Inhibition of NMDA-induced protein kinase C translocation by a Zn chelator: Implication of intracellular Zn

The role of intracellular Zn²⁺ in the translocation of protein kinase C from cytosol to membrane fractions was examined by the [³H]phorbol 12,13-dibutyrate (PDBu) binding method in guinea pig cerebral synaptoneurosomes. N-methyl-d-aspartate (NMDA, 100 μM) and calcium ionophore A23187 (0.3–30 μM) decreased the binding activity in the cytosol with a concomitant increase in the membrane fractions. Pretreatment of synaptoneurosomes with a heavy metal chelator, N,N,N′,N′-tetrakis-(2-pyridylmethyl)ethylenediamine (TPEN), inhibited the NMDA- and A23187-induced changes of the distribution of [³H]PDBu binding sites in cytosol and membrane fractions. The inhibitory effect of TPEN was negated by a preincubation of TPEN with equimolar Zn²⁺ but not by that with Ca²⁺. The addition of 500 μM Zn²⁺ to the lysate of synaptoneurosomes induced an increase of [³H]PDBu binding activity in the membrane fraction with a concomitant decrease in the cytosol fraction, as did 100 μM Ca²⁺. Low concentrations of Zn²⁺ (10 μM), which alone had no effect on the distribution of the binding, significantly enhanced the effect of 10 μM Ca²⁺ in the lysate. Under those conditions TPEN inhibited the Zn²⁺-potentiated Ca²⁺-dependent changes in the binding. These results suggest that intracellular Zn²⁺ is essential for the agonist-induced translocation of protein kinase C in guinea pig synaptoneurosomes.     

鞘内注射吗啡加可乐定对切口痛大鼠脊髓背角蛋白激酶A催化亚单位表达的影响

Objective To observe the effect of intrathecal clonidine plus morphine on expression of protein kinase A (PKA) catalytic subunit in the spinal dorsal horn in a rat model of incisional pain. Methods Eighty male Sprague-Dawley rats were divided randomly into five groups: sham group, control group, pre-incisional morphine 2.5 μg group, pro-incisional clonidine 5 μg group and preincisional morphine 2.5 μg plus clonidine 5 lag group (n=16). lntrathecal catheter and the model of incisional pain were pro-duced according to Yaksh and Brennan's described method respectively. Changes of pain behavior were assessed by mechanical with-drawal threshold (MWT) and thermal withdrawal latency(TWL). The expressions of PKA catalytic subunit in the spinal dorsal horn were assessed by immunohistochemical method and western blotting analysis. Results Compared with sham group, MWT and TWL in control group were decreased significantly at 2 h after incision (P<0.01) and the number of positive cells and protein expression of PKA catalytic subunit in the spinal dorsal horn were increased significantly in control group (P<0.01). Compared with control group, MWT and TWL in pre-incision morphine 2 μg plus clonidine 5 lag group were increased significantly at 2 h after incision (P<0.01) and the number of positive cells and protein expression of PKA catalytic subunit in the spinal dorsal horn were decreased significantly in pre-incision morphine 2 μg plus clonidine 5 μg group (P<0.01). However, MWT, TWL and the number of positive cells and pro-tein expression of PKA catalytic subunit in the spinal dorsal horn changed with no statistical significance in pre-incisional morphine 2.5 μg group and pre-incisional clonidine 5 μg group compared with control group. Conclusion lntrathecal clonidine significantly enhances the antinociceptive effect of intrathecal morphine in a rat model of incisional pain, which might be associated with inhibi-tion of the increased expression of PKA catalytic subunit in spinal cord.     

Triterpenoid saponins, new metalloprotease snake venom inhibitors isolated from Pentaclethra macroloba.

We report here the antiproteolytic and antihemorrhagic properties of triterpenoid saponin inhibitors, named macrolobin-A and B, from Pentaclethra macroloba, against Bothrops snake venoms. The inhibitors were able to neutralize the hemorrhagic, fibrin(ogen)olytic, and proteolytic activities of class P-I and P-III metalloproteases isolated from B. neuwiedi and B. jararacussu venoms. Clotting and fibrinogenolytic activities induced by snake venoms and isolated thrombin-like enzymes were partially inhibited. Furthermore, the potential use of these inhibitors to complement antivenom therapy as an alternative treatment and/or used as molecular models for development of new therapeutical agents in the treatment of snake bite envenomations needs to be evaluated in future studies.     

Raf-1 kinase,epidermal growth factor receptors,and mutant ras proteins in colonic carcinomas

Epidermal growth factor receptors (EGFR) andras mutations are known to play a significant role in controlling cell growth and tumor promotion. Both of them transmit mitogenic signals to the nucleus by activation of Raf-1 kinase. In this study, the expression of EGFR and mutant Ras proteins, and, for the first time, the expression, phosphorylation and kinase activity of Raf-1 kinase have been determined in paired samples of colorectal cancer and mucosa. The tumor and mucosa samples did not differ significantly with regard to Raf-1 kinase content and activity. A major difference between tumors and mucosa was found, however, in the phosphorylation of Raf-1. Most of the mucosa samples (13/20), but only 1/20 of the cancer samples, contained hyperphosphorylated Raf-1. EGFR were significantly (p=0.0025) decreased in the tumors. The decreased phosphorylation of Raf-1 in colonic carcinomas could be the result of activation of Raf-1 phosphatases or inactivation of kinases phosphorylating Raf-1. New forms of treatment based on EGFR overexpression do not seem to be suitable for the majority of colonic cancers.This work was supported by the state of Baden-Württemberg (Verbundforschungsprojekt: Aufklärung von Mechanismen der Tumorentstehung und Tumorabwehr).     

胆囊癌组织中NDPK／nm23的表达及意义

作者用免疫组化ＡＢＣ法对４１例胆囊癌标本核苷二磷酸激酶（ＮＤＰＫ，下同）／ｎｍ２３表达进行了测定，结果发现：ｎｍ２３在恶性肿瘤中的表达率明显高于良性病变（Ｐ＜０．０５）。ＮＤＰＫ／ｎｍ２３表达与胆囊癌组织的分化、局部浸润及淋巴转移密切相关（Ｐ＜０．０１）。ＮＤＰＫ／ｎｍ２３阳性患者生存中位数１２．２５个月，阴性患者６．５个月，两者存在显著差异（Ｐ＜０．０１），提示ｎｍ２３检测对预后有重要价值。     

补肾中药对肾虚骨质疏松症大鼠红细胞膜PKC、 Ca2+-Mg2+- ATP酶活性影响的实验研究

本实验研究切除卵巢造成肾虚骨质疏松症大鼠模型。通过观测红细胞膜蛋白激酶Ｃ（ＰＫＣ）和Ｃａ２＋－Ｍｇ２＿－ＡＴＰ酶的活性，探讨肾虎骨质疏松症病理机制中肌醇脂质系统的变化，并结合全身和脊柱骨密度（ＢＭＤ）指标观察了补肾中药（密骨灵）的疗效，与正常对照组、模型空白组和阳性药（骨疏康颗粒剂）对照组进行对照，探讨补肾法的防治机理。结果表明；模型空白组大鼠红细胞膜ＰＫＣ和Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶、Ｍｇ２＋－ＡＴＰ酶的活性明显低于正常组（ｐ均＜０．０５）；密骨灵组与骨疏康组大鼠全身、脊柱ＢＭＤ和红细胞膜ＰＫＣ、Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶的活性均明显高于模型空白组（ｐ均＜０．０５），并且与正常组大鼠无明显差别（ｐ均＞０．０５）；密骨灵组大鼠红细胞膜Ｍｇ２＋－ＡＴＰ酶活性高于模型空白组和骨疏康组（ｐ＜０．０５），并且与正常组无显著性差异（ｐ＞０．０５）；密骨灵组大鼠红细胞膜ＰＫＣ活性高于骨疏康组（Ｐ＜０．０５）。结论：肾虎骨质疏松症具有红细胞膜ＰＫＣ和Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶、Ｍｇ２＋－ＡＴＰ酶活性的改变；密骨灵可以恢复肾虎骨质疏松症大鼠全身骨量，达到防治目的；补肾中药可以恢复红细胞膜ＰＫＣ活性和钙镁泵的活性，是补     

Lines of Murine Oligodendroglial Precursor Cells Immortalized by an Activated neu Tyrosine Kinase Show Distinct Degrees of Interaction with Axons In Vitro and In Vivo

Replication-defective retroviruses expressing the t- neu oncogene, or a hybrid protein with the neu tyrosine kinase linked to the external region of the human epidermal growth factor receptor ( egfr-neu ), were used to establish lines of murine oligodendroglial precursor cells. Differentiation of the t- neu lines into myelin-associated glycoprotein (MAG)-positive oligodendrocytes was induced by dibutyryl cAMP, and the egfr-neu line showed limited differentiation in vitro upon withdrawal of epidermal growth factor. Cerebellar granule cell neurons expressed mitogens for the cell lines. Upon transplantation into demyelinated lesions, t- neu line cells engaged with the demyelinated axons whereas the egfr-neu line cells differentiated further and ensheathed the axons. These cell lines thus interact with neurons in vitro and in vivo and can be used as tools to define the molecules involved in different stages of neuron-glia interaction.     

增殖细胞核抗原及nm23在胃癌中的表达及意义

目的 :探讨增殖细胞核抗原 (PCNA)及nm2 3基因在胃癌中的表达及其与生物学行为的关系。方法 :应用免疫组化SP法研究 85例胃癌手术标本中PCNA及nm2 3基因的表达。结果 :在 85例胃癌中PCNA、nm2 3的总阳性表达率分别为 5 2 9% (4 4 / 85例 )和 4 4 .7% (38/ 85例 ) ,PCNA及nm2 3在胃癌中的表达与其淋巴结转移、浸润深度、分化程度有关 (P <0 0 5 ,P <0 0 1 ) ;PCNA与分化程度无关 ,P >0 0 5。结论 :PCNA及nm2 3参与了胃癌的发生、发展、浸润及转移     

鞘内注射吗啡对切口疼痛大鼠脊髓背角蛋白激酶Cγ免疫反应的影响

目的 研究鞘内注射吗啡对切口疼痛大鼠脊髓背角蛋白激酶Cγ(PKCγ)免疫反应的影响。方法 SD雄性大鼠24只,随机分为4组(每组6只):假手术组(Ⅰ组)、对照组(Ⅱ组)术前30 min鞘内注射人工脑脊液20μl,术后吗啡治疗组(Ⅲ组)、术前吗啡治疗组(Ⅳ组)分别于术后和术前30min鞘内注射吗啡5μg(10 μl)。所有大鼠均按Brennan法制成切口疼痛模型,用免疫组织化学方法观察脊髓背角PKCγ的表达。结果 Ⅱ组术侧脊髓背角PKCγ-IR表达高于非术侧及Ⅰ组(P<0.01)。与Ⅱ组比较,Ⅲ组、Ⅳ组脊髓背角PKCγ-IR表达降低(P<0.05或0.01),而Ⅲ组、Ⅳ组比较差异无显著性。结论 在大鼠切口疼痛模型中,鞘内注射吗啡的镇痛作用可能与抑制脊髓背角的PKCγ-IR免疫反应有关。