bluuebunny/crossref_metadata_2025 huggingface dataset:
ORIGINAL ARTICLE: Under‐filled blood collection tubes containing K2EDTA as anticoagulant are acceptable for automated complete blood counts, white blood cell differential, and reticulocyte count
Authors: XU M. , ROBBE V. A. , JACK R. M. , RUTLEDGE J. C.
Published: December 2009

Current laboratory standards from Clinical Laboratory Standards Institute (CLSI) and manufacturer’s (Becton Dickinson) data indicate that under‐filling K2EDTA blood collection tubes can result in erroneous hematology values. To accommodate under‐filled tubes and reduce collection volumes while optimizing our automation, we explored the acceptable limit of under‐filled tubes for hematology values. We collected 8.0 ml of blood from 30 normal adult volunteers. Each donation was aliquoted in the following volumes: 4.0, 2.0, 1.0, 0.5 ml × 2. These samples were analyzed within 1 h of blood collection on Sysmex XE‐2100 (Sysmex America Inc., Mundelein, IL, USA) for complete blood count, reticulocyte, and white blood cell differentials. Results of the under‐filled tubes were compared to those of the standard volume. The Deming regression analysis show excellent correlation for all parameters between each under‐filled blood collection volume compared to a standard 4 ml volume. The Bland and Altman analysis shows good agreement between both 1.0 and 2.0 ml compared to a 4.0 ml volume. The 0.5 ml compared to a 4.0 ml volume, however, shows increased variation on many parameters. In addition all three collection volumes show negative bias compared to the standard volume for platelet count, but the difference is considered insignificant with a percent difference of 5.5%, 3.2%, and 1.5% for 0.5, 1.0, and 2.0 ml collection volume respectively. Finally for 0.5 ml collection volume we noticed a low level of false positive flagging rate for white blood cell. Acceptable complete blood count values of under‐filled powdered K2EDTA tubes can be obtained with as little as 1.0 ml of blood.
Influence of hyperoxia on muscle metabolic responses and the power–duration relationship during severe‐intensity exercise in humans: a31P magnetic resonance spectroscopy study
Authors: Vanhatalo Anni , Fulford Jonathan , DiMenna Fred J. , Jones Andrew M.
Published: December 2009

Severe‐intensity constant‐work‐rate exercise results in the attainment of maximal oxygen uptake, but the muscle metabolic milieu at the limit of tolerance (Tlim) for such exercise remains to be elucidated. We hypothesized thatTlimduring severe‐intensity exercise would be associated with the attainment of consistently low values of intramuscular phosphocreatine ([PCr]) and pH, as determined using31P magnetic resonance spectroscopy, irrespective of the work rate and the inspired O2fraction. We also hypothesized that hyperoxia would increase the asymptote of the hyperbolic power–duration relationship (the critical power, CP) without altering the curvature constant (W′). Seven subjects (mean ±s.d., age 30 ± 9 years) completed four constant‐work‐rate knee‐extension exercise bouts to the limit of tolerance (range, 3–10 min) both in normoxia (N) and in hyperoxia (H; 70% O2) inside the bore of 1.5 T superconducting magnet. The [PCr] (∼5–10% of resting baseline) and pH (∼6.65) at the limit of tolerance during each of the four trials was not significantly different either in normoxia or in hyperoxia. At the same fixed work rate, the overall rate at which [PCr] fell with time was attenuated in hyperoxia (mean response time: N, 59 ± 20versusH, 116 ± 46 s;P< 0.05). The CP was higher (N, 16.1 ± 2.6versusH, 18.0 ± 2.3 W;P< 0.05) and theW′ was lower (N, 1.92 ± 0.70versusH, 1.48 ± 0.31 kJ;P< 0.05) in hyperoxia compared with normoxia. These data indicate thatTlimduring severe‐intensity exercise is associated with the attainment of consistently low values of muscle [PCr] and pH. The CP andW′ parameters of the power–duration relationship were both sensitive to the inspiration of hyperoxic gas.
Synthesis, characterization, and photoactivity of InTaO4 and In0.9Ni0.1TaO4 thin films prepared by electron evaporation
Authors: Rico V. J. , Frutos F. , Yubero F. , Espinos J. P. , Gonzáles-Elipe A. R.
Published: December 2009

In Ta O 4 and In0.9Ni0.1TaO4 thin films have been prepared by electron evaporation of successive layers of the single oxide components and posterior annealing at T>800°C. The annealed thin films presented the monoclinic crystallographic structure typical of these mixed oxides. The electrical and optical behaviors of the films, assessed by C-V measurements, surface conductivity as a function of temperature, and UV-vis absorption spectroscopy, indicate that these oxides are wide band gap semiconductors with a variable dielectric constant depending on the annealing conditions. By reflection electron energy loss spectroscopy some electronic states have been found in the gap at an energy that is compatible with the activation energy deduced from the conductivity versus 1∕T plots for these oxides. The photoactivity of these materials has been assessed by looking to the evolution of the wetting contact angle as a function of the irradiation time. All the films became superhydrophilic when irradiated with UV light, while the In0.9Ni0.1TaO4 thin films also presented a small partial decrease in wetting angle when irradiated with visible photons.
Pharmacokinetic-Pharmacodynamic Modeling of Alpha Interferon Response Induced by a Toll-Like 7 Receptor Agonist in Mice
Authors: Benson Neil , de Jongh Joost , Duckworth Jonathan D. , Jones Hannah M. , Pertinez Henry E. , Rawal Jaiessh K. , van Steeg Tamara J. , Van der Graaf Piet H.
Published: December 2009

Recombinant alpha interferon (IFN-α) is used in the treatment of hepatitis C virus (HCV)-infected patients but is not optimal in terms of efficacy or tolerability. Toll-like 7 receptor (TLR-7) agonists stimulate the innate immune system to produce, among other cytokines, IFN-α and are being evaluated as alternative drugs to treat HCV infection. This paper describes the application of pharmacokinetic-pharmacodynamic (PK-PD) modeling to understanding the behavior of a TLR-7 agonist [9-benzyl-8-hydroxy-2-(2-methoxyethoxy) adenine (BHMA)] in mice, using IFN-α as a biomarker. This is the first report of such a PK-PD model, and the conclusions may be of utility in the clinical development of TLR-7 agonists for HCV infection.
Elucidation of the Pharmacokinetic/Pharmacodynamic Determinant of Colistin Activity againstPseudomonas aeruginosain Murine Thigh and Lung Infection Models
Authors: Dudhani Rajesh V. , Turnidge John D. , Coulthard Kingsley , Milne Robert W. , Rayner Craig R. , Li Jian , Nation Roger L.
Published: December 2009

Colistin is increasingly used as last-line therapy against Gram-negative pathogens. The pharmacokinetic (PK)/pharmacodynamic (PD) index that best correlates with the efficacy of colistin remains undefined. The activity of colistin against three strains ofPseudomonas aeruginosawas studied in neutropenic mouse thigh and lung infection models. The PKs of unbound colistin were determined from single-dose PK studies together with extensive plasma protein binding analyses. Dose-fractionation studies were conducted over 24 h with a dose range of 5 to 160 mg/kg of body weight/day. The bacterial burden in the thigh or lung was measured at 24 h after the initiation of treatment. Relationships between antibacterial effect and measures of exposure to unbound (f) colistin (area under the concentration-time curve [fAUC/MIC], maximum concentration of drug in plasma [fCmax]/MIC, and the time that the concentration in plasma is greater than the MIC [fT> MIC]) were examined by using an inhibitory sigmoid maximum-effect model. Nonlinearity in the PKs of colistin, including its plasma protein binding, was observed. The PK/PD index that correlated best with its efficacy wasfAUC/MIC in both the thigh infection model (R2= 87%) and the lung infection model (R2= 89%). ThefAUC/MIC targets required to achieve 1-log and 2-log kill against the three strains were 15.6 to 22.8 and 27.6 to 36.1, respectively, in the thigh infection model, while the corresponding values were 12.2 to 16.7 and 36.9 to 45.9 in the lung infection model. The findings of thisin vivostudy indicate the importance of achieving adequate time-averaged exposure to colistin. The results will facilitate efforts to define the more rational design of dosage regimens for humans.
QseC MediatesSalmonella entericaSerovar Typhimurium VirulenceIn VitroandIn Vivo
Authors: Moreira Cristiano G. , Weinshenker David , Sperandio Vanessa
Published: December 2009

The autoinducer-3 (AI-3)/epinephrine (Epi)/norepinephrine (NE) interkingdom signaling system mediates chemical communication between bacteria and their mammalian hosts. The three signals are sensed by the QseC histidine kinase (HK) sensor.Salmonella entericaserovar Typhimurium is a pathogen that uses HKs to sense its environment and regulate virulence.Salmonellaserovar Typhimurium invades epithelial cells and survives within macrophages. Invasion of epithelial cells is mediated by the type III secretion system (T3SS) encoded inSalmonellapathogenicity island 1 (SPI-1), while macrophage survival and systemic disease are mediated by the T3SS encoded in SPI-2. Here we show that QseC plays an important role inSalmonellaserovar Typhimurium pathogenicity. AqseCmutant was impaired in flagellar motility, in invasion of epithelial cells, and in survival within macrophages and was attenuated for systemic infection in 129x1/SvJ mice. QseC acts globally, regulating expression of genes within SPI-1 and SPI-2in vitroandin vivo(during infection of mice). Additionally, dopamine β-hydroxylase knockout (Dbh−/−) mice that do not produce Epi or NE showed different susceptibility toSalmonellaserovar Typhimurium infection than wild-type mice. These data suggest that the AI-3/Epi/NE signaling system is a key factor duringSalmonellaserovar Typhimurium pathogenesisin vitroandin vivo. Elucidation of the role of this interkingdom signaling system inSalmonellaserovar Typhimurium should contribute to a better understanding of the complex interplay between the pathogen and the host during infection.
Three-Dimensional Visualizations in Teaching Genomics and Bioinformatics: Mutations in HIV Envelope Proteins and Their Consequences for Vaccine Design
Authors: TAKAYAMA KATHY M.
Published: December 2009

This project addresses the need to provide a visual context to teach the practical applications of genome sequencing and bioinformatics. Present-day research relies on indirect visualization techniques (e.g., fluorescence-labeling of DNA in sequencing reactions) and sophisticated computer analysis. Such methods are impractical and prohibitively expensive for laboratory classes. More importantly, there is a need for curriculum resources that visually demonstrate the application of genome sequence information rather than the DNA sequencing methodology itself. This project is a computer-based lesson plan that engages students in collaborative, problem-based learning. The specific example focuses on approaches to Human Immunodeficiency Virus-1 (HIV-1) vaccine design based on HIV-1 genome sequences using a case study. Students performed comparative alignments of variant HIV-1 sequences available from a public database. Students then examined the consequences of HIV-1 mutations by applying the alignments to three-dimensional images of the HIV-1 envelope protein structure, thus visualizing the implications for applications such as vaccine design. The lesson enhances problem solving through the application of one type of information (genomic or protein sequence) into concrete visual conceptualizations. Assessment of student comprehension and problem-solving ability revealed marked improvement after the computer tutorial. Furthermore, contextual presentation of these concepts within a case study resulted in student responses that demonstrated higher levels of cognitive ability than was expected by the instructor.
Morphopédologie et anomalie géochimique
Authors: Bamba Ousmane
Published: December 2009

L’intense altération géochimique, qui a affecté l’ensemble de la zone transcontinentale des boucliers pendant plusieurs millions d’années, a dissous partiellement la partie supérieure de la croûte continentale dont une partie des éléments résiduels (essentiellement du quartz) est aujourd’hui associée aux phases supergènes, issues de la reprécipitation à l’échelle régionale d’une partie du fer, de la silice et de l’aluminium parental. Il s’en suit la formation d’un manteau de débris parfois chapeauté par des cuirasses ferrugineuses, alumineuses ou manganésifères. Cette configuration implique une difficulté de traçage des signatures parentales des minéralisations primaires, la localisation et l’interprétation des anomalies géochimiques. En effet, les processus pédologiques et géomorphologiques, en occurrence le cuirassement, affectent l’expression de la localisation de ces anomalies. Le paysage de la zone d’étude, interprété et traduit en terme de susceptibilité à rendre d’éventuelles anomalies géochimiques, en d’autres termes du caractère résiduel ou transporté de celles-ci, donne quatre classes à potentiel de déplacement d’anomalie : (i) anomalie résiduelle, (ii) anomalie sub-résiduelle, (iii) anomalie déplacée, (iv) anomalie fortement déplacée et (ou) masquée. Une telle caractérisation et spatialisation de l’espace à prospecter constitue un support substantiel pour l’orientation des campagnes de prospections géochimiques. La cartographie des altérites doit se poser comme une composante essentielle des techniques modernes, novatrices d’exploration géochimique, qui créent le besoin croissant de mieux comprendre aussi bien la cuirasse transportée que la mesure suivant laquelle elle cache ou révèle des minéralisations en profondeur.
Nature of the Elzevir–Mazinaw domain boundary, Grenville Orogen, Ontario
Authors: Cureton James S. , Pluijm Ben A. van der , Essene Eric J.
Published: December 2009

The Mooroton shear zone (MSZ) of the Metasedimentary Belt of the Grenville Orogen in Ontario separates the Mazinaw domain to the east from the Elzevir domain. The shear zone is composed of mafic metavolcanic, metaclastic, and marble mylonites, and is characterized by a subvertical foliation, which crosscuts the regional foliation, and a near-vertical stretching lineation. Microstructures indicate deformation occurred under crystal–plastic conditions, and shear-sense indicators give movement of east (Mazinaw) side up. The geometry of the MSZ, which follows the eastern margin of the Elzevir tonalite, implies that lithologic anisotropy guided its location. Garnet–biotite and garnet–hornblende peak temperatures are juxtaposed across the MSZ, with temperatures ranging from 460 to 530 °C in the southeastern Elzevir and 490 to 620 °C in the southwestern Mazinaw, conditions in amphibolite facies. Limiting barometers applied to rocks in both domains show no significant offset. Petrologic data within the shear zone show that deformation occurred at amphibolite-facies conditions. New and previously published hornblende 40Ar/39Ar ages around the shear zone range from 927 ± 3 to 1006 ± 3 Ma, and show no systematic offset; similarly, muscovite 40Ar/39Ar ages in the area cluster around ca. 900 Ma. These combined data indicate that displacement had ceased along the MSZ by the time the rocks cooled through the closure temperature of hornblende (i.e., before ca. 1000 Ma), and most likely before the last regional metamorphism in the area (i.e., ca. 1030 Ma). Thus the Elzevir and Mazinaw domains acted as a coherent tectonic unit during at least the later part of the Grenville orogenic cycle.
Geological setting, U–Pb geochronology, and radiogenic isotopic characteristics of the Permo-Triassic Kutcho Assemblage, north-central British Columbia
Authors: Childe Fiona C. , Thompson John F.H.
Published: December 2009

The Kutcho Assemblage is a latest Permian to Early Triassic volcano-sedimentary sequence within the fault-bounded King Salmon Allochthon. Volcanic and volcaniclastic rocks consist of massive to pillowed flows and tuffs of basaltic to basaltic andesitic composition, as well as flows, mass flows, and pyroclastic flows of rhyodacitic to rhyolitic composition. The volcanic sequence is intruded by gabbro, diorite, trondhjemite, and quartz–plagioclase porphyry. Volcanic and intrusive rocks have tholeiitic magmatic affinities, with die exception of the gabbro sills and dykes, which are chemically similar to alkaline arc magmas. Cu–Zn volcanogenic massive sulphide mineralization at die Kutcho Creek deposit is hosted by rhyolite mass flows near me top of the Kutcho Assemblage. Rhyolite mass flows from the hanging wall and footwall to mineralization have U–Pb ages of 242 ± 1 and [Formula: see text], respectively, whereas a quartz–plagioclase porphyritic intrusion to the south of the mineralization has a U–Pb age of 244 ± 6 Ma. The dates determined in this study constrain a previously unknown age for massive sulphide mineralization in the Canadian Cordillera. Furthermore, the age of the Kutcho Assemblage and the primitive Pb isotopic signature of its contained syngenetic mineralization (207Pb/206Pb = 0.83988–0.84112 and 208Pb/206Pb = 2.0517–2.0556) are inconsistent with formation as part of the adjacent Stikine or Quesnel terranes. Primitive Nd isotopic signatures (εNd(initial) = +7.5 to +9.1) and trace and rare earth element chemistry indicate that volcanic rocks of the Kutcho Assemblage, related intrusions, and volcanogenic massive sulphide mineralization formed in an intraoceanic island arc environment, probably directly on oceanic crustal basement. Gabbro sills and dykes, which are interpreted to be slightly younger than volcanic rocks of the Kutcho Assemblage, appear to have formed in response to a change in the tectonic regime, perhaps as a result of a collisional event.
Stratigraphy and paleomagnetism of the Late Miocene Davis Creek silt, East Block of the Cypress Hills, Saskatchewan
Authors: Barendregt R. W. , Vreeken W. J. , Irving E. , Baker J.
Published: December 2009

Paleomagnetic measurements and a dated tephra from outcrops of Davis Creek silt overlying ancient geomorphic surfaces in the East Block of the Cypress Hills, Saskatchewan, indicate that these sediments were deposited during several polarity intervals of the Late Miocene C4 polarity chron. Polarity and tephra data reported in this study provide minimum ages for the formation of underlying depositional and erosional surfaces, while previous studies provide maximum ages based on fossils and tephra underlying the oldest depositional surfaces. Collectively, these suggest that most of the Davis Creek silt was deposited over about a 1 Ma time span from about 9.3 to 8.3 Ma, confirming that the Cypress Hills region acquired most of its topographic relief and preglacial surficial deposits during the first half of the Late Miocene. Based on polarity and tephra studies, as well as magnetostratigraphic correlation of the two study sites, we conclude that rates of loess accumulation in the Cypress Hills were apparently very low during the Late Miocene.
Paleomagnetic and geobarometric study of the mid-Cretaceous Whitehorse Pluton, Yukon Territory
Authors: Harris M. J. , Symons D. T. A. , Blackburn W. H. , Hart C. J. R.
Published: December 2009

This is the first of several Lithoprobe paleomagnetic studies underway to examine geotectonic motions in the northern Canadian Cordillera. Except for one controversial study, estimates for terranes underlying the Intermontane Belt in the Yukon have been extrapolated from studies in Alaska, southern British Columbia, and the northwestern United States. The Whitehorse Pluton is a large unmetamorphosed and undeformed tonalitic body of mid-Cretaceous age (~112 Ma) that was intruded into sedimentary units of the Whitehorse Trough in the Stikinia terrane. Geothermobarometric estimates for eight sites around the pluton indicate that postmagnetization tilting has been negligible since cooling through the hornblende-crystallization temperature and that the pluton is a high-level intrusion. Paleomagnetic measurements for 22 of 24 sites in the pluton yield a well-defined characteristic remanent magnetization (ChRM) direction that is steeply down and northwards. The ChRM direction gives a paleopole of 285.5°E, 81.7°N (dp = 53°, dm = 5.7°). When compared with the 112 Ma reference pole for the North American craton, this paleopole suggests that the northern Stikinia terrane has been translated northwards by 11.0 ± 4.8° (1220 ± 530 km) and rotated clockwise by 59 ± 17°. Except for an estimate from the ~70 Ma Carmacks Group volcanics, this translation and rotation estimate agrees well with previous estimates for units in the central and southern Intermontane Belt. They suggest that the terranes of the Intermontane Belt have behaved as a fairly coherent unit since the Early Cretaceous, moving northward at a minimum average rate of 2.3 ± 0.4 cm/a between ~140 and ~45 Ma.
First evidence of juvenile ceratopsians (Reptilia: Ornithischia) from the Frenchman Formation (late Maastrichtian) of Saskatchewan
Authors: Tokaryk Tim T.
Published: December 2009

The first occurrence from the Frenchman Formation (late Maastrichtian) of juvenile ceratopsians (Chasmosaurinae) is reported here based on two postorbital horn-cores. The sutures confirm that the frontal attaches along the medial side of the postorbital much like that in Centrosaurinae and cannot be used as a tool for distinguishing the two ceratopsid subfamilies.
Inland, Coastal, and Offshore Magnetotelluric Measurements in Eastern Canada
Authors: Srivastava S. P. , White A.
Published: December 2009

For six weeks during the summer of 1966 simultaneous magnetic and electric field recordings were made on the east coast of Canada at Fredericton, N.B., Halifax, N.S., and Sable Island. The data from these stations have been analyzed using power spectral techniques. Comparison of the simultaneous recordings from Halifax and Sable Island with those from Fredericton and Agincourt indicate some enhancement in the intensity of the vertical component of the magnetic field for periods less than 40 min at Halifax and attenuation in its intensity for periods less than 3 h at Sable Island. The enhancement at Halifax has been interpreted in terms of the "coast effect" while the effect of the island and of differences in the subsurface conductivity under the continent and under the ocean have been shown to be possible causes of the relative attenuation in the Z variations at Sable Island.
Superimposed Deformations in the Missi Meta-sedimentary Rocks near Flin Flon, Manitoba
Authors: Stauffer Mel R. , Mukherjee Amar
Published: December 2009

Within the Flin Flon Basin, Precambrian meta-sandstones and conglomerates belonging to the Missi Group have been complexly deformed as a result of three periods of deformation. The first two periods (P1 and P2) involved folding but no apparent faulting, the last (P3) involved both folding and faulting. Progressive metamorphism (M2), within the greenschist facies, occurred during the second phase (P2) and aided in the formation of a pronounced axial-plane foliation (S2). Small-scale folding and retrograde metamorphism (M3) occurred along faults formed during the last phase (P3).The faults in this area all appear to be high angle, oblique-slip reverse faults and can be interpreted as having formed during a single orogenic event (P3) although there is sequence in their initiation. The net-slip directions of different faults are approximately the same, and plunge moderately to the southeast, with either the east or south side upthrown, depending on the attitude of the fault.
Distribution of Fusulinaceans in the Western Canadian Cordillera
Authors: Monger J. W. H. , Ross C. A.
Published: December 2009

Fusulinacean faunas in Upper Paleozoic lithological sequences containing volcanic rocks in the western Canadian Cordillera form two assemblages based on geographic association of genera. One assemblage, in Permian strata, is dominated by genera of the family Schwagerinidae and occupies belts in the eastern and western parts of the western Cordillera. This assemblage is associated with brachiopods, bryozoans, horn corals, and crinoids and is in limestones interbedded with clastic rocks and volcanic rocks of variable composition. The other Permian assemblage is dominated by genera of the family Verbeekinidae and occupies a central belt where it occurs with crinoid detritus and algae in thick, regionally extensive limestones associated with cherts, basalt, and ultramafic rocks. The less-well documented Pennsylvanian fusulinaceans appear to occupy similar belts. Because fossils of both assemblages are at least in part time equivalent, their distribution may well be due to differing local environments. In addition, or alternatively, this diversity may be brought about by major crustal movements juxtaposing originally isolated biogeographic provinces.
A paleoenvironmental study of the molluscs from the Don Formation (Sangamonian?) Don Valley Brickyard, Toronto, Ontario
Authors: Kerr-Lawson L. J. , Karrow P. F. , Edwards T. W. D. , Mackie G. L.
Published: December 2009

The Don Formation comprises 8–9 m of fossiliferous stratified sand and clay, lying between glacial deposits of Wisconsinan and presumed Illinioan age. It has yielded a diverse fossil flora and fauna indicating a climate as warm as or warmer than present and is considered to be of last, or Sangamonian, interglacial age. About 2 t of sediment were processed from the type section of the Don Formation at Toronto, Ontario, and yielded approximately 18 000 identifiable mollusc shells, representing 45 taxa. Previously unpublished taxa include 11 freshwater gastropod species, 12 pelecypod species (Sphaeriidae), and 7 terrestrial gastropod species. The molluscs are mainly concentrated in the lower two-thirds of the formation and are dominated by Valvata perdepressa, with abundant Valvata sincera, Probythinella lacustris, Amnicola limosa, Amnicola walkeri, Pleurocera acuta, Elimia livescens, Pisidium casertanum, Pisidium compressum, Pisidium fallax, and Sphaerium striatinum. All the mollusc species are modern inhabitants of the Great Lakes region. Their known ecological tolerances suggest deposition in relatively shallow waters of a large temperate lake having substantial fluvial input nearby. Stratigraphic variations in the relative abundance of different aquatic taxa may reflect variations in water depth or fluvial activity. Stable isotope data from several mollusc species and a single wood specimen, together with taxonomic paleoenvironmental interpretation, are consistent with deposition during the climatic optimum of the Sangamonian interglaciation. Environmental conditions and faunas are similar to those of the Nipissing phase (Hypsithermal) of the eastern Great Lakes.
Pressure–temperature conditions of Early Proterozoic metamorphism during the Trans-Hudson Orogen as determined from rocks straddling the Flin Flon – Kisseynew boundary at Niblock and File lakes, Manitoba
Authors: Briggs William , Foster C. T.
Published: December 2009

The Niblock Lake and File Lake areas straddle the boundary between the Kisseynew gneiss belt and the Flin Flon belt, near the town of Snow Lake, Manitoba. The region contains pelitic schists metamorphosed to lower to middle almandine–amphibolite facies. Metamorphic conditions were studied by examining relative timing of growth of metamorphic minerals by geothermobarometry of selected samples. Calculated temperatures and pressures are compared with those estimated from mineral assemblages and reactions on a petrogenetic grid.Two metamorphic (M1 and M2) and deformation (D1 and D2) phases have been recognized in the Niblock Lake and File Lake areas. M1 (contemporaneous with D1 folding) was characterized by growth of micas but no higher grade minerals. Temperatures and pressures of M1, therefore, were probably less than about 475 °C and 3.5 kbar (1 kbar = 100 MPa). Peak conditions, reached during M2 (late- to post-D2 folding), resulted in growth of garnet, staurolite, sillimanite, and (in the Niblock Lake area) andalusite. In the Niblock Lake area, M2 temperatures range from 525 to 625 °C, with most samples between 550 and 600 °C; pressures range from 2.5 to 5 kbar, with most samples between 2.5 and 4 kbar. In the File Lake area, M2 temperatures range from approximately 560 to 625 °C; pressures range from 3.3 to 4.6 kbar.
Selective inhibition of cathepsin B with cell-permeable CA074Me negatively affects L6 rat myoblast differentiation
Authors: Jane Derek T , Morvay Leslie C , Allen Francis , Sloane Bonnie F , Dufresne Michael J
Published: December 2009

Active cathepsin B, in concert with other cellular proteases, has been implicated in the catabolic restructuring associated with myotube formation during skeletal myoblast cell differentiation (i.e., myogenesis). We have examined this role in differentiating myoblasts using the cell-permeable, cathepsin B selective inhibitor CA074Me. Cathepsin B activity levels in differentiating L6 rat myoblasts treated with CA074Me were significantly lower than levels in control myoblasts. Inhibition of cathepsin B activity by CA074Me occurred at each stage of differentiation and was dose related. Myotube size and number and induced levels of fusion-related creatine phosphokinase activity and myosin heavy-chain protein were reduced from 30 to 50% in CA074Me-treated myoblasts. These reductions were also dose related. In contrast, CA074Me did not affect levels of myogenin, an early marker of myogenesis, or levels of cathepsin L type and myokinase activities, two nonspecific enzymes. The negative effects associated with CA074Me were reversed when the drug was removed. Collectively, these data suggest that active cathepsin B plays a role in myoblastmyoblast fusion and consequently may be necessary for the complete expression of those genes associated with the fusion process.Key words: cathepsin B, CA074Me, myogenesis.
Acute regulation of hepatic lipase secretion by rat hepatocytes
Authors: Galan Xavier , Peinado-Onsurbe Julia , Robert Monique Q , Soley Maria , Llobera Miquel , Ramírez Ignasi
Published: December 2009

Hepatic lipase is involved in cholesterol uptake by the liver. Although it is known that catecholamines are responsible for the daily variation of enzyme activity, the mechanisms involved are poorly understood. Rat hepatocytes incubated with adrenaline or other Ca2+-mobilizing hormones were used as an experimental model. Adrenaline reduced in a similar proportion the secretion of both hepatic lipase and albumin. The effect of adrenaline disappeared completely in cells exposed to cycloheximide. Adrenaline decreased incorporation of [35S]Met into cellular and secreted proteins, but it affected neither degradation of [35S]Met-prelabeled proteins nor the abundance of total and specific (albumin, hepatic lipase, beta-actin) mRNA. Other Ca2+-mobilizing agents had the opposite effect on hepatic lipase secretion: it was decreased by vasopressin but was increased by epidermal growth factor. Vasopressin and epidermal growth factor had the opposite effect on [35S]Met incorporation into cellular and secreted proteins, but neither affected hepatic lipase mRNA. The acute effect of adrenaline, vasopressin, and epidermal growth factor on hepatic lipase secretion is the consequence of the effect of these hormones on protein synthesis and is therefore nonspecific.Key words: adrenaline, vasopressin, epidermal growth factor, albumin secretion.
A ribosomal defect in dystrophic hamsters
Authors: Jolicoeur C. , Brakier-Gingras L.
Published: December 2009

Polysomes were isolated from the skeletal muscle, the heart, and the liver of dystrophic and normal hamsters and their protein synthesis activity was assessed in a cell-free wheat germ extract as a source of soluble factors and tRNAs. Our results show that there is a shift of the optimal magnesium concentration required for protein synthesis with polysomes from the skeletal muscle and the heart of dystrophic hamsters, as compared with control hamsters. As a consequence of this shift, polysomes from the skeletal muscle and the heart of dystrophic hamsters were less active than normal ones at low magnesium concentrations, but more active at high magnesium concentrations. These changes in activity were age dependent since, with skeletal muscle, they were observed at 30 days and disappeared at 60 days but reappeared at 120 and 200 days. With heart polysomes, on the other hand, the changes in activity were observed at 60 days but not in younger or older animals. No change in activity was observed with liver polysomes. Similar results were obtained when endogenous mRNAs were replaced by an exogenous messenger such as poly(U). This suggests that the differences in protein synthesis activity between polysomes from dystrophic and normal hamsters are not due to changes in the endogenous mRNAs but result from a ribosomal abnormality.
Determination of the levels of HPr and enzyme I of the phosphoenolpyruvate–sugar phosphotransferase system in Escherichia coli and Salmonella typhimurium
Authors: Mattoo Roshan L. , Waygood E. Bruce
Published: December 2009

The levels of histidine-containing protein HPr and enzyme I of the phosphoenolpyruvate–sugar phosphotransferase system of Escherichia coli strains 1100, NC3, W3110, and P650 and Salmonella typhimurium strains SB3507 and LJ144 have been determined by quantitative sugar phosphorylation assay and immunochemically. The levels have been determined for cells grown on minimal salts with glucose, fructose, mannitol, glycerol, and lactate and on nutrient broth. All determinations indicate a two- to three-fold change in the levels of enzyme I and HPr between growth on hexoses, which gave the higher levels, and the other growth substrates. The highest levels were not always found in glucose-grown cells. Antibodies were produced in rabbits using purified proteins from E. coli P650. The activity measurements and immunochemically determined enzyme I protein gave specific activities in the crude extracts of E. coli strains which were similar to that of the pure enzyme. The wild-type S. typhimurium enzyme I in crude extracts did not have the same immunochemical reactivity, although there was a considerable cross-reaction and the specific activity appeared to be half that of pure enzyme I. The HPr from both E. coli and S. typhimurium behaved identically and, although the immunoprecipitation was weak, it did indicate that HPr assays may not be as reliable as the enzyme I assays. The relative amounts of enzyme I and HPr found indicate that there are between 10- and 20-fold more HPr molecules in a cell than enzyme I subunits which form active dimers.
Effect of liver plasma membranes on G-actin. I. Possible implication of membrane NPases in inactivation of G-actin
Authors: Gruda Julian , Pollender Jean-Marc , Therien Helene-Marie
Published: December 2009

G-actin incubated in the presence of a liver fraction enriched in plasma membranes is rapidly inactivated, as indicated by the biphasic loss of polymerizability and DNase inhibition. The rates of inactivation as measured by viscosity are greatly influenced by temperature, but almost independent of membrane concentrations at least in the low range of concentrations tested (< 250 μg protein/mL). The loss of DNase inhibition capacity proceeds at rates two to three times slower than the loss of polimerizability. The inactivation of actin in the presence of membranes cannot be attributed to proteolysis nor to a phosphorylation of actin by membranes. However, it is shown that in the course of the incubation, medium ATP is rapidly converted into AMP and adenosine and that the destruction of ATP is almost complete at the start of the inactivation process. A mechanism is presented relating the destruction of ATP to actin inactivation.
Effect of liver plasma membranes on G-actin. II. Fate of actin-bound nucleotide
Authors: Thérien Helene-Marie , Gruda Julian
Published: December 2009

G-actin incubated in presence of a liver fraction enriched in plasma membranes rapidly denatures, as evidenced by the biphasic loss of polymerizability and DNase inhibition. The inactivation is shown to result from the loss of actin-bound nucleotide induced by the rapid destruction of free nucleotides by membrane NPases. This is further supported by the observation that addition of either ATP or ADP to actin that has been exposed to membranes completely stops the denaturation process and partly restores polymerizing capacity. The biphasic aspect of inactivation is explained by the protective action of AMP and (or) adenosine formed in the course of the incubation.
A series of N-carbamoyloxyurea resistant cell lines with alterations in ribonucleotide reductase: lack of coordination in pyrimidine and purine reductase activity
Authors: Hards Robert G. , Wright Jim A.
Published: December 2009

N-Carbamoyloxyurea is cytotoxic for cells in culture and, like hydroxyurea and guanazole, the drug is an effective inhibitor of mammalian ribonucleotide reductase and thus DNA synthesis. In addition to ribonucleotide reductase, N-carbamoyloxyurea has a second site of action which also appears to be in the pathway of DNA synthesis. A series of drug-resistant cell lines, which contain alterations in ribonucleotide reduction, have been sequentially selected in the presence of increasing concentrations of N-carbamoyloxyurea. CDP and ADP reductase activities in these drug-resistant lines have been investigated and two types of alterations have been identified: elevated levels of enzyme activity with wild-type sensitivity to drug and altered levels of reductase with reduced drug sensitivity, probably owing to structural modification of the enzyme. Furthermore, N-carbamoyloxyurea resistant lines contain another alteration as well, presumably at a second site of drug action. They are also cross-resistant to hydroxyurea and guanazole, and studies on enzyme activity levels support our previous findings with cells selected for resistance to hydroxyurea, which showed changes in CDP reductase activity are not always coordinated with changes in ADP reductase. Although several possibilities exist, these observations are most easily explained by the existence of independent enzyme substrate binding subunits which are regulated by different mechanisms. Moreover, increases in cellular resistance were accompanied by significant increases in CDP but not ADP reductase, suggesting that an ability to maintain an adequate level of CDP reductase activity is especially important to achieve resistance to DNA synthesis inhibitors like N-carbamoyloxyurea, hydroxyurea, and guanazole.
Applications of 31P nuclear magnetic resonance to studies of protein structure and function
Authors: Sykes Brian D.
Published: December 2009

Selective illustrative applications of phosphorus-31 nuclear magnetic resonance spectroscopy to the study of protein structure and function are reviewed, including the enzymes alkaline phosphatase, myosin, actin, and glycogen phosphorylase.
Influence of temperature and growth phase on desaturase activity of the mesophilic yeast Candida lipolytica
Authors: Ferrante G. , Ohno Y. , Kates M.
Published: December 2009

Microsomal membranes prepared from Candida lipolytica cells grown at 10 °C had a higher lipid content and degree of unsaturation than membranes prepared from cells grown at 25 °C. The specific activities of stearoyl-CoA (18:0-CoA), oleoyl-CoA (18:1-CoA), and dioleoyl phosphatidylcholine (18:1-PC) desaturases in microsomes of cells grown at either 25 or 10 °C showed maximum values near midlog phase, coinciding with the respective maximum absolute content of linoleic (18:2) in the microsomal preparations. The 18:1-CoA desaturase activity in 10 °C cells was nearly double that in 25 °C cells, while the 18:0-CoA and 18:1-PC desaturases had considerably lower activities in 10 °C cells. An increase in aeration rate (shaking speed, 70 to 130 rpm) resulted in increased proportions of 18:2 (32 to 47%, respectively) in microsomes of cells grown at 25 °C and in increased 18:1-CoA desaturase specific activity (83 to 140 pmol∙min−1∙mg−1); however, no significant changes occurred in 18∙0-CoA or 18:1-PC desaturase activities.
Comparison of glucagon, cAMP, and cGMP effects on lipogenesis in hepatocytes
Authors: Hayden Lawrence J. , Cohen Steven , Levin Kerry , Margolis Simeon
Published: December 2009

Control of lipogenesis by glucagon and cyclic nucleotide derivatives was examined in freshly isolated hepatocytes. [14C]Acetate was incorporated at a linear rate for 2 h into cellular lipids and for at least 6 h into medium lipids. About 80% of the incorporated label was recovered in fatty acids. Incorporation of [1-14C]acetate and 3H2O into cellular and medium lipids was inhibited by glucagon (K50 = 8 × 10−10 M), dibutyryladenosine 3′:5′-cyclic monophosphate (K50 = 7.5 × 10−8 M), and guanosine 3′:5′-cyclic monophosphate and its dibutyryl and 8-bromo derivatives, each with K50 = 2.9 × 10−6 M. Glucagon (10 nM) reduced incorporation of [14C]acetate and 3H2O into fatty acid by 73 and 52%, respectively, and into cholesterol by 24 and 10%, respectively. When added together to hepatocytes at submaximally inhibitory concentrations, dibutyryl cAMP and dibutyryl cGMP exerted additive effects. However, maximal inhibitory concentrations of both produced the same effect as the addition of either nucleotide alone. Thus, this preparation of rat hepatocytes responded to physiological concentrations of glucagon and low concentrations of dibutyryl cAMP. Cyclic guanosine derivatives inhibited lipogenesis, but 100 times greater concentration was required when compared with dibutyryl cAMP. Dibutyryl cAMP and dibutyryl cGMP did not act synergistically.
Sequential isolation of lamellar bodies and surfactant fractions from rat lungs
Authors: Boudreau J. , Beaudoin A. R. , Nadeau D.
Published: December 2009

In the present study, we developed a simple procedure, shorter than most, which allows the sequential isolation of lamellar bodies and surfactant fractions from rat lungs. The surfactant was isolated from serial bronchoalveolar lavages obtained with a balanced salt solution (Ca2+ and Mg2+ free). The cell-free supernatants from the lavages were layered on 20% sucrose (0.58 M) and centrifuged at 4.9 × 106 g∙min. The interface was collected and washed by centrifugation. The enriched surfactant fraction was recovered as a tight pellet. From the same animals, the lavaged lungs were homogenized in 0.25 M sucrose and centrifuged at 2.6 × 105 g∙min. The upper loose pellet was layered on 0.58 M sucrose and centrifuged at 1.1 × 107 g∙min. As for the surfactant fraction, the lamellar bodies were also collected at a 0.25 M – 0.58 M sucrose interface, washed, and recovered as a tight pellet. Both electron microscopy and marker enzyme studies confirmed the structural integrity of the two fractions, as well as the relative absence of major contaminants such as lysosomes, mitochondria, and microsomes. Biochemical analysis such as phospholipid to protein ratios (surfactant, 8.0; lamellar bodies, 6.7), phospholipid compositions (phosphatidylcholines and phosphatidylglycerols: respectively, ~80 and ~10% for both fractions), fatty acid analysis (palmitic acid in phosphatidylcholines and phosphatidylglycerols: respectively, 69 and 62% for the lamellar bodies and 76 and 60% for the surfactant), and minimum surface tension measurements (10 mN∙m−1 for the surfactant and 12 mN∙m−1 for the lamellar bodies) confirmed the close relationship between the two lung fractions. From three major hydrolases detected in the lamellar bodies and surfactant fractions, only the alkaline phosphatase was enriched in the surface active material isolated from the alveolar lung lining. Our results indicate that this alkaline phosphatase may represent a potential marker by which the synthesis and secretion processes of lung surfactant could be monitored.
In vitro translation of elastin mRNA and processing of the translated products and the signal sequence of elastin a
Authors: Krawetz Stephen A. , Narayanan A. Sampath , Anwar Rashid A.
Published: December 2009

Chick embryo aorta mRNAs were translated in a gel-filtered reticulocyte lysate. The translated products showed two elastin-related proteins (a and b; relative mass ~ 70 000). The translated elastin a protein was separated essentially free of the b protein by centrifugation and sodium dodecyl sulfate (SDS) – polyacrylamide gel electrophoresis. The a protein was then electroeluted from the SDS–polyacrylamide gel and a partial sequence was determined by automated Edman degradation. The NH2-terminal presequence of the elastin a protein is[Formula: see text]The assigned sequence is identical to that reported for the b protein. Translation of chick embryo aorta mRNA in the presence of dog pancreas microsomal membranes segregated the a and b proteins into membrane vesicles and cotranslationally cleaved their respective presequences. The processed a and b elastin proteins were isolated together and NH2-terminal proline positions were determined. These are[Formula: see text]These proline positions 4 and 8 are identical to those for NH2-terminal sequence for tropoelastin. This suggests that the signal peptidase removes the 24-residue signal peptide and thus directly generates the tropoelastin sequence, with no NH2-terminal prosequence as the intermediate.
Improved purification of β-galactosidase from rabbit brain: two separable fractions share kinetic and structural properties
Authors: Fraser Nancy L. , Mahuran Donald , Freeman Stuart J. , Callahan John W.
Published: December 2009

β-Galactosidase has been purified from rabbit brain by a procedure which gives substantially greater purification and yield than the previously reported method. The enzyme was solubilized in 4% aqueous butanol and purified by a procedure which included affinity chromatography on columns of concanavalin A – Sepharose (ConA-Sepharose) and aminophenylthiogalactoside Sepharose (APTgalactoside-Sepharose). The activity was resolved by DEAE-Sepharose chromatography into two fractions; the first did not bind to the column and was eluted in the unbound fraction, while the second bound to the column and could be eluted with a salt gradient. The unbound and bound fractions were purified 7600-fold and 4900-fold, respectively, by the newly developed procedure. Both gave two closely migrating protein bands on polyacrylamide gel electrophoresis and the major contaminating protein was β-hexosaminidase in each case. The enzyme in the unbound fraction had an isoelectric point (pI) of 6.7 and an apparent molecular weight by gel filtration of 114 000 ± 10 000. The enzyme that bound to DEAE-Sepharose at pH 8.0 and comprised about 60% of the total acid β-galactosidase activity of rabbit brain eluted from Sephacryl S-200 as a single peak with apparent molecular weight 140 000 ± 10 000. The two fractions displayed similar relative specific activities towards the synthetic substrates and ganglioside GM1 and lactosyl ceramide. Neither enzyme hydrolyzed galactosyl ceramide. We have immunological evidence which suggests that the two fractions of β-galactosidase are also structurally related.
Cell-free synthesis of porcine proopiomelanocortin: two distinct primary translation products
Authors: Boileau G. , Gossard F. , Seidah N. G. , Chrétien M.
Published: December 2009

Polyadenylated RNA prepared from porcine pituitary intermediate lobes was translated in the cell-free rabbit reticulocyte system. Two translation products with apparent relative masses (Mrs) of 37 500 and 35 000 on polyacrylamide – sodium dodecyl sulfate gel electrophoresis were immunoprecipitated with a β-melanophore-stimulating hormone (β-MSH) antiserum. Tryptic digestions after citraconylation of the lysine residues and purification of the peptides by high performance liquid chromatography demonstrated that both polypeptides contained authentic β-endorphin sequences. N-terminus microsequencing of the translation products labeled with [3H]leucine revealed the following partial amino acid sequence for the polypeptides with Mrs of 37 500 and 35 000: Leu8, 11, 12, 13, 15,16, 17, 20, 28, and 36 and Leu 3, 11, 12, 13, 15, 16, 17, 28, and 36, respectively. These results taken together prove the existence of two distinct mRNAs coding for proopiomelanocortin in the porcine pituitary intermediate lobe.