Quantitative Characterization of Epicardial Wave Fronts During Regional Ischemia and Elevated Extracellular Potassium Ion Concentration

This study applied zero-delay wave number spectral estimation as a means of quantifying the changes in activation and recovery sequences of propagating plane waves on the epicardial surface of in situ porcine hearts during regional hyperkalemia and ischemia. Unipolar electrograms (104) were recorded from the left ventricular surface of nine hearts using a plaque electrode array with 1 mm spatial sampling intervals. The objectives were (1) to define a set of parameters capable of quantifying the spatial and temporal changes in measured extracellular potentials associated with localized ischemia prior to the onset of conduction block; (2) to elevate regional levels of extracellular potassium ion concentration and quantify potential changes due to this known physiologic manipulation; and (3) to use quantitative parameters to make statistical comparisons in order to distinguish wave fronts during normal, ischemic and hyperkalemic conditions. Results showed that the parameters of wave number and average temporal frequency and the associated power, as determined from the wave number spectrum, provided statistically significant (p < 0.05) quantification of changes in wave front features during normal and ischemic or hyperkalemic conditions. The results were consistent with results obtained from conventional time–space domain methods like isochronal mapping and electrograms, with the advantage of a quantitative result enabling simple comparisons and trend analysis for large numbers of heart beats. © 1998 Biomedical Engineering Society. PAC98: 8759Wc, 8722Fy, 8780+s     

Regional differentiation of sympathetic activity during hypothalamic heating and cooling in anesthetized rabbits

Summary In anesthetized rabbits immobilized with succinyl choline, the discharges of sympathetic efferents supplying cutaneous and visceral regions were simultaneously recorded. The effects of thermal stimulation of the hypothalamic region were tested on the basis of the integrated discharges. During hypothalamic heating cutaneous sympathetic activity decreased, corresponding to increased ear blood flow, while visceral sympathetic activity increased. During hypothalamic cooling there was, on the average, no significant change of regional sympathetic activity. However, in single experimental periods an increase of cutaneous and a decrease of visceral sympathetic activity was found.The observed responses of regional sympathetic activity were compared with findings about regional cutaneous and intestinal blood flow under the same thermal stimulus and further with corresponding former investigations on regional blood flow and regional sympathetic activity during spinal thermal stimulation. It is suggested by this comparison that regional differentiation of sympathetic activity represents a specific thermoregulatory response of the vasomotor system mediated by the hypothalamic thermoregulatory center.     

光化学诱导的血栓形成性脑缺血及其代谢改变

本文用光化学法激发大鼠局部脑血栓形成，以组织病理学、局部脑血流量、皮层水含量、三磷酸腺苷、二磷酸腺苷，一磷酸腺苷、能量负荷、肌酸及乳酸为指标，探讨局部脑血栓形成后５天ｒＣＢＦ明显增高的可能机理。结果表明，血栓形成后局部脑组织ＡＴＰ水平进行性减少（Ｐ＜０．０１）、ＡＤＰ／ＡＴＰ及ＡＭＰ／ＡＴＰ比值明显升高（Ｐ均＜０．０１），ＬＡ及脑水含量显著增加（Ｐ＜０．０１）。这些因素既是能量衰竭、无氧酵解的结果     

左心室局部心肌梗塞时的组分式模型及计算机仿真

为研究左心室局部心肌梗塞时心肌各部分的能量供需状况及心脏辅助装置对改善心肌能量供给的影响，我们建立了一个由左心室正常区域心肌和梗塞区域心肌两部分组成的组分式模型，我们的模型以Ｓｕｎａｇａｗａ的模型为基础，并在此基础上加以扩展，与Ｓｕｎａｇａｗａ的模型相比，我们的模型允许梗塞区域心肌的收缩性在一定范围内变化，从而可以模拟各种不同范围和不同程度的梗塞情况。用建立好的左心室组分式模型取代我们原有的狗的心     

海人藻酸注射大鼠纹状体边缘区后c-fos原癌基因蛋白在脑内的表达

为研究纹状体边缘区与脑内其他和学习记忆等功能有关结构间的关系，将海人藻酸注射于大鼠纹状体边缘区，观察c-fos原癌基因蛋白（FOS）在脑内的表达。海人藻酸注射4h后，脑内有少量FOS表达．海人藻酸注射6h后，脑内FOS表达增至最高峰．在嗅脑、基底前脑、海马、杏仁核，大脑皮质以及丘脑的中线核和网状核中有大量密集的FOS表达。另外，在纹状体、Meynert基底核、脚内核、丘脑底核、黑质外侧都及其背外侧区可见较多FOS表达．在视前区、丘脑下部外侧区、外侧缰核和中脑中央灰质等部位可见少量FOS表达。海人藻酸注射纹状体边缘区后18～24h，上述各部位的阳住表达逐渐减少，齿状回的表达消失．海人藻酸注射后48h，脑内各部位的FOS阳性反应均消失。本研究结果提示：纹状体边缘区和脑内与学习记忆功能有关的结构间有密切的功能联系，但边缘区在脑学习记忆功能中的地位以及与脑中其他学习记忆有关结构间的关系尚待进一步研究．     

三氧化二砷持续区域肝动脉灌注治疗肝癌的临床研究

目的探讨三氧化二砷（As2O3）注射液单药连续区域动脉灌注化疗原发性肝癌的临床疗效。方法55例手术不能切除的非晚期原发性肝癌患者,随机分为两组：（1）As2O3治疗组26例：患者采用经股动脉肝动脉碘油栓塞后埋置皮下化疗泵,予以连续区域灌注As2O3化疗,20mg/d,每天1次,共7d,间隔4周重复,共5疗程。（2）对照组29例：采用经股动脉肝动脉栓塞化疗（TACE）,2次TACE15例,3次TACE14例。结果As2O3治疗组总有效率为34.6%（9/26）、肿瘤复发率为15.4%（4/26）、1年生存率为80.7%（21/26）;TACE组分别是31.0%（9/29）、37.9%（11/29）、51.7%（15/29）。统计学分析表明,两组的总有效率差异无统计学意义,P〉0.05;肿瘤复发率和1年生存率差异有统计学意义,P〈0.05。As2O3治疗组较对照组不良反应轻微,未见不可逆不良反应。结论经股动脉肝动脉碘油栓塞后埋置皮下化疗泵予以连续区域灌注As2O3化疗用于治疗原发性肝癌不良反应轻微、疗效确切,具有一定的临床应用前景。     

Premature targeting of a cell division protein to midcell allows dissection of divisome assembly in Escherichia coli

Cell division in Escherichia coli requires the recruitment of at least 10 essential proteins to the bacterial midcell. Recruitment of these proteins follows a largely linear dependency pathway in which depletion of one cell division protein leads to the absence from the division site of "downstream" proteins in the pathway. Analysis of events that underlie this pathway is complicated by the fact that a protein's ability to recruit "downstream" proteins is dependent on its own recruitment by "upstream" proteins. Hence, one cannot separate the individual contributions of various upstream proteins to any specific recruitment step. Here we present a method--premature targeting--for bypassing the normal localization requirements of a cell division protein and apply it to FtsQ, a protein recruited midway through the pathway. We fused FtsQ to the FtsZ-binding protein ZapA such that FtsQ was targeted to FtsZ rings independently of proteins FtsA and FtsK, which are normally required for FtsQ localization. Analysis of the resulting ZapA-FtsQ fusion suggests that FtsQ associates with a large complex of cell division proteins and that premature targeting of FtsQ can restore localization of this complex under conditions in which neither FtsQ nor the associated proteins would normally be localized.     

Patterns of differentiation in various sympathetic efferents induced by hypoxic and by central thermal stimulation in decerebrated rabbits

Summary The patterns of regional changes of sympathetic efferent activity evoked by thermal stimulation of the spinal cord and by arterial and primary tissue hypoxia were investigated in decerebrated, anesthetized and immobilized rabbits. Decerebration was performed either at the mid- or infracollicular level. The responses of the decerebrated rabbits evoked by spinal thermal stimulation were the same as those of intact rabbits, i.e., splanchnic and cardiac sympathetic activity increased and cutaneous sympathetic activity decreased during warming, while the reverse response was elicited by cooling. It is concluded that the typical thermoregulatory response pattern of the sympathetic nervous system can be produced also after the loss of hypothalamic integration, i.e., by integrative mechanisms in the lower brain stem and the spinal cord. In contrast, the responses of decerebrated rabbits to arterial and primary tissue hypoxia differed from those of intact rabbits in that they consisted in an overall activation in all investigated sympathetic branches. It is confirmed by this result that suprabulbar integration is essential for the generation of the inhibitory components in the differential sympathetic responses to hypoxia, which typically consist in cutaneous and cardiac sympathetic inhibition with splanchnic activation during arterial hypoxia and in cutaneous sympathetic inhibition with cardiac and splanchnic sympathetic activation during primary tissue hypoxia.     

Normal aging decreases regional homogeneity of the motor areas in the resting state

Our knowledge about aging modulation of the central motor system remains sparse and contradictory. In the current study, we used functional MRI (fMRI) to study the aging influence on regional homogeneity of the motor-related brain areas in the resting state. We found that regional homogeneity in extensive motor regions, like the cingulate motor area, cerebellum, primary motor cortex, premotor area, supplementary motor area, thalamus, globus pallidus and putamen was significantly decreased in aged subjects. Our study indicates that normal aging process may disrupt the function of motor areas in the resting state, which may contribute to the declined motor ability in aged population.     

Somite cell cycle analysis using somite-staging to measure intrinsic developmental time.

Somite stages were employed as units of intrinsic developmental time to measure cell doubling rate and other cell cycle parameters of chick forelimb level somites. Somite cell nuclei doubled over an interval corresponding to approximately 7+ somite stages (7+ ss; approximately 11 hr) and approximately 24 new primary myotome cells are born per somite stage ( approximately 16/hr). FACS analysis of DNA content in dissociated paraxial mesoderm cells indicated that slightly more than half are in G1/G0 phase of the cell cycle and that the average combined length of the S phase and G2 phase intervals is approximately 3 ss ( approximately 4.5 hr). A wavefront of increased mitotic nuclei per segment coincident with somite budding potentially reflects a surge in the number of cells entering S phase 3 ss earlier as each PSM segment becomes unresponsive to FGF signaling as it passes through the determination front.