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941.
人重组C3片段通过IL-2自分泌效应对CTLL-2细胞产生促增殖作用 总被引:1,自引:0,他引:1
目的研究补体C3片段的体外生物学活性及其作用机理,进一步探讨C3片段与免疫细胞的关联。方法利用重组DNA技术表达纯化C3活性片段(命名为C33),观察其对IL-2依赖性的小鼠杀伤性T细胞株CTLL-2细胞的促增殖效应,并通过抗体封闭途径和分子杂交技术研究C33作用的机理。结果发现C33蛋白对CTLL-2细胞具有明显的促增殖作用,并呈剂量依赖关系;这一作用能够部分地被抗小鼠CD11b抗体所封闭,能够完全被抗小鼠IL-2抗体所封闭;分子杂交显示C33蛋白能够明显刺激CTLL-2细胞的IL-2mRNA表达。结论人重组C3片段C33可通过IL-2的自分泌效应对CTLL细胞产生促增殖作用,补体受体CR3参与这一作用。 相似文献
942.
H. Gron R. Pike J. Potempa J. Travis I. B. Thøgersen J. J. Enghild S. V. Pizzo' 《Journal of periodontal research》1997,32(1):61-68
Porphyromonas gingivalis is closely associated with the development of some forms of periodontitis. The major cysteine proteinases released by this bacterium hydrolyze peptide bonds only after arginyl (gingipain R) or lysyl residues (gingipain K). No target protein inhibitors have been identified for either enzyme, leading us to investigate their inhibition by human plasma α2 -macroglobulin (α2 M). Both 50- and 95 kDa gingipain R were efficiently inhibited by α2 M, whereas the catalytic activity of gingipain K could not be eliminated. All 3 enzymes were, however, inhibited by a homologous macroglobulin from rat plasma, α1 -inhibitor-3 a-Macroglobulins must be cleaved in the so-called "bait region" in order to inhibit proteinases by a mechanism involving physical entrapment of the enzyme. A comparison of the aminio acid sequences of the 2 macroglobulins indicates that the lack of lysyl residues within the bait region of α2 M protects Lys-specific proteinases from being trapped. On this basis, other highly specific proteinases might also not be inhibited by α2 M, possibly explaining the inability of the inhibitor to control proteolytic activity in some bacterially induced inflammatory states, despite its abundance (2-5 mg/ml) in vascular fluids. 相似文献
943.
Previous study has shown that α2D-adrenoceptors are involved in modulation of peristalsis in the rat ileum. The aim of the present study was to determine the
tissue location of α-adrenoceptors in the rat ileum by using a recently devised method. The pre-synaptic α-adrenoceptors were
characterised by measuring the potencies of agonists to inhibit transmurally-evoked (1 ms pulses, 10 Hz, 8-10 s trains) contractions
of the longitudinal and circular muscles and the affinities of antagonists. Post synaptic α-adrenoceptors were identified
by screening agonists and antagonists in carbachol-contracted tissues. In the circular muscle the order of potencies for inhibiting
transmurally-induced contraction was: clonidine ≥ oxymetazoline ≥ UK 14,304 ≥ guanfacine > talipexole > phenylephrine > azepexole.
The potency ratios relative to clonidine correlated to those previously derived using the rat ileum peristaltic reflex preparation.
Most of the α-adrenoceptor agonists, however, caused only small inhibitions of the longitudinal muscle contraction in response
to transmural stimulation, except phenylephrine and azepexole. RX 821002, yohimbine, rauwolscine, BRL 44408, phentolamine,
idazoxan, ARC 239, and prazosin inhibited the effect of clonidine on the circular muscle response with apparent pKB values best correlated with pKB or pKi values derived from the rat ileum peristaltic reflex preparation and other tissues known to have the α2D-subtype. The rank order of potencies at inhibiting carbachol-induced responses of both muscle layers was: phenylephrine ≥
oxymetazoline > clonidine ≥ talipexole > azepexole >> guanfacine. UK 14,304 was inactive up to 10 μM. The EC50 value of each agonist on the longitudinal muscle was not significantly different to the corresponding value on the circular
muscle. Prazosin was more potent than yohimbine at inhibiting the relaxant effect of phenylephrine in both muscle layers of
carbachol-contracted tissues. It is concluded that the recently identified α2D-adrenoceptors of the rat ileum are located on cholinergic neurons controlling circular muscle contraction. The study also
demonstrated the presence of postsynaptic α1-adrenoceptors involved in mediating relaxation in both muscle layers.
Received: 4 November 1996 / Accepted: 10 April 1997 相似文献
944.
兴奋性氨基酸类神经毒剂与粉防己碱(tetrandrine,Tet)共同作用于原代培养胎鼠大脑皮层神经元24小时,发现107,106mol·L1Tet明显降低50μmol·L1谷氨酸(glutamate,Glu),300μmol·L1βNmethylaminoLalanine(BMAA,NMDA受体激动剂)和20μmol·L1βNoxalylaminoLalanine(BOAA,nonNMDA受体激动剂)导致的培养液乳酸脱氢酶(lactatedehydrogenase,LDH)活性的增高;细胞形态损害减轻,细胞数量增加。对20μmol·L1NMDA介导的神经元损伤改变无影响。提示Tet对某些Glu类神经毒剂引起的胎鼠大脑皮层神经元损伤有一定保护作用,其机制可能是抑制细胞膜上的Na+通道开放,阻止膜去极化而影响电压依赖性Ca2+通道启动。对NMDA受体可能亦有一定作用。 相似文献
945.
研究地西泮、苯巴比妥、普萘洛尔和西咪替丁对地西泮氧化代谢的影响及其药酶蛋白的初步分析,应用HPLC,SDS聚丙烯酰胺凝胶电泳和薄层扫描测定地西泮及其代谢物,并对大鼠肝微粒体和酶蛋白进行分离和含量测定。结果表明地西泮、普萘洛尔和西咪替丁使肝微粒体中P450含量明显降低。地西泮和普萘洛尔明显抑制地西泮C3羟化活性,大剂量普萘洛尔尚能抑制地西泮N脱甲基。苯巴比妥明显诱导P450生成,增强地西泮N脱甲基和C3羟化酶活性及分子量为51,000和59,000的电泳蛋白带,而地西泮、普萘洛尔则呈抑制作用。并发现,地西泮N脱甲基酶活性和分子量为59,000蛋白含量呈线性相关(P<0.05),而C3羟化酶活性则与51,000蛋白含量呈线性相关(P<0.01)。因此地西泮C3羟化代谢可能与51,000的P450酶蛋白有关,而N脱甲基代谢则可能与59,000的P450酶蛋白有关。 相似文献
946.
7β-(6-取代-2-喹诺酮-3-乙酰氨基)头孢菌素的合成 总被引:1,自引:0,他引:1
以6-取代-2-喹诺酮-3-乙酸为侧链,用CDI法和潘化酯法与7-ADCA,7-ACA,7-ACT,和7-ACD缩合,合成了16个新的7β-(6-取代-2-喹诺酮-3-乙酰氨基)头孢菌素类化合物,通过溶媒转提,葡聚糖凝胶(Sephadex LH-20)柱层析及离心薄层层析分离精制,得到纯品。初步体外抑菌试验表明:新化合物对革兰氏阳性及某些阴性菌具有高度敏感性。大多数化合物对所试试验菌的抗菌活性与头孢唑啉和青霉素G钠相当,有些比它们还强。 相似文献
947.
Patrice Venault Georges Chapouthier Jacques Simiand Robert H. Dodd Jean Rossier 《Brain research bulletin》1987,19(3)
Benzodiazepines are known to induce a profound anterograde amnesia in man. In this report, it is shown that methyl β-carboline-3-carboxylate (β-CCM), an inverse agonist of the benzodiazepine receptor, has the opposite effect; it enhances performance in learning and memory tasks. Three different learning models were used: habituation to a new environment and passive avoidance in mice and imprinting in chicks. The opposite effects of both β-CCM and the benzodiazepine diazepam were blocked by administration of the benzodiazepine receptor antagonist Ro 15-1788, provicling evidence that the benzodiazepine receptor is involved in these effects. 相似文献
948.
Kim Hahn Le Quan Sang Jean-Luc Elghozi Philippe Meyer Marie-Aude Devynck 《Clinical and experimental pharmacology & physiology》1987,14(3):187-189
1. Plasma renin activity (PRA) and platelet cytosolic free calcium concentration ([Ca2+]i) were simultaneously determined in 18 untreated essential hypertensive subjects and 17 normotensive controls. A significant positive correlation was found between [Ca2+]i and PRA (slope = 42 nmol/l/ng/ml/h) in these 35 subjects. 2. Two determinations more than one week apart in nine subjects confirmed the parallel fluctuations of [Ca2+]i and PRA. A strict sodium restriction produced a progressive PRA elevation associated with a parallel rise in [Ca2+]i in one subject. 3. These results are consistent with the hypothesis that angiotensin II causes a concentration-dependent calcium mobilization. 相似文献
949.
Low numbers of parasites from cloned lines of the rodent malaria parasites, Plasmodium chabaudi chabaudi AS and P. yoelii yoelii A, injected into CBA/Ca mice produce acute but usually self-limiting infections. During crisis, i.e. 1-2 days after peak parasitaemia, 'pre-immune' mice experiencing such 'background' infections were reinfected intravenously with homologous parasites or parasites of heterologous strains or species. P. c. chabaudi AS pre-immune mice controlled an AS challenge with essentially the same kinetics as the background infection. Reinfection of AS pre-immune mice with the heterologous (CB and IP-PCI) P. c. chabaudi strains or P. chabaudi adami DS had little effect on the initial growth of these parasites, although eventually the parasitaemia was controlled. In contrast, a partial inhibitory effect on the growth of P. vinckei lentum DS was evident. Challenge with the non-lethal (A) or lethal (YM) variants of P. y. yoelii resulted in an increase in both the growth and virulence of these parasites. P. y. yoelii A pre-immune mice controlled a homologous challenge, but were less effective at controlling the YM variant. In addition, they were unable to clear rapidly a P. c. chabaudi AS or P. v. lentum DS challenge. Both the multiplication and virulence of P. berghei ANKA were enhanced. These findings demonstrate that resolution of the primary acute parasitaemia in P. c. chabaudi AS- and P. y. yoelii A-infected mice is predominantly mediated by species- and strain-specific mechanisms. 相似文献
950.
Hikaru Tanaka Naofumi Uesato Koki Shigenobu 《Naunyn-Schmiedeberg's archives of pharmacology》1995,351(4):391-397
Chronotropic and inotropic effects of histamine were examined in isolated atrial and ventricular preparations from embryonic and hatched chicken hearts. Histamine produced positive chronotropic and inotropic responses both in embryonic and hatched hearts. The responses to histamine in middle embryonic myocardia, which were observed in the micromolar range, were antagonized by H2 antagonists but not by H1, H3 antagonists and propranolol. Isobutylmethylxantine, an inhibitor of phosphodiesterase, produced a leftward shift of the concentration-response curve for the chronotropic effect of histamine in the embryo. The responses to histamine in myocardia from hatched chicks, which were observed in the milimolar range, appeared concurrently with the responses to tyramine during development and were antagonized by beta adrenoceptor antagonists but not by any of the histamine antagonists. The positive inotropic response to histamine in hatched ventricular preparations were greatly attenuated by reserpine pretreatment or in the presence of desipramine. Thus, we demonstrated that exogenously applied histamine produces positive chronotropic and inotropic responses in developing chicken hearts and that the mechanisms are different between embryonic and hatched chicks: direct action on H2 receptors in the embryonic heart and release of norepinephrine from sympathetic nerve terminals in hatched hearts. 相似文献