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Mostrando 13-24 de 48 artigos, teses e dissertações.
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13. Thixotropic behaviour of human finger flexor muscles with accompanying changes in spindle and reflex responses to stretch.
Prompted by previous reports on muscle thixotropy, we have investigated changes in inherent and reflex stiffness of the finger flexor muscles of human subjects at rest, following transient conditioning manoeuvres involving contractions and/or length changes of the finger flexors. The stiffness measurements were combined with electromyographic recordings from
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14. Modeling the impact of global tuberculosis control strategies
An epidemiological model of tuberculosis has been developed and applied to five regions of the world. Globally, 6.7 million new cases of tuberculosis and 2.4 million deaths from tuberculosis are estimated for 1998. Based on current trends in uptake of the World Health Organization’s strategy of directly observed treatment, short-course, we expect a total o
The National Academy of Sciences.
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15. Template definition by Tetrahymena telomerase reverse transcriptase
The ribonucleoprotein enzyme telomerase extends chromosome ends by copying a specific template sequence within its integral RNA component. An active recombinant telomerase RNP is minimally composed of this RNA and the telomerase reverse transcriptase (TERT) protein, which contains sequence motifs conserved among viral reverse transcriptases (RTs), flanked by
Oxford University Press.
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16. On the site of impulse initiation in a neurone.
In the preceding paper (Moore & Westerfield, 1983) the effects of changes in membrane properties and non-uniform geometry on impulse propagation and threshold parameters were investigated. In this paper the contributions of these and other parameters to the site of initiation of an impulse were determined by computer simulations using the Hodgkin-Huxley memb
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17. Structural aspects of activation pathways of aspartic protease zymogens and viral 3C protease precursors
The three-dimensional structures of the inactive protein precursors (zymogens) of the serine, cysteine, aspartic, and metalloprotease classes of proteolytic enzymes are known. Comparisons of these structures with those of the mature, active proteases reveal that, in general, the preformed, active conformations of the residues involved in catalysis are r
The National Academy of Sciences.
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18. The ventricular surface of the subcommissural organ: a scanning and transmission electron microscopic study.
The subcommissural organ of the rat has been studied by a combination of light, scanning and transmission electron microscopy. Special attention has been paid to the appearance of the ventricular surface of the organ. The ependyma-derived cells on the surface of the organ are extremely long with a width which diminishes steadily from the base, where the nucl
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19. Germiston virus transcriptase requires active 40S ribosomal subunits and utilizes capped cellular RNAs.
The transcriptase associated with Germiston virus was assayed in an in vitro reaction in which transcription was coupled to translation by adding reticulocyte lysate under the appropriate salt conditions. When analyzed in polyacrylamide gels, the major transcripts migrated like authentic S mRNAs and possessed 12- to 18-base-long nontemplated 5' extensions si
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20. Induction of neurite outgrowth by a conditioned-medium factor bound to the culture substratum
Heart-cell conditioned medium (HCM) induces rapid neurite outgrowth from isolated neurons in culture. The following evidence indicates that this action of HCM is due to a trypsin-sensitive factor which attaches to the polyornithinecoated culture substratum: (i) Pretreatment of the culture substratum with HCM allows rapid neurite outgrowth to occur even in un
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21. Attachment of Trypanosoma cruzi to mammalian cells requires parasite energy, and invasion can be independent of the target cell cytoskeleton.
We have previously shown that the binding of Trypanosoma cruzi trypomastigotes to glutaraldehyde-fixed mammalian cells has the characteristics of a receptor-mediated process and that it mimics the attachment step of the invasion of live cells by this parasite. In this study we examined the metabolic requirements for the attachment of trypomastigotes to gluta
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22. Sequence, structural and evolutionary relationships between class 2 aminoacyl-tRNA synthetases.
Class 2 aminoacyl-tRNA synthetases, which include the enzymes for alanine, aspartic acid, asparagine, glycine, histidine, lysine, phenylalanine, proline, serine and threonine, are characterised by three distinct sequence motifs 1,2 and 3 (reference 1). The structural and evolutionary relatedness of these ten enzymes are examined using alignments of primary s
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23. Scanning electron microscopy of the endometrium during the secretory phase.
Scanning electron microscopy was used to study the surface morphology of the rabbit endometrium during the secretory phase of the oestrous cycle. The free surfaces of ciliated and of inactive active secretory cells are described. Changes in secretory cell surface morphology resulting from accumulation and secretion of material involve the apparent retraction
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24. Down-regulation of Rap1 activity is involved in ephrinB1-induced cell contraction
Ephrins are cell surface ligands that activate Eph receptor tyrosine kinases. This ligand–receptor interaction plays a central role in the sorting of cells. We have previously shown that the ephrinB–EphB signalling pathway is also involved in the migration of intestinal precursor cells along the crypts. Using the colon cell line DLD1 expressing the EphB2
Portland Press Ltd..