coli strains that are susceptible to thymineless death. Rifampicin suppresses the appearance of these breaks, consistent with our hypothesis that transcription may be accompanied by repairable single-strand breaks in DNA. DNA turnover is enhanced severalfold in strands containing 5-bromodeoxyuridine in place of thymidine, possibly because the analog (or the deoxyuridine, following debromination) is sometimes recognized and excised

  15. Peningkatan Komitmen Organisasi untuk Menurunkan Angka Turnover Karyawan

    Directory of Open Access Journals (Sweden)

    Elita Halimsetiono

    2014-05-01

    Full Text Available Komitmen organisasi dapat diartikan sebagai suatu sikap yang harus dimiliki oleh setiap pegawai untuk menunjukkan loyalitas terhadap organisasi tempat mereka bekerja. Pada dasarnya, komitmen organisasi berkaitan erat dengan aspek-aspek psikologis dalam menerima dan memercayai nilai-nilai dan tujuan organisasi yang muncul sebagai keinginan untuk tetap mempertahankan keanggotaan dalam organisasi. Permasalahan yang sering dikaitkan dengan rendahnya komitmen organisasi adalah pindah kerja (turnover. Masalah ini memiliki dampak yang merugikan organisasi karena dapat menghambat efektivitas dan efisiensi kerja yang selanjutnya akan menurunkan tingkat produktivitas organisasi. Oleh karena itu, untuk mencegah tingginya turnover karyawan, organisasi perlu meningkatkan komitmen organisasi karyawannya. Caranya adalah dengan mengetahui faktor-faktor apa saja yang memengaruhi komitmen organisasi dan bagaimana cara untuk meningkatkan komitmen organisasi tersebut. Artikel ini membahas faktor-faktor apa saja yang memengaruhi komitmen organisasi dan cara-cara yang dapat digunakan untuk meningkatkan komitmen organisasi sebagai upaya untuk menurunkan angka turnover karyawan. Organizational commitment can be interpreted as an attitude that should be owned by every employee to demonstrate loyalty to the organization where they work. Basically, organizational commitment is closely related to the psychological aspects in the acceptance and confidence to the values and objectives of the organization that are presented through the existence of a desire to maintain membership in the organization. Problems which are associated with low organizational commitment is turnover. This problem has an adverse impact on the organization because it can inhibit the effectiveness and efficiency of the work that would lower the level of productivity of the organization. Therefore, to prevent the high employee turnover, the organization should increase the organizational commitment of

  16. Platelet monoamine oxidase: specific activity and turnover number in headache

    International Nuclear Information System (INIS)

    Summers, K.M.; Brown, G.K.; Craig, I.W.; Peatfield, R.; Rose, F.C.

    1982-01-01

    Monoamine oxidase turnover numbers (molecules of substrate converted to product per minute per active site) have been calculated for the human platelet enzyme using [ 3 H]pargyline. Headache patients with high and low monoamine oxidase specific activities relative to controls were found to have turnover numbers very close to those for controls. This finding suggests that their specific activities vary because of differences in the concentration of active monoamine oxidase molecules, rather than differences in the ability of those enzyme molecules to catalyse the deamination reaction. (Auth.)

  17. [Pharmaceutical logistic in turnover of pharmaceutical products of Azerbaijan].

    Science.gov (United States)

    Dzhalilova, K I

    2009-11-01

    Development of pharmaceutical logistic system model promotes optimal strategy for pharmaceutical functioning. The goal of such systems is organization of pharmaceutical product's turnover in required quantity and assortment, at preset time and place, at a highest possible degree of consumption readiness with minimal expenses and qualitative service. Organization of the optimal turnover chain in the region is offered to start from approximate classification of medicaments by logistic characteristics. Supplier selection was performed by evaluation of timeliness of delivery, quality of delivered products (according to the minimum acceptable level of quality) and time-keeping of time spending for orders delivery.

  18. The Escherichia coli antiterminator protein BglG stabilizes the 5 ...

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Antitermination; mRNA stability; RNA binding protein ... factor, Rho, and the pBR322 copy number protein, Rop, have been .... Transcription analysis using the oligo- ..... Retarded RNA turnover in Escherichia coli a means of main-.

  19. Substance Abuse-Specific Knowledge Transfer or Loss? Treatment Program Turnover versus Professional Turnover among Substance Abuse Clinicians

    Science.gov (United States)

    Eby, Lillian T.; Curtis, Sara L.

    2014-01-01

    This longitudinal study investigated the extent to which substance abuse (SA) clinician turnover is associated with SA-specific knowledge loss due to change in professions (professional turnover) versus SA-specific knowledge transfer due to movement from one SA clinical setting to another (treatment program turnover). For this study, clinicians had to voluntarily leave their current treatment program. Eligible clinicians completed a quantitative survey while employed and a qualitative post-employment exit interview 1 year later. Compared to those that exited the SA profession (N = 99), clinicians who changed treatment programs (N = 120) had greater SA-specific formal knowledge and were more likely to be personally in recovery. No differences were found between the two groups in terms of SA-specific practical knowledge. PMID:25115318

  20. Deep proton tunneling in the electronically adiabatic and non-adiabatic limits: Comparison of the quantum and classical treatment of donor-acceptor motion in a protein environment

    Energy Technology Data Exchange (ETDEWEB)

    Benabbas, Abdelkrim; Salna, Bridget; Sage, J. Timothy; Champion, Paul M., E-mail: champ@neu.edu [Department of Physics and Center for Interdisciplinary Research on Complex Systems,Northeastern University, Boston, Massachusetts 02115 (United States)

    2015-03-21

    Analytical models describing the temperature dependence of the deep tunneling rate, useful for proton, hydrogen, or hydride transfer in proteins, are developed and compared. Electronically adiabatic and non-adiabatic expressions are presented where the donor-acceptor (D-A) motion is treated either as a quantized vibration or as a classical “gating” distribution. We stress the importance of fitting experimental data on an absolute scale in the electronically adiabatic limit, which normally applies to these reactions, and find that vibrationally enhanced deep tunneling takes place on sub-ns timescales at room temperature for typical H-bonding distances. As noted previously, a small room temperature kinetic isotope effect (KIE) does not eliminate deep tunneling as a major transport channel. The quantum approach focuses on the vibrational sub-space composed of the D-A and hydrogen atom motions, where hydrogen bonding and protein restoring forces quantize the D-A vibration. A Duschinsky rotation is mandated between the normal modes of the reactant and product states and the rotation angle depends on the tunneling particle mass. This tunnel-mass dependent rotation contributes substantially to the KIE and its temperature dependence. The effect of the Duschinsky rotation is solved exactly to find the rate in the electronically non-adiabatic limit and compared to the Born-Oppenheimer (B-O) approximation approach. The B-O approximation is employed to find the rate in the electronically adiabatic limit, where we explore both harmonic and quartic double-well potentials for the hydrogen atom bound states. Both the electronically adiabatic and non-adiabatic rates are found to diverge at high temperature unless the proton coupling includes the often neglected quadratic term in the D-A displacement from equilibrium. A new expression is presented for the electronically adiabatic tunnel rate in the classical limit for D-A motion that should be useful to experimentalists working

  1. Exploring correlates of turnover among nursing assistants in the National Nursing Home Survey.

    Science.gov (United States)

    Temple, April; Dobbs, Debra; Andel, Ross

    2011-01-01

    High turnover of nursing assistants (NAs) has implications for the quality of nursing home care. Greater understanding of correlates of NA turnover is needed to provide insight into possible retention strategies. This study examined nursing home organizational characteristics and specific job characteristics of staff in relation to turnover of NAs. Cross-sectional data on 944 nationally representative nursing homes were derived from the 2004 National Nursing Home Survey. Using a 3-month turnover rate, 25% of the facilities with the lowest turnover rates were classified as low turnover, 25% of the facilities with the highest turnover were classified as high turnover, and the remaining 50% of the facilities were classified as moderate turnover. Multinomial logistic regression was used to examine organizational and job characteristics associated with low and high turnover compared with moderate turnover. One organizational characteristic, staffing levels at or greater than 4.0 hours per patient day, was associated with greater odds of low NA turnover and reduced odds of high NA turnover. Job characteristics including higher wages and union membership were associated with greater odds of low NA turnover, whereas wages, fully paid health insurance, employee assistance benefits, and involvement in resident care planning were associated with reduced odds of high NA turnover. The results of this study suggest that job characteristics of NA staff may be particularly important for turnover. Specifically, the provision of competitive wages and benefits (particularly health insurance) and involvement of NAs in resident care planning could potentially reduce NA turnover, as could maintaining high levels of nurse staffing.

  2. Effects of catecholamines on rat myocardial metabolism. II. Influence of catecholamines on 32p-incorporation into rat myocardial adenylic nucleotides and their turn-over.

    Science.gov (United States)

    Merouze, P; Gaudemer, Y; Gautheron, D

    1975-01-01

    1. The influence of catecholamines (adrenaline and noradrenaline) on 32Pi incorporation into intracellular phosphate and adenylic nucleotides has been studied on rat myocardium slices; consequently, the turn-over of nucleotides could be determined and compared under the influence of these two hormones. 2. In order to specify the site of action of these catecholamines, several inhibitors and activators of energetic metabolism were included in the incubation medium: 3'5'-AMP, caffein, ouabain, oligomycin, rotenone + antimycin. 3. Both catecholamines favour Pi exchanges between intra and extracellular spaces; ATP turn-over is greatly increased, while ADP turn-over is slightly decreased, and 32P-incorporation into ADP is increased. 4. 3'5'-AMP and caffein are without effect on Pi penetration; however, caffein increases catecholamine effects on this penetration. ATP turn-over is slightly increased by 3'5'-AMP or caffein. 5. Ouabain decreases ATP turn-over but does not prevent the adrenaline induced acceleration. Inhibitors of oxidative phosphorylation and electron transport decrease ATP-turn-over severely; this inhibition is not released by catecholamines. 6. It is concluded that the catecholamine effects observed are dependent on the oxidative phosphorylations process. The increase of Pi exchange by catecholamines may be related to the increase of extracellular space and cation translocations we observed with the hormones.

  3. The Au-S bond and SAM-protein contact in long-range electron transfer of pure and biomimetic metalloproteins via functionalized alkanethiol linkers

    DEFF Research Database (Denmark)

    Chi, Qijin; Ford, Michael J.; Halder, Arnab

    disentangled a wealth of data to identify the nature of the crucial Au-S contact, all suggesting prevalence of a Au(0)-thiyl radical unit. Molecular packing is further determined by the SAM molecular structure and involves binding either to Au-atoms mined out of the surface or directly to a flat surface. We...... functionalized alkanethiols have emerged as core linkers. We have studied molecular linking in the long-range ET (LRET) processes in detail using electrochemistry, in situ STM and AFM, and electronic structure computations. A focus is the electronic structure of the Au-S link and the SAM packing. We have...... is exceedingly sensitive to the structure of the thiol-based SAM molecules, testifying to the crucial importance of SAM packing and Au-S binding, and of the SAM link to the protein. Some of the subtleties are illustrated simpler by similar size (5-6 nm) nanoparticles (NPs). Biomimetic NPs must possess a certain...

  4. Firm-level innovation activity, employee turnover and HRM practices

    DEFF Research Database (Denmark)

    Eriksson, Tor; Qin, Zhihua; Wang, Wenjing

    2014-01-01

    This paper examines the relationship between employee turnover, HRM practices and innovation in Chinese firms in five high technology sectors. We estimate hurdle negative binomial models for count data on survey data allowing for analyses of the extensive as well as intensive margins of firms' in...

  5. Employees as Customers: Exploring Service Climate, Employee Patronage, and Turnover

    Science.gov (United States)

    Abston, Kristie A.; Kupritz, Virginia W.

    2011-01-01

    The role of retail employees as customers was explored by quantitatively examining the influence of service climate and employee patronage on employee turnover intentions. Employees representing all shifts in two stores of a national retailer participated. Results indicated that employee patronage partially mediates the effects of service climate…

  6. Psychological contract as precursor for turnover and self-employment

    NARCIS (Netherlands)

    Stormbroek-Burgers, van R.G.B.M.; Blomme, R.J.

    2017-01-01

    Purpose The purpose of this paper is to examine the effect of psychological contract (PC) fulfilment and violation on turnover intention and self-employment intentions. Design/methodology/approach A sample of 132 Dutch organizationally employed individuals was used to test the effect of PC

  7. Some Determinants of Employee Turnover in a Psychiatric Facility.

    Science.gov (United States)

    Zautra, Alex J.; And Others

    1987-01-01

    Used research from illness-prevention and job-enrichment approaches to enhancing quality of work environments to create instruments assessing number of job stressors and level of task interest on psychiatric hospital units. Instruments successfully predicted employee turnover during one year. Job stress and interaction between job stress and task…

  8. System wide cofactor turnovers can propagate metabolic stability between pathways

    DEFF Research Database (Denmark)

    Yang, Y.; Guan, Y.H.; Villadsen, John

    2016-01-01

    . Furthermore, we elaborated the criteria to tell if a multi-enzyme over-all reaction path is of in vivo nature or not at the metabolic level. As new findings, we discovered that there are interactions between the enzyme feedback inhibition and the CI turnover, and such interactions may well lead to metabolic...

  9. Turnover of nursing employees in a Gauteng hospital group

    Directory of Open Access Journals (Sweden)

    Japie Greyling

    2010-11-01

    Research purpose: The purpose of this study was to investigate individual determinants of voluntary turnover to identify a risk-group profile. Motivation for the study: Nursing employers should have a clearer understanding of the dynamics around nurses’ turnover behaviour and embark on strategies to retain their talent. Research design, approach and method: A survey measuring voluntary turnover was conducted among 262 professional and assistant nurses in three selected hospitals in Gauteng province using the McCarthy, Tyrrell and Cronin (2002 instrument. Pearson’s chi square with Yates’s continuity correction tested the relationship among the variables presented in a contingency table, in other words the risk group and each of the individual determinants. Main findings: Discontent with salaries was the major determinant of the nurses’ resignation. Organisational causes were nursing practices, the work environment, physical-emotional costs and employment opportunities after resignation. Practical/managerial implications: Hospital management could indeed establish a good rapport with nursing staff while facilitating respectful and ethical conduct by doctors towards nursing staff. Putting into place effective labour practices and business strategies could improve job satisfaction in the workplace. Contribution/value-add: This study contributed to a greater understanding of the personal and organisational determinants of the turnover of nurses in South African hospitals.

  10. Chinese Teachers' Work Stress and Their Turnover Intention

    Science.gov (United States)

    Liu, Shujie; Onwuegbuzie, Anthony J.

    2012-01-01

    This survey study employed qualitative dominant mixed research to explore the sources of teacher stress in China and the possible reasons for Chinese teachers' turnover intention. The data were collected in Jilin Province of China, and 510 teachers participated in the survey. Quantitatively, 40.4% of the surveyed teachers reported that they…

  11. Relationships between Emotional Labor, Job Performance, and Turnover

    Science.gov (United States)

    Goodwin, Robyn E.; Groth, Markus; Frenkel, Stephen J.

    2011-01-01

    The present study investigates the relationship between the emotional labor strategies surface acting and deep acting and organizational outcomes, specifically, employees' overall job performance and turnover. Call center employees from two large financial service organizations completed an online survey about their use of surface and deep acting.…

  12. The Prediction of Teacher Turnover Employing Time Series Analysis.

    Science.gov (United States)

    Costa, Crist H.

    The purpose of this study was to combine knowledge of teacher demographic data with time-series forecasting methods to predict teacher turnover. Moving averages and exponential smoothing were used to forecast discrete time series. The study used data collected from the 22 largest school districts in Iowa, designated as FACT schools. Predictions…

  13. Teachers' Perceptions of Administrative Support and Antecedents of Turnover

    Science.gov (United States)

    Russell, Elizabeth Morgan; Williams, Sue W.; Gleason-Gomez, Cheryl

    2010-01-01

    The purpose of this pilot study was to determine the degree to which teachers' age, perceptions of fair pay, receipt of employer-sponsored health insurance, and administrative support, as operationalized by the Competing Values Framework, predicted antecedents of turnover. Teachers' thoughts of leaving their current job and commitment to a center…

  14. Turn-over of Stratijm Corneum in Leprosy

    Directory of Open Access Journals (Sweden)

    R P Okhandiar

    1987-01-01

    Full Text Available Stratum corneum showed increased proliferative activity on the patches of leprosy as evidenced by a significantly fast stratum corneum turnover time (p 0.001 measured by fluorescent staining technic with dansyl chloride. These findings suggest imperfect keratinization on the patches of leprosy leading to formation of structurally weak stratum corneum.

  15. Principal Turnover: Upheaval and Uncertainty in Charter Schools?

    Science.gov (United States)

    Ni, Yongmei; Sun, Min; Rorrer, Andrea

    2015-01-01

    Purpose: Informed by literature on labor market and school choice, this study aims to examine the dynamics of principal career movements in charter schools by comparing principal turnover rates and patterns between charter schools and traditional public schools. Research Methods/Approach: This study uses longitudinal data on Utah principals and…

  16. Steroid implants and markers of bone turnover in steers | Knetter ...

    African Journals Online (AJOL)

    The current study was designed to test the hypothesis that recently identified indicators of bone and cartilage turnover could be detected in the peripheral circulation, and that these markers might reflect accelerated ageing effects of the widely used steroidal implants, trenbolone acetate (TBA) and estradiol-17β (E2).

  17. Influence of Religiosity on Turnover Intention: Empirical Evidence ...

    African Journals Online (AJOL)

    This study examined the influence of employees' religiosity on their turnover intentions. The ex-post facto research design and the convenient sampling technique were employed in this study. A hundred and forty-nine (149) employees in Lagos and Ogun States of Nigeria were sampled as the study participants.

  18. Adeprene influence on the turnover rate of brain noradrenaline

    International Nuclear Information System (INIS)

    Tyutyulkova, N.I.; Gorancheva, J.I.; Ankov, V.K.

    1978-01-01

    The influence of Adeprene - Bulgarian antidepressant - on the content and the turnover rate of the rat brain noradrenaline was studied. The animals were injected intraperitoneally during 5 days with 20 mg/kg Adeprene. One hour after the last administration of Adeprene, Tyrosine, labelled with 14 C was injected. The animals were sacrified on the 1st, 2nd and 4th hours after the injection of 14 C-Tyrosine. The tyrosine and noradrenaline concentration were determined spectrofluorimetrically the concentration of the compounds labelled with 14 C by means of a liquid scintillator. The turnover rate constant of noradrenaline was calculated on the basis of the obtained results and the respective formula. It was established that under the influence of Adeprene, the noradrenaline concentration in the brain rises from 0,5 g/g in the control animals to 0,6 in treated mice. The turnover rate constant of noradrenaline, however, drops to 0,9 g/g/hour as compared to 0,15 g/g/hours in the controls. The determination of the turnover rate provides an idea about the intensity of utilization and synthesis of the mediator and is considered consequently as a more radiosensitive index for the neuronal activity then the total amine content. (A.B.)

  19. The Effects of Turnover: What We Know about Teacher Attrition

    Science.gov (United States)

    DeAngelis, Karen

    2012-01-01

    School business officials are likely to know better than anyone else about the financial costs to districts and schools associated with teacher attrition. Perhaps less well-known, though, is what else has been learned about this issue in recent years--information that may affect how one thinks about teacher turnover. Here is some of that research:…

  20. Bone turnover biomarkers in obese postmenopausal Saudi women ...

    African Journals Online (AJOL)

    Background: There is a high prevalence of diabetes mellitus type-2 (T2DM) and osteoporosis are problems worldwide. In this study, we evaluated the correlation between T2DM and bone turnover in diabetic obese postmenopausal Saudi women. Subjects and Methods: The present study included total of 65 T2-DM obese ...