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1.
Syst Rev ; 5: 59, 2016 Apr 12.
Article in English | MEDLINE | ID: mdl-27072140

ABSTRACT

BACKGROUND: Information technologies can facilitate the implementation of health interventions, especially in the case of widespread conditions such as pain. Tailored Web-based interventions have been recognized for health behavior change among diverse populations. However, none of the systematic reviews looking at Web-based interventions for pain management has specifically addressed the contribution of tailoring. METHODS: The aims of this systematic review are to assess the effect of tailored Web-based pain management interventions on pain intensity and physical and psychological functions. Randomized controlled trials including adults suffering from any type of pain and involving Web-based interventions for pain management, using at least one of the three tailoring strategies (personalization, feedback, or adaptation), will be considered. The following types of comparisons will be carried out: tailored Web-based intervention with (1) usual care (passive control group), (2) face-to-face intervention, and (3) standardized Web-based intervention. The primary outcome will be pain intensity measured using a self-report measure such as the numeric rating scale (e.g., 0-10) or visual analog scale (e.g., 0-100). Secondary outcomes will include pain interference with activities and psychological well-being. A systematic review of English and French articles using MEDLINE, Embase, CINAHL, PsycINFO, Web of Science, and Cochrane Library will be conducted from January 2000 to December 2015. Eligibility assessment will be performed independently in an unblinded standardized manner by two reviewers. Extracted data will include the following: sample size, demographics, dropout rate, number and type of study groups, type of pain, inclusion and exclusion criteria, study setting, type of Web-based intervention, tailoring strategy, comparator, type of pain intensity measure, pain-related disability and psychological well-being outcomes, and times of measurement. Disagreements between reviewers at the full-text level will be resolved by consulting a third reviewer, a senior researcher. DISCUSSION: This systematic review is the first one looking at the specific ingredients and effects of tailored and Web-based interventions for pain management. Results of this systematic review could contribute to a better understanding of the mechanisms by which Web-based interventions could be helpful for people facing pain problems. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42015027669.


Subject(s)
Internet , Pain Management , Systematic Reviews as Topic , Adult , Humans , Research Design
2.
Nat Nanotechnol ; 10(9): 791-5, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26237346

ABSTRACT

Platforms that offer massively parallel, label-free biosensing can, in principle, be created by combining all-electrical detection with low-cost integrated circuits. Examples include field-effect transistor arrays, which are used for mapping neuronal signals and sequencing DNA. Despite these successes, however, bioelectronics has so far failed to deliver a broadly applicable biosensing platform. This is due, in part, to the fact that d.c. or low-frequency signals cannot be used to probe beyond the electrical double layer formed by screening salt ions, which means that under physiological conditions the sensing of a target analyte located even a short distance from the sensor (∼1 nm) is severely hampered. Here, we show that high-frequency impedance spectroscopy can be used to detect and image microparticles and living cells under physiological salt conditions. Our assay employs a large-scale, high-density array of nanoelectrodes integrated with CMOS electronics on a single chip and the sensor response depends on the electrical properties of the analyte, allowing impedance-based fingerprinting. With our platform, we image the dynamic attachment and micromotion of BEAS, THP1 and MCF7 cancer cell lines in real time at submicrometre resolution in growth medium, demonstrating the potential of the platform for label/tracer-free high-throughput screening of anti-tumour drug candidates.


Subject(s)
Biosensing Techniques/instrumentation , Cytological Techniques/instrumentation , Molecular Imaging/instrumentation , Semiconductors , Cell Line , Equipment Design , High-Throughput Screening Assays/instrumentation , Humans , Molecular Imaging/methods , Nanotechnology/instrumentation
3.
Bull Entomol Res ; 103(2): 182-92, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23036316

ABSTRACT

Anthropogenic range expansion and cultural practices have modified the distribution, abundance and genetic diversity of domesticated organisms, thereby altering multitrophic assemblages through space and time. The putative Mesoamerican domestication centre of the common bean, Phaseolus vulgaris L., in Mexico allows investigating the effects of plant domestication on the genetic structure of members of a multitrophic system. The aim of this study was to compare the evolutionary history of Horismenus parasitoids (Hymenoptera: Eulophidae) to those of their bruchid beetle hosts (Coleoptera: Bruchidae) and their domesticated host plant (P. vulgaris), in the context of traditional agriculture in Mexico. We analyzed the population genetic structure of four Horismenus species in Mexico using mitochondrial COI haplotype data. The two most abundant parasitoid species were Horismenus depressus and Horismenus missouriensis. Horismenus missouriensis were infected by Wolbachia endosymbionts and had little to no population differentiation (F(ST) = 0.06). We suspect the mitochondrial history of H. missouriensis to be blurred by Wolbachia, because differentiation among infected vs. non-infected individuals exists (F(ST) = 0.11). Populations of H. depressus were found to be highly differentiated (F(ST) = 0.34), but the genetic structuring could not be explained by tested spatial components. We then compared the genetic structure observed in this parasitoid species to previously published studies on bruchid beetles and their host plants. Despite extensive human-mediated migration and likely population homogenization of its two Acanthoscelides bruchid beetle hosts, H. depressus populations are structured like its host plant, by a recent dispersal from a diverse ancestral gene pool. Distinct evolutionary dynamics may explain inconsistent patterns among trophic levels. Parasitoids likely migrate from wild bean populations and are poorly adapted to bean storage conditions similar to their bruchid beetle hosts. Integrating several trophic levels to the study of evolutionary history has proven to be fruitful in detecting different ecological responses to human-mediated disturbances and host parasite interactions.


Subject(s)
Biological Evolution , Coleoptera/genetics , Food Chain , Phaseolus/genetics , Wasps/genetics , Animals , Coleoptera/parasitology , Genetic Variation , Host-Parasite Interactions , Mexico , Phylogeography , Wasps/microbiology , Wolbachia/isolation & purification
4.
Environ Technol ; 31(12): 1371-9, 2010 Nov.
Article in English | MEDLINE | ID: mdl-21121460

ABSTRACT

Canada's agricultural emissions accounted for 60 Mt or 8% of national greenhouse gas (GHG) emissions in 2007. The estimation of CH4 emission factor (B0) from manure management systems in Canada is prone to uncertainty owing to lack of B0 values for Canadian conditions. Therefore, in this study, manure samples from six Canadian animal farms, two each of swine, beef and dairy cattle, were investigated in order to estimate their methane production potential (B0). The ultimate anaerobic biodegradability was measured with ISO standard batch fermentation. The extent of biodegradation of the manure samples with or without sodium benzoate was always greater than 60% and hence showed no inhibitory effect on methane production by the manure. The impact of use of antibiotics in the animal feed on methane production was also considered; however, no inhibitory effect on methane production could be observed. The plateau of methane production in all cases was achieved by 63 d of anaerobic digestion process and the final pH was within 6-8. The calculated B0 were in the range of 0.47-0.42, 0.21-0.19 and 0.35-0.30 for swine, beef cattle and dairy cattle, respectively. The uncertainties associated with B0 values were +/- 9% for swine, +/- 3% for beef cattle and, +/- 6 and +/- 2% for dairy cows.


Subject(s)
Manure/microbiology , Methane/metabolism , Models, Chemical , Anaerobiosis , Animal Husbandry , Animals , Canada , Carbon Dioxide/analysis , Carbon Dioxide/metabolism , Cattle , Global Warming , Hydrogen-Ion Concentration , Methane/analysis , Reproducibility of Results , Sewage , Swine
5.
J Agric Saf Health ; 15(3): 225-40, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19728546

ABSTRACT

In-barn manure separation systems are becoming popular due to various environmental pressures on the swine industry. According to the literature, separation of feces and urine directly underneath the slats should have a positive impact on barn air quality. Removal and rapid separation of the two phases (solid/liquid) would reduce the dust and bioaerosol emissions, which would significantly improve the air quality in pig-housing facilities. From an occupational health and safety perspective, the maximum endotoxin and total bacteria concentrations to ensure workers' safety should not exceed 450 endotoxin units per cubic meter of air (EU m(-3)) and 10(4) colony-forming units per cubic meter of air (CFU m(-3)), respectively. In the current study, the effect on air quality of six in-barn manure handling systems was measured. A flat scraper system and four separation systems installed under the slats (a conveyor belt system, a conveyor net system, and a V-shaped scraper operated at two operation frequencies) were evaluated and compared to a conventional pull-plug system (control). The experiment took place in twelve independent and identical rooms housing four grower-finisher pigs each, and air samples were collected and analyzed for total dust, endotoxins, bacteria, and mold counts. The results obtained from this experimental setup show that the separation of feces and urine under the slats would concentrate at least 80% of the phosphorus in the solid phase. The total bacteria and endotoxin concentrations are lower than those found in commercial hog barns but remain higher than the recommended levels. Only the total dust concentrations are approximately 10% of their regulated value. This separation has no impact on dust and bioaerosol concentrations compared to the control.


Subject(s)
Agriculture/statistics & numerical data , Air Pollution, Indoor/statistics & numerical data , Housing, Animal/standards , Manure , Occupational Exposure/statistics & numerical data , Aerosols/adverse effects , Air Microbiology/standards , Animals , Bacteria/growth & development , Dust , Fungi/growth & development , Humans , Nitrogen/toxicity , Phosphorus/toxicity , Swine
6.
Kidney Int ; 73(5): 556-66, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18033240

ABSTRACT

Nephrin is a slit diaphragm protein critical for structural and functional integrity of visceral glomerular epithelial cells (podocytes) and is known to be tyrosine phosphorylated by Src family kinases. We studied the role of phosphoinositide 3-kinase (PI3K), activated via the phosphorylation of nephrin, in actin cytoskeletal reorganization of cultured rat podocytes. Phosphorylation of rat nephrin by the Fyn kinase markedly increased its interaction with a regulatory subunit of PI3K. Stable transfection of rat nephrin in the podocytes with podocin led to nephrin tyrosine phosphorylation, PI3K-dependent phosphorylation of Akt, increased Rac1 activity, and an altered actin cytoskeleton with decreased stress fibers and increased lamellipodia. These changes were reversed with an inhibitor of PI3K and not seen when the nephrin-mutant Y1152F replaced wild-type nephrin. Rac1 and Akt1 contributed to lamellipodia formation and decreased stress fibers, respectively. Finally, in the rat model of puromycin aminonucleoside nephrosis, nephrin tyrosine phosphorylation, nephrin-PI3K association, and glomerular Akt phosphorylation were all decreased. Our results suggest that PI3K is involved in nephrin-mediated actin reorganization in podocytes. Disturbed nephrin-PI3K interactions may contribute to abnormal podocyte morphology and proteinuria.


Subject(s)
Actins/metabolism , Actins/ultrastructure , Membrane Proteins/metabolism , Phosphatidylinositol 3-Kinases/physiology , Podocytes/metabolism , Podocytes/ultrastructure , Animals , Cell Membrane/metabolism , Cells, Cultured , Membrane Proteins/genetics , Phosphorylation , Proto-Oncogene Proteins c-akt/metabolism , Rats , Tyrosine/metabolism , rac1 GTP-Binding Protein/metabolism
7.
Biopolymers ; 87(2-3): 141-8, 2007.
Article in English | MEDLINE | ID: mdl-17626297

ABSTRACT

DNA in solution can be condensed into dense aggregates by multivalent counterions. Here we investigate the effect of a nearby surface on the morphology of DNA condensates. We show that, contrary to what has often been assumed, interactions between DNA condensates and the surface can strongly influence the observed morphology. This limits the usefulness of surface probes such as atomic force microscopy for studying the morphology of condensates in bulk solution. Surprisingly, we find that the most negatively charged surface disturbs the condensate morphology most, suggesting that the microscopic mechanism resulting in DNA condensation is also responsible for the attractive force between DNA and the surface.


Subject(s)
Bacteriophage lambda/chemistry , DNA, Viral/chemistry , Spermidine/chemistry , Ions , Microscopy, Atomic Force
8.
Proc Natl Acad Sci U S A ; 104(19): 7770-5, 2007 May 08.
Article in English | MEDLINE | ID: mdl-17470799

ABSTRACT

We use micrometer-sized fluidic channels to confine and measure electrophoresis of freely suspended individual microtubules. We measure orientation-dependent velocities of microtubules and the electro-osmotic flow mobility in our channels to infer the anisotropic electrophoretic mobility of microtubules under physiological conditions. We discuss the difference between electrophoresis and purely hydrodynamic motion and its implications for interpreting mobility measurements. We show that the mobility anisotropy is a factor of 0.83, clearly different from the well known anisotropy factor of 0.5 in Stokes drag coefficients for cylindrical objects. We also show that the velocity is independent of microtubule length, which would be different for hydrodynamic motion. We demonstrate that the electric force on the counterions has important consequences for the interpretation of electrophoresis experiments and that ignoring this can lead to an underestimation of the effective charge by orders of magnitude. From the electrophoresis measurements, we calculate an effective surface-charge density of -36.7 +/- 0.4 mC/m2 for microtubules. Electrophoretic measurements of subtilisin-digested microtubules, which have the negatively charged C termini on the outer surface removed, show a 24% decrease in mobility and, correspondingly, in surface charge, but no change in anisotropy.


Subject(s)
Microtubules/physiology , Anisotropy , Dimerization , Electrophoresis , Microtubules/chemistry , Solutions , Surface Properties , Tubulin/chemistry
9.
Phys Rev Lett ; 98(5): 058103, 2007 Feb 02.
Article in English | MEDLINE | ID: mdl-17358905

ABSTRACT

Using magnetic tweezers, we study in real time the condensation of single DNA molecules under tension. We find that DNA condensation occurs via discrete nucleated events. By measuring the influence of an imposed twist, we show that condensation is initiated by the formation of a plectonemic supercoil. This demonstrates a strong interplay between the condensation transition and externally imposed mechanical constraints.


Subject(s)
DNA/chemistry , DNA/ultrastructure , Nucleic Acid Conformation , Biophysical Phenomena , Biophysics , Magnetics , Microscopy, Atomic Force , Thermodynamics
10.
J Anim Sci ; 83(6): 1413-22, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15890820

ABSTRACT

Three experiments were conducted to assess water intake, water wastage, and a means to decrease water wastage by growing-finishing pigs from nipple drinkers. In Exp. 1, 48 pigs were studied during two periods (average BW = 53 and 72 kg for Period 1 and 2, respectively). Water disappearance and wastage were determined for 4 d, while nipple drinkers were set at 50 mm above the shoulder height of the smallest pig in the pen (recommended heights), with flow rates at 700 mL/min during Period 1, and 1,000 mL/min during Period 2. Water intake rate was assessed at two nipple flow rates, approximately 650 and 1,300 mL/min during the Period 1, and 1,000 and 2,000 mL/min during the Period 2. The average water intake was 4.01 and 5.38 +/- 0.19 L.pig(-1).d(-1) during Periods 1 and 2, respectively (P < 0.01). Water wastage as a percentage of water disappearance was similar between the two periods (25.8 and 27.0 +/- 1.9% for Periods 1 and 2, respectively). Water intake rate was 467 and 795 mL/min (+/-34.2; P < 0.01) during Period 1, and 722 and 1,422 mL/min (+/-80.0; P < 0.01) during Period 2, at the lower and higher flow rates, respectively. In Exp. 2, 32 pigs were used in a 2 x 2 factorial design to determine effects of nipple heights (recommended vs. unadjusted = 330 mm) and flow rates (500 vs. 1,000 mL/min) on water intake and wastage. Water wastage was increased (P < 0.01) on the unadjusted vs. recommended nipple height, and the higher flow rate also resulted in greater wastage (P = 0.03) compared with the lower rate. In Exp. 3, water disappearance and manure output in 16 pens of 18 pigs per pen were monitored for 12 wk (average initial BW = 32 kg) using four drinker treatments (bowl drinker, nipple drinker at recommended heights, an unadjusted nipple set at 480 mm, and high nipple drinker height of 730 mm with a step underneath). For pigs on the high nipple drinker, the average water disappearance and manure output did not differ from those of the pigs on the recommended nipple heights and bowl drinker, but these measurements were 15 and 12% lower, respectively, than for the pigs on the low nipple drinker. The results indicate that growing-finishing pigs can maintain adequate water intake from a variety of drinker types and management. Water wastage can be controlled through drinker management.


Subject(s)
Animal Husbandry/instrumentation , Animal Husbandry/methods , Drinking/physiology , Swine/physiology , Animals , Drinking Behavior , Female , Manure , Videotape Recording
11.
Phys Rev E Stat Nonlin Soft Matter Phys ; 72(6 Pt 1): 061501, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16485949

ABSTRACT

Charge inversion occurs when the effective charge of a surface exposed to solution reverses polarity due to an excess of counterions accumulating in the immediate vicinity of the surface. Using atomic force spectroscopy, we have directly measured the effect on charge inversion of changing the dielectric constant of the solvent and the surface-charge density. Both decreasing the dielectric constant and increasing the bare surface-charge density lower the charge-inversion concentration. These observations are consistent with the theoretical proposal that spatial correlations between ions are the dominant driving mechanism for charge inversion.

12.
Phys Rev Lett ; 93(17): 170802, 2004 Oct 22.
Article in English | MEDLINE | ID: mdl-15525062

ABSTRACT

We have directly observed reversal of the polarity of charged surfaces in water upon the addition of trivalent and quadrivalent ions using atomic force microscopy. The bulk concentration of multivalent ions at which charge inversion reversibly occurs depends only very weakly on the chemical composition, surface structure, size, and lipophilicity of the ions, but is very sensitive to their valence. These results support the theoretical proposal that spatial correlations between ions are the driving mechanism behind charge inversion.


Subject(s)
Metals/chemistry , Polylysine/chemistry , Silicon Dioxide/chemistry , Cobalt/chemistry , Cyanides/chemistry , Ferricyanides/chemistry , Ferrous Compounds/chemistry , Ions/chemistry , Iron Compounds/chemistry , Lanthanoid Series Elements/chemistry , Microscopy, Atomic Force , Organometallic Compounds/chemistry , Static Electricity
13.
Nature ; 432(7015): 371-4, 2004 Nov 18.
Article in English | MEDLINE | ID: mdl-15549099

ABSTRACT

The interplay between discrete vibrational and electronic degrees of freedom directly influences the chemical and physical properties of molecular systems. This coupling is typically studied through optical methods such as fluorescence, absorption and Raman spectroscopy. Molecular electronic devices provide new opportunities for exploring vibration-electronic interactions at the single molecule level. For example, electrons injected from a scanning tunnelling microscope tip into a metal can excite vibrational excitations of a molecule situated in the gap between tip and metal. Here we show how current directly injected into a freely suspended individual single-wall carbon nanotube can be used to excite, detect and control a specific vibrational mode of the molecule. Electrons tunnelling inelastically into the nanotube cause a non-equilibrium occupation of the radial breathing mode, leading to both stimulated emission and absorption of phonons by successive electron tunnelling events. We exploit this effect to measure a phonon lifetime of the order of 10 ns, corresponding to a quality factor of well over 10,000 for this nanomechanical oscillator.

14.
J Agric Saf Health ; 9(4): 285-302, 2003 Nov.
Article in English | MEDLINE | ID: mdl-14679877

ABSTRACT

In Saskatchewan, some recent incidents have lead us to believe that certain manure management activities can potentially release high concentrations of H2S into the atmosphere of shallow-pit barns. The objectives of the monitoring project reported here were to evaluate worker exposure to H2S during the completion of the following tasks: emptying of in-barn shallow manure pits, power washing of barn rooms, and agitation and emptying of outdoor manure storage facilities. In-barn monitoring was performed in gestation, farrowing, nursery, and grow-finish sections in the summer of 2001 and the winter of 2002 on four different farms. Plug pulling can generate very high concentrations of H2S. The maximum values recorded during some of the monitored events reached 1,000 ppm. The H2S released as a plug is being pulled does not follow a predictable pattern when considering the level that will be reached, the concentration variations during the event, and the time at which the peak concentration will be observed. Power washing generated lower H2S concentrations than plug pulling. However, as the task to be performed generally takes time, the 15 min time-weighed average of 15 ppm (STEL) can be reached after the task started and can be exceeded for a long period of time, which for some of the monitored events was more than 30 min. Finally, monitoring at the storage facilities showed that the risks of exposure to excessive H2S concentrations during the agitation and emptying of outside manure storage facilities were very limited. Results from this study suggest that pig production buildings involving short-term storage of liquid manure may present H2S exposure risks that have been underestimated until now. All workers should be provided with an H2S monitor and safety equipment to ensure that workers are protected when the H2S concentration rises. As well, engineering controls have to be developed to prevent H2S formation in the manure or H2S emission into the worker/pig space.


Subject(s)
Air Pollutants, Occupational/analysis , Animal Husbandry/methods , Hydrogen Sulfide , Manure/analysis , Occupational Exposure/prevention & control , Animals , Environmental Monitoring/methods , Housing, Animal , Humans , Occupational Exposure/standards , Protective Devices , Risk Assessment , Saskatchewan , Swine , Waste Management
15.
Nature ; 412(6847): 617-20, 2001 Aug 09.
Article in English | MEDLINE | ID: mdl-11493914

ABSTRACT

The drive towards the development of molecular electronics is placing increasing demands on the level of control that must be exerted on the electronic structure of materials. Proposed device architectures ultimately rely on tuning the interactions between individual electronic states, which amounts to controlling the detailed spatial structure of the electronic wavefunctions in the constituent molecules. Few experimental tools are available to probe this spatial structure directly, and the shapes of molecular wavefunctions are usually only known from theoretical investigations. Here we present scanning tunnelling spectroscopy measurements of the two-dimensional structure of individual wavefunctions in metallic single-walled carbon nanotubes; these measurements reveal spatial patterns that can be directly understood from the electronic structure of a single graphite sheet, and which represent an elegant illustration of Bloch's theorem at the level of individual wavefunctions. We also observe energy-dependent interference patterns in the wavefunctions and exploit these to directly measure the linear electronic dispersion relation of the metallic single-walled carbon nanotube.

16.
J Biol Chem ; 276(21): 18430-6, 2001 May 25.
Article in English | MEDLINE | ID: mdl-11278744

ABSTRACT

Activin, a member of the TGFbeta family inhibits cell growth in various target tissues. Activin interacts with a complex of two receptors that upon activation phosphorylate specific intracellular mediators, the Smad proteins. The activated Smads interact with diverse DNA binding proteins and co-activators of transcription in a cell-specific manner, thus leading to various activin biological effects. In this study, we investigated the role and mechanism of action of activin in the human breast cancer T47D cells. We found that activin treatment of T47D cells leads to a dramatic decrease in cell growth. Thus activin appears as a potent cell growth inhibitor of these breast cancer cells. We show that activin induces the Smad pathway in these cells but also activates the p38-mitogen-activated protein kinase pathway, further leading to phosphorylation of the transcription factor ATF2. Finally, specific inhibitors of the p38 kinase (SB202190, SB203580, and PD169316) but not an inactive analogue (SB202474) or the MEK-1 inhibitor PD98059 completely abolish the activin-mediated cell growth inhibition of T47D cells. Together, these results define a new role for activin in human breast cancer T47D cells and highlight a new pathway utilized by this growth factor in the mediation of its biological effects in cell growth arrest.


Subject(s)
Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Inhibins/pharmacology , Mitogen-Activated Protein Kinases/metabolism , Activins , Cell Division/drug effects , Female , Humans , MAP Kinase Signaling System/drug effects , Signal Transduction/drug effects , Transforming Growth Factor beta/pharmacology , Tumor Cells, Cultured , p38 Mitogen-Activated Protein Kinases
17.
Mol Cell Biol ; 21(4): 1077-88, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11158295

ABSTRACT

The protein tyrosine kinase (PTK) Csk is a potent negative regulator of several signal transduction processes, as a consequence of its exquisite ability to inactivate Src-related PTKs. This function requires not only the kinase domain of Csk, but also its Src homology 3 (SH3) and SH2 regions. We showed previously that the Csk SH3 domain mediates highly specific associations with two members of the PEP family of nonreceptor protein tyrosine phosphatases (PTPs), PEP and PTP-PEST. In comparison, the Csk SH2 domain interacts with several tyrosine phosphorylated molecules, presumed to allow targetting of Csk to sites of Src family kinase activation. Herein, we attempted to understand better the regulation of Csk by identifying ligands for its SH2 domain. Using a modified yeast two-hybrid screen, we uncovered the fact that Csk associates with PTP-HSCF, the third member of the PEP family of PTPs. This association was documented not only in yeast cells but also in a heterologous mammalian cell system and in cytokine-dependent hemopoietic cells. Surprisingly, the Csk-PTP-HSCF interaction was found to be mediated by the Csk SH2 domain and two putative sites of tyrosine phosphorylation in the noncatalytic portion of PTP-HSCF. Transfection experiments indicated that Csk and PTP-HSCF synergized to inhibit signal transduction by Src family kinases and that this cooperativity was dependent on the domains mediating their association. Finally, we obtained evidence that PTP-HSCF inactivated Src-related PTKs by selectively dephosphorylating the positive regulatory tyrosine in their kinase domain. Taken together, these results demonstrate that part of the function of the Csk SH2 domain is to mediate an inducible association with a PTP, thereby engineering a more efficient inhibitory mechanism for Src-related PTKs. Coupled with previously published observations, these data also establish that Csk forms complexes with all three known members of the PEP family.


Subject(s)
Protein Tyrosine Phosphatases/chemistry , Protein Tyrosine Phosphatases/metabolism , Protein-Tyrosine Kinases/chemistry , Protein-Tyrosine Kinases/metabolism , Amino Acid Sequence , Animals , Binding Sites/genetics , COS Cells , CSK Tyrosine-Protein Kinase , Conserved Sequence , Hematopoietic Stem Cells/enzymology , Humans , Macromolecular Substances , Mice , Molecular Sequence Data , Protein Tyrosine Phosphatases/genetics , Protein Tyrosine Phosphatases, Non-Receptor , Protein-Tyrosine Kinases/genetics , Rats , Sequence Homology, Amino Acid , Signal Transduction , Transfection , Two-Hybrid System Techniques , Tyrosine/chemistry , src Homology Domains , src-Family Kinases
18.
Acta Crystallogr D Biol Crystallogr ; 57(Pt 1): 61-8, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11134928

ABSTRACT

The dynamic response of tetragonal lysozyme crystals to dehydration has been characterized in situ using a combination of X-ray topography, high-resolution diffraction line-shape measurements and conventional crystallographic diffraction. For dehydration from 98% relative humidity (r.h.) to above 89%, mosaicity and diffraction resolution show little change and X-ray topographs remain featureless. Lattice constants decrease rapidly but the lattice-constant distribution within the crystal remains very narrow, indicating that water concentration gradients remain very small. Near 88% r.h., the c-axis lattice parameter decreases abruptly, the steady-state mosaicity and diffraction resolution degrade sharply and topographs develop extensive contrast. This transformation exhibits metastability and hysteresis. At fixed r.h. < 88% it is irreversible, but the original order can be almost completely restored by rehydration. These results suggest that this transformation is a first-order structural transition involving an abrupt loss of crystal water. The front between transformed and untransformed regions may propagate inward from the crystal surface and the resulting stresses along the front may degrade mosaicity. Differences in crystal size, shape and initial perfection may produce the observed variations in degradation timescale. Consequently, the success of more general post-growth treatments may often involve identifying procedures that either avoid lattice transitions, minimize disorder created during such transitions or maintain the lattice in an ordered metastable state.


Subject(s)
Muramidase/chemistry , Crystallography, X-Ray , Humidity , Protein Conformation
19.
Hum Mutat ; 16(3): 274-5, 2000 Sep.
Article in English | MEDLINE | ID: mdl-10980545

ABSTRACT

We studied the NF1 gene in 93 unrelated patients with neurofibromatosis type1, focusing the analysis on four exons that contain the highest number of possible mutations occurring at CpG sites. We used denaturing gradient gel electrophoresis to analyse exons 16, 28, 29 and 49, which contain 45 (25%) of the 183 possible mutations that could occur at the 120 CpG dinucleotides of the coding sequence. Six different mutations were identified, five of which are novel: two truncating mutations, W1810X and 5448insG, located in exon29; two splice defects leading to exon29 skipping, 5206-2A>G and 5546G>A; and one missense mutation, L844F, located in exon16. The already described R1748X mutation located in exon29 was found in two unrelated patients. The 5546G>A and R1748X mutations are located at CpG sites, whereas the W1810X involves a CpNpG site. Four novel polymorphisms, which may be helpful for family studies, were also identified. Overall, all but one mutations were found in exon29, a result which suggests that all the CpG sites of the NF1 coding sequence do not have the same mutability, and that exon29, the most CpG-rich exon, contains mutational hotspots associated with NF1.


Subject(s)
CpG Islands/genetics , Exons/genetics , Neurofibromatosis 1/genetics , Adolescent , Adult , Aged , Cell Line , Child , Cohort Studies , DNA Mutational Analysis , Electrophoresis, Agar Gel/methods , Electrophoresis, Polyacrylamide Gel , Genes, Neurofibromatosis 1 , Humans , Middle Aged , Mutation , Nucleic Acid Denaturation/genetics
20.
Chest ; 118(3): 852-60, 2000 Sep.
Article in English | MEDLINE | ID: mdl-10988215

ABSTRACT

STUDY OBJECTIVES: A study was conducted to evaluate the acute health effects of wearing an N-95 disposable respirator in a swine confinement facility. DESIGN: A crossover trial design was used in the study. SETTING: The study was carried out at the research facilities of the Centre for Agricultural Medicine, the Royal University Hospital, and the Prairie Swine Centre Inc, Saskatoon, Saskatchewan, Canada. PARTICIPANTS: Twenty-one nonsmoking healthy male subjects with no previous swine barn exposure participated in the study. INTERVENTIONS: The subjects participated in a laboratory session (baseline day), a 4-h exposure in a traditional swine room wearing the respirator (intervention day), and a 4-hour exposure in a traditional swine room without a respirator (nonintervention day). MEASUREMENTS: Lung function, methacholine challenge tests, blood counts, nasal lavage, and cytokines in serum and nasal lavage fluid. RESULTS: Mean (+/- SE) shift change in FEV(1), from preexposure to postexposure, was highest on nonintervention day (-8.1+/-1.01%) and was significantly different from intervention day (0.32+/-0.62%; p<0.0001) and baseline day (1.57+/-0.51%; p<0.0001). Similar patterns were observed in the mean values of the provocative concentration of a substance (methacholine) causing a 20% fall in FEV(1) (nonintervention day, 130.4+/-36.9 mg/mL; intervention day, 242.0+/-38.0 mg/mL; and baseline day, 328.0 mg/mL +/-34.1 mg/mL). Significant increases in serum neutrophil levels and nasal cell counts were observed on the nonintervention day in comparison to the baseline and intervention days. Significant increases also were found in the levels of cytokines interleukin (IL)-6 and IL-8 in nasal lavage fluid and in the levels of IL-6 in serum for the nonintervention day in comparison to the other 2 days. CONCLUSIONS: The results demonstrate that an N-95 disposable respirator can help to significantly reduce acute negative health effects in subjects not previously exposed to a swine barn environment.


Subject(s)
Air Pollutants, Occupational/adverse effects , Bronchial Hyperreactivity/prevention & control , Disposable Equipment , Occupational Diseases/prevention & control , Respiratory Protective Devices , Adolescent , Adult , Animals , Bronchial Hyperreactivity/etiology , Bronchial Hyperreactivity/metabolism , Bronchial Hyperreactivity/physiopathology , Bronchial Provocation Tests/methods , Cross-Over Studies , Disposable Equipment/standards , Humans , Interleukin-6/blood , Interleukin-8/metabolism , Leukocyte Count , Male , Methacholine Chloride , Nasal Lavage Fluid/chemistry , Nasal Lavage Fluid/cytology , Occupational Diseases/etiology , Occupational Diseases/metabolism , Occupational Diseases/physiopathology , Quality Control , Respiratory Function Tests , Respiratory Protective Devices/standards , Surveys and Questionnaires
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