Showing papers by "Colorado State University published in 1993"

Disseminated tuberculosis in interferon gamma gene-disrupted mice.

Abstract: The expression of protective immunity to Mycobacterium tuberculosis in mice is mediated by T lymphocytes that secrete cytokines. These molecules then mediate a variety of roles, including the activation of parasitized host macrophages, and the recruitment of other mononuclear phagocytes to the site of the infection in order to initiate granuloma formation. Among these cytokines, interferon gamma (IFN-gamma) is believed to play a key role is these events. In confirmation of this hypothesis, we show in this study that mice in which the IFN-gamma gene has been disrupted were unable to contain or control a normally sublethal dose of M. tuberculosis, delivered either intravenously or aerogenically. In such mice, a progressive and widespread tissue destruction and necrosis, associated with very high numbers of acid-fast bacilli, was observed. In contrast, despite the lack of protective immunity, some DTH-like reactivity could still be elicited. These data, therefore, indicate that although IFN-gamma may not be needed for DTH expression, it plays a pivotal and essential role in protective cellular immunity to tuberculosis infection.

Stewardship: Choosing Service Over Self-Interest

Abstract: The article reviews the book “Stewardship: Choosing Service Over Self-Interest,” by Peter Block.

Carbon and Nitrogen Distribution in Aggregates from Cultivated and Native Grassland Soils

Abstract: Long-term cultivation of grassland soils reduces soil organic C and N content and has been associated with a deterioration in the aggregate structure of the soil. This study examined the effects of bare fallow (moldboard plow), stubble mulch fallow (subtill), and no-till fallow management on aggregate size distribution and aggregate organic C and N contents compared with a native (virgin) grassland soil. Aggregate size fractions were separated by wet sieving and the proportion of soil was quantified for each aggregate size class. Mineralassociated (silt and clay) organic matter was isolated by dispersing aggregates in sodium hexametaphosphate and removing the sand and particulate organic matter (POM) by passing the dispersed aggregates through a 53-/un sieve. The POM fraction is composed primarily of partially decomposed root fragments and has an average C/N ratio of about 16. A large proportion of the total soil dry weight (50-60%) was isolated in the small macroaggregate (250-2000 fan) size class. The native grassland soil was more stable than the cultivated soils when slaked, and the no-till soil was more stable than the stubble mulch and bare fallow soil when slaked. Reduced tillage management is effective at increasing the proportion of macroaggregates and results in the accumulation of wheat (Triticum aestivum L.) derived POM within the aggregate structure compared with bare fallow soil. It has previously been shown that the POM fraction accounts for the majority of the soil organic matter (SOM) initially lost as a result of cultivation of grassland soils. The data reported in this study relates the loss of structural stability from cultivation to losses of organic C and N from the POM fraction. N GRASSLAND SOILS are generally highly structured and rich in SOM. Cultivation reduces SOM content (Jenny, 1941; Haas et al., 1957) and results in a deterioration of the aggregate structure (Chancy and Swift, 1984). The POM fraction, which is composed primarily of partially decomposed root fragments, accounts for the majority of the SOM initially lost as a result of cultivation of grassland soils (Cambardella and Elliott, 1992). Reductions in aggregate stability after cultivation are most pronounced in soil macroaggregates, while the stability of soil microaggregates remains unchanged (Tisdall and Oades, 1982; Oades, 1984). As macroaggregates disintegrate with tillage, the proportion of microaggregates increases, since microaggregates are not destroyed by cultivation (Tisdall and Oades, 1980; Elliott, 1986). Microaggregates have a lower organic matter concentration than macroaggregates (Dormaar, 1983) and this organic matter is less labile than that associated with macroaggregates (Elliott, 1986; Gupta and Germida, 1988). The disintegration of macroaggregates with cultivation into nutrient-poor microaggregates and the subsequent release of plant-available nutrients may be one explanation for the observed pattern of lower orC.A. Cambardella, USDA-ARS, National Soil Tilth Lab., 2150 Pammel Drive, Ames, IA 50011; and E.T. Elliott, Natural Resource Ecology Lab., Colorado State Univ., Fort Collins, CO 80523. Received 30 June 1992. \"Corresponding author. Published in Soil Sci. Soc. Am. J. 57:1071-1076 (1993). ganic matter contents and reduced nutrient-supplying efficiencies in cultivated soils when compared with grassland soils (Elliott, 1986). Sustainable production has become a key issue in the management of cropping systems. Reduced tillage and no-till management have been initiated to mitigate some of the detrimental effects of intensive cultivation, such as reduction of soil organic matter and the concomitant increase in erosion and decrease in soil fertility (Fenster and Peterson, 1979). Little information exists in the literature on the effect of reduced tillage or no-till management on the nutrient contents of soil aggregates and their associated organic matter. This study examined the effects of bare fallow (moldboard plow), stubble mulch fallow (subtill), and notill management on aggregate size distributions and aggregate organic C and N contents compared with native grassland. MATERIALS AND METHODS

A molecular, isozyme and morphological map of the barley (Hordeum vulgare) genome.

Abstract: A map of the barley genome consisting of 295 loci was constructed. These loci include 152 cDNA restriction fragment length polymorphism (RFLP), 114 genomic DNA RFLP, 14 random amplified polymorphic DNA (RAPD), five isozyme, two morphological, one disease resistance and seven specific amplicon polymorphism (SAP) markers. The RFLP-identified loci include 63 that were detected using cloned known function genes as probes. The map covers 1,250 centiMorgans (cM) with a 4.2 cM average distance between markers. The genetic lengths of the chromosomes range from 124 to 223 cM and are in approximate agreement with their physical lengths. The centromeres were localized to within a few markers on all of the barley chromosomes except chromosome 5. Telomeric regions were mapped for the short (plus) arms of chromosomes 1, 2 and 3 and the long (minus) arm of chromosomes 7.

An unambiguous nomenclature for xyloglucan‐derived oligosaccharides

Abstract: A revised system of abbreviated names is proposed for xyloglucan-derived oligosaccharides. Each (1→4)-linked β-D-glucosyl residue (and the reducing terminal n-glucose moiety) of the backbone is given a one-letter code according to its substituents. The name of the oligosaccharide consists of these code letters listed in sequence from non-reducing to reducing terminus of the backbone

A Climatology of Intense (or Major) Atlantic Hurricanes

Abstract: The variability of intense (or major) hurricanes in the Atlantic basin is investigated on both intraseasonal and interannual time scales. Differences are highlighted in characteristics between intense hurricanes and the weaker minor hurricanes and tropical storms. Intense hurricanes show a much more peaked annual cycle than do weaker tropical cyclones. Ninety-five percent of all intense hurricane activity occurs during August to October. In addition, over 80% of all intense hurricanes originate from African easterly waves, a much higher proportion than is observed for weaker cyclones. Of all classes of Atlantic basin tropical cyclones, the intense hurricanes display the greatest year-to-year variability. The incidence of intense hurricanes also has decreased during the last two decades. A small portion of this decreased activity appears to be due to an overestimation of hurricane intensity during the period spanning the 1940s through the 1960s. After adjusting for this bias, however, a substantia...

Dispositional affectivity as a predictor of work attitudes and job performance

Abstract: Previous research has shown that dispositional negative affect (NA) is associated with lower levels of job satisfaction. Little research has been conducted, however, on other organizational implications of negative affect or on the potential effects of dispositional positive affect (PA). The present studies examined the relationship of both positive and negative affectivity to organizational commitment, turnover intentions, global job satisfaction and performance. In the first study both NA and PA were associated with organizational commitment and turnover intentions. Additionally, commitment mediated the relationship between dispositional affectivity and turnover. Finally, PA and tenure interacted to predict job performance, such that PA and job performance were positively related, but only for high tenure employees. In Study 2 the findings were generally similar, but not identical. Both NA and PA were related to global job satisfaction and turnover intentions. However, only PA was related to affective organizational commitment. Moreover, both job satisfaction and affective commitment mediated the relationship between dispositional affectivity and turnover intentions. Finally, unlike Study 1, PA was not related to job performance. Rather, NA and tenure interacted such that when individuals were lower in tenure, NA was negatively related to performance.

T Cell Response to Mycobacterium tuberculosis

Abstract: The T cell-mediated acquired immune response to infection with Mycobacterium tuberculosis, both in humans and in experimental models in the mouse, is a complex event believed to involve a variety of T cell subsets that manifest themselves in numerous functions, including protection, delayed-type hypersensitivity, cytolysis, and the establishment of a state of memory immunity. These functions in turn involve the secretion of an array of cytokines, several of which direct cells of the monocyte/macrophage axis to contain and destroy the invading bacilli. This article reviews the development of these ideas, both from clinical experience and from basic research in animal models. In addition, the newly emerging hypothesis that the secreted or export proteins of M. tuberculosis are the key protective antigens leading to the initial expression of acquired specific resistance to this organism is examined.

Cytokine secretion by CD4 T lymphocytes acquired in response to Mycobacterium tuberculosis infection.

Abstract: The results of this study, in which CD4 T cells were harvested from mice at various times during the course of a virulent Mycobacterium tuberculosis infection and examined for their secretion of cytokines during culture in vitro with bone marrow-derived macrophages presenting mycobacterial Ag, provide evidence for the existence of two separate waves of cytokine-producing CD4 cells. The first, which peaks at the time at which protective immunity was maximally expressed, was characterized as a IFN-gamma-secreting cell population that preferentially recognized macrophages presenting mycobacterial culture filtrate proteins, or that were infected with the live organism. A second population, which emerged 20 to 40 days later at a time when the infection had been contained, secreted IL-4 in response to the filtrate proteins, but also reacted particularly strongly to the 65-kDa (hsp60) heat shock protein molecule of M. tuberculosis. These data indicate that acquired immunity to tuberculosis infection involves the production of both Th1- and Th2-like cell populations that differ in terms of their kinetics of emergence and loss, and in terms of their Ag specificity.

Calcium and signal transduction in plants

Abstract: Environmental and hormonal signals control diverse physiological processes in plants. The mechanisms by which plant cells perceive and transduce these signals are poorly understood. Understanding biochemical and molecular events involved in signal transduction pathways has become one of the most active areas of plant research. Research during the last 15 years has established that Ca2+ acts as a messenger in transducing external signals. The evidence in support of Ca2+ as a messenger is unequivocal and fulfills all the requirements of a messenger. The role of Ca2+ becomes even more important because it is the only messenger known so far in plants. Since our last review on the Ca2+ messenger system in 1987, there has been tremendous progress in elucidating various aspects of Ca(2+) -signaling pathways in plants. These include demonstration of signal-induced changes in cytosolic Ca2+, calmodulin and calmodulin-like proteins, identification of different Ca2+ channels, characterization of Ca(2+) -dependent protein kinases (CDPKs) both at the biochemical and molecular levels, evidence for the presence of calmodulin-dependent protein kinases, and increased evidence in support of the role of inositol phospholipids in the Ca(2+) -signaling system. Despite the progress in Ca2+ research in plants, it is still in its infancy and much more needs to be done to understand the precise mechanisms by which Ca2+ regulates a wide variety of physiological processes. The purpose of this review is to summarize some of these recent developments in Ca2+ research as it relates to signal transduction in plants.

Honesty in the workplace.

Abstract: Understanding Honesty in the Workplace Honesty and Dishonest Behaviour in the Workplace Problems in predicting and detecting dishonesty and deception Psychological Behavioural and other indirect Methods of Detection Using Self Reports to detect deception and dishonesty Situational Causes, Correlates and Methods of Control defining situations Encouraging Honesty in Organizations Pitfalls and Promise in the pursuit of honesty in organizations.

Continuation and path following

Abstract: The main ideas of path following by predictor–corrector and piecewise-linear methods, and their application in the direction of homotopy methods and nonlinear eigenvalue problems are reviewed. Further new applications to areas such as polynomial systems of equations, linear eigenvalue problems, interior methods for linear programming, parametric programming and complex bifurcation are surveyed. Complexity issues and available software are also discussed.

Role of intracellular calcium in NI-35-evoked collapse of neuronal growth cones

Abstract: A myelin-associated protein from the central nervous system, the neurite growth inhibitor NI-35, inhibits regeneration of lesioned neuronal fiber tracts in vivo and growth of neurites in vitro. Growth cones of cultured rat dorsal root ganglion neurons arrested their growth and collapsed when exposed to liposomes containing NI-35. Before morphological changes, the concentration of free intracellular calcium ([Ca2+]i) showed a rapid and large increase in growth cones exposed to liposomes containing NI-35. Neither an increase in [Ca2+]i nor collapse of growth cones was detected in the presence of antibodies to NI-35. Dantrolene, an inhibitor of calcium release from caffeine-sensitive intracellular calcium stores, protected growth cones from collapse evoked by NI-35. Depletion of these caffeine-sensitive intracellular calcium stores prevented the increase in [Ca2+]i evoked by NI-35. The NI-35-evoked cascade of intracellular messengers that mediates collapse of growth cones includes the crucial step of calcium release from intracellular stores.

The Assessment of IADL Motor Skills: An Application of Many­ Faceted Rasch Analysis

Abstract: Traditional methods of developing tests have been driven by item content specification and have relied on the use of summed ordinal scores in an attempt to create a quantitative index of ability. There are fundamental problems with this approach to test development. The first problem is that the summing of qualitative ordinal counts to create a total score does not result in a number that is a valid means of making quantitative comparisons of performances. The second problem is that reliance on content experts does not ensure that the test items indeed test the construct in question. As a result, the development of functional assessments based on Rasch measurement models is becoming a preferred method among rehabilitation professionals for constructing tests. Rasch measurement models offer an alternative approach to instrument development that results in unidimensional linear measures based on additive numbers. Rasch analyses also generate goodness-of-fit statistics that can be used to perform confirmatory construct validity analyses of the constructed scales based on (a) formulating expectations about what should happen when a group of persons take a test, and then (b) confirming that the test items fit that model. This paper describes how the many-faceted Rasch model was used to develop the motor scale of the Assessment of Motor and Process Skills (AMPS) (Fisher, 1992). The process of beginning test development with a theory of expectations related to a constructed scale and then confirming that the scale conforms to these expectations also is demonstrated.

Nature and Consequences of Halo Error : A Critical Analysis

Abstract: The definition of halo error that dominated researchers' thinking for most of this century implied that (a) halo error was common; (b) it was a rater error, with true and illusory components; (c) it led to inflated correlations among rating dimensions and was due to the influence of a general evaluation on specific judgments; and (d) it had negative consequences and should be avoided or removed. We review research showing that all of the major elements of this conception of halo are either wrong or problematic. Because of unresolved confounds of true and illusory halo and the often unclear consequences of halo errors, we suggest a moratorium on the use of halo indices as dependent measures in applied research. We suggest specific directions for future research on halo that take into account the context in which judgments are formed and ratings are obtained and that more clearly distinguish between actual halo errors and the apparent halo effect. When an individual is rated on multiple performance dimensions or attributes, the rater's overall impression or evaluation is thought to strongly influence ratings of specific attributes (Cooper, 1981 b), a phenomenon that is referred to as halo error (Thorndike, 1920). Discussions of halo error are most frequently encountered in the context of evaluative judgment (e.g., in interviews and performance appraisals), but similar phenomena have been noted in research on illusory correlation (Chapman & Chapman, 1969), implicit personality theory (Lay & Jackson, 1969), and interpersonal judgments (Nisbett & Wilson, 1977).

Hurricane Spiral Bands

Abstract: The spiral bands that occur in tropical cyclones can be conveniently divided into two classes—outer bands and inner bands. Evidence is presented here that the outer bands form as the result of nonlinear effects during the breakdown of the intertropical convergence zone (ITCZ) through barotropic instability. In this process a zonal strip of high potential vorticity (the ITCZ shear zone or monsoon trough) begins to distort in a varicose fashion, with the potential vorticity (PV) becoming pooled in local regions that are connected by filaments of high PV. As the pooled regions become more axisymmetric, the filaments become thinner and begin to wrap around the PV centers. It is argued that inner bands form in a different manner. As a tropical cyclone intensifies due to latent heat release, the PV field becomes nearly circular with the highest values of PV in the cyclone center. The radial gradient of PV provides a state on which PV waves (the generalization of Rossby waves) can propagate. The nonline...

Predicting Atlantic Basin Seasonal Tropical Cyclone Activity by 1 August

Abstract: More than 90% of all seasonal Atlantic tropical cyclone activity typically occurs after 1 August. A strong predictive potential exists that allows seasonal forecasts of Atlantic basin tropical cyclone activity to be issued by 1 August, prior to the start of the active portion of the hurricane season. Predictors include June-July meteorological information of the stratospheric quasi-biennial oscillation (QBO), West African rainfall, the El Nino-Southern Oscillation (ENSO) as well as sea level pressure anomalies (SLPA), and the upper-tropospheric zonal-wind anomalies (ZWA) in the Caribbean basin. Use of a combination of these global and regional predictors provides a basis for making cross-validated (jackknifed) 1 August hindcasts of subsequent Atlantic seasonal tropical cyclone activity that show substantial skill over climatology. This relationship is demonstrated in 41 years of hindcasts of the 1950-90 seasons. It is possible to independently explain more than 60% of the year-to-year variability...

Analysis of the interactions of actin depolymerizing factor with G- and F-actin

Abstract: Chick actin depolymerizing factor (ADF) is an actin binding protein previously shown to rapidly depolymerize actin filaments in vitro, yielding a 1:1 complex of ADF and actin monomer. Here we show that ADF protects actin monomer from denaturation by EDTA by inhibiting the exchange of actin-bound nucleotide. Under low ionic strength conditions, the approximate dissociation constant (KD) for the ADF-actin complex determined from exchange of nucleotide (1,N6-etheno-ATP) is about 150 and is calcium-independent. Addition of ADF to monomeric actin inhibits actin assembly as well as the ATP hydrolysis that normally accompanies assembly. Complex formation is demonstrated between ADF and actin containing either ATP, ADP, or AMPPNP as the bound nucleotide. A KD of 0.1-0.2 microM was calculated for both the ADF-ATP-actin and ADF-AMPPNP-actin complexes, whereas the KD for the ADF-ADP-actin complex is about 1.3 microM. ADF can either depolymerize or cosediment with F-actin in a stoichiometric fashion, but these reciprocal activities are pH-dependent. At pHs between 6.5 and 7.1, ADF cosediments with F-actin and demonstrates only weak depolymerizing activity. ADF binding is cooperative and saturates at a 1:1 ADF:actin molar ratio. At pHs between 7.1 and 7.7, ADF shows increasing depolymerizing activity and less F-actin binding. At pH 8.0, ADF depolymerizes F-actin in a stoichiometric manner. Both the F-actin binding and the depolymerizing activities of ADF are inhibited by phalloidin.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of acute resistance exercise on postexercise energy expenditure and resting metabolic rate

Abstract: Two separate experiments were performed to determine the effect of acute resistive exercise on postexercise energy expenditure in male subjects previously trained in resistive exercise. In experime...

PCR with arbitrary primers: approach with care.

Abstract: New techniques have recently been described that employ the polymerase chain reaction (PCR) to amplify arbitrary regions of a genome using a single primer. The techniques reveal polymorphisms in insect taxa that lack allozyme variation and, for the first time, permit genetic polymorphisms to be rapidly analysed in small arthropods (e.g. mites, endoparasitic wasps). The methods have been used in identification of sub-species and cryptic species, and have applications in population genetics and genetic fingerprinting. They are fairly inexpensive, do not require the use of radioactivity, are relatively simple to learn and can easily be adapted to most laboratories. However, their application is not without technical problems and practical limitations. The purpose of this note is to indicate the critical factors to consider before launching into their use. We chiefly emphasize that most polymorphisms revealed by these methods segregate as dominant markers. Furthermore, application of these techniques requires extensive standardization and may not prove to be reproducible among various laboratories especially those employing different types of thermal cyclers. There are some unique features of these polymorphisms to consider when using them in genetic fingerprinting. In addition, because the techniques amplify arbitrary regions of genomes, similarly sized fragments amplified between two species may not be homologous. This argument and empirical observations suggest that PCR with arbitrary primers will have limited application in molecular systematics above the intraspecific level.

A sensory role for neuronal growth cone filopodia

Abstract: The dynamic nature of neuronal growth cone filopodia led to the suggestion that the primary function of filopodia is to sample their immediate environment, responding to and transducing environmental signals that affect growth cone behaviour and shape. Filopodia seem well suited to serve as antenna-like sensors, their broad span allows sampling of information over a greatly enhanced radius, and forward-projecting filopodia encounter potential cues in the molecular terrain long before the advancing growth cone itself. Filopodia in culture can serve structural roles, exert mechanical tension and selectively adhere to their surrounding. Whether or not filopodia have a general sensory role has not been tested directly, largely because of their small size, which limits an electrophysiological approach, and their integral relationship with the parent growth cone, which prevents resolution of their different functions. Here we use surgical procedures to isolate individual filopodia from their parent growth cone and, by monitoring their morphology and calcium second messenger systems, we show that neuronal growth cone filopodia contain signal transduction mechanisms that allow autonomous responses and the transmission of distant environmental information to their parent growth cone.

Adding learning to the cellular development of neural networks: Evolution and the baldwin effect

Abstract: A grammar tree is used to encode a cellular developmental process that can generate whole families of Boolean neural networks for computing parity and symmetry. The development process resembles biological cell division. A genetic algorithm is used to find a grammar tree that yields both architecture and weights specifying a particular neural network for solving specific Boolean functions. The current study particularly focuses on the addition of learning to the development process and the evolution of grammar trees. Three ways of adding learning to the development process are explored. Two of these exploit the Baldwin effect by changing the fitness landscape without using Lamarckian evolution. The third strategy is Lamarckian in nature. Results for these three modes of combining learning with genetic search are compared against genetic search without learning. Our results suggest that merely using learning to change the fitness landscape can be as effective as Lamarckian strategies at improving search.

Calculation of nitrogen mineralization in soil food webs

Abstract: In agricultural practices in which the use of inorganic fertilizer is being reduced in favour of the use of organic manure, the availability of nitrogen (N) in soil for plant growth depends increasingly on N mineralization. In simulation models, N mineralization is frequently described in relation to the decomposition of organic matter, making a distinction in the quality of the chemical components available as substrate for soil microbes. A different way to model N mineralization is to derive N mineralization from the trophic interactions among the groups of organisms constituting the soil food web. In the present study a food web model was applied to a set of food webs from different sites and from different arable farming systems. The results showed that the model could simulate N mineralization rates close to the rates obtained from in situ measurements, from nitrogen budget analyses, or from a decomposition based model. The outcome of the model suggested that the contribution of the various groups of organisms to N mineralization varied strongly among the different sites and farming systems.

Synoptic and mesoscale weather conditions during air pollution episodes in athens, greece

Abstract: Based on regular climatological and air quality data from the Greater Athens Area (GAA), the air pollution episodes observed in Athens during the period 1983–1990 were analysed and classified. The main characteristics of atmospheric conditions during days with high air pollution concentrations are summarized too. Model simulations show that the worst air pollution episodes in Athens occur during days with a critical balance between synoptic and mesoscale circulations and/or during days with warm advection in the lower troposphere.