p27kip1 Regulates cdk2 activity in the proliferating zone of the mouse intestinal epithelium: potential role in neoplasia

BACKGROUND & AIMS: Reduced p27(kip1) expression is a marker of poor prognosis in colorectal neoplasia, and inactivation of p27 in mice (p27(Delta51/Delta51)) causes increased intestinal epithelial cell proliferation and small and large intestinal neoplasia in a diet-dependent manner. Here, we addressed the role of p27 in untransformed intestinal epithelial cells in vivo and the consequence of its targeted inactivation. METHODS: A sequential fractionation procedure was used to isolate murine intestinal epithelial cells relative to their position along the crypt-villus axis, and the levels of cyclins, cyclin-dependent kinases (cdks), and cdk inhibitors and of the complexes formed among them was determined by immunoprecipitation-immunoblotting and kinase assays. RESULTS: As cells exited the proliferative crypt compartment, expression and activity of both cdk2 and cdk4 decreased, in parallel with reduced expression of cyclin A and proliferating cell nuclear antigen (PCNA); expression of cyclin D1, D2, and cyclin E showed little change. As expected, expression of the cdk inhibitors p21, p57, and p16 was highest in differentiated villus cells. Unexpectedly, p27 protein expression was highest in cells of the proliferative crypt compartment where it bound both cdk2 and cdk4. Cdk2 activity was increased in crypt cells from p27(Delta51/Delta51) mice, although cyclin D-associated kinase activity was unchanged (indeed, cyclin D1/2-cdk4 complex levels were reduced). Importantly, cdk2 activity was unchanged in crypt cells from p21(-/-) mice, which do not develop intestinal tumors. CONCLUSIONS: We propose that p27 contributes to intestinal epithelial homeostasis by regulating cdk2 activity in proliferating cells, thus gating cell cycle progression and suppressing intestinal neoplasia.     

人参皂苷Rb1对大鼠心室肌细胞L型钙电流和瞬时外向钾电流的调控作用

目的 研究参松养心胶囊的药物单体-人参皂苷Rb1对大鼠心室肌细胞L型钙电流(Ica,L)和瞬时外向钾电流(Ito)的调控作用.方法 Langendroff灌流装置、胶原酶和蛋白酶混合急性分离大鼠心室肌细胞,用含40μmol/L的人参皂苷Rb1的细胞外液灌流心室肌细胞,每个细胞采用给药前后自身对照,标准的全细胞膜片钳技术记录Ica,L,Ito,所有数据均在细胞破膜后20min内完成,观察人参皂苷Rb1对Ica,L和Ito通道电流的影响.结果 40 μmol/L的人参皂苷Rb1对Ica,L和Ito均有抑制作用.在-10mV测试电压下,40 μmol/L的人参皂苷Rb1可使Ica,L的最大激活峰值电流密度从(- 11.423±-3.125)pA/pF下降至(-5.786±-2.976)pA/pF,抑制率为49.34％±9.78％(n=7,p＜0.05),电流密度-电压(I-V)曲线上移,但不改变激括电位、峰电位、反转电位以及曲线的形状;在+60mV测试电压下,40μ mol/L的人参皂苷Rb1 可使Itof的最大激活峰值电位从 35.342±3.126pA/pF下降至26.783±4.153pA/pF,抑制率为24.21％±8.35％ (n=8,p ＜0.05),I-V曲线下移.两通道电流经Boltemann方程拟合的稳态激活曲线给药前后无明显影响,但药物可使稳态失活增快以及失活后恢复减慢(n=7,p＜ 0.05),且人参皂苷Rb1主要抑制Ito的快速电流成分Itof(峰电位),对慢电流成分Itos(维持电位)无明显影响.结论 人参皂苷Rb1对Ica,L和Ito通道的电流有显著抑制作用,但不改变Ica,L的通道动力学.     

红金消结片的制备与质量控制

目的:研究红金消结片的制备及其质量控制方法.方法:鉴别采用薄层色谱法,用高效液相色谱法测定人参皂苷Rg1含量.色谱柱为Cmsmosil C18(200mm×4.6mm,5μm),乙腈-0.05%磷酸溶液(21:79)为流动相;检测波长为203nm,柱温为25℃.结果:红金消结片中人参皂苷Rg1在0.7～6.3μg呈良好线性关系,r=0.999 2.结论:红金消结片制备工艺简单,质量控制方法可靠,重现性好.     

抑癌基因p16、Rb在急性淋巴细胞白血病患者中的表达及其临床意义

 目的 观察抑癌基因p16、Rb在急性淋巴细胞白血病（ALL）患者中的蛋白表达水平，探索其在ALL发病中的临床意义。方法 应用Western Blot及SP免疫组织化学染色技术检测抑癌基因p16、Rb在ALL患者白血病细胞中的蛋白表达水平。结果 32.14 % ALL患者p16蛋白表达缺失，与对照组比较差异具有统计学意义（P＜0.05）；免疫组织化学染色白血病细胞阳性率降低为11.3 %，与对照组比较差异具有统计学意义（P＜0.05）；28.57 % ALL患者pRb蛋白表达缺失，与对照组比较差异有统计学意义（P＜0.05）；免疫组织化学染色白血病细胞阳性率降低为41.6 %，与对照组比较差异有统计学意义（P＜0.05）；ALL患者p16与pRb蛋白表达水平经等级相关分析呈负相关（rs =－0.9247，P＜0.001）。结论 p16、Rb基因的异常表达在ALL的发生及演变过程中有重要意义，两者之间可能存在着负反馈调节机制。     

高效液相色谱法测定三七伤药片中3组分的含量

目的建立以高效液相色谱法测定三七伤药片中三七皂苷R1和人参皂苷Rg1、Rb1含量的方法。方法色谱柱为VP-ODS(150mm×4.6mm,5μm),使用梯度洗脱系统,流动相为乙腈-水(0~20min(20∶80),20~26min(40∶60),26~35min(20∶80)),流速为1.0mL.min-1,柱温为室温,检测波长为203nm。结果三七皂苷R1的线性范围为0.261~7.83μg(r=0.9999),平均回收率为(101.12±2.03)%(RSD=2.1%);人参皂苷Rg1的线性范围为0.6025~18.075μg(r=0.9997),平均回收率为(97.22±3.33)%(RSD=1.9%);人参皂苷Rb1的线性范围为0.5375~16.125μg(r=0.9996),平均回收率为(100.71±2.4)%(RSD=1.6%)。结论该法可用于测定三七伤药片中三七皂苷R1、人参皂苷Rg1、Rb1的含量。     

高效液相色谱法同时测定姜参胶囊中人参皂苷Rg_1、Re的含量

目的:建立以高效液相色谱法同时测定姜参胶囊中人参皂苷Rg1、Re含量的方法。方法:色谱柱为Kromasil C18,流动相为乙腈-0.05%磷酸溶液(21∶79),检测波长为203nm,流速为1.0mL.min-1。结果:人参皂苷Rg1、Re进样量分别在0.502~4.016μg(r=0.9997)、1.090~8.720μg范围内呈良好的线性关系(r=0.9998);平均回收率分别为98.8%(RSD=1.24%)、99.4%(RSD=1.68%)。结论:本法操作简便、快速、准确可靠,可用于姜参胶囊的质量控制。     

HPLC测定止鼾胶囊中三七皂苷R1与人参皂苷Rg1、Rb1含量

目的:测定止鼾胶囊中三七皂苷R1与人参皂苷Rg1、Rb1的含量。方法:采用HPLC,phenomenexC18柱(4.6mm×150mm,5μm),流动相:乙腈-水(20∶80)保持15min,15min后乙腈-水(40∶60)。流速:1.0mL.min-1,检测波长为203nm。结果:三七皂苷R1对照品在0.42～2.09μg线性关系良好,平均回收率为97.63%,RSD=1.16%(n=6);人参皂苷Rg1对照品在1.64～8.21μg线性关系良好,平均回收率为97.69%,RSD=1.49%(n=6);人参皂苷Rb1对照品在1.62～8.11μg线性关系良好,回收率为98.50%,RSD=1.70%(n=6)。结论:本实验三七皂苷R1、人参皂苷Rg1和人参皂苷Rb1的含量测定方法简单,结果稳定可靠,可作为止鼾胶囊中三七皂苷R1、人参皂苷Rg1和人参皂苷Rb1的定量分析方法。