低剂量甲基汞在小鼠体内分布及其对细胞周期进程的影响

连续９０天饮用含甲基汞浓度为１／１０００ＬＤ５０、１／１００ＬＤ５０、１／５０ＬＤ５０和１／１０ＬＤ５０的自来水的雄性昆明小鼠，各脏器中总汞含量均高于对照组（Ｐ＜０．０５～０．００５），并且随着染毒剂量增加，脏器中总汞含量也随之增高。同时采用ＦＡＣＳｃａｎ流式细胞仪和“ＣｅｌｌＦＩＴ”软件分析脾细胞周期进程，发现除１／１０００ＬＤ５０剂量组外，其余各剂量组从Ｇｏ／Ｇ１时相进入Ｓ时相的脾细胞百分数均明显高于对照组（Ｐ＜０．０５），与染毒剂量呈明显正相关。表明连续经口摄入低剂量甲基汞小鼠脾细胞周期进程加快，细胞ＤＮＡ复制增强。     

细小病毒H－1对正常仓鼠肝细胞DNA周期动力学的影响

健康成年金黄仓鼠腹腔内接种ＰＶＨ－１（５×１０６ｐｆｕ），ＦＣＭ动态检测肝细胞ＤＮＡ周期动力学变化，结果显示：ＰＶＨ－１接种后处于Ｇ０＋Ｇ１期的肝细胞与对照组动物相比无显著差异。Ｓ期肝细胞在第３天显著高于对照组动物（Ｐ＜０．０５），且在第７天时仍呈上升趋势，第１４天到３０天趋于正常水平。Ｇ２＋Ｍ期肝细胞在ＰＶＨ－１接种后第３０天升高（Ｐ＜０．０５）。结果提示，动物在ＰＶＨ－１接种后第３到第７天是病毒在肝细胞中的复制高峰，并阻滞仓鼠处于Ｓ期肝细胞分裂进入Ｇ２＋Ｍ期，但是这种阻滞作用较短暂、并可逆，在ＰＶＨ－１接种后１４～３０天自然消失。     

Bifurcation properties of the two process model

Abstract Daan's two process model is known to be one of the most powerful models, covering various situations from free-running to sleep deprivation. In this study, bifurcation properties of the model dynamics as function of a gap, D , between the threshold processes are clarified using a circle map. As a function of D , we will show that the model has the different types of the mutual entrainment regions that are intervened by the tangent bifurcation. The variable behavior of human circadian rhythm is suggested to be systematically understood based on the bifurcation properties of the two process model.     

A neural network confirms that physical exercise reverses EEG changes in depressed rats

The use of an artificial neural network (ANN) system to differentiate the EEG power density spectra in depressed from normal rats was tried. The beneficial effects of chronic physical exercise in reducing the effects of stress and therefore depression was also to be tested in animals by the same method. In this study, rats were divided into 4 groups, subjected to (i) chronic stress (D group); (ii) chronic exercise by treadmill running (EO group); (iii) exercise with stress (ES group) and (iv) handling (C group). The prefrontal cortical EEG, EMG and EOG were recorded simultaneously on paper and the digitized EEG signals were also stored in the hard-disk of a PC-AT through an ADC. After filtering the digitize signals, the EEG power spectra were calculated by an FFT routine. Three successive 4 s artefact-free epochs were averaged. The REM and NREM sleep periods as well as the awake period signals were analyzed separately. The FFT values from each of the 3 states, in the 4 groups of animals were tested by an ANN with 30 first layer neurons and a 2nd layer of a majority-vote-taker. The ANN could distinguish the depressed from the normal rats' EEG very well in REM (99%) sleep, NREM (95%) sleep and awake (81%) states. In most of the cases it identified the exercised rats' EEG as normal.     

宫颈粘液过氧化物酶在月经周期中的变化规律

本文对29例月经周期正常妇女的宫颈粘液过氧化物酶进行了30个周期的研究。在月经周期不同时间测定宫颈粘液过氧化物酶(CMPx)活性及血清促黄体生成素(LH)、雌二醇(E_2)和孕酮(P)。结果表明:在排卵前三天酶活性明显下降,至排卵后一天开始上升。卵泡期,酶活性与E_2呈负相关(r=-0.67);黄体期,酶活性与P呈正相关(r=0.79)。本研究提示:1.CMPx在排卵周期具有特定的变化规律,其变化受体内激素水平影响,可作为预告排卵的指标。2.如简化测定方法,可为自然避孕提供新途径。     

Frequency and Output-Dependent Change in Conduction Over Slow Pathways in a Patient with Sustained Ventricular Tachycardia Unrelated to Coronary Artery Disease

In a patient with sustained ventricular tachycardia, we obtained two different paced QRS morphologies from a single pacing site. In one QRS morphology the stimulus to the QRS complex was long, 150 msec, and in the other it was 100 msec. At the paced cycle length of 600 msec and the stimulus output of 4 V, one QRS morphology with the stimulus to the onset of QRS activation (St-QRS) interval of 150 msec was observed. At the paced cycle length of 400 msec, the other QRS morphology with a St-QRS interval of 100 msec was observed alternatively with the former. At the paced cycle length of 353 msec or 316 msec, the latter with a shorter St-QRS interval was exclusively observed. When the stimulus output was increased from 4 to 10 V, keeping with the paced cycle length at 400 msec, the St-QRS interval was shortened from 100 to 80 msec. For the two QRS morphologies with two St-QRS intervals, two slowly conducting pathways would be responsible. The site of the block in the faster pathway must be located at the proximity of the pacing site and the conduction at a shorter paced cycle length would be explained by "supernormal conduction."     

Influence of sinus impulses on the parasystolic cycle length

Recently, it has been shown that in most clinical cases of parasystole, the parasystolic rhythm is not completely independent of the sinus rhythm. In this study, to disclose the mechanism of such "irregular" parasystole, parasystolic cycles with an intervening sinus QRS complex (XSX) were compared with their immediately adjacent pure parasystolic cycles without any intervening nonparasystolic QRS complexes (XX) in 10 cases of ventricular parasystole. In eight cases, the XSX interval was equal to or nearly equal to the adjacent pure XX interval; in one, the XSX interval was shorter than the XX interval; and in only one, the XSX interval was longer than the XX interval. In six cases in which the XSX interval was almost equal to the XX interval, calculated XSX intervals with a later intervening sinus QRS complex were obtained from the differences between the XSSX interval (ie, interectopic interval with two intervening sinus QRS complexes) and its adjacent XX interval. In five of the six cases, the calculated XSX interval was shorter than the XX interval. These observations suggest that in most cases of parasystole, early intervening sinus impulses do not change the parasystolic cycle, whereas late intervening sinus impulses shorten the parasystolic cycle. This suggests the presence of type I second-degree entrance block as the mechanism of "irregular" parasystole.     

Effects of estrus cycle on thermoregulatory responses during exercise in rats

Summary In female rats, rectal temperature (T _re), tail vasomotor response, oxygen uptake , and carbon dioxide production were measured in proestrus and estrus stages during treadmill running at two different speeds at an ambient temperature (T _a) of 24° C. Experiments were performed at 2.00–6.00 a.m., when the difference inT _re was greatest between the two stages;T _re at rest in the estrus stage was 0.54° C higher than in the proestrus stage. In a mild warm environment, thresholdT _re for a rise in tail skin temperature (T _tail) was also higher in the estrus stage than in the proestrus stage. In contrast, no difference was seen in the thresholdT _re and steady stateT _re at the end of exercise between proestrus and estrus stages. These values were higher at the higher work intensity. was also similar between the two stages, except in the second 5 min after the beginning of exercise, when was greater andT _re rose more steeply in the proestrus stage. These data indicate that deep body temperature during exercise is regulated at a certain level depending on the work intensity and is not influenced by the estrus cycle.This study was supported in part by a Grant-in Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (Grant No. 62480114)