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31.
Insulin-like growth factor-binding proteins (IGFBPs) play an integral role in modifying insulin-like growth factor actions in a wide variety of cell types. Recent evidence suggests that IGFBP-3 and IGFBP-5 also have effects on cell growth that are insulin-like growth factor-independent. In investigating possible mechanisms for this effect, the intracellular trafficking of IGFBP-3 and IGFBP-5, both of which contain sequences with the potential for nuclear localization, was studied in T47D cells. Nuclear uptake of fluorescently labeled IGFBP-3 and IGFBP-5 was observed in a proportion of T47D cells that appeared to be rapidly dividing. IGFBP-1 and IGFBP-2, which do not possess the putative domain for nuclear translocation, were not transported to the nuclei of T47D cells. When T47D cells were preincubated with excess unlabeled IGFBP-3, nuclear localization of labeled IGFBP-3 or IGFBP-5 was not detected, indicating that their nuclear translocation involves a common pathway. Inhibition of receptor-mediated endocytosis did not affect nuclear uptake of IGFBP-3, suggesting that it uses an alternative non-classical import pathway for transport across the plasma membrane. In addition, a variant form of IGFBP-3 with a mutation in the putative nuclear localization sequence was unable to translocate to the nuclei of T47D cells, suggesting that nuclear translocation of IGFBP-3 was dependent on these carboxyl-terminal basic residues. 相似文献
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The course of two neonates and one 4-month-old infant with laboratory and clinical evidence of central hypothyroidism is described. All three presented with failure to thrive and improved after L-T4 therapy. Early recognition and treatment of newborns and infants with central hypothyroidism is important to maximize the potential for growth and development. Two of the three infants have been documented to have transient central hypothyroidism of hypothalamic origin, not previously reported. 相似文献
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Hereditary inclusion body myopathies comprise autosomal recessive and autosomal dominant muscle disorders that have a variable clinical phenotype but share similar morphological features. These include rimmed vacuoles within muscle fibres and collections of intrasarcoplasmic and intranuclear tubulofilamentous inclusions, 16-18 nm in external diameter. The resemblances and the differences between the sporadic and the hereditary inclusion body myopathies are discussed. Recent advances in the identification of various proteins involved in these diseases are mentioned because they have provided better insight into their underlying pathophysiological mechanisms. Linkage studies have allowed the localization of the genetic defect of some hereditary inclusion body myopathies and related disorders, contributing to their individualization. 相似文献
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This paper examines the view that productive teaching in the operating theatre requires a recognition of the unique set of factors which may influence the process of communication. For tutor-student interaction to occur in a productive manner, the tutor's behaviour will need to be modified to suit the demands of the other tasks in which both tutor and student are involved. The particular value of recognizing the role of nonverbal behaviours during interaction is discussed, with the use of specific examples related to the positioning of the tutor and student, and their use of facial expression, the eyes and voice. 相似文献
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GA Dudley RS Staron TF Murray FC Hagerman A Luginbuhl 《Canadian Metallurgical Quarterly》1983,54(2):582-586
The relationship between fiber type composition and the increase in blood ammonia was examined following a maximal O2 consumption (VO2max) test. Muscle biopsies were taken from the middle portion of the vastus lateralis for determination of fiber type percentages. Two subject groups were selected on the basis of a high (HST) or low (LST) percentage of slow-twitch fibers and compared for blood ammonia and lactate levels after exercise at work loads of approximately 85 and 110% of VO2max. An inverse relationship was found between the percentage of slow-twitch fibers and the increase in blood ammonia. Blood ammonia increased after exercise at both 85 and 110% of VO2max. However, the increase was twofold greater for the LST group following the 110% work effort. The increases in blood ammonia and lactate were positively correlated for both groups following exercise. The results suggest that the proportion of slow-twitch fibers plays an important role in determining the magnitude of the increase in blood ammonia after intense exercise. 相似文献