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Dense multichannel recordings of scalp electroencephalogram (EEG) were obtained in the vicinity of primary somatosensory cortex, time-locked to repetitive vibrotactile stimulation of sites on the right index finger of a single human subject. Frequency-domain analysis of cross-trial averages revealed prominent 'driving' responses in the EEG at the frequency of stimulation, which under specific stimulus conditions displayed pronounced changes in amplitude and topographic organization over brief (4 s) durations of stimulus exposure. The changes were systematic and physiologically coherent, evolving toward driving-response topographies observed in the same subject in conjunction with periodic microstimulation of single mechanoreceptive afferents whose receptive fields occupied corresponding positions on the digit. This dynamic process was orderly and reproducible, and could be controlled by manipulating factors such as the amplitude, frequency, and temporal spacing of the stimuli. The results are tentatively interpreted in light of a previously proposed neurophysiological model of stimulus-driven response plasticity in mammalian somatosensory cortex. 相似文献
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Retrospective analysis of the Beijing family of Mycobacterium tuberculosis in preserved lung tissues
L Qian JD Van Embden AG Van Der Zanden EF Weltevreden H Duanmu JT Douglas 《Canadian Metallurgical Quarterly》1999,37(2):471-474
Direct repeat spoligotyping of 85 paraffin-embedded lung biopsies was used to investigated the occurrence around Beijing of the Beijing family of Mycobacterium tuberculosis. Samples ranged in time from 1956 to 1990. Hybridization patterns were found with 49 (58%) samples, and 45 (92%) produced typical Beijing family patterns extending over the 34-year period. 相似文献
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M Kassem L Ankersen EF Eriksen BF Clark SI Rattan 《Canadian Metallurgical Quarterly》1997,7(6):514-524
The proliferative capacity and cellular and biochemical characteristics of human trabecular bone osteoblasts were analysed throughout their replicative lifespan in vitro. Like several other cell types, human osteoblasts demonstrated a typical Hayflick phenomenon of cellular aging comprising a period of rapid proliferation until cumulative population doubling level (CPDL) 22 to 24, followed by a phase of slow growth and the final cessation of cell division at CPDL 32 to 34. Comparing young cells (less than 20% lifespan completed) and old cells (more than 90% lifespan completed) revealed a progressive increase in population doubling (PD) time, a decrease in attachment frequency, a decrease in the number of S-phase positive cells, a decrease in the rates of DNA, RNA and protein synthesis, an increase in the protein content per cell and an increased proportion of senescence-specific beta-galactosidase positive cells. While osteoblastic production of collagen type I decreased progressively during aging, alkaline phosphatase activity dropped rapidly after the first few passages and then remained constant during the rest of the proliferative lifespan, Significant morphological changes from thin and spindle-shaped early passage young cells to large, flattened and irregularly shaped late passage old cells full of intracellular debris were observed. In comparison, osteoblasts established from an osteoporotic bone sample showed a maximum CPDL of less than 5, had a longer PD time and exhibited abnormal senescent morphology. Thus, we have demonstrated for the first time that human osteoblasts, like several other diploid cell types, have a limited proliferative capacity in vitro and undergo aging and senescence as measured by various cellular and biochemical markers. In addition, preliminary studies show that cells from osteoporotic bone have a severely reduced proliferative capacity. This model of bone cell aging facilitates study of the molecular mechanisms of osteoblast senescence as well as factors related to osteoblast dysfunction in patients with osteoporosis. 相似文献
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A telephone survey was conducted of all the 71 Danish hospitals with the capacity to receive acutely ill medical patients. The purpose was to register treatment regimes used in acute asthma and exacerbations in chronic obstructive pulmonary disease (COPD). The house officer on duty was interviewed and questioned about the use of nebulizers, oxygen therapy, bronchodilators, steroids, theophyllins and monitoring of the patient's condition. The physician survey was supplemented by a smaller survey among emergency room nurses about nebulizing systems. The answers showed inadequate knowledge of nebulizing systems. There was a noticeable variation in the dosing of oxygen and in the dosing of bronchodilators and steroids. beta 2-agonist treatment by nebulizer differed with a factor 14 in dose. The majority of the physicians had no specific parameters for monitoring severity of disease. CONCLUSION: There is a need for improvement of the knowledge of nebulizing systems, including specific knowledge of the appropriate use of propellant gasflow and time of nebulizing for optimum performance of the used nebulizer. Divergent answers from the nurses and the physicians show the need for interdisciplinary instruction. The noticeable variation in treatment in this Danish survey displays a need for quality control in terms of concise guidelines for medical therapy in acute exacerbations of asthma and COPD and guidelines for monitoring of the response to the treatment. A suggestion for a treatment regime is proposed. 相似文献
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Disturbed eating behaviour and disturbed body experience are important features for the differential diagnosis of eating disorders from other disorders. Eating disorders occur mainly in young females. The one-year prevalence of anorexia nervosa is 0.4% and that of bulimia nervosa 1.5% among young females. To motivate patients for treatment it is important to discuss physical problems and the high risk of severe complications with them. It is difficult to motivate patients for treatment, because anorexia nervosa patients deny their illness and bulimia nervosa patients are ashamed and hide their disturbed eating behaviour. The treatment of anorexia nervosa consists of two partly overlapping phases: normalizing the eating pattern to improve weight restoration and psychotherapeutic treatment for underlying emotional problems. Family therapy is effective for patients younger than 18 years with a short duration of illness. Cognitive behaviour therapy is the most important form of treatment for bulimia nervosa. 相似文献
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EF Hoffenberg P Kozlowski TA Salerno R Deslauriers 《Canadian Metallurgical Quarterly》1996,62(1):135-143
Methylguanidine, guanidinoacetic acid and guanidinosuccinic acid are endogenous substances in body tissues. Extremely high levels of these substances are known to be related to the pathogenesis of epilepsy and renal failure such as uremia. In this study it was demonstrated that methylguanidine, guanidinoacetic acid and guanidinosuccinic acid, and arginine generate hydroxyl radicals in aqueous solution. These findings suggest that a high level of guanidino compounds accumulating near or within cells such as neurons (in an epileptogenic focus) or nephrons (in uremic patients) may cause free radical damage leading to these clinical disorders. Arginine may have a similar role in the pathogenesis of hyperarginemia. 相似文献