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111.
A persistent problem in stress research has been that some individuals may show impairment, while others show improvement or no change in performance under stress. Attempts to relate this variance in performance to general anxiety or other personality variables have generally not been too successful. Based upon responses to a fear of shock item in an attitude questionnaire, Ss were classified as “high fear of shock” or “low fear of shock” types. Half of the Ss in each group were assigned a perceptual-motor task; the others were assigned a cognitive-interference task. After training, all Ss were informed that they would be required to maintain their training performance levels in a situation in which they would be shocked if performance declined. Performance and heart rate measures taken during training were compared with the same measures taken under the threat-of-shock conditions. Results indicate significant differences between groups in both performance and physiological activity with “high fear of shock”Ss exhibiting relatively greater performance impairment and increased heart rate. 相似文献
112.
J. Bernheim E. Podjarny A. Pomeranz M. Rathaus 《Journal of molecular medicine (Berlin, Germany)》1988,66(20):1024-1028
Summary It is generally accepted that the main action of glomerular prostanoids (GPs) on glomerular filtration rate (GFR) is to modulate the activity of different vasoconstrictors, specially in states of renal hypoperfusion. However it was also suggested that GPs may directly affect GFR. The present study was focused on this last hypothesis, in different experimental models, in rats.In adriamycin induced acute renal failure, the transient decrease of GFR is associated with higher levels of thromboxane B2. Later on, when GFR returns to normal, vasodilator prostaglandins synthesis was also increased.In captopril induced renal failure in Na depleted rats (where GPs synthesis remained normal), stimulation of PGE2 and PGI2 production by K and NaCl was associated with a significant improvement of GFR. Furthermore, the increase in GFR induce by NaCl was prevented by inhibition of prostaglandin synthesis.Infusion of atrial natriuretic peptide in euvolemic rats induce a marked elevation both of GFR and PGE2 synthesis. It was abolished by previous administration of prostaglandin synthesis inhibitor.In conclusion, glomerular prostanoids may influence GFR, either directly, or as mediator or modulator of other vasoactive hormones.Abbreviations GPs
glomerular prostanoids
- PG
prostaglandin
- TX
thromboxane
- ANP
atrial natriuretic peptide
- GFR
glomerular filtration rate
- PE
polyethylene
Nachtrag zu den Hauptreferaten des 19. Kongresses der Gesellschaft für Nephrologie in Göttingen (Klin Wochenschr 66/18) 相似文献
113.
Yuan B. Peng Qing Lin W. D. Willis 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1997,114(3):561-570
The effects of a protein kinase C (PKC) activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), on the activity and periaqueductal gray (PAG)-induced inhibition of rat dorsal horn
neurons of the lumbar spinal cord were tested. A microdialysis fiber was placed through the dorsal horn for the purpose of
local application of pharmacological agents. Extracellular single-unit recordings from dorsal horn neurons were made near
the microdialysis fiber. TPA was tested on nociceptive dorsal horn cells. There was a significant increase in the background
activity and responses to ”brush”, with no changes in responses to pressure and pinch stimuli. TPA also significantly blocked
the PAG-induced inhibition of responses to brush, press, and pinch. These effects were eliminated by coadministration of the
PKC inhibitor NPC-15437. The solvent, which contained dimethyl sulfoxide, was also tested for its effect on the responses
to peripheral mechanical stimuli and PAG-induced inhibition of the dorsal horn neurons. There were no significant changes.
This experiment suggests that activation of the PKC second messenger system might increase the activity of dorsal horn neurons
and their responses to peripheral stimuli; in addition, the phorbol ester attenuated the PAG-induced descending inhibition
of the dorsal horn neuron activity.
Received: 15 May 1996 / Accepted: 14 November 1996 相似文献
114.
为了研究不同心电序列转换方式及不同谱估计方法对心率变异性(HRV)信号谱分析结果的影响,本文对积分脉冲频率调制(IPFM)模型及修正积分脉冲频率调制(MIPFM)模型在输入不同振幅与频率的正弦信号时所产生的随机点过程,用两种心电序列转换方法进行转换得到仿真HRV信导;然后,采用周期图与自回归(AR)谱估计方法计算这种厉真HRV信号的功率谱。研究结果表明:①对于MIPFM模型产生的随机点过程,同一心电序列转换方法所得出的仿真HRV信号的AR谱与周期图的谱峰功率估计基本一致;而对IPFM模型则不完全一致。②MIPFM模型仿真实验表明,对实际HRV信号谱分析,使用低,高频谱峰功率比(RF)作为反映心脏自主神经张力平衡的指标时,除心电序列传换及谱估计方法可能造成的误差外,当低频谱峰靠近极低频谱峰时,根据RF值解释生理实验结果会有校大误差。③座分析实际HRV信号的工作中,不同心电序列转换方式产生的伪谐波对HRV谱分析结果的影响不大。 相似文献
115.
Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II. 相似文献
116.
117.
118.
Rapid eye movements (REMs), EEG alpha, and tonic heart rate (HR) were measured during 6 types of cognitive tasks—imagining a liked person, suppressing thoughts of the person, searching one's mind for alternative solutions, arithmetic involving little concentration, problems involving high concentration, and choosing a preferred activity. The latter 3 required verbalization, the former 3 did not. Only suppression and search did not differ significantly from each other on at least one physiological variable. Imagining, suppression, and search yielded few REMs, high alpha, and low HR. High concentration yielded many REMs, low alpha, and high HR. Choice yielded many REMs, low alpha, and intermediate HR. Low concentration yielded few REMs, low alpha, and high HR. Suppression produced somewhat less alpha than imagining but did not differ significantly in REMs. 相似文献
119.
Improvement in Doppler ultrasound human foetal heart rate records by signal correlation 总被引:1,自引:0,他引:1
D. L. Tuck 《Medical & biological engineering & computing》1982,20(3):357-360
An improved method for the determination of foetal heart rate from Doppler ultrasound signals is described and evaluated.
It determines the most probable pulse interval from the recurrence times of multiple echoes generated by each cardiac pulse.
The method, when optimised, is shown to offer an improvement over current systems, especially in reduced signal loss. 相似文献
120.
In this study, the relationship between physiological arousal, as indexed by heart rate variability, was examined in boys with fragile X syndrome (FXS) and typically developing boys matched on chronological age. In addition, the relationship of heart activity to clinical and molecular factors in the group of boys with FXS was examined. Results suggest that boys with FXS have higher levels of heart activity during the passive phases, as reflected in shorter heart periods. This high level of heart activity appears to be due to increased sympathetic activity and reduced parasympathetic activity. Boys with FXS did not display the expected patterns of heart activity in response to phases of increasing challenge, and sympathetic and parasympathetic systems did not appear coordinated in these boys with FXS. Clinical factors may be related to neural regulation of heart activity while molecular factors do not appear to be. 相似文献