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81.
J Ya MW Markman GT Wagenaar PJ Blommaart AF Moorman WH Lamers 《Canadian Metallurgical Quarterly》1997,249(4):495-505
Tip growth of plant cells has been suggested to be regulated by a tip-focused gradient in cytosolic calcium concentration ([Ca2+]c). However, whether this gradient orients apical growth or follows the driving force for this process remains unknown. Using localized photoactivation of the caged calcium ionophore Br-A23187 we have been able to artificially generate an asymmetrical calcium influx across the root hair tip. This led to a change in the direction of tip growth towards the high point of the new [Ca2+]c gradient. Such reorientation of growth was transient and there was a return to the original direction within 15 min. Root hairs forced to change the direction of their growth by placing a mechanical obstacle in their path stopped, reoriented growth to the side, and grew past the mechanical blockage. However, as soon as the growing tip had cleared the obstacle, growth returned to the original direction. Confocal ratio imaging revealed that a tip-focused [Ca2+]c gradient was always centered at the site of active growth. When the root hair changed direction the gradient also reoriented, and when growth returned to the original direction, so did the [Ca2+]c gradient. This normal direction of apical growth of Arabidopsis thaliana (L.) Heynh, root hairs was found to be at a fixed angle from the root of 85 +/- 6.7 degrees. In contrast, Tradescantia virginiana (L.) pollen tubes that were induced to reorient by touch or localized activation of the caged ionophore, did not return to the original growth direction, but continued to elongate in their new orientation. These results suggest that the tip-focused [Ca2+]c gradient is an important factor in localizing growth of the elongating root hair and pollen tube to the apex. However, it is not the primary determinant of the direction of elongation in root hairs, suggesting that other information from the root is acting to continuously reset the growth direction away from the root surface. 相似文献
82.
Three patients, one healthy and two immunocompromised, developed cutaneous reactions that histologically mimicked granuloma annulare at sites of resolved varicella-zoster virus (VZV) reactivation infections. Variable latency periods between the infection and the granulomatous reaction were noted. As in other case reports, the presence of VZV DNA in these lesions was inconsistently demonstrated by the polymerase chain reaction (PCR) and appears more common in early, as opposed to late, post-zoster granulomas. In addition to various granulomatous reactions, vasculitic and neoplastic eruptions following resolved VZV infections have been described and are reviewed here. Therapeutically, topical, intralesional and systemic corticosteroids, as well as acyclovir, have been tried with inconsistent results. Although the pathogenesis remains unclear, the presence of VZV DNA in early lesions that histologically do not display viral cytopathic changes, suggests the virus induces an atypical delayed hypersensitivity reaction not affected by antiviral therapy. 相似文献
83.
Personnel at the general intensive care unit at the University of Heidelberg Children's Hospital aim for a maximum of openness and transparency for parents regarding everything relevant to their own child. In this context ward nurses were interviewed about diverse aspects of their work. Aside from technical-medical activities, nurses regarded the relationship to the parents to be a central point in their work. The recognize that the relationship to the parents influences the relationship to the child and partially even the nursing of the child. Nurses are in favor of openness and transparency in relating to parents, however, reality reveals contradictions. Nurses differentiated attitude and the consequences for physicians, psychologists and parents are discussed. A case example is presented. 相似文献
84.
M Komeda A DeAnda JR Glasson AF Bolger GT Daughters NB Ingels DC Miller 《Canadian Metallurgical Quarterly》1997,64(5):1250-1255
BACKGROUND: The benefit of left ventricular (LV) unloading for preserving LV function is commonly accepted, but its efficacy remains incompletely defined. METHODS: We studied the influence of complete LV unloading on LV systolic and diastolic mechanics using an in situ isovolumic preparation with two different coronary perfusion pressures (CPPs) in 12 dogs during prolonged normothermic cardiopulmonary bypass. RESULTS: Multivariate analysis of covariance with time as a covariate revealed that a high CPP (143 +/- 36 mm Hg; n = 6) was associated with better preservation of systolic LV function over time as assessed by LV end-systolic elastance (p < 0.001) and the end-systolic pressure-volume relation physiologic intercept (p < 0.001) compared with a moderate CPP (107 +/- 18 mm Hg; p < 0.005 versus a high CPP by t-test; n = 6). Dobutamine (2 micrograms.kg-1.min-1) improved LV end-systolic elastance (p < 0.005) and LV physiologic intercept (p < 0.01) only in the high-CPP group. Conversely, impaired LV diastolic function (as measured by LV stiffness) was observed (p < 0.001) with a high CPP, but did not change with a moderate CPP. CONCLUSIONS: These observations in canine hearts suggest that complete LV unloading may not preserve LV systolic function adequately over time when CPP is maintained in the accepted clinical range. A higher CPP is required to prevent deterioration over prolonged cardiopulmonary bypass times, but diastolic dysfunction still occurs. 相似文献
85.
86.
Using a balanced placebo drink administration procedure, 48 undergraduate male social drinkers were presented with erotic and nonerotic stimuli after completing the Mosher Forced-Choice Guilt Scale. Selective attention and recognition memory were measured in both visual and auditory modalities; penile tumescence was recorded continuously in reponse to auditory stimuli. The belief that alcohol had been consumed increased penile tumescence to both heterosexual and homosexual stimuli, but only in Ss high in sex guilt. Mild intoxication itself had no effect. Alcohol impaired memory for visual stimuli, while the belief that alcohol had been drunk facilitated memory for stimuli in the auditory modality. Correlational analysis did not support the hypothesis that alcohol expectation's impact on sexual responsiveness is mediated directly through its influence on selective attention and memory processes. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
87.
Chronic obstructive pulmonary disease is on the increase. Therapeutic improvement is limited by the irreversible nature of lung tissue loss. Basic lung function tests can detect early loss of function, which may facilitate smoking cessation and other interventions likely to delay disease progression. The advent of inexpensive portable spirometers promises to permit such testing in the primary care physician's office. 相似文献
88.
GT Matioli 《Canadian Metallurgical Quarterly》1998,50(5):375-383
Considerable advances have been made in reconstructive venous surgery in the past two decades because of an increased recognition of venous disease and because of extensive experimental work. Meaningful evaluation of longterm patency of bypass grafts and midterm patency of stent placement are now available and seem appropriate to provide guidelines. Based on our experience and on the literature, this article highlights the techniques and the respective indications of surgical and endovascular treatment of large vein reconstructions. 相似文献
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90.