Transplantation of central nervous tissue

Studies of post-lesional reorganization of central nervous connections have shown that central nerve fibers respond to nearby denervation by sprouting and formation of new terminals. The connections in the central nervous system (CNS) are accordingly much more plastic than was thought for a long time. This has revived the interest in transplantation of central nervous tissue. In this study we present some historical data on CNS transplantation supplemented by recent results obtained in our laboratory. Pieces of hippocampal tissue from embryonic or early postnatal rats were transplanted to different parts of the brain of littermates or adult rats. About two-thirds of the transplants were recovered after survival times ranging from 4 d to 2 years, and their cytological organization and intrinsic connections were monitored by cell and fiber stains and histochemical methods (AChE staining and Timm sulphide silver method). Comparison with both a normal and a lesioned control material revealed that in most transplants the tissue had developed as it does when left in situ in the donor brain, but deprived of its major afferent connections. In several instances we found evidence of a major exchange of connections between the transplants and host brains. The conditions needed for this to occur appeared to involve growth stimulation of host brain fibers by transection (host to transplant) and denervation of host neuropil (transplant to host). In cases where these conditions are met, the use of transplants may have future implications in attempts to repair lesions in the central nervous systems.     

Characterization of ramified microglia in tissue culture: pinocytosis and motility

Functional properties of ramified microglia were investigated in primary cultures of rat cerebral cortical cells. These microglia could be readily identified in both fixed and living cultures through previously established features. Based on their destruction by 5 mM L-leucine methyl ester, a high level of intrinsic endocytotic activity was established. When cultures were incubated with fluorescent latex beads to assess phagocytosis, little or no such activity was exhibited by ramified cells. However, when cultures were incubated with dyes or other soluble tracer compounds, these cells always exhibited labeling. This labeling was selective for ramified microglia in the cultures and was demonstrated using a variety of compounds, including trypan blue, lucifer yellow, horseradish peroxidase (HRP), and India ink. Intracellular label could be observed in vesicular structures; this localization corresponded to an active cellular process. Also, cellular labeling was inhibited by the presence of colchicine. These features supported the inference that the labeling was attributable to pinocytosis, and this process appeared to account for the vast majority of endocytotic activity in the ramified microglia. Possible physiological significance of this pinocytotic activity was indicated by the accumulation of various neurotransmitters/modulators: gamma-aminobutyric acid and vasoactive intestinal polypeptide (VIP). Ramified cells in these cultures have been previously noted to exhibit a constant and rapid pattern of motility, which was consistently observed here through time-lapse video recording; pinocytosis and rapid motility were shown to concur in individual cells. Based on their high intrinsic pinocytotic activity and pattern of cellular motility, the ramified microglia specifically are suggested to serve a constitutive function of fluid cleansing within the interstitial spaces of brain tissue.     

Distribution of calcium-activated neutral protease inhibitor in the central nervous system of the rat.

The ubiquitous existence of calcium-activated neutral protease (CANP, calpain), an enzyme whose activity is regulated by calcium ions and a specific endogenous CANP inhibitor (calpastatin), is well known. Although there has been much investigation concerning the distribution and role of CANP, investigations of the distribution of the CANP inhibitor using immunohistochemical techniques are rare. We made antiserum against a 40K fragment of cDNA corresponding to two C-terminal repeats of rat liver CANP inhibitor expressed in Escherichia coli. Using this antiserum, we examined the distribution of CANP inhibitor in the rat central nervous system by the ABC technique and compared it with the distribution of CANP. Neurons and glias were stained, with the cytosol stained diffusely and the cell membranes stained clearly and strongly. Axons and myelin were stained faintly, but nuclei and vessels were not stained. The distribution of CANP inhibitor was thus found to be similar to that of CANP.     

清热中药对大鼠下丘脑组织中AVP含量的影响

选用典型的清热中药黄芩、银花、连翘组成清热方,从体温调节中枢神经介质方面来探讨清热类中药的解热作用机制。实验表明影响体温调节中枢解热介质AVP代谢,增加其含量,从而抑制体温调定点上移是清热中药作用机理之一。     

大鼠翼腭神经节SIF细胞的年龄变化

用醛诱发荧光法观察了不同年龄组大鼠翼腭神经节小强荧光（ＳＩＦ）细胞的数量，发现出生１天时ＳＩＦ细胞数量最少，１周内急剧增加，１－２周数量无明显，至４周数量继续增加，成年时数量最多，老年时比成年时无明显的数量变化，表明大鼠翼腭神经节ＳＩＦ细胞的数量随年龄增长而增加。     

荞麦花粉抗贫血作用的实验研究

用荞麦花粉的水提取液进行了抗大白鼠缺铁性贫血的研究，结果表明：荞麦花粉具有和硫酸亚铁相似的抗缺铁性贫血作用．饮用荞麦花粉提取液３５ｄ的大白鼠，生长发育良好，主要脏器未见损害．该研究为荞麦花粉的开发利用提供了实验依据．     

Estrogenic Induction of NADPH- Diaphorase Activity in the Preoptic Neurons Containing Estrogen Receptor Immunoreactivity in the Female Rat

Nitric oxide and estrogen have been shown to play a critical role in the control of female reproductive function. In order to determine an anatomical relationship between nitric oxide generating neurons and estrogen target neurons, NADPH-diaphorase histochemistry was combined with estrogen receptor immunohistochemistry in the female medial preoptic area. While only a few weakly stained neurons for NADPH-diaphorase were found in ovariectomized control rats, a drastic increase in NADPH-diaphorase activity was observed in the medial preoptic nucleus of estradiol-treated ovariectomized animals. The total number of NADPH-diaphorase neurons in the estradiol-treated group increased three-fold relative to controls, and more than 80% of those neurons contained estrogen receptor-immunoreactivity in their nuclei. Since neuronal NADPH-diaphorase is nitric oxide synthase, the present result suggests that nitric oxide synthase activity can be positively regulated by estradiol in neurons containing estrogen receptor in the female medial preoptic nucleus.     

Development and experimental in vivo validation of mathematical modeling of laser coagulation

Most clinical procedures using the laser are based on thermal laser-tissue interactions. The treatment often consists of inducing damage of given degree and extent by heating the tissue. The aim of this study was to develop a model called HELIOS. The ability of HELIOS to predict thermal coagulation was evaluated by comparison with in vivo experimental results. Conversion of laser light in tissue was studied using the beam-broadening model. Temperature was described by the heat conduction equation solved using the finite difference method. The tissue dena-turation was modeled by the Henriques equation leading to the determination of the damage coefficient ω. For a given set of laser and tissue parameters, HELIOS makes a graphic representation of coagulation necrosis and temperature evolution in tissue. HELIOS was validated by experimental studies in vivo on rat liver using a CW Nd:YAG laser, a CO₂ laser, and an argon laser. For given sets of laser parameters, temperature measurements were performed using an infrared camera. Histological examinations were carried out on samples to quantify the depth of coagulation necrosis. Experimental data obtained in vivo were compared with those calculated using HELIOS and similar sets of parameters. The difference between the predicted temperature evolution on tissue surface and that measured by the infrared camera was < 5°C in all cases. The difference between the predicted coagulation necrosis depth and the corresponding experimental one was < 10%. In conclusion, HELIOS allows good prediction of tissue temperature and coagulation necrosis. © 1994 Wiley-Liss, inc.     

白术茯苓汤及其配伍对脾虚大鼠胃肠激素的影响

目的：探讨益气健脾方剂治疗脾虚证的配伍规律。方法：采用苦寒泻下法复制大鼠脾虚模型，运用放射免疫分析法（RIA）检测白术茯苓汤及其与补气药。行气药及除湿药的不同配伍对脾虚大鼠胃泌素（GAS）、胃动素（MTL）及血管活性肠肽（VIP）的含量影响。结果：与正常对照组比较，脾虚模型大鼠GAS、MTL降低（P＜0．01），VIP升高（P＜0．01）；与自然恢复组比较，各治疗组以上部分或全部指标均有不同程度的改善，其中，以综合配伍组改善作用最优。结论：白术茯苓汤的脾虚大鼠胃肠激素的紊乱的某些指标，有一定的改善作用，综合配合组以上指标的改善，优于白术茯苓汤组及其余各配伍组，说明中医关于复方配伍的理论与实践，有其科学价值。