Characterization of the mechanism underlying stonustoxin-mediated relaxant response in the rat aorta in vitro

Stonustoxin (SNTX) is a lethal factor isolated from the venom of the stonefish Synanceja horrida. Although SNTX exhibits a multitude of biological activities, the primary cause of death upon administration of the toxin is attributed to marked hypotension. We investigated the possible mechanisms underlying the vascular hyporeactivity of this novel toxin. Cumulative doses of SNTX (5-320 ng/mL) induced concentration-dependent relaxation in phenylephrine (PE)--precontracted rat aortic rings with intact endothelium. Endothelium removal abolished the relaxation induced by SNTX. Tetraethylammonium (TEA), an inhibitor of K(+) channels, partially inhibited SNTX-induced relaxation. Similarly, SNTX-induced relaxation was partially attenuated by the SP receptor antagonist (NATB), whereas the inducible iNOS inhibitor, AMT-HCl, completely abolished the relaxation caused by SNTX. From the results obtained, it can be postulated that a component of SNTX-mediated vasorelaxation is via binding of either SNTX or SP to the SP receptors that are located on the endothelial cells. Occupation of these SP receptors causes subsequent production of NO and activation of K(+) channels, thus leading to vasorelaxation of the rat aortic rings.     

痛泻要方对肠易激综合征作用机制的实验研究

目的探讨痛泻要方对内脏高敏感性肠易激综合征(IBS)模型大鼠的疗效和作用机制。方法采用结肠慢性刺激法制作内脏高敏感性的IBS大鼠模型。将实验动物分为正常组,模型组,阳性对照(得舒特)组,痛泻要方低、高剂量组。观察各组大鼠肠道内扩张引起腹部抬起和背部拱起的容量阈值和大鼠肠道内不同容量下扩张期间腹壁收缩次数,检测5-羟色胺(5-HT)、P物质(SP)、降钙素基因相关肽(CGRP)水平。结果与模型组相比,各治疗组大鼠行为学和电生理指标均有明显改善;各治疗组模型大鼠5-HT、SP水平明显下降,CGRP水平增加,且有一定的量效关系。结论痛泻药方能降低内脏高敏感性IBS模型大鼠血清5-HT、血浆SP水平,增加CGRP水平,大剂量痛泻药方疗效优于得舒特。痛泻药方的作用机制可能是通过降低模型大鼠血清5-HT、血浆SP水平,减弱背角神经元兴奋性,从而提高内脏痛阈、消除肠道过敏而达到治疗目的。     

润肠通便浓缩丸治疗慢性功能性便秘30例临床观察及对患者血中SP、NO影响的研究

目的:观察润肠通便浓缩丸对慢性功能性便秘(CFC)的治疗作用及对患者血中SP、NO的影响。方法:选择60例CFC患者,随机分为治疗组和对照组,每组30例,分别给予润肠通便浓缩丸和麻子仁丸治疗,观察两组患者的主症、次症变化与总积分的变化,并检测血液肽类神经递质(SP)、一氧化氮(NO)水平。结果:润肠通便浓缩丸治疗CFC,能明显改善其排便周期、粪便性状、排便时间及排便不适感、腹胀不舒、口干咽燥等症状,疗效确切;SP和NO检测结果表明,CFC患者血中SP、NO较健康人差异明显(P<0.01),治疗前两组患者血中的SP和NO含量比较无显著性差异(P>0.05),两组经治疗后血中SP和NO的含量均较治疗前有高度显著性差异(P<0.01),两组之间比较无显著性差异(P>0.05)。结论:润肠通便浓缩丸具有标本兼治以纠正CFC的良好功效,能使患者血中SP和NO的含量较治疗前明显改善,有高度显著性差异(P<0.01)。     

海藻多糖对肿瘤细胞膜流动性的影响

目的 研究海藻多糖的抗肿瘤作用机制。方法 采用荧光探针DPH法，观察海藻多糖对S180和H22小鼠细胞膜流动性的影响。结果 海藻多糖可升高S180荷瘤小鼠肿瘤细胞的膜流动性，降低H22荷瘤小鼠肿瘤细胞膜流动性。结论 海藻多糖可恢复肿瘤细胞膜流动性至正常细胞膜流动性而达到抗肿瘤的作用。     

Effects of tachykinin receptor agonists and antagonists on the guinea-pig isolated oesophagus

1. Vagal nerve stimulation of the guinea-pig isolated oesophagus produced a triphasic tetrodotoxin (TTX)-sensitive contractile response. The third phase, which was resistant to ganglion blocking drugs, was selectively abolished by capsaicin, suggesting the involvement of one or more neuropeptides released from afferent neurons. Receptors on cholinergic neurons were subsequently activated because the response was atropine sensitive. Contractile responses resulting from exogenous substance P were abolished by atropine and TTX and enhanced by physostigmine. These findings suggest that the third phase may be mediated by the action of a substance P-like neuropeptide released from sensory nerve endings that subsequently activated cholinergic neurons. 2. The tachykinin receptors in the body of the guinea-pig oesophagus were characterized by determining the relative agonist potencies of natural tachykinins as well as tachykinin receptor-selective analogues. Antagonist affinities were also determined. The results indicated the presence of both NK2 and NK3 receptors. In addition, the effects of a cocktail of peptidase inhibitors (captopril, thiorphan and amastatin) on responses to various tachykinins and synthetic analogues were determined. The results indicate that one or more peptidases are present in this preparation. 3. Experiments using various tachykinin receptor antagonists were performed to determine whether the activation of tachykinin receptors played a role in the mediation of the third phase of the response to vagal nerve stimulation. While this response was unaffected by NK1 and NK2 receptor-selective antagonists, it was only partially inhibited (23%) by the NK3 receptor antagonist SR 142801. Thus, in the guinea-pig oesophagus, it appears that NK3 receptors play only a minor role in mediating a contractile response when afferent neurons are excited by vagal nerve stimulation.     

Expression profile of an operationally-defined neural stem cell clone

Neural stem cells (NSCs) are the most primordial and least committed cells of the nervous system, the cells that exist before regional specification develops. Because immunocytochemically-detectable markers that are sufficiently specific and sensitive to define an NSC have not yet been fully defined, we have taken the strong view that, to be termed a "stem cell" in the nervous system--in contrast to a "progenitor" or "precursor" (whose lineage commitment is further restricted)--a single neuroectodermally-derived cell must fulfill an operational definition that is essentially similar to that used in hematopoiesis. In other words, it must possess the following functional properties: (1) "Multipotency", i.e., the ability to yield mature cells in all three fundamental neural lineages throughout the nervous system--neurons (of all subtypes), astrocytes (of all types), oligodendrocytes--in multiple regional and developmental contexts and in a region and developmental stage-appropriate manner. (2) The ability to populate a developing region and/or repopulate an ablated or degenerated region of the nervous system with appropriate cell types. (3) The ability to be serially transplanted. (4) "Self-renewal", i.e., the ability to produce daughter cells (including new NSCs) with identical properties and potential. Having identified a murine neural cell clone that fulfills this strict operational definition--in contrast to other studies that used less rigorous or non-operational criteria for defining an NSC (e.g., the "neurosphere" assay)--we then examined, by comparing gene expression profiles, the relationship such a cell might have to (a) a multipotent somatic stem cell from another organ system (the hematopoietic stem cell [HSC]); (b) a pluripotent stem cell derived from the inner cell mass and hence without organ assignment (an embryonic stem cell); (c) neural cells isolated and maintained primarily as neurospheres but without having been subjected to the above mentioned operational screen ("CNS-derived neurospheres"). ESCs, HSCs, and operationally-defined NSCs--all of which have been identified not only by markers but by functional assays in their respective systems and whose state of differentiation could be synchronized--shared a large number of genes. Although, as expected, the most stem-like genes were expressed by ESCs, NSCs and HSCs shared a number of genes. CNS-derived neurospheres, on the other hand, expressed fewer "stem-like" genes held in common by the other operationally-defined stem cell populations. Rather they displayed a profile more consistent with differentiated neural cells. (Genes of neural identity were shared with the NSC clone.) Interestingly, when the operationally-defined NSC clone was cultured as a neurosphere (rather than in monolayer), its expression pattern shifted from a "stem-like" pattern towards a more "differentiated" one, suggesting that the neurosphere, without functional validation, may be a poor model for predicting stem cell attributes because it consists of heterogeneous populations of cells, only a small proportion of which are truly "stem-like". Furthermore, when operational definitions are employed, a common set of stem-like genes does emerge across both embryonic and somatic stem cells of various organ systems, including the nervous system.     

Sensory innervation of normal and hypospadiac prepuce: possible implications in hypospadiology

Sensory innervation of the skin influences wound healing through the release of neuropeptides from the nerve endings. The purpose of this study was to investigate the differences in the sensory innervation of the normal and the hypospadiac prepuce. The prepuce from 10 healthy children undergoing routine circumcision and 10 age-matched children undergoing hypospadias repair were submitted for immunohistochemistry, using antibodies against protein gene product (PGP) 9.5, calcitonin gene-related peptide (CGRP), and substance P (SP). The hypospadiac prepuce was found to be hypo-innervated for PGP 9.5 and CGRP positive nerves when compared with the normal prepuce (p<0.05). The number of SP-positive nerves were increased in the hypospadiac prepuce, but not to statistical significance (p=0.06, confidence interval >95%). There may be differences in the sensory innervation of the normal and hypospadiac prepuce. These differences in tissue environment may partly explain the postoperative edema, poor wound healing leading to urethrocutaneous fistula (UF), and increased analgesia requirements in patients undergoing hypospadias surgery.     

Capsaicin facilitates carotid sinus baroreceptor activity in anesthetized rats

AIM: To study the effect of capsaicin on carotid sinus baroreceptor activity (CBA). METHODS: The functional curve of carotid baroreceptor (FCCB) was constructed and the functional parameters of carotid sinus baroreceptor were measured by recording sinus nerve afferent discharge in anesthetized rats with perfused isolated carotid sinus. RESULTS: Low-concentration of capsaicin (0.2 μmol/L) had no significant effect on CBA, while perfusion of the isolated carotid sinus with middle-concentration of capsaicin (1 μmol/L) could shift FCCB to the left and upward, with peak slope (PS) increased from (2.47 %±0.14 %)/mmHg to (2.88 %±0.10 %)/mmHg (P<0.05) and peak integral value of carotid sinus nerve discharge (PIV) enhanced from 211 %±5 % to 238 %±6 % (P<0.01). The threshold pressure (TP) and saturation pressure (SP) were significantly decreased from 68.0±1.1 to 62.7±1.0 mmHg (P<0.01) and from 171.0±1.6 to 165.0±0.6 mmHg (P<0.01). By perfusing with high-concentration of capsaicin (5μmol/L), FCCB was shi     

Histamine releasing peptide (HRP) has proinflammatory effects and is present at sites of inflammation

Albumin, the most abundant plasma protein, readily enters sites of inflammation during the period of increased vascular permeability. There it encounters proteases released from mast cells and invading leukocytes which earlier work has shown can act on albumin to liberate the peptide, histamine releasing peptide (HRP), first identified and named by its ability to stimulate histamine release from isolated mast cells. In this report we show that HRP releases histamine from cutaneous mast cells in vivo resulting in increased vascular permeability and persistent edema while in vitro, HRP promotes chemotaxis of leukocytes and enhances macrophage phagocytosis. Moreover, we show that the level of HRP is increased with the induction of an acute cutaneous inflammatory response in rats, that HRP is present at sites of acute and chronic inflammation in humans and that HRP is rapidly degraded by proteases thereby limiting its action to the area of its generation. We suggest that HRP is a pro-inflammatory peptide that helps amplify and perpetuate the inflammatory response. Inhibitors of inflammatory proteases or antagonists that block the action of peptides like HRP may, therefore, be useful in breaking the cycle of inflammation.     

加味补阳还五汤对易卒中自发性高血压大鼠血清微量元素的影响

目的观察易卒中自发性高血压大鼠服用加味补阳还五汤后,其血清微量元素锌、铜、铁、硒、锰含量的变化。方法将20只8周龄雄性易卒中自发性高血压大鼠分为两组,用药组(n=10):喂含补阳还五汤的饲料,对照组(n=10):常规饲养;另设同龄WKY大鼠为空白组(n=10)。实验周期3个月,观察指标为:大鼠血清微量元素锌、铜、铁、硒、锰含量。结果空白组锌、锰、硒含量明显高于用药组(P<0.01),用药组又明显高于对照组(P<0.01);而空白组铜含量低于用药组(P<0.05),用药组又低于对照组(P<0.05);血清内铁含量三组间无显著差异(P>0.05)。结论加味补阳还五汤对自发性高血压大鼠血清锌、铜、铁、硒、锰具有一定的调控作用。