Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Km

  • apparent km
  • lower km
  • several km

  • Terms modified by Km

  • km area
  • km deep
  • km depth
  • km distant
  • km downstream
  • km grid
  • km long
  • km radius
  • km ratio
  • km reach
  • km resolution
  • km square
  • km thick
  • km upstream
  • km value
  • km west
  • km wide

  • Selected Abstracts

    Environmental Manipulation to Avoid a Unique Predator: Drinking Hole Excavation in the Agile Wallaby, Macropus agilis

    ETHOLOGY, Issue 2 2007
    J. Sean Doody
    The simplest way of avoiding an ambush predator is to entirely avoid the habitat in which it hunts. However, this strategy requires that the prey species find alternative, risk-free sources of essential resources. Herein we describe a novel strategy used by agile wallabies (Macropus agilis) to avoid saltwater crocodile (Crocodylus porosus) predation: the creation of risk-free sites to obtain water. We studied the anti-predator behaviour of agile wallabies for 3 yr during the dry season along the Daly River, Northern Territory, Australia. Wallabies excavated holes in the sand 0.5,18.0 m from the water's edge, and preferred to drink from these holes over drinking from the river. We determined a hierarchy of preferred drinking-site options for the wallabies: non-river sites: springs, puddles, excavated holes; and river sites: sites with cover, shallow water sites and deep water sites. Drinking holes were twice as far from the water's edge in a river stretch with high crocodile density (2/km) than those in a stretch with low crocodile density (0.08/km). However, site differences could also be explained by river bank morphology. Collectively, our findings indicate that agile wallabies excavate drinking holes to avoid crocodile predation. We contend that this behaviour represents environmental manipulation specifically to alter the risk associated with obtaining a key resource. [source]

    Tectono-thermal Evolution in the Bachu Uplift, Tarim Basin, China

    QIU Nansheng
    Abstract: The thermal evolution of source rocks in the Paleozoic has long been a problem to petroleum exploration in the Bachu uplift, Tarim basin, since the thermal history in the Paleozoic could not be rebuilt objectively due to lack of effective thermal indicators in the Lower Paleozoic successions. The apatite and zircon (U-Th)/He thermochronometry can be used as a new kind of technique to study the thermal history and tectonic uplift of sedimentary basins. Based on the measured apatite and zircon (U-Th)/He ages, apatite fission track data and equivalence vitrinite reflectance (%EVRo), the tectonothermal histories in 5 wells of the Bachu uplift were modeled. The modeling results show that there was relatively high gradient at the Early Paleozoic in the Bachu uplift and it decreased gradually during the entire Paleozoic: 33,35°C/km in the Cambrian-Ordovician, 32,33°C/km in the Silurian-Devonian, 30,32°C/km at the end of Carboniferous and 27.5,31°C/km at the end of Permian. Therefore, the thermal history can be modeled by combining multiple thermal indicators of AFT, (U-Th)/He ages and EVRo data. Especially, this provides a new method to rebuild the thermal history for the Low Paleozoic carbonate successions in the Tarim Basin. [source]

    Late Cretaceous-Cenozoic exhumation of the Yanji area, northeast China: Constraints from fission-track thermochronology

    ISLAND ARC, Issue 1 2010
    Xiaoming Li
    Abstract The Yanji area, located at the border of China, Russia, and Korea, where the Phanerozoic granitoids have been widely exposed, was considered part of the orogenic collage between the North China Block in the south and the Jiamusi,Khanka Massifs in the northeast. In this study, the cooling and inferred uplift and denudation history since the late Mesozoic are intensively studied by carrying out apatite and zircon fission-track analyses, together with electron microprobe analyses (EMPA) of chemical compositions of apatite from the granitoid samples in the Yanji area. The results show that: (i) zircon and apatite fission-track ages range 91.7,99.6 Ma and 76.5,85.4 Ma, respectively; (ii) all apatite fission-track length distributions are unimodal and yield mean lengths of 12,13.2 µm, and the apatites are attributed to chlorine-bearing fluorapatite as revealed by EMPA results; and (iii) the thermal history modeling results based on apatite fission-track grain ages and length distributions indicate that the time,temperature paths display similar patterns and the cooling has been accelerated for each sample since ca 15 Ma. Thus, we conclude that sequential cooling, involving two rapid (95,80 Ma and ca 15,0 Ma) and one slow (80,15 Ma) cooling, has taken place through the exhumation of the Yanji area since the late Cretaceous. The maximum exhumation is more than 5 km under a steady-state geothermal gradient of 35°C/km. Combined with the tectonic setting, this exhumation is possibly related to the subduction of the Pacific Plate beneath the Eurasian Plate since the late Cretaceous. [source]

    Tectono-thermal Evolution in the Bachu Uplift, Tarim Basin, China

    QIU Nansheng
    Abstract: The thermal evolution of source rocks in the Paleozoic has long been a problem to petroleum exploration in the Bachu uplift, Tarim basin, since the thermal history in the Paleozoic could not be rebuilt objectively due to lack of effective thermal indicators in the Lower Paleozoic successions. The apatite and zircon (U-Th)/He thermochronometry can be used as a new kind of technique to study the thermal history and tectonic uplift of sedimentary basins. Based on the measured apatite and zircon (U-Th)/He ages, apatite fission track data and equivalence vitrinite reflectance (%EVRo), the tectonothermal histories in 5 wells of the Bachu uplift were modeled. The modeling results show that there was relatively high gradient at the Early Paleozoic in the Bachu uplift and it decreased gradually during the entire Paleozoic: 33,35°C/km in the Cambrian-Ordovician, 32,33°C/km in the Silurian-Devonian, 30,32°C/km at the end of Carboniferous and 27.5,31°C/km at the end of Permian. Therefore, the thermal history can be modeled by combining multiple thermal indicators of AFT, (U-Th)/He ages and EVRo data. Especially, this provides a new method to rebuild the thermal history for the Low Paleozoic carbonate successions in the Tarim Basin. [source]

    Late Cretaceous-Cenozoic Exhumation History of the Lüliang Mountains, North China Craton: Constraint from Fission-track Thermochronology

    Xiaoming LI
    Abstract: The Lüliang Mountains, located in the North China Craton, is a relatively stable block, but it has experienced uplift and denudation since the late Mesozoic. We hence aim to explore its time and rate of the exhumation by the fission-track method. The results show that, no matter what type rocks are, the pooled ages of zircon and apatite fission-track range from 60.0 to 93.7 Ma and 28.6 to 43.3 Ma, respectively; all of the apatite fission-track length distributions are unimodal and yield a mean length of ,13 ,m; and the thermal history modeling results based on apatite fission-track data indicate that the time-temperature paths exhibit similar patterns and the cooling has been accelerated for each sample since the Pliocene (c.5 Ma). Therefore, we can conclude that a successive cooling, probably involving two slow (during c.75,35 Ma and 35,5 Ma) and one rapid (during c.5 Ma-0 Ma) cooling, has occurred through the exhumation of the Lüliang Mountains since the late Cretaceous. The maximum exhumation is more than 5 km under a steady-state geothermal gradient of 35°C/km. Combined with the tectonic setting, this exhumation may be the resultant effect from the surrounding plate interactions, and it has been accelerated since c.5 Ma predominantly due to the India-Eurasia collision. [source]


    H. I. Petersen
    Oil shales and coals occur in Cenozoic rift basins in central and northern Thailand. Thermally immature outcrops of these rocks may constitute analogues for source rocks which have generated oil in several of these rift basins. A total of 56 oil shale and coal samples were collected from eight different basins and analysed in detail in this study. The samples were analysed for their content of total organic carbon (TOC) and elemental composition. Source rock quality was determined by Rock-Eval pyrolysis. Reflected light microscopy was used to analyse the organic matter (maceral) composition of the rocks, and the thermal maturity was determined by vitrinite reflectance (VR) measurements. In addition to the 56 samples, VR measurements were carried out in three wells from two oil-producing basins and VR gradients were constructed. Rock-Eval screening data from one of the wells is also presented. The oil shales were deposited in freshwater (to brackish) lakes with a high preservation potential (TOC contents up to 44.18 wt%). They contain abundant lamalginite and principally algal-derived fluorescing amorphous organic matter followed by liptodetrinite and telalginite (Botryococcus-type). Huminite may be present in subordinate amounts. The coals are completely dominated by huminite and were formed in freshwater mires. VR values from 0.38 to 0.47%Ro show that the exposed coals are thermally immature. VR values from the associated oil shales are suppressed by 0.11 to 0.28%Ro. The oil shales have H/C ratios >1.43, and Hydrogen Index (HI) values are generally >400 mg HC/g TOC and may reach 704 mg HC/ gTOC. In general, the coals have H/C ratios between about 0.80 and 0.90, and the HI values vary considerably from approximately 50 to 300 mg HC/gTOC. The HImax of the coals, which represent the true source rock potential, range from ,160 to 310 mg HC/g TOC indicating a potential for oil/gas and oil generation. The steep VR curves from the oil-producing basins reflect high geothermal gradients of ,62°C/km and ,92°C/km. The depth to the top oil window for the oil shales at a VR of ,0.70%Ro is determined to be between ,1100 m and 1800 m depending on the geothermal gradient. The kerogen composition of the oil shales and the high geothermal gradients result in narrow oil windows, possibly spanning only ,300 to 400 m in the warmest basins. The effective oil window of the coals is estimated to start from ,0.82 to 0.98%Ro and burial depths of ,1300 to 1400 m (,92°C/km) and ,2100 to 2300 m (,62°C/km) are necessary for efficient oil expulsion to occur. [source]


    CYTOPATHOLOGY, Issue 2006
    I. Penman
    There is increased recognition of the importance of accurate staging of malignancies of the GI tract and lung, greater use of neoadjuvant therapies and more protocol-driven management. This is particularly important where regional lymph node involvement significantly impacts on curability. Multidetector CT and PET scanning have resulted in greater detection of potential abnormalities which, if positive for malignancy, would change management. There is also a greater recognition that many enlarged nodes may be inflammatory and that size criteria alone are unreliable in determining involvement. In other situations, especially pancreatic masses, not all represent carcinoma as focal chronic pancreatitis, autoimmune pancreatitis etc can catch out the unwary. A preoperative tissue diagnosis is essential and even if unresectable, oncologists are increasingly reluctant to initiate chemotherapy or enroll patients into trials without this. The approach to obtaining tissue is often hampered by the small size or relative inaccessibility of lesions by percutaneous approaches. As such novel techniques such as endoscopic ultrasound (EUS) guided FNA have been developed. A 120cm needle is passed through the instrument and, under real-time visualisation, through the gastrointestinal wall to sample adjacent lymph nodes or masses. Multiple studies have demonstrated the safety and performance of this technique. In oesophageal cancer, confirmation of node positivity by has a major negative influence on curative resection rates and will often lead to a decision to use neoadjuvant chemotherapy or a non-operative approach. Sampling of lymph nodes at the true coeliac axis upstages the patient to M1a status (stage IV) disease and makes the patient incurable. In NSCLC, subcarinal lymph nodes are frequently present but may be inflammatory. If positive these represent N2 (stage IIIA) disease and in most centres again makes the patient inoperable. Access to these lymph nodes would otherwise require mediastinosocopy whereas this can be done simply, safely and quickly by EUS. Overall the sensitivity for EUS , FNA of mediastinal or upper abdominal lymph nodes is 83,90% with an accuracy of 80,90%. In pancreatic cancer performance is less good but pooled analysis of published studies indicates a sensitivity of 85% and accuracy of 88%. In a recent spin-off from EUS, endobronchial ultrasound (EBUS) instruments have been developed and the ability to sample anterior mediastinal nodes has been demonstrated. It is likely that this EBUS , FNA technique will become increasingly utilised and may replace mediastinoscopy. The development of techniques such as EUS and EBUS to allow FNA sampling of lesions has increased the role of non-gynaecological cytology significantly in recent years. Cytology therefore remains important for a broad range of specialties and there is ongoing need for careful and close co-operation between cytologists and clinicians in these specialties. References:, 1. Williams DB, Sahai AV, Aabakken L, Penman ID, van Velse A, Webb J et al. Endoscopic ultrasound guided fine needle aspiration biopsy: a large single centre experience. Gut. 1999; 44: 720,6. 2. Silvestri GA, Hoffman BJ, Bhutani MS et al. Endoscopic ultrasound with fine-needle aspiration in the diagnosis and staging of lung cancer. Ann Thorac Surg 1996; 61: 1441,6. 3. Rintoul RC, Skwarski KM, Murchison JT, Wallace WA, Walker WS, Penman ID. Endobronchial and endoscopic ultrasound real-time fine-needle aspiration staging of the mediastinum ). Eur Resp J 2005; 25: 1,6. [source]

    Frequency and clinical correlates of adult separation anxiety in a sample of 508 outpatients with mood and anxiety disorders

    S. Pini
    Pini S, Abelli M, Shear KM, Cardini A, Lari L, Gesi C, Muti M, Calugi S, Galderisi S, Troisi A, Bertolino A, Cassano GB. Frequency and clinical correlates of adult separation anxiety in a sample of 508 outpatients with mood and anxiety disorders. Objective:, To evaluate the frequency and clinical correlates of adult separation anxiety disorder in a large cohort of patients with mood and anxiety disorders. Method:, Overall, 508 outpatients with anxiety and mood disorders were assessed by the structured clinical interview for diagnostic and statistical manual (IV edition) axis I disorders for principal diagnosis and comorbidity and by other appropriate instruments for separation anxiety into adulthood or childhood. Results:, Overall, 105 subjects (20.7%) were assessed as having adult separation anxiety disorder without a history of childhood separation anxiety and 110 (21.7%) had adult separation anxiety disorder with a history of childhood separation anxiety. Adult separation anxiety was associated with severe role impairment in work and social relationships after controlling for potential confounding effect of anxiety comorbidity. Conclusion:, Adult separation anxiety disorder is likely to be much more common in adults than previously recognized. Research is needed to better understand the relationships of this condition with other co-occurring affective disorders. [source]

    Engineered Pyranose 2-Oxidase: Efficiently Turning Sugars into Electrical Energy

    ELECTROANALYSIS, Issue 7-8 2010
    Oliver Spadiut
    Abstract Due to the recent interest in enzymatic biofuel cells (BFCs), sugar oxidizing enzymes other than the commonly used glucose oxidase are gaining more importance as possible bioelements of implantable microscale-devices, which can, for example, be used in biosensors and pacemakers. In this study we used rational and semi-rational protein design to improve the catalytic activity of the enzyme pyranose 2-oxidase (P2Ox) with its alternative soluble electron acceptors 1,4-benzoquinone and ferricenium ion, which can serve as electron mediators, to possibly boost the power output of enzymatic BFCs. Using a screening assay based on 96-well plates, we identified the variant H450G, which showed lower KM and higher kcat values for both 1,4-benzoquinone and ferricenium ion compared to the wild-type enzyme, when either D -glucose or D -galactose were used as saturating electron donors. Besides this variant, we analyzed the variants V546C and T169G/V546C for their possible application in enzymatic BFCs. The results obtained in homogeneous solution were compared with those obtained when P2Ox was immobilized on the surface of graphite electrodes and either "wired" to an osmium redox polymer or using soluble 1,4-benzoquinone as mediator. According to the spectrophotometrically determined kinetic constants, the possible energy output, measured in flow injection analysis experiments with these variants, increased up to 4-fold compared to systems employing the wild-type enzyme. [source]

    Methane oxidation kinetics differ in European beech and Norway spruce soils

    D. M. Degelmann
    Summary Coniferous forest soils often consume less of the greenhouse gas methane (CH4) than deciduous forest soils. The reasons for this phenomenon have not been resolved. It might be caused by differences in the diffusive flux of CH4 through the organic layer, pH or different concentrations of potentially inhibitory compounds. Soil samples were investigated from three adjacent European beech (Fagus sylvatica) and Norway spruce (Picea abies) stands in Germany. Maximal CH4 oxidation velocities (Vmax(app)) and Michaelis Menten constants (KM(app)), retrieved from intact soil cores at constant CH4 concentrations, temperature and matric potential, were twice as great in beech as in spruce soils. Also atmospheric CH4 oxidation rates measured in homogenized soil samples displayed the same trend. Greatest atmospheric CH4 oxidation rates were detected in the Oa horizon or in the upper 5 cm of the mineral soil. In contrast to the beech soils, the Oa horizon of the spruce soils consumed no CH4. A differential effect due to divergent diffusive flux through the litter layer was not found. pH and ammonium concentration were similar in samples from both forest soil types. Ethylene accumulation in all soils was negligible under oxic conditions. These collective results suggest that the different atmospheric CH4 uptake by beech and spruce soils is caused by different CH4 oxidizing capacities of methanotrophic communities in the Oa horizon and top mineral soil. [source]

    Phosphorus-limited growth dynamics in two Baltic Sea cyanobacteria, Nodularia sp. and Aphanizomenon sp.

    Jenny Degerholm
    Abstract Rates of carbon (C) specific growth and nitrogen (N2) fixation were monitored in cultures of Baltic Sea Nodularia and Aphanizomenon exposed to gradual limitation by inorganic phosphorus (P). Both cyanobacteria responded by decreased cellular P content followed by lowered rates of growth and N2 fixation. C-specific growth and cellular N content changed faster in Aphanizomenon both when inorganic P was lowered as well as during reintroduction of P. Aphanizomenon also showed a more rapid increase in N-specific N2 fixation associated with increased C-specific growth. When ambient concentrations of inorganic P declined, both cyanobacteria displayed higher rates of alkaline phosphatase (APase) activity. Lower substrate half-saturation constants (KM) and higher Vmax : KM ratio of the APase enzyme associated with Nodularia suggest a higher affinity for dissolved organic P (DOP) substrate than Aphanizomenon. Aphanizomenon, which appears more sensitive to changes in ambient dissolved inorganic P, may be adapted to environments with elevated concentrations of P or repeated intrusions of nutrient-rich water. Nodularia on the other hand, with its higher tolerance to increased P starvation may have an ecological advantage in stratified surface waters of the Baltic Sea during periods of low P availability. [source]

    Functional and structural analysis of five mutations identified in methylmalonic aciduria cbIB type,

    HUMAN MUTATION, Issue 9 2010
    Ana Jorge-Finnigan
    Abstract ATP:cob(I)alamin adenosyltransferase (ATR, E.C. converts reduced cob(I)alamin to the adenosylcobalamin cofactor. Mutations in the MMAB gene encoding ATR are responsible for the cblB type methylmalonic aciduria. Here we report the functional analysis of five cblB mutations to determine the underlying molecular basis of the dysfunction. The transcriptional profile along with minigenes analysis revealed that c.584G>A, c.349-1G>C, and c.290G>A affect the splicing process. Wild-type ATR and the p.I96T (c.287T>C) and p.R191W (c.571C>T) mutant proteins were expressed in a prokaryote and a eukaryotic expression systems. The p.I96T protein was enzymatically active with a KM for ATP and KD for cob(I)alamin similar to wild-type enzyme, but exhibited a 40% reduction in specific activity. Both p.I96T and p.R191W mutant proteins are less stable than the wild-type protein, with increased stability when expressed under permissive folding conditions. Analysis of the oligomeric state of both mutants showed a structural defect for p.I96T and also a significant impact on the amount of recovered mutant protein that was more pronounced for p.R191W that, along with the structural analysis, suggest they might be misfolded. These results could serve as a basis for the implementation of pharmacological therapies aimed at increasing the residual activity of this type of mutations. Hum Mutat 31:1033,1042, 2010. © 2010 Wiley-Liss, Inc. [source]

    Understanding the design of information technologies for knowledge management in organizations: a pragmatic perspective

    Tom Butler
    Abstract., Researchers report mixed findings on the successful application of information technologies (IT) for knowledge management (KM). The primary difficulty is argued to be the use of information management techniques and concepts to design and develop KM Tools. Also problematic is the existence of a multiplicity of KM technologies, the application and use of which differs across organizations. This paper argues that these problems stem, in part, from the information system field's over-reliance on design concepts from the functionalist paradigm. Hence, our contention that alternative perspectives, which bring into focus issues of ontology and epistemology, need to be brought to bear in order to understand the challenges involved in the design and deployment of IT artefacts in knowledge management systems (KMS). The philosophy of technology, with its emphasis on the primacy of praxis, and which incorporates ontological and epistemological concepts from phenomenology and hermeneutics, is applied to the findings of a participative action research study to illustrate how social actors interpret and understand worldly phenomena and subsequently share their knowledge of the life-world using IT. The outcome of this marriage of situated practical theory and philosophy is a set of design principles to guide the development of a core KM Tool for KMS. [source]

    Knowledge management in enterprises: a research agenda

    Konstantinos Ergazakis
    Knowledge management (KM) is an emerging area, which is gaining interest by both enterprises and academics. The effective implementation of a KM strategy is considering as a ,must' and as a precondition of success for contemporary enterprises, as they enter the era of the knowledge economy. However, the field of KM has been slow in formulating a universally accepted methodology, due to the many pending issues that have to be addressed. This paper attempts to propose a novel taxonomy for KM research by co-instantaneously presenting the current status with some major themes of KM research. The discussion presented on these issues should be of value to researchers and practitioners. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Managing knowledge in the healthcare sector.

    A review
    Over the past decade, knowledge management (KM), as a concept and a set of practices, has penetrated into the fabric of organizational and managerial processes in the healthcare sector, which has been the site of numerous innovative KM practices. As a result scholars from a range of academic (and non-academic) fields have begun to document how KM is conceived and practised in health care, what the recurrent issues are and how they can be addressed. The purpose of this paper is to review the current literature on KM concepts, policies and practices in the healthcare sector. Based on the analysis of the most relevant contributions in the last six years, three overarching themes that have occupied the interests of authors are identified and discussed: the nature of knowing in the healthcare sector, the type of KM tools and initiatives that are suitable for the healthcare sector, and the barriers and enablers to the take up of KM practices. The paper concludes with some considerations on what the literature tells us about the state of the art and the future of KM in this important sector of Western economies. [source]

    Effect of different liquid cultures of live yeast strains on performance, ruminal fermentation and microbial protein synthesis in lambs

    M. K. Tripathi
    Summary Three yeast strains, Kluyveromyces marximanus NRRL-3234 (KM), Saccharomyces cerevisiae NCDC-42 (SC) and Saccharomyces uvarum ATCC-9080 (SU), and a mixed culture (1:1:1 ratio) were evaluated for their value as probiotics in lamb feeding in two experiment. In experiment I and II, 20 and 30 pre-weaner lambs were fed for 63 and 60 days in two and three equal groups respectively. All lambs were offered ad libitum a creep mixture and Zizyphus nummularia leaves, and yeasts were dosed orally. In experiment I, one group received no yeast, the other of the mixed culture (1.5,2 × 1010 live cells/ml). In experiment II, yeast cultivation was modified yielding 1.5,2 × 1013 live cells/ml. Lambs of the three experimental groups received 1 ml/kg live weight of one of the individual yeasts. Feed intake did not differ among groups of both experiments with the exception of SC-supplemented lambs in experiment II which showed a trend to higher intakes per kg metabolic body weight and in percentage of body weight when compared with KM- and SU-supplemented lambs. Supplementation of the mixed yeast culture had no effect on intakes of digestible crude protein and metabolisable energy, nutrient digestibility, nitrogen balance and rumen fermentation characteristics (pH, ammonia, volatile fatty acid concentration, protozoa count) and urinary allantoin as an indicator of microbial protein synthesis. The same was true for comparisons in experiment II except ciliate protozoa counts, which showed a trend to be the highest with SU and the lowest with SC. The results of present study show that the response of lambs to supplemented live yeast cultures is inconsistent, as it lacked to have an effect in the present study, and that differences among strains were small, even when supplemented at a much higher live cell count. [source]

    Cytosolic NADP phosphatases I and II from Arthrobacter sp. strain KM: Implication in regulation of NAD+/NADP+ balance

    Shigeyuki Kawai
    NADP phosphatase (NADPase) is an enzyme that converts NADP+ into NAD+ through dephosphorylation of NADP+, and is considered to be one of the possible candidates for regulation of the NAD+/NADP+ balance in vivo. In order to obtain an intrinsic NADPase, the NADP+ -degrading activity in a membrane-free cell extract of a Gram-positive bacterium, Arthrobacter sp. strain KM, was first assessed and demonstrated to be mainly achieved through the NADPase reaction, indicating NADPase is essential for degradation of NADP+ and therefore for regulation of the NAD+/NADP+ balance in cytosol. Then, the isolation of cytosolic NADPase was attempted using NADP+ as a substrate. Two NADPase isozymes, designated as NADPases I and II, were purified from the cell extract of the bacterium, and were indicated to be the sole cytosolic NADPases regulating the balance of NAD+/NADP+. NADPases I and II are homodimers of 32 and 30 kDa subunits, respectively, and most active at pH 7,8. The N-terminal amino acid sequences of the two enzymes are similar to each other. Among the biological substrates tested, both enzymes showed the highest activity toward NADP+ and NADPH. AMP, ADP, and pyridoxal 5,-phosphate were also dephosphorylated, but to lower extents. Comparison of the features of NADPases I and II with those of other acid phosphatases possessing NADPase activity suggested that NADPases I and II are novel enzymes participating in regulation of the NAD+/NADP+ balance in the cytosol. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Purification and characterization of solvent-tolerant, thermostable, alkaline metalloprotease from alkalophilic Pseudomonas aeruginosa MTCC 7926

    Ulhas Patil
    Abstract BACKGROUND: Microbial proteases are becoming imperative for commercial applications. The protease secreted by Pseudomonas aeruginosa MTCC 7926, isolated from solvent-contaminated habitat was purified and characterized for activity at various edaphic conditions. The purified alkaline protease was investigated for dehairing of animal skin, anti-staphylococcal activity and processing of X-ray film. RESULTS: The protease was 24-fold purified by ammonium sulfate fractionation, sephadex G-100 gel filtration and DEAE-cellulose, with 36% recovery. KM and Vmax, using casein were 2.94 mg mL,1 and 1.27 µmole min,1, respectively. The apparent molecular mass by SDS-PAGE was 35 kDa. Alkaline protease was active at pH 6,11 and temperature 25,65 °C. Its activity was (a) 86.8% in 100 mmol L,1 NaCl, (b) >95% in metal ions (Mn2+, Ca2+, Mg2+, Fe2+) for 1 h, (c) >90% in bleaching agents and chemical surfactants, (d) 135.4 ± 2.0% and 119.9 ± 6.2% with rhamnolipid and cyclodextrin, respectively, (e) stable in solvents for 5,30 days at 27 °C, and (f) inhibited by EDTA, indicating metalloprotein. CONCLUSION: This work showed that purified protease retained its activity in surfactants, solvents, metals, and bleaching agents. The enzyme is an alternative for detergent formulations, dehairing of animal skin, X-ray film processing, treatment of staphylococcal infections and possibly non-aqueous enzymatic peptide synthesis. Copyright © 2009 Society of Chemical Industry [source]

    Monoamine oxidase activity in kidney and heart of Piaractus mesopotamicus (Holmberg)

    C. M. C. Salles
    The values of Michaelis,Menten constant (KM) and maximum velocity (VMAX) for kidney and heart monoamine oxidase (MAO) from pacu Piaractus mesopotamicus were determined. The mean ±s.e. KM values were 17·28 ± 2·27 ,M for kidney and 15·38 ± 1·86 ,M for heart. MAO activities were 111·60 ± 3·25 and 15·12 ± 0·30 nmols min,1 g,1 of wet tissue for kidney and heart, respectively. In addition, MAO inhibitory studies in these two tissues indicate that this enzyme may be a different isoform of MAO. [source]

    Characterization of Honey Amylase

    Sibel Babacan
    ABSTRACT:, The major ,-amylase in honey was characterized. The optimum pH range and temperature were determined for the enzyme as 4.6 to 5.3 and 55 °C, respectively. The enzyme was stable at pH values from 7 to 8. The half-lives of the purified enzyme at different temperatures were determined. The activation energy for heat inactivation of honey amylase was 114.6 kJ/mol. The enzyme exhibited Michaelis,Menten kinetics with soluble starch and gave KM and Vmax values of 0.72 mg/mL and 0.018 units/mL, respectively. The enzyme was inhibited by CuCl (34.3%), MgCl2 (22.4%), and HgCl2 (13.4%), while CaCl2, MnCl2, and ZnSO4 did not have any effect. Starch had a protective effect on thermal stability of honey amylase. Therefore, it might be critical to process or control the amylase in honey before incorporation into starch-containing foods to aid in the preservation of starch functionality. One step could involve heat treating honey with other ingredients, especially those that dilute and acidify the honey environment. [source]

    Purification and Characterization of an ,-L-Rhamnosidase from Aspergillus terreus of Interest in Winemaking

    M.V. Gallego
    ABSTRACT: An enzyme with ,-L-rhamnosidase activity was purified to homogeneity from a culture filtrate of Aspergillus terreus after growth in a medium containing L-rhamnose as the sole carbon source. The biosynthesis of this enzyme was repressed by glucose. The enzyme had a molecular mass of 96 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an isoelectric point of 4.6 as determined by analytical isoelectric focusing. The pH and temperature optima for the enzyme were found to be 4.0 and 44 °C, respectively. Using p-nitrophenyl-,-L-rhamnopyranoside as a substrate, the enzyme exhibited Michaelis-Menten kinetics with KM and Vmax values of 0.17 mM and 84 U/mg, respectively. The enzyme was inhibited competitively by L-rhamnose (K1 2.5 mM). Divalent cations such as Ca2+ Mg2+ Zn2+ and Co2+ stimulated the a-L-rhamnosidase activity, whereas this was inhibited by Hg2+ and Cd2+. Ethanol (12% v/v) and glucose (21% w/v) decreased enzyme activity by approximately 20%, while this was not affected by SO2. [source]

    Comparison of Presumptive Blood Test Kits Including Hexagon OBTI

    Emma Johnston M.Sc.
    Abstract:, Four presumptive blood tests, Hexagon OBTI, Hemastix®, Leucomalachite green (LMG), and Kastle-Meyer (KM) were compared for their sensitivity in the identification of dried bloodstains. Stains of varying blood dilutions were subjected to each presumptive test and the results compared. The Hexagon OBTI buffer volume was also reduced to ascertain whether this increased the sensitivity of the kit. The study found that Hemastix® was the most sensitive test for trace blood detection. Only with the reduced buffer volume was the Hexagon OBTI kit as sensitive as the LMG and KM tests. However, the Hexagon OBTI kit has the advantage of being a primate specific blood detection kit. This study also investigated whether the OBTI buffer within the kit could be utilized for DNA profiling after presumptive testing. The results show that DNA profiles can be obtained from the Hexagon OBTI kit buffer directly. [source]

    Mitochondrial oxidation of 4-hydroxy-2-nonenal in rat cerebral cortex

    Tonya C. Murphy
    Abstract 4-Hydroxy- trans -2-nonenal (HNE) is a neurotoxic product of lipid peroxidation whose levels are elevated in multiple neurodegenerative diseases and CNS trauma. The detoxification of HNE may take the route of glutathione conjugation to the C3 carbon and the oxidation or reduction of the C1 aldehyde. In this work, we examined whether the oxidation of HNE to its corresponding carboxylic acid, 4-hydroxy- trans -2-nonenoate (HNEAcid) was detoxifying event, if it occurred in rat cerebral cortex, and in which subcellular compartments. Our results show that HNEAcid did not form protein adducts and was non-toxic to Neuro 2A cells. HNEAcid formation occurred in rat cerebral cortex slices following exposure to HNE in a time-dependent and dose-dependent fashion. Homogenate studies indicated that HNEAcid formation was NAD+ dependent. Subcellular fractionation demonstrated that mitochondria had the highest specific activity for HNEAcid formation with a KM of 21 µm HNE. These data indicate that oxidation of HNE to its corresponding acid is a major detoxification pathway of HNE in the CNS and that mitochondria play a role in this process. [source]

    Red cells playing as activated platelets in thalassemia intermedia

    See also Taher AT, Musallam KM, Karimi M, El-Beshlawy A, Belhoul K, Daar S, Saned M, Cesaretti C, Cappellini MD. Splenectomy and thrombosis: the case of thalassemia intermedia. This issue, pp 2152,8. [source]

    The effect of organizational culture on knowledge management practices and innovation

    Mario J. Donate
    In this paper we analyze the relationships between certain knowledge management (KM) practices, organizational culture, and the technological results of companies. In the last few years, KM literature has highlighted the important role of cultural values on the way KM processes are developed and applied in organizations. From this viewpoint, and focusing on a set of knowledge storage and transfer practices, we try to empirically analyze the existence of a multiplier effect of the knowledge-centered organizational culture on the relationship between these kinds of knowledge practices and the technological performance of firms. The results of the empirical study show the existence of a significant moderating effect, although the consequences on the innovative performance in terms of product or process technologies are found to be different, depending on the practice (storage or transfer) which is considered. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Knowledge use, capitalisation and sharing in the audit and consultancy professions

    Sophie Mignon
    The introduction of knowledge management (KM) systems has become a key factor that potentially leads to competitive advantage. To take fully advantage of KM systems it is often necessary to make adjustments along a variety of dimensions to the organisations concerned. This paper proposes a KM model built around four factors: strategic; organisational; technical and informational; cultural and human. With special focus on the audit and consultancy profession, this paper identifies the respective influence of individual factors on the use and capitalisation of the knowledge contained in the KM system that is introduced into an organisation. The results show that use of the system is facilitated by technical and information systems (knowledge bases) developed as a significant part of the group's strategy and culture. However, despite organisational actions that focus o knowledge, knowledge capitalisation remains problematic, in large part, due to human and cultural reticence over sharing. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Applying wikis to managing knowledge,A socio-technical approach

    Miia Kosonen
    As organizations are increasingly moving towards geographically dispersed and virtual forms of collaboration, knowledge sharing through social software such as wikis is widely acknowledged as an important area of research and practice. However, social software remains an under-investigated issue in the literature on knowledge management (KM), and there is a lack of studies demonstrating how organizations can successfully incorporate these technologies into their everyday operations. To bridge this gap, our paper examines a case of successful wiki implementation. We claim that understanding the implementation of wikis requires a socio-technical perspective focusing on the organizational context and activity system in which they are implemented rather than on their technological proficiency. Furthermore, we claim that their implementation brings about change in existing social systems, and results in new kinds of social constellations, interactions, and identities, which are manageable and controllable only to a limited extent. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Strategic processes @ Nike,making and doing knowledge management

    George Stonehouse
    This paper contrasts theory with practice through a case study of strategic processes of knowledge management (KM) at Nike Incorporated. From its origins as a small specialist enterprise in 1972 to a multi-billion dollar global brand, the corporation has been continuously at the forefront of developments in management practice and business innovation. This case study has been compiled from interviews with senior managers and numerous secondary sources. The paper begins with a discussion of an insider perspective on the trajectory of the organization in terms of its strategic goals and decisions on markets, customers, products, services and business processes. It then goes on to explore and critique the dynamic interplay of the processes of strategizing, learning, creativity and innovation at Nike as the basis for its knowledge-based competitive advantage (CA). The case thus represents KM as a unique combination of processes in which learning; strategy and creativity are organized and strategically embedded within a large global organization. This has implications for future theorizing in KM, which, as we illustrate in this paper, demands a more integrative approach to research and practice. One of the key lessons for practice is that span of activity, as well as strategy, will influence the relationship between strategizing, organizing and learning and this interplay determines the success (or failure) of KM. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Generational differences in soft knowledge situations: status, need for recognition, workplace commitment and idealism

    Peter Busch
    Much knowledge management (KM) literature is focused on the improvements that can be made to organisations if they use their knowledge resource effectively. A great deal of knowledge rests in the heads of employees. Little to date has discussed the differences in soft knowledge utilisation amongst different generations of employees particularly in the IT sector. By generations we refer to the Baby Boomers, Generation X and Generation Y. Our study establishes that there were a number of differences between how the three Generations would deal with certain IT soft knowledge situations. These differences were along the following lines; issues of status in the workplace; need for recognition, typically by younger employees; issues of commitment to the workplace and finally idealism in the place of work. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    ICTs adoption and knowledge management: the case of an e-procurement system

    Silvia Massa
    The purpose of the research is to articulate a framework for analysing the effects of e-procurement adoption in terms of knowledge management. Starting from this position, a case study in a leader firm in electronics devices was developed and a consolidated knowledge perspective was adopted. Empirical evidence confirms that it is not information and communication technology itself that can provide positive or negative effects on organizations but how the technology is used in conjunction with complementary human resources. In fact, according to the case study, two different phases emerged in the e-procurement (EP) adoption. Both are characterized by the same technology but different behaviours that determined very different results. While the framework can be applied to read EP development in several contexts, it would be a mistake to generalize the results from this example. While multiple informants from different hierarchical levels, triangulation using different types of data sources and a systematic data analysis serve to attenuate many of the problems with reliability, generalizability remains more of an issue. Finally, it is worth noting that studying adoption of inter-organizational systems-like EP systems are, has proved to be, difficult because such systems span the company boundaries. Consequently, future developments will aim at broadening the research along the entire supply chain. The proposed framework could be a useful tool to check an EP project in progress and to motivate the involved actors by suggesting a means to interpret how the project is impacting on organization, keeping in mind that effects on KM anticipate improvements in traditional procurement performances. Copyright © 2007 John Wiley & Sons, Ltd. [source]