头低位卧床(OHDT,-6°)对人尿儿茶酚胺分泌昼夜节律的影响

我们利用头低位(-6°)卧床作为模拟失重模型进行了6名男性志愿者卧床一周的实验,目的是分析卧床条件下人尿肾上腺素(E)、去甲肾上腺素(NE)昼夜节律特点以及心血管功能的反应。结果表明,卧床期E、NE 及E+NE 昼夜节律的水平和幅度显著降低;儿茶酚胺(CA)各成份的相位发生了内部解离,上述变化在卧床后5天内皆恢复正常。说明头低位卧床能影响人尿CA 的昼夜节律。     

Injections of muscimol into the median raphe nucleus produce hippocampal theta rhythm in the urethane anesthetized rat

It has previously been shown that serotonergic [5-hydroxytryptamine (5-HT)] neurons of the median raphe nucleus (MR) are critically involved in the control of the hippocampal electroencephalogram (EEG). Activation of MR 5-HT neurons desynchronizes the hippocampal EEG, whereas inhibition of MR 5-HT activity produces hippocampal theta rhythm. The MR contains an intrinsic population of gamma-aminobutyric acid (GABA) containing neurons that synapse on 5-HT cells of the MR. The present study examined the effects on the hippocampal EEG of injections of the GABA_A agonist muscimol hydrobromide into the MR. Low doses of muscimol (0.5 μg) produced hippocampal theta rhythm at a mean latency of 6.81 min and for a mean duration of 23.6 min. Higher doses (1.0 μg and 3.0 μg, respectively) produced theta at mean latencies of 2.24 min and 3.2 min and for mean durations of 31.84 min and 24.88 min. Injections of muscimol into regions adjacent to the MR generated theta at significantly longer latencies or were without effect. The present results indicate that MR injections of muscimol produce theta by inhibiting the activity of MR 5-HT neurons. It is concluded that MR GABAergic systems, via their influence on MR 5-HT cells, serve an important role in the control of the hippocampal EEG.     

家兔恒速静滴氟尿嘧啶时血药浓度的昼夜规律

对9只新西兰兔进行恒速持续静滴氟尿嘧啶24小时,其间每隔3小时取静脉血少许备用,经高效液相色谱法测定血样本中的氟尿嘧啶浓度,并对血药浓度系列作方差分析和Cosinor分析。实验结果显示在恒速持续静滴5-FU过程中血药浓度随时间变化,且平均血浆5-FU浓度符合昼夜节律变化规律。高峰估计值在13时,低谷估计值在1时。     

Mid- and Long–Term Similarity of Ventricular Response to Paroxysmal Atrial Fibrillation: Digoxin versus Placebo

The effects of digoxin on ventricular response during atrial fibrillation (API and consequent effects on arrhythmic symptoms have still not been fully explained. This study investigated whether the treatment by digoxin contributes to mid– and long–term stabilization of ventricular cycles in patients with paroxysmal AF. A population of 45 patients with paroxysmal AF underwent 24–hour ECG recordings during each arm of a randomized crossover trial comparing digoxin and placebo. This yielded 30 Holter recordings from 22 patients that contained AF episodes lasting in excess of 2 minutes and with acceptably low Holter noise. Each AF episode was divided into nonoverlapping segments of 30 seconds and the distribution of RR intervals in each segment was compared with the distribution of all other AF segments in the same recording using the Kolmogorov–Smimov test. The percentage of tests that revealed significant differences at levels of P ≤ 0.01, and P ≤ 0.001 were sorted according to the time between the segments compared. The comparisons of these results were performed between: (a) all recordings on placebo (n = 16) and all recordings on digoxin (n = 14), and (b) between recordings on placebo and on digoxin in 8 patients in whom paired analysis was possible. Adjacent AF segments (distance 0) differed significantly only in < 30% of both recordings on placebo and on digoxin. However, with increasing the distance between segments, the proportion of the significant differences between RR interval distributions increased more with placebo than with digoxin (P < 10⁻³⁰⁰, Chi-square test). Paired data revealed larger differences between placebo and digoxin with increasing distance between segments. Thus in patients with paroxysmal AF, digoxin leads to more reproducible patterns of ventricular cycles that may be better tolerated clinically.     

Melatonin Concentration in the Cerebral Vascular Sinuses of Sheep and Evidence for Its Episodic Release

Blood was collected from the cerebral sinuses and from the jugular vein of 5 ewes during both the day and night. Cerebral sinus samples were collected by means of a permanently indwelling cannula (roughly every 5 min) while jugular vein samples were collected by venipuncture (roughly every 10 min). In each of the 5 animals mean nighttime melatonin concentrations were greater at night than during the day. In 2 animals, cerebral sinus plasma melatonin concentrations were greater than in the jugular vein; in 2 animals the sinus and jugular plasma had similar melatonin levels; in 1 ewe jugular vein blood melatonin levels exceeded those in the cerebral sinus plasma. These differences among animals are presumably due to slight positional differences in the cerebral venous cannula placement. In several animals episodic release of melatonin was apparent. Whereas the episodes were most obvious in the cerebral venous blood at night, they were also apparent in 1 case in the jugular vein plasma and in 1 animal during the day. When episodes appeared they occurred about every 15-20 min.     

模拟失重（悬吊—30°）对大白鼠肾上腺髓质儿茶酚胺昼夜节律的影响

利用头低位(-30°)悬吊大白鼠8天的实验,对320只大白鼠观察对照日、悬吊第2、3、8天肾腺髓质儿茶酚胺(CA)含量的昼夜节律特征。实验数据用最小二乘法—余弦法数学分析。结果表明,悬吊第2天肾上腺素(E)节律水平显著下降,去甲肾上腺素(NE)的最大相位角移到夜间;悬吊第3天E 和NE 的最大相位角都移到夜间;悬吊第8天E 和NE 的水平都显著升高,最大相位角仍在夜间出现。以上结果说明模拟失重显著地影响了正常的大白鼠肾上腺髓质CA 的昼夜节律。     

Reappearance of Persistent Normal Sinus Rhythm in a Patient with the Sick Sinus Syndrome Following Cardiac Pacing for 10.5 Years

A patient with symptomatic sick sinus syndrome which manifested as a brady-tachy syndrome, was admitted to our institute in 1969. Following cardiac pacing for 10.5 years, the brady-tachy syndrome disappeared and normal sinus rhythm was restored. Her stable normal sinus rate has persisted up to the present, 2.5 years after termination of pacing.     

Retinal melatonin is not involved in corneal mitotic rhythms in the Japanese quail: Effects of formoguanamine hydrochloride and eye-lid suture

Abstract: Relation between retinal melatonin and corneal mitotic rhythms in the Japanese quail was investigated in experiments manipulating the ocular physiology by treatments with formoguanamine hydrochloride (FG) and eye-lid suture. In experiment 1, we investigated the effects of FG, which is known to induce photoreceptor degeneration, on retinal melatonin and corneal mitotic rhythms. FG-treatment completely abolished the retinal melatonin rhythms in both LD 12: 12 and constant darkness (DD), but the corneal mitotic rhythm was maintained with high mitotic rate in darkness under a LD cycle and subjective night under DD. The result suggests that 1) the photoreceptor cells in the retina are the site for melatonin production and/or for the oscillator which drives the circadian rhythm in retinal melatonin, and 2) melatonin is not involved in generation of the corneal mitotic rhythm. In experiment 2, we investigated the effects of eye-lid suture, which is known to induce eye enlargement and bulgy cornea, on the retinal melatonin and corneal mitotic rhythms. Eye-lid suture abolished the corneal mitotic rhythm in both LD and DD, with a high mitotic rate being maintained throughout 24 hr. But retinal melatonin maintained its rhythm with high levels in darkness under a LD cycle and in subjective night under DD. The result suggests that 1) bulgy cornea in the sutured eye was induced by the increase in mitotic rate in the light period, and 2) disappearance of the corneal mitotic rhythm does not have a relation to retinal melatonin. These results suggest that retinal melatonin is not involved in generation of the corneal mitotic rhythm and that there are two circadian clock systems in the eye.     

硝苯地平缓释片对高血压昼夜节律的作用

本文用24h动态血压监测方法观察了硝苯地平缓释片对高血压病人血压昼夜节律的作用，结果表明，与硝苯地平片相比，硝苯地平缓释片能选择性降低非构型高血压病人的夜间高血压，而对构型的夜间血压无显著影响。认为硝苯地平缓释片有改善高血压昼夜节律的作用。