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41.
An advanced analysis of the mechanical properties of bone should include information about the microarchitecture of cancellous bone in addition to its density. It has recently been shown that high-resolution quantitative computed tomography and magnetic resonance imaging have the potential to assess such information in a noninvasive way in patients. Both techniques, however, lack sufficient spatial resolution to image the individual trabeculae with true precision. In this work, a new parameter, Ridge number density (RND), is introduced. RND is a measure for the trabecular number, which can be extracted directly from high-resolution three-dimensional (3D) images of patients. We applied the RND technique to a test group of nine healthy, postmenopausal women measured repetitively with a high-resolution 3D peripheral quantitative computed tomography (3D-pQCT) system with 165 × 165 × 165 μm3 voxel size. Simultaneously with the RND determination, the trabecular bone density (TBD) was also assessed in the same volume of interest. The examination site was the distal radius. The intersubject variability of the measured test group was 10.5% for RND and 26.3% for TBD. The root mean square error between first and second examinations (midterm reproducibility) was 1.6% and 1.1%, respectively. RND is determined independently from TBD and pertains to the structure of the cancellous bone. As such, it might add crucial information in cases where bone mass or bone density measurements alone give ambigous results. 相似文献
42.
Nicoletta Desideri Isabella Sestili Maria Luisa Stein Stefano Manarini Giuseppe Dell'Elba Chiara Cerletti 《Archiv der Pharmazie》1997,330(4):100-106
6-[(4-Quinolinyl)oxy]hexanoic acids and the corresponding esters were designed and synthesized as inhibitors of the production of arachidonic acid metabolites. The inhibitory activities were assayed in vitro by evaluation of serum leukotriene B4 and thromboxane B2 production. While all 6-[(4-quinolinyl)oxy]hexanoic acids and their esters proved to be inactive, the N-alkyl-4-quinolones, obtained as by-products in their synthesis, were found to be a new class of leukotriene biosynthesis inhibitors. 相似文献
43.
The electrodeposition of Ag on Pt(100)-(1 × 1) in perchlorate electrolyte was studied by means of time-resolved in situ scanning tunnelling microscopy (STM) and cyclic voltammetry. One monolayer of Ag is deposited underpotentially (upd) ca. 500 mV positive of the Ag+/Ag equilibrium potential. Several millivolts positive of the equilibrium potential, a second well defined upd layer forms. Its growth was observed to proceed via island formation and coalescence. This process occurs in two separate stages that manifest themselves in voltammetric peaks as well as in the STM images. 相似文献
44.
When administered systemically, glucose attenuates deficits in memory produced by several classes of drugs, including cholinergic antagonists and opiate agonists. Glucose also enhances memory in aged rats, mice, and humans. In addition, glucose ameliorates age-related reductions in paradoxical sleep. Because deficits in paradoxical sleep are most marked in those individual aged rats that also have deficits in memory, treatments which improve one of these functions may similarly improve the other. The present experiments show that glucose attenuates deficits in paradoxical sleep and memory after atropine administration, with similar dose-response curves for both actions. In the first experiment, rats received saline, atropine (1 mg/kg), glucose (100 mg/kg) or combinations of atropine + glucose (10, 100, 250, and 500 mg/kg) 30 min before assessment on a spontaneous alternation task. In the second experiment, 3-h EEGs were assessed for spontaneous daytime sleep in rats administered saline, atropine (1 mg/kg), glucose (100 mg/kg) or combinations of atropine + glucose (10, 100 and 250 mg/kg). In both experiments, glucose significantly attenuated deficits at an optimal dose of 100 mg/kg. A third experiment assessed blood glucose levels after injections of atropine + glucose (100 mg/kg) and determined that blood glucose levels were similar to those produced by other treatments which enhance memory. These results are consistent with the view that paradoxical sleep and at least one test of memory are similarly influenced by atropine and glucose. 相似文献
45.
G. Dewasmes B. Bothorel A. Hoeft V. Candas 《European journal of applied physiology》1993,66(6):542-546
Summary Thermoregulatory sweating [total body (m
sw,b), chest (m
sw,c) and thigh (m
sw,t) sweating], body temperatures [oesophageal (T
oes) and mean skin temperature (T
sk)] and heart rate were investigated in five sleep-deprived subjects (kept awake for 27 h) while exercising on a cycle (45 min at approximately 50% maximal oxygen consumption) in moderate heat (T
air andT
wall at 35° C. Them
sw,c andm
sw,t were measured under local thermal clamp (T
sk,1), set at 35.5° C. After sleep deprivation, neither the levels of body temperatures (T
oes,T
sk) nor the levels ofm
sw, b,m
sw, c orm
sw, t differed from control at rest or during exercise steady state. During the transient phase of exercise (whenT
sk andT
sk,1 were unvarying), them
sw, c andm
sw, t changes were positively correlated with those ofT
oes. The slopes of them
sw, c versusT
oes, orm
sw, t versusT
oes relationships remained unchanged between control and sleep-loss experiments. Thus the slopes of the local sweating versusT
oes, relationships (m
sw, c andm
sw, t sweating data pooled which reached 1.05 (SEM 0.14) mg·cm–2·min–1°C–1 and 1.14 (SEM 0.18) mg·cm–2·min–1·°C–1 before and after sleep deprivation) respectively did not differ. However, in our experiment, sleep deprivation significantly increased theT
oes threshold for the onset of bothm
sw, c andm
sw, t (+0.3° C,P<0.001). From our investigations it would seem that the delayed core temperature for sweating onset in sleep-deprived humans, while exercising moderately in the heat, is likely to have been due to alterations occurring at the central level. 相似文献
46.
With the method of rapid gel sequencing, the complete nueleotide sequence of Fasciolopsis buski 5S rRNA has been determined: AAC GGG AUG AAG CUA GAC AUG UGG CGG CCU AGU UGG AGG UCG GAA CUC GGA AGU UAA GGA AUG UUG GGC CUG GUU AGU ACU GGU AUG GGU GAC CUU GGG AAU ACC GGG UGU UGC GUC CA_(OH) This have been compared with 553 species of other organisms 5S rRNA sequences previously published and fitted to a secondary structural model. 相似文献
47.
Flumazenil exerts intrinsic activity on sleep EEG and nocturnal hormone secretion in normal controls
A. Steiger J. Guldner C. J. Lauer C. Meschenmoser T. Pollmächer F. Holsboer 《Psychopharmacology》1994,113(3-4):334-338
The physiological function of benzodiazepine (BDZ) receptors includes regulation of sleep and neuroendocrine activity. Most of the pharmacological effects of BDZ are blocked by flumazenil. However, recent neurological and behavioral studies suggest that flumazenil has its own central intrinsic activity. This issue was addressed in a study of the sleep EEG and the nocturnal secretion of growth hormone and cortisol in ten normal male controls, who were given flumazenil either alone or in combination with the BDZ agonist midazolam, placebo and midazolam alone. Flumazenil prompted an increase in sleep onset latency, a decrease in slow wave sleep and an increase in wakefulness. Plasma cortisol concentrations after flumazenil administration were lower than after midazolam. Both flumazenil and midazolam decreased nocturnal growth hormone secretion. After simultaneous application of both BDZ receptor ligands the growth hormone blunting was amplified. Our study demonstrates that at the level of the sleep EEG and neuroendocrine activity flumazenil is capable of exerting both agonistic and inverse agonistic or antagonistic effects.Parts of this study were presented at the 69th Meeting of the Deutsche Physiologische Gesellschaft, Freiburg, 6–8 March, 1991 相似文献
48.
49.
失眠症患者睡眠质量的主观评估与多导睡眠图参数对比分析 总被引:3,自引:0,他引:3
目的 探讨失眠症患者对睡眠质量的主观评估,并通过对多导睡眠图(PSG)睡眠参数的定量分析,对失眠症患者的睡眠状况进行客观评估,进一步将二者进行对比分析.方法 对失眠症患者和健康人各100例运用匹兹堡睡眠质量指数问卷(PSQI)进行评定,并分别进行多导睡眠图的整夜睡眠描记,次日晨起后询问夜间睡眠情况.结果 失眠症组PSQI各成分得分及总分均高于对照组,差异有统计学意义(P<0.01).与对照组相比,失眠症组的睡眠潜伏期(min)延长(失眠症组43.69±11.54,对照组16.01±10.44)、总睡眠时间(min)减少(失眠症组314.65±91.89,对照组446.41±77.81)、睡眠效率降低(失眠症组64.51%±18.59%,对照组91.32%±3.58%)、快眼动睡眠时间(min)减少(失眠症组33.26±15.61,对照组93.21±21.63),差异有统计学意义(P<0.01).失眠症组对总睡眠时间的评估较PSG检测值显著减低、对睡眠潜伏期的评估较PSG检测值显著增高,自我评估与实际睡眠情况不一致.结论 失眠症患者睡眠质量较差.失眠症患者的PSG各睡眠参数有特征性的改变,利用PSG检查发现失眠症患者对失眠情况的主客观评估不一致,存在过高估价睡眠潜伏期和过低估价睡眠时间的倾向. 相似文献
50.
微乳对难溶性药物增溶机理的研究 总被引:17,自引:1,他引:16
目的:初步探讨微乳对难溶性药物的增溶机理.方法:经处方筛选及相图研究确定(BL-9/正丁醇3∶1)/油/水比例为9∶1∶40的微乳处方;以二氢吡啶类药物为模型药物,测定其在微乳、胶束和油相中的溶解度及油/水分配系数;根据化学结构,采用计算机软件计算药物的特性参数,并结合模型药物的特性分析微乳增溶难溶性药物的机理.结果:微乳对药物的增溶效果远大于油相和胶束,并随药物的脂溶性和空间结构的改变而变化.结论:微乳可用于增溶难溶性药物,且脂溶性越大,空间位阻越小,增溶效果越明显. 相似文献