SRBC膜提取物对猪PBMNC第二信使的影响

胰酶水解绵羊红细胞（ＳＲＢＣ）释放膜表面活性蛋白组分Ⅲ（ＴＲＦ－Ⅲ），单独作用可使猪外周血单个核细胞（ＰＢＭＮＣ）胞内ｃＡＭＰ水平升高，以１００μｇ／ｍｌ浓度刺激达最高峰，由对照组０．９４±０．１４ｐｍｏｌ／Ｌ升高到２．７５±０．２５ｐｍｏｌ／Ｌ（Ｐ＜０．０１）。如果ＰＢＭＮＣ事先与腺苷酸环化酶（ＡＣａｓｅ）抑制剂ＬｉC１孵育后再以ＴＲＦ－Ⅲ或ＰＡＨ刺激。ｃＡＭＰ增高受到抑制（Ｐ＜０．０１）；而ＥＤＴＡ－２Ｎａ（一种磷酸二酯酶ＰＤＥ抑制剂）对此ｃＡＭＰ升高无影响。结果提示，此ｃＡＭＰ升高主要是通过活化ＡＣａｓｅ水解ＡＴＰ生成ｃＡＭＰ，而不像是抑制ＰＤＥ减少ｃＡＭＰ降解引起的。ＴＲＦ－Ⅲ诱导猪ＰＢＭＮＣ胞内Ｃａ~(２＋)浓度升高，以１００μｇ／ｍｌ刺激２分钟升高最多，由对照组的２４２±７ｎｍｏｌ／Ｌ升高到３２３±１５ｎｍｏｌ／Ｌ（Ｐ＜０．０１）。以ＥＧ－ＴＡ除去胞外Ｃａ~(２＋)再以ＴＲＦ－Ⅲ或ＰＡＨ刺激，仅观察到小范围［Ｃａ~(２＋)］ｉ升高。看来这一过程包括了刺激胞内Ｃａ~(２＋)释放和胞外Ｃａ~(２＋)内流两种方式。以上结果证明，ＴＲＦ－Ⅲ对淋巴细胞功能影响与细胞内第二信使有关。     

c—myb对大鼠黄体细胞孕酮和雌二醇生成的影响

本文观察了反义ｃ－ｍｙｂＯＤＮ对黄体细胞ｈＣＧ诱导的Ｐ和Ｅ２产生的影响,并探讨了与二丁酰ｃＡＭＰ和ｖｅｒａｐａｍｉｌ的关系。结果发现, ｃ－ｍｙｂＯＤＮ能呈剂量相关方式抑制黄体细胞ｈＣＧ诱导的Ｐ和Ｅ２的产生。同时使ｃ－ｍｙｂ蛋白染色了性的黄体细胞百分数下降,而无义ｔａｔＯＤＮ上应的作用。当１０＾－４ｍｏｌ／Ｌ二丁酰ｃＡＭＰ与反义ｃ－ｍｙｂＯＤＮ共同作用时能明显逆转反义ｃ－ｍｙｂＯＤＮ对Ｐ、Ｅ２产生     

α—干扰素对正常与甲亢甲状腺细胞生成c—AMP的调节作用

采用甲状腺细胞单层培养及标记免疫分析法，对比研究α－干扰素（ＩＦＮ－α）对正常与Ｇｒａｖｅｓ病（ＧＤ）甲状腺细胞生成ｃＡＭＰ的影响，结果显示：（１）基础状态下，１０＾－３、１０＾－１和１０ｕ／ｍｌ的ＩＦＮ－α可刺激正常甲状腺细胞产生ＣＡＭＰ，刺激强度随ＩＦＮ－α浓度的增大而减弱，当试验剂量达１０＾３ｕ／ｍｌ时，ＣＡＭＰ的生成量与无刺激的对照组比较无统计学差异，此浓度区间的ＩＦＮ－α对ＧＤ甲状腺细胞     

蛋白激酶C抑制剂对去甲肾上腺素促进大鼠巨噬细胞I_a抗原表达的影响

我室以前的工作证明，在去甲肾上腺素（ＮＥ）促进大鼠巨噬细胞（ＭΦ）Ｉａ抗原表达的效应中，细胞内的第二信使物质三磷酸肌醇（ＩＰ－３）和Ｃａ￣２＋起着必不可少的作用。然而，另一第二信使物质甘油二酯（ＤＧ）的作用如何，尚待阐明。为此，我们用４α－佛　波醇－１２，１３－二癸酸盐（４α－ｐｈｏｒｂｏｌ－１２，１３－ｄｉｄｅｃａｎｏａｔｅ，４α－ＰＤＤ）抑制ＭΦ内的蛋白激酶Ｃ（ｐｒｏｔｅｉｎｋｉｎａｓｅＣ，ＰＫＣ）以阻断ＤＧ的作用，结果使ＮＥ促进ＭΦＩａ抗原表达的效应显著减弱（Ｐ＜０．０１，Ｐ＜０．０１），说明在ＮＥ促进ＭΦＩａ抗原表达的效应中，ＩＰ－３、Ｃａ￣２＋和ＤＧ都起重要的作用。     

生长抑素抑制内皮素刺激的家兔血管平滑肌细胞增殖

为探讨生长抑素（ＳＳＴ）对内皮素（ＥＴ）刺激细胞增殖的作用其机理，本工作在培养的兔主动脉血管平滑肌细胞（ＶＳＭＣ）上发现，１０＾－８ｍｏｌ／ＬＥＴ刺激细胞增殖（＾３Ｈ＝ＴｄＲ参入增多）和丝裂素活化蛋白激酶（ＭＡＰＫ）激活，１０＾－８ｍｏｌ／ＬＳＳＴ单独作用可抑制细胞增玩具增殖但不曩ＭＡＰＫ活性。ＳＳＴ不仅呈浓度依赖性地抑制ＥＴ刺激的ＶＳＭＣ增殖（Ｐ〈０．０１），而且亦抑制ＥＴ刺激的细胞ＭＡＰＫ激     

乙酰胆碱对大鼠腹腔巨噬细胞内钙离子浓度和表面Ia抗原表达的影响

用Ｆｕｒａ－２作为荧光探针测定大鼠腹腔巨噬细胞（Ｍ）内钙离子浓度（［Ｃａ￣（２＋）］ｉ），ＡＰＡＡＰ桥联酶标法检测Ｍ表面Ｉａ抗原的表达。结果表明：５×１０￣（－６）ｍｏｌ／Ｌ的乙酞胆碱（Ａｃｈ）可使Ｍ［Ｃａ￣（２＋）］ｉ；明显上升，可促进Ｍ表面Ｉ－Ａ和Ｉ－Ｅ抗原的表达，而阿托品（１０￣（－５）ｍｏｌ／Ｌ）可阻断Ａｃｈ升高［Ｃａ￣（２＋）］ｉ的作用。阿托品、三氟啦嚎（ＴＦＰ，５０μｍｏｌ／Ｌ）、ＥＧＴＡ（６ｍｍｏｌ／Ｌ）均可阻断Ｍ促进ＭＩａ抗原表达的作用，ｃＡＭＰ依赖性蛋白激酶抑制剂（ＰＫＩ，２５μｇ／ｍｌ）对Ａｃｈ促进ＭＩａ抗原表达的作用无影响。     

抑制NF-_κB对鼻咽癌细胞CNE-2中MMP-9表达的影响

目的　　为探讨高转移性和高复发性的鼻咽癌中ＭＭＰ－９的表达及ＮＦ－κＢ抑制剂ＰＤＴＣ对其表达的影响。方法　　采用常规培养的鼻咽癌细胞ＣＮＥ－２,通过流式细胞仪检测ＣＮＥ－２中ＭＭＰ－９的表达及核因子κＢ抑制剂ＰＤＴＣ对其表达的影响。结果　　ＣＮＥ－２中有高表达的ＭＭＰ－９,ＰＤＴＣ可有效抑制其ＭＭＰ－９的表达。结论　　ＭＭＰ－９在肿瘤转移过程中起重要作用,抑制ＮＦ－κＢ和ＭＭＰ－９可抑制肿瘤转移。     

小鼠胸腺基质细胞系（MTEC1）对裸鼠骨髓细胞的诱…

在体外建立的小鼠胸腺基质细胞系（ＭＴＥＣ１）及其培养上清（ＭＴＥＣ１－ＳＮ）与裸鼠骨髓（ＢＭ）细胞共同培养，通过直接荧光素标记抗体，ＦＡＣＳ分析其细胞表面标志表明，ＭＴＥＣ１及ＭＴＥＣ１－ＳＮ均有诱导促进Ｔｈｙ·１＾－ＣＤ＾－４ＣＤ＾－８的ＢＭ细胞表达Ｔｈｙ·１，ＣＤ４及ＣＤ８分子的作用。在培养或共育三天时，ＭＴＥＣ１－ＳＮ可促进ＢＭ细胞分化形成ＣＤ＾＋４Ｔｈｙ·１＾－，ＣＤ＾－４Ｔｈｙ·１＾＋细     

粘附分子对CD3介导的胸腺细胞[Ca^2＋]i应答的影响

ＬＦＡ－１和ＩＣＡＭ－１广泛表达于各胸腺细胞亚群，但ＩＣＡＭ－１在ＰＮＡ￣＋细胞的表达下调。本文报道：用抗ＬＦＡ－１／ＩＣＡＭ－１和抗ＣＤ３单抗，分析了粘附分子ＬＦＡ－１／ＩＣＡＭ－１对抗ＣＤ３诱导的胸腺细胞［Ｃａ￣（２＋）］ｉ应答的影响。结果显示，可溶性抗ＬＦＡ－１／ＩＣＡＭ－１可抑制ＣｏｎＡ刺激的胸腺细胞增殖，且以抗ＬＦＡ－１抗体的作用更为显著，在ＣｏｎＡ或抗ＣＤ３诱导的胸腺细胞［Ｃａ￣（２＋）］ｉ应答中，抗ＬＦＡ－１单抗可明显抑制［Ｃａ￣（２＋）ｉ升高。但如果用二抗交联ＣＤ３和ＬＦＡ－１，胸腺细胞［Ｃａ￣（２＋）ｉ则显著高于单独交联ＣＤ３时的水平（Ｐ＜０．０１），而ＣＤ３与ＩＣＡＭ－ｌ交联却无此效应，此外，仅交联ＬＦＡ－１或ＩＣＡＭ－１也无诱导［Ｃａ￣（２＋）］ｉ应答的作用。提示在ＬＦＡ－ｌ与ＩＣＡＭ－１介导的胸腺细胞与胸腺基质细胞相互作用中，ＬＦＡ－１可为ＴＣＲ／ＣＤ３途径介导的胸腺细胞活化提供复合刺激信号。     

COMPARISON OF BREAST MASS SIZE ON ULTRASONOGRAPHY,CUT-SURFACE OF RESECTED SPECIMEN,AND PALPATION

ＣＯＭＰＡＲＩＳＯＮＯＦＢＲＥＡＳＴＭＡＳＳＳＩＺＥＯＮＵＬＴＲＡＳＯＮＯＧＲＡＰＨＹ，ＣＵＴ－ＳＵＲＦＡＣＥＯＦＲＥＳＥＣＴＥＤＳＰＥＣＩＭＥＮ，ＡＮＤＰＡＬＰＡＴＩＯＮＣＯＭＰＡＲＩＳＯＮＯＦＢＲＥＡＳＴＭＡＳＳＳＩＺＥＯＮＵＬＴＲＡＳＯＮＯＧＲ...     

Role of protein kinase C in expression of granulocyte-colony stimulating factor and granulocyte macrophage-colony stimulating factor in lung cancer cells

We examine the role of protein kinase C (PKC) pathways in the constitutive expression of granulocyte-colony stimulating factor (G-CSF) and granulocyte macrophage-colony stimulating factor (GM-CSF) in lung cancer cells. Two cell lines, OKa-C-1 and MI-4, constitutively produce an abundant dose of G-CSF and GM-CSF. The PKC activator phorbol 12-myristate 13-acetate (PMA) stimulated the production of GM-CSF in a dose-dependent manner and reduced G-CSF in the cell lines. The PKC inhibitor staurosporine had effects opposite to those of PMA in the cell lines. Another PKC activator (4beta-phorbol 12, 13-dibutyrate) and six specific PKC inhibitors (bisindolylmaleimide I, calphostin C, chelerythrine chloride, G? 6976, PKC inhibitor 19-27, and Ro-32-0432) also worked as well as PMA and staurosporine, respectively. The induction of GM-CSF expression via PKC activation was mediated by the activation of nuclear factor-kappaB. The induction of G-CSF expression via PKC inhibition was mediated by p44/42 mitogen-activated protein kinase and c-Jun N-terminal kinase pathway signaling. GM-CSF may accelerate cell growth and inhibit cell death via PKC activation in the cell lines. G-CSF also seems to reverse growth suppression and cell death induced by PKC inhibition.     

蛋白激酶C在脂多糖诱导内皮细胞β-1,4-半乳糖基转移酶-Ⅰ表达中的作用

目的 研究蛋白激酶c(PKC)对脂多糖(LPS)诱导内皮细胞β-1,4-半乳糖基转移酶-Ⅰ(β-1,4-galactosyltransferase-Ⅰ,β-1,4-GalT-Ⅰ)表达的调节作用,以及对内皮细胞骨架结构改变及其黏附能力的影响.方法 分别用PKC激动剂或几种不同类型的PKC抑制剂预处理人脐静脉内皮细胞(HUVECs)30 min,LPS刺激HUVECs 4 h后,RT-PCR、Western blot方法 检测β-1,4一GalT-Ⅰ表达变化,细胞荧光染色观察β-1,4-GalT-Ⅰ催化的糖链表达变化及细胞骨架结构的改变,通过内皮-单核细胞黏附试验观察HUVECs黏附能力的改变.结果 几种不同类型的PKC抑制剂均能不同程度地抑制LPS刺激HUVECs引起的β-1,4-GalT-Ⅰ表达的上调,PKC激动剂能够使上调的β-1,4-GalT-Ⅰ的表达进一步增加;在HUVECs中β-1,4-GalT-Ⅰ与细胞骨架有共同定位,PKC抑制剂显著抑制LPS诱导的内皮细胞骨架蛋白的重构和β-1,4-GalT-Ⅰ细胞内的再分布;PKC抑制剂显著抑制LPS诱导的内皮-单核细胞黏附能力的上调.结论 PKC可能参与调节LPS诱导的HUVECs β-1,4-GalT-Ⅰ的表达,可能多种类型的PKC参与了这一调节过程;PKC可能通过对β-1,4-GalT-Ⅰ的调节进而影响炎症过程中内皮细胞骨架蛋白的重构及内皮细胞与单核细胞的黏附能力.     

PKC和ROCK对硝苯地平舒张血管作用的影响

目的:探讨蛋白激酶C(PKC)及Rho相关激酶(ROCK)对硝苯地平舒张大鼠离体胸主动脉血管环作用的影响。方法:采用离体血管环灌流装置观察硝苯地平对基础状态血管环及去甲肾上腺素(NE,10~(-6)mol/L)或KCl(60mmol/L)预收缩血管环的张力变化,并利用PKC抑制剂和ROCK抑制剂等工具药观察对硝苯地平舒血管作用的影响并探讨可能机制。结果:系列浓度硝苯地平对基础状态血管环张力无明显影响,对NE和KCl预收缩的血管环具有浓度依赖性舒张作用(P 0. 05),去内皮组舒张作用与内皮完整组比较无明显差异。预孵PKC抑制剂星孢菌素(STA,10~(-8)mol/L)及激动剂佛波酯(PMA,10~(-7)mol/L)后,STA能增强硝苯地平对血管的舒张作用,而PMA能减弱硝苯地平对血管的舒张作用(P 0. 05);预孵ROCK抑制剂法舒地尔(fasudil,10~(-6)mol/L)及激动剂血管紧张素Ⅱ(Ang-Ⅱ,10-9mol/L)后,fasudil能增强硝苯地平对血管的舒张作用,而Ang-Ⅱ能减弱硝苯地平对血管的舒张作用(P 0. 05);钾通道阻滞剂BaCl_2(10~(-4)mol/L)、四乙胺(10~(-3)mol/L)、格列本脲(10~(-5)mol/L)和4-氨基吡啶(10~(-3)mol/L)对硝苯地平的舒张血管作用无明显影响。在无钙且含高浓度KCl的溶液中,硝苯地平可浓度依赖性地抑制累积浓度的CaCl_2对大鼠离体主动脉环的收缩作用(P 0. 05)。在无钙液中,硝苯地平对NE所引起的收缩无明显影响。结论:硝苯地平能够呈浓度依赖性地舒张大鼠主动脉,其舒张血管作用为非内皮依赖性,且与抑制细胞外钙内流密切相关,其舒张血管作用部分与抑制PKC和ROCK作用相关。     

Hyperglycemia in vitro attenuates insulin-stimulated chemokinesis in normal human neutrophils. Role of protein kinase C activation.

This study was performed to test whether the inhibitory effect of elevated D-glucose concentrations on insulin-stimulated chemokinesis in normal human neutrophils is mediated by increase in protein kinase C (PKC) activity. Activation of PKC with phorbol 12-myristate 13-acetate (PMA) at 0-100 nM dose-dependently inhibited neutrophil random locomotion in the absence of insulin. Sub-optimal concentrations of PMA (0.1-0.5 nM) inhibited the chemokinetic effect of 160 microU/mL insulin in a dose-dependent way. The specific PKC inhibitor bisindolylmaleimide (GF 109203x) did not affect the insulin-stimulated chemokinesis at 5 mM glucose but restored the chemokinetic effect of insulin at 15 mM glucose. These results therefore suggest that glucose-induced PKC activation may mediate the inhibitory effects of high glucose levels on insulin-stimulated chemokinesis in normal human neutrophils.     

Protein kinase C regulation of rat jejunal transport systems: mechanisms involved in bicarbonate absorption

We examined whether protein kinase C (PKC) modulates the transport systems involved in bicarbonate movements across the plasma membranes of rat jejunum. Results of enzymatic assays provide evidence that under basal conditions conventional PKC (cPKC) is present in both basolateral membranes (BLMs) and apical (brush border) membranes (BBMs) of the enterocyte. In BLMs the basal expression of the kinase is low compared to expression in BBMs; however, treatment with Ca(2+) and phorbol 12-myristate 13-acetate (PMA) causes a significant increase, thus suggesting an asymmetrical kinase translocation. To explore the effect of PKC activation on membrane-bound transport mechanisms, 'in vitro' phosphorylated membrane vesicles were used to perform uptake studies. Results suggest that PKC activation exerts an inhibitory effect on the basolateral Cl(-)-HCO(3)(-) antiporter, whereas the basolateral HCO(3)(-) conductive pathway seems to be stimulated and Cl(-) conductance unaffected. The apical, but not basolateral, Na(+)-H(+) exchanger is inhibited by PKC activation. The specificity of the response to PKC was confirmed by using the kinase inhibitor staurosporine or the inactive phorbol ester 4-alpha-PMA. The inhibition of both apical Na(+)-H(+) and basolateral Cl(-)-HCO(3)(-) exchange activities suggests that the overall action of PKC causes a reduction of transepithelial bicarbonate transport.     

Protein kinase C is involved in clozapine's facilitation of N-methyl-D-aspartate- and electrically evoked responses in pyramidal cells of the medial prefrontal cortex

We have previously shown that the atypical antipsychotic drug clozapine facilitates N-methyl-D-aspartate (NMDA)- and electrically evoked responses in pyramidal cells of the medial prefrontal cortex (mPFC). In the present study, we investigated the role of protein kinase C (PKC) in the action of clozapine. Bath administration of the PKC activator phorbol-12-myristate 13-acetate (PMA), but not the inactive isomer 4alpha-PMA, significantly enhanced the NMDA-evoked inward current and electrically evoked excitatory postsynaptic currents. Chelerythrine, a selective blocker of PKC, completely prevented the potentiating action produced by either clozapine or PMA on these currents in the mPFC cells. Intracellular injection of the PKC inhibitor PKC-I, but not the control substance PKC-S, through the recording electrode totally blocked clozapine's potentiating effect, indicating that a post-synaptic expressed PKC is critically involved in the augmenting action of clozapine on NMDA-evoked currents. Of the PKC inhibitor PKC-I, but not the control substance PKC-S, through the recording electrode totally blocked clozapine's potentiating effect, indicating that a post-synaptic expressed PKC is critically involved in the augmenting action of clozapine on NMDA-evoked currents. To further test the role of PKC in mediating the augmenting action of clozapine, we performed experiments in PKCgamma mutant and wild-type mice. In contrast to results in pyramidal cells from rats or wild-type mice, neither clozapine nor PMA was able to potentiate NMDA-induced currents in the mPFC from the PKCgamma mutant mice. Taken together, these results suggest that the PKC signal transduction pathway is critically involved in the facilitating action of clozapine on the NMDA-induced responses in pyramidal cells of the mPFC.     

Involvement of annexin V in the antiproliferative effect of GnRH agonist on cultured human uterine leiomyoma cells

The objective of this study was to elucidate the role of annexin V, an endogenous inhibitor of protein kinase C (PKC), with regard to the antiproliferative effect of gonadotrophin-releasing hormone (GnRH) agonist (buserelin) on cultured human uterine leiomyoma cells. Uterine leiomyoma tissue was collected from the surgical specimens of patients and cells from 37 specimens (15 cases) were cultured. For up to 96 h after the addition of buserelin to the cultured cells, a time-dependent antiproliferative effect was noted in the group to which 10(-5) mol/l buserelin was added. Both the intracellular concentration of annexin V and the expression of annexin V mRNA increased time-dependently with the addition of buserelin. The intracellular concentration of annexin V increased with the addition of PKC activator (12-O:-tetradecanoylphorbor-13-acetate; TPA) much as it did with the addition of buserelin, and the rise in the concentration caused by the addition of buserelin was completely attenuated by pretreatment with PKC inhibitor (calphostin C). Our findings suggest that buserelin inhibits cell proliferation in cultured human uterine leiomyoma cells accompanied with an increase in the intracellular concentration of annexin V, mediated, at least in part, by the activation of PKC.     

Differing roles of protein kinase C on the antiproliferative effects of tumor necrosis factor alpha and beta on LoVo cells

In this study we examined whether the antiproliferative effects of tumor necrosis factor (TNF)-alpha and beta were associated with the activation of protein kinase C (PKC), using the LoVo human colon cancer cell line which is resistant to both TNFs. In combination with 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent activator of PKC, TNF-alpha caused marked growth inhibition of LoVo cells, but TNF-beta had little antiproliferative effect. There was no difference in the effect when TPA was added 1 h before or 4 h after TNF-alpha administration. A PKC inhibitor, H-7, not only decreased the sensitivity of LoVo cells to TNF-alpha but also caused a slight promotion of cell proliferation and dose-dependently blocked the growth inhibition induced by TNF-alpha and TPA. These results suggested a possible regulatory function of PKC within the TNF-alpha-mediated intracellular signalling pathway. PKC may act at a later stage in the transduction pathway.     

Genistein, a selective protein tyrosine kinase inhibitor, inhibits interleukin-2 and leukotriene B4 production from human mononuclear cells.

In this study, genistein, a selective protein tyrosine kinase (PTK) inhibitor, inhibited peripheral blood mononuclear cell (PBMC) proliferation and interleukin-2 production from cultures that were stimulated with phytohemagglutinin (PHA), phorbol 12-myristate 13-acetate (PMA) plus A23187, or PHA plus PMA, and genistein effectively blocked the PHA plus IL-2-induced PBMC proliferation. Further, we also found that genistein inhibited LTB4 production from A23187-stimulated cultures whereas H-7, a PKC inhibitor, had no effect on LTB4 production. Our results suggest that PTK may be necessary for the synthesis of LTB4.     

Amyloid precursor protein processing is separately regulated by protein kinase C and tyrosine kinase in human astrocytes

Regulation of amyloid precursor protein (APP) processing by protein kinase C (PKC) and phosphotyrosine pathways was investigated in cultured human astrocytes. Phorbol 12, 13-dibutyrate (PDBu), a PKC activator, increased secretion of APPalpha 2-3-fold over control values, and GF109203X, a PKC inhibitor, blocked this effect. Similarly, platelet derived growth factor (PDGF) increased the secreted form of APPalpha (sAPPalpha) level two-fold, and genistein, a tyrosine kinase inhibitor, blocked the stimulatory effect of PDGF. Co-treatment of PDGF and PDBu resulted in a five-fold increase in the sAPPalpha production, and genistein and GF109203X did not block the stimulatory effects of PDBu and PDGF, respectively. These results indicate that both PKC and phosphotyrosine pathways are involved in APP processing in human astrocytes, but they act independently. The two pathways appear to converge to mitogen-activated protein kinase (MAPK) because PD98059, a MAPK inhibitor, blocked the effects of PDBu and PDGF on APPalpha secretion.