Rare-male mating advantage: An artifact caused by differential storage conditions?

Virgin males (or females) of some species ofDrosophila, when stored singly, are known to be superior in mating to males (or females) stored in groups. This may create a spurious rare-male effect on some occasions. When no account is taken of this storage effect in an experimental setup designed to show rare-male mating advantage, bias in favor of a raremale effect may result. It is shown that merely by storing the rare males singly and the common males in groups, with males not differing in any other respect, a very strong spurious rare-male effect can be produced. Similarly, it is shown that a spurious rare-female effect is possible too. It is proposed that the very strong rare-male effect for pepperment scent as found by Dal Molin [(1979).Am. Nat. 113:951–954] is merely a result of such a bias. The relevance for natural populations of the mating advantage associated with the single housing condition is discussed. In the experiments designed to show a spurious rare-male effect, mating chambers of two different sizes were used. It is shown that sexual selection is more severe in the small chambers, for both males and females.     

兔眼前房压强在体连续测量方法的研究

为了解眼睛房水压强变化规律,进一步建立闭角型青光眼模型和对疾病的治疗及视功能康复提供参考,探讨一种在体连续测量正常兔眼前房压强的方法。将正常成年新西兰白兔麻醉后,先用静脉留置针(20G)自角膜缘外行前房穿刺术,然后通过套管将Millar导管植入兔眼的前房,兔眼的前房压强信号经过Powerlab系统进行滤波、放大和模数转换后,通过Chart软件进行实时显示。结果表明:用该方法测得的正常兔眼24 h前房压强的变化范围为(1.31±0.21—2.74±0.83)KPa。前房压强的分布凌晨较低(0~5点),然后逐渐升高(5~10点),到中午或下午(11—17点)时达到最高峰,晚上又逐渐下降(18~23点)。结果证明本实验在体连续测量兔眼前房压强的方法是可行的。     

The hippocampus and neurotransplantation

The present article is a review of our own results from histological and electron microscopic studies of hippocampal neurotransplants with different levels of integration with recipient brains. A model providing complete isolation from the brain was obtained using transplants developing in the anterior chamber of the eye. The growth, development, and cytological composition of transplanted tissue was found to depend on factors such as the age of the donor embryo tissue, the genetic compatibility between the donor and recipient, and the level of integration with the brain. Ultrastructural analysis of intraocular and intracortical transplants showed that overall, nerve and glial cells have the characteristics of highly differentiated, mature elements; the numerical density and structures of synaptic contacts were similar to those in normal conditions. However, transplanted tissues contained morphological features providing evidence of continuing growth of several nerve processes and increases in non-synaptic and transport-metabolic intercellular interactions. The ultrastructural deviations observed here are regarded as the manifestations of compensatory-adaptive changes during the development of tissues in conditions deficient in natural afferent synaptic influences. It is also demonstrated that the axons of transplanted neurons lacking adequate cellular targets can establish functional synaptic contacts with neuronal elements in the recipient brain which are not their normal targets.Translated from Zhurnal Vysshei Nervnoi Deyatelnosti, Vol. 54, No. 2, pp. 149–162, March–April, 2004.     

Transwell侵袭小室技术的改良及其在人骨髓间充质干细胞诱导分化中的应用

目的：分离、培养和鉴定人骨髓间充质干细胞（Mesenchymal stem cells，MSCs），应用改良的Transwell侵袭小室技术，探讨血管内皮生长因子（VEGF）及内皮细胞条件诱导液对其体外诱导分化中的作用。方法：采用Percoll（1．073g／ml）分离液分离骨髓单个核细胞，体外培养MSCs，流式细胞术分析鉴定MSCs的纯度，Transwell侵袭小室技术结合LSCM，实时监测MSCs在Matrigel与VEGF／内皮细胞条件诱导液构成的内皮细胞生长微环境中的运动迁移情况。结果：经Percoll分离、体外培养扩增的MSCs，细胞纯度可达95％左右；VEGF组迁移的深度虽高于对照组（P〈0．05），但迁移至聚碳酸脂膜下的细胞与对照组相比，并无统计学意义（P〉0．05）。内皮细胞条件诱导液促进MSCs的迁移，在Matrigel内迁移的深度及迁移至聚碳酸脂膜下的细胞均明显多于对照组（P〈0．05）。结论：共聚焦激光扫描显微术与Transwell侵袭小室技术的结合，能够从时间和空间上对后者进行观察，使该实验得到改良；利用内皮细胞条件诱导液与Matrigel模拟体外内皮细胞生长的微环境，并从空间上观测了MSCs穿越人工基底膜的情况，为MSCs向内皮细胞体外诱导开辟了新的思路。     

A method for simultaneous recording of electrical activities and spectrophotometric signals from brain slice preparations in vitro

Organ spectrophotometry has been applied to analyze cytochrome redox changes in brain slice preparations. An interface-chamber method for maintaining metabolism of brain slice tissues was devised to reduce noise on recording traces of spectrophotometric signals, and then used for continuous monitoring and simultaneous recording of electrical and optical signals from brain slices. With this method, the noise level during the recording of redox states of cytochromes was decreased to 0.0004 A unit.     

一种平板流动腔重力灌流系统的力学分析

本文分析了一种采用重力灌流的平板流动腔灌流系统，并根据实验结果确定出相应的阻力系数，获得平板流动腔剪应力、雷诺数以及入口长度与流体重力灌流高度的关系。     

The Effects of Magnetic Resonance Imaging on Implantable Pulse Generators

The effects of magnetic resonance imaging were assessed on four dual chamber and two single chamber pulse generators. The tests were performed with a resistive, water-cooled magnet operating at 0.15 T. The 6.4-MHz radiofrequency (RF) field was operated at a maximum power of 1,000 watts with a period adjusted from 130 to 500 ms. Reed switch closure occurred in all six pulse generators tested when placed near the entrance of the magnetic resonance imaging scanner, and the generators reverted to asynchronous operation unless programmed to the "magnet off" mode. None of the pulse generators exhibited any alterations in programmed parameters or in the ability to be reprogrammed after RF pulsing. When the RF field was turned on, there was no change in the asynchronous paced cycle length in four pulse generators; however, during RF scanning there was rapid cardiac stimulation at the RF pulse period in one single chamber and one dual chamber pulse generator.     

流动腔系统的研究进展

流动腔装置广泛用于体外研究流动环境中的细胞力学行为,是研究细胞粘附及应力与生长关系特性的主要手段之一。作者从流动腔系统的分类、数值模拟(包括后向台阶的流动腔数值模拟)、系统构建等三个方面对流动腔系统作一综述。     

Lack of Influence of Atrioventricular Delay on Stroke Volume at Rest in Patients with Complete Atrioventricular Block and Dual Chamber Pacing

Dual chamber pacing (DDD) maintains atrioventricular (AV) sequence; AV delay programmability modifies the relationship between atrial and ventricular contraction. To evaluate the hemodynamic effects of such a modification, ten patients with a DDD unit for complete AV block were studied by time-motion (M-mode) and Doppler echocardiography during inhibited ventricular pacing (VVI), atrial-triggered ventricular pacing (VDD) and atrioventricular sequential pacing (DVI) at different AV delay (90, 140, 190, 240 msec). A significant improvement in stroke volume (SV) (15%-20%, P less than 0.05) was seen during DDD versus VVI pacing; no changes, however, were observed in the same patient with different AV delay or during DVI versus VDD pacing. These data suggest that programming of AV delay does not affect systolic performance at rest; longer diastolic filling times recorded during DDD pacing with "short" AV delay (90-140 msec) do not seem to be a hemodynamically relevant epi-phenomenon of PM programming.