酪醇诱导肝癌细胞NQO1酶基因表达增加及细胞增殖的抑制

目的:研究酪醇诱导肝癌细胞Ⅱ相脱毒酶NAD(P)H:醌氧化还原酶-1(NQO₁)基因表达情况和对细胞增殖的影响以及两者之间的关系。方法:肝癌细胞SMMC-7721接种后24h经β-酪醇处理24h,分别测定NQO₁酶活性,mRNA表达和细胞增殖情况。NQO₁酶活性采用微孔板直接测定法,诱导结果用NQO₁酶比活性=NQO₁酶活性/细胞数;mRNA水平的变化采用定量RT-PCR;细胞增殖采用结晶紫显色法。结果:NQO₁酶活性诱导上,酪醇大于60mg/L时有明显的剂量效应关系,且每一浓度点(60mg/L,70mg/L,80mg/L,90mg/L)与空白组比较均有显著差异(P＜0.05),80mg/L的酪醇与80μmol/L的β-NF(阳性对照)诱导的酶比活性相当;mRNA表达量存在剂量依赖性增加(r=0.824,P＜0.05),且与酶比活性存在明显的相关性(r=0.951,P＜0.01);酪醇在70mg/L-100mg/L范围内,其抑制细胞增殖的能力随着浓度的增加而增加。另外,细胞增殖与酶比活性呈负相关(r=-0.410,P＜0.01)。结论:酪醇在培养肝癌细胞SMMC-7721上能使NQO₁酶活性与mRNA表达量诱导性增加,同时酪醇能抑制细胞的增殖,这种增殖抑制与酶活性诱导增加有关。     

川芎嗪对实验性肾炎肾皮质内血小板活化因子、血栓素B2的影响

目的：探讨川芎嗪对实验性肾炎肾皮质内血小板活化因子（PAF）、血栓素B₂（TXB₂）水平的影响。方法：复制大鼠加速型抗肾小球基膜（GBM）肾炎模型。分为肾炎组、肾炎+川芎嗪组（治疗组）。结果：治疗组各期尿蛋白量较肾炎组减少（P<0.05, P<0.01）,第21 d时血清肌酐含量低于肾炎组（P<0.05）,光镜和电镜下肾脏病理改变较肾炎组为轻,同时肾皮质内PAF、TXB₂含量少于肾炎组（P<0.01）。结论：川芎嗪治疗实验性肾炎有效,其机理可能与减少肾皮质内PAF、TXB₂等有关。     

羊水与自体血培养后刺激花生四烯酸代谢物的释放

目的：探讨人羊水在体外刺激自体血细胞释放前列环素（PGI₂）、血栓素A₂（TXA₂）和白三烯C₄（LTC₄）等花生四烯酸代谢物的作用。方法：取产妇羊水与自体血进行培养,用放射免疫分析法检测血中血栓素B₂（TXB₂）和6-酮前列腺素F_1α（6-Keto-PGF_1α）的含量,用酶联免疫法检测LTC₄。结果：羊水能刺激血细胞释放TXA₂和LTC₄,胎粪污染的羊水作用更为明显。TXB₂的含量由加羊水培养前的(63.5±52.0) ng/L增加到培养后的(189.1±102.0) ng/L（P<0.01）,用胎粪污染羊水与血培养后增加到(289.2±113.2) ng/L（P<0.01）;LTC₄的含量由培养前的(40.1±39.7) ng/L增加到培养后的(293.5±206.1) ng/L（P<0.01）,胎粪污染组增加到(387.2±214.6)ng/L（P<0.01）,但前列环素仅有轻度增加,无显著性差异(P>0.05)。结论：羊水能刺激血细胞释放花生四烯酸类生物活性物质,使其正常的平衡状态被破坏,可能与羊水栓塞的发生机理有关。     

牙髓创伤时牙髓PGE2、PGI2和TXA2浓度改变的研究

目的:探讨前列腺素与牙髓炎的关系。方法:建立大鼠创伤性牙髓炎模型,动态观察创伤后大鼠牙髓的组织学改变和检测牙髓中PGE₂,6-Keto-PGF_1α和TXB₂ 浓度的变化。结果:创伤后大鼠牙髓呈明显炎症改变,PGE₂,6-Keto-PGF_1α和TXB₂ 浓度升高,在创伤 6h后达到高峰。结论:前列腺素参与急性牙髓炎的发病。     

血管内皮生长因子拮抗H2O2诱导的血管内皮细胞凋亡

目的：探讨血管内皮生长因子（VEGF）预防血管成形术后再狭窄的机制。方法：构件含人VEGF₁₆₅基因的重组腺病毒载体并感染体外培养的血管平滑肌细胞，72 h后收集含VEGF的条件培养液，将对数生长期的人脐静脉内皮细胞（HUVEC）分成对照组、H₂O₂处理组和H₂O₂+VEGF处理组，12 h后采用原位末端标记法和流式细胞术检测各组细胞的凋亡发生情况。结果：H₂O₂处理组细胞凋亡明显多于对照组和H₂O₂+VEGF处理组（P<0.01）。结论：H₂O₂能诱导HUVEC凋亡，而VEGF能部分拮抗上述作用。     

慢性低O2高CO2大鼠神经细胞凋亡与脑MDA、NOS的水平变化

目的：探讨慢性低O₂高CO₂脑神经细胞凋亡与MDA、NOS关系。方法：将SD大鼠分为正常对照组（C组）和低O₂高CO₂4周组（E组），采用原位末端标记（TUNEL）、流式细胞技术检测凋亡细胞，并测脑组织MDA、NOS水平。结果：①E组脑MDA、NOS水平高于C组（P<0.01）；②E组大脑皮质、海马、丘脑等部位见神经细胞凋亡；神经细胞凋亡百分率为11.51%，并与MDA和NOS水平呈正相关（r=0.652, P<0.05和r=0.716, P<0.05）。结论：慢性低O₂高CO₂时氧自由基和一氧化氮生成增加是神经细胞凋亡形成的重要机制之一。     

硫氮卓酮对慢性低O2高CO2大鼠肺动脉压力和结构型一氧化氮合酶及其基因表达的影响

目的：探讨硫氮卓酮对慢性低O₂高CO₂大鼠肺动脉压力的影响及其作用机制。方法：将Sprague-Dawley大鼠分为正常对照组（A组）、四周低O₂高CO₂组（B组）和四周低O₂高CO₂+硫氮卓酮组（C组），采用透射电镜、图像分析、免疫组化、原位杂交等方法，研究硫氮卓酮对慢性低O₂高CO₂大鼠肺动脉平均压（mPAP）、颈动脉平均压（mCAP）及肺动脉显微和超微结构、肺动脉结构型一氧化氮合酶（ceNOS）及其基因表达的影响。结果：①B组mPAP明显高于A组（P<0.01），C组mPAP明显低于B组（P<0.01），A组和B组mCAP无明显差异（P>0.05），C组mCAP低于B组（P<0.01）；②光镜下，肺细小动脉管壁面积/管总面积比值（WA/TA）C组明显低于B组（P<0.01）；电镜下，C组大鼠肺细小动脉内皮损伤、中膜平滑肌细胞和胶原纤维增生明显轻于B组；③免疫组化见C组肺细小动脉ceNOS的平均吸光度值明显高于B组（P<0.01）；原位杂交发现C组肺细小动脉ceNOS mRNA平均吸光度值明显高于B组（P<0.01）。结论：硫氮卓酮可抑制慢性低O₂高CO₂性肺动脉高压形成和肺血管结构重建，肺动脉ceNOS及其基因表达的增加为其重要作用机制，硫氮卓酮可能为治疗COPD、肺动脉高压伴高血压或室上性心律失常患者较为理想的药物。     

噻庚啶和山莨菪碱拮抗TNFα诱导的内皮细胞[Ca2+]i增高

目的：研究噻庚啶（Cyp）和山莨菪碱（Ani）对肿瘤坏死因子（TNFα）诱导单个内皮细胞内Ca²⁺浓度（[Ca²⁺]_i）变化的影响，以探TNFα介导休克和Cyp、Ani的抗休克的机制。方法：人脐静脉内皮细胞株（ECV304）接种于35 mm含2 mL DMEM培养基的组织培养盘中培养。Fluo-3/AM负载细胞，激光扫描共聚焦显微技术（LSCM）测定单个内皮细胞[Ca²⁺]_i。结果：TNFα使单个内皮细胞[Ca²⁺]_i呈剂量依赖性升高，在60 s内达到峰值，然后下降并保持在基础水平之上。共聚焦扫描图像显示细胞核区[Ca²⁺]_i升高比胞浆区明显，下降比胞浆区慢。Cyp（3×10^-5 mol/L或6×10^-5 mol/L）、Ani（2×10^-5 mol/L或4×10^-5 mol/L）均能显著抑制由TNFα（1.2×10^-9 mol/L）诱导的单个内皮细胞[Ca²⁺]_i升高。结论：TNFα诱导内皮细胞[Ca²⁺]_i升高可能是TNFα介导休克的重要机制；Cyp和Ani抑制TNFα诱导的[Ca²⁺]_i升高可能是其抗休克作用的机制之一。     

糖尿病大鼠肾小管TGF-β1和MAPK1/3表达的动态观察

目的:动态观察糖尿病大鼠肾小管转化生长因子-β₁(TGF-β₁)、丝裂原活化蛋白激酶(MAPK_1/3)和纤维连接蛋白(FN)的变化,探讨其在肾小管间质病变发生发展中的作用。方法:将大鼠分为正常对照组;糖尿病1周、2周、4周和8周组。用链脲菌素复制糖尿病模型;免疫组化法检测肾小管间质TGF-β₁、MAPK_1/3和FN的表达;Western blot检测TGF-β₁蛋白质;HE和PAS染色,光镜观察动物肾组织形态;生化法测定血糖、血肌酐及尿蛋白。结果: 正常肾小管可见少量MAPK_1/3表达,而未见TGF-β₁表达。糖尿病1周可见肾小管上皮细胞表达TGF-β₁,并且随着病程发展而增加。MAPK_1/3和FN从糖尿病两周开始表达亦呈持续增加,并且与TGF-β₁及肾重/体重比呈正相关。糖尿病1周时MAPK_1/3与TGF-β₁无显著相关,但与FN呈正相关。 结论:大鼠糖尿病状态诱导肾小管表达TGF-β₁并激活MAPK_1/3,MAPK_1/3介导高糖和TGF-β₁的信号而促进FN的生成和沉积,在糖尿病肾脏肥大和纤维化中可能起重要作用。     

西洋参二醇组皂苷对糖尿病肾病大鼠肾脏葡萄糖转运蛋白、尿β2-微球蛋白的影响

目的： 初步探讨西洋参二醇皂苷（PQS）对大鼠糖尿病肾病（DN）的治疗作用及其作用机制。方法: 将Wistar大鼠腹腔注射链脲佐菌素（STZ）建立DN模型，按空腹血糖值及体重将大鼠随机分为模型组、西洋参二醇皂苷小、大剂量（西洋参二醇组皂苷100、200 mg/kg）组、阳性药组（卡托普利10 mg/kg），连续灌胃给药，每10 d测定一次血糖，35 d后酶免法测定尿β₂-MG、免疫组化法检测肾脏GLUT-1。结果: 西洋参二醇皂苷小、大剂量组大鼠β₂-MG、肾脏GLUT-1明显低于模型组（P<0.05，P<0.01），西洋参二醇皂苷大剂量组血糖值明显低于模型组（P<0.05）。结论: 西洋参二醇皂苷对DN大鼠有治疗作用，其机制可能与其降低血糖及肾脏GLUT-1功能有关。     

Extinction of liver/bone/kidney alkaline phosphatase in osteosarcoma hybrid cells

We have constructed a series of interspecific somatic cell hybrids between the human osteoblast-like osteosarcoma, TE85, and a mouse fibrosarcoma, La^–t^–. In these whole-cell hybrids, we observed a 10-fold reduction of human liver/bone/kidney (L/B/K) alkaline phosphatase steady-state mRNA and alkaline phosphatase protein activity. The phenomenon of loss of tissue-specific gene expression has been termed extinction. Subclones of these hybrids were isolated, which reexpressed the alkaline phosphatase gene product. These late-passage hybrids had a reduced number of mouse fibroblast chromosomes when compared to earlier passages. This suggests that atrans-acting negative regulatory element, encoded in the fibroblast genome, regulates expression of L/B/K alkaline phosphatase. This is the first evidence that extinction plays a role in the regulation of osteoblast gene expression.     

Frequency and significance of antibodies to soluble liver antigen/liver pancreas in variant autoimmune hepatitis

BACKGROUND: Antibodies to soluble liver antigen/liver pancreas are highly specific markers of autoimmune hepatitis. AIMS: Determine the frequency and clinical significance of these antibodies in the variant syndromes. METHODS: Antibodies to soluble liver antigen/liver pancreas were determined in 28 patients with variant forms, including 10 with cryptogenic chronic hepatitis and 18 with cholestatic variants. One hundred and seventy-two patients with classical autoimmune hepatitis were similarly tested. RESULTS: Seven of the 28 patients with variant forms had the antibodies, and this frequency was not statistically different than that in classical disease (25 vs. 12%, p = 0.08). Antibodies were most common in patients with cryptogenic chronic hepatitis (40%). Seropositive patients were indistinguishable from seronegative patients with variant forms, and they responded as well to corticosteroid therapy as patients with autoimmune hepatitis. Relapse after corticosteroid withdrawal invariably occurred in the seropositive patients whether with variant or classical disease, and HLA DR3 was more common in the seropositive patients with variant forms than in normal subjects (60 vs. 15%, p = 0.03). CONCLUSIONS: Antibodies to soluble liver antigen/liver pancreas occur commonly in the variant forms of autoimmune hepatitis and identify patients that closely resemble classical disease. Seropositivity is associated with relapse after corticosteroid withdrawal and HLA DR3. The antibodies may be surrogate markers of a genetic propensity to relapse that is independent of clinical phenotype.     

The endothelin/nitric oxide balance determines small-for-size liver injury after reduced-size rat liver transplantation

Small-for-size (SFS) liver graft injury is probably related to microcirculatory disorders due to an imbalance of vasoconstricting, e.g. endothelin (ET)-1, and vasorelaxing mediators, e.g. nitric oxide (NO). We studied the role of ET-1/NO balance and the effect of an endothelin A receptor (ETAR) antagonist on SFS injury after liver resection and reduced-size liver transplantation (RSLT). One hundred twenty-six Lewis rats were divided into five groups: (I) 70% liver resection, (II) 70% liver resection treated with the ETAR antagonist LU 135252 (1 mg/kg b.w. i.v.), (III) RSLT (30% residual liver volume), (IV) RSLT treated with the ETAR antagonist, (V) sham operation. Liver microcirculation was measured by intravital microscopy. ET-1, ETAR, endothelial NO-synthase (eNOS), activation of Kupffer cells (KCs) and parenchymal injury were studied by immunohistology. Survival and liver function were followed up to 14 days. RSLT led to increased ET-1, ETAR and decreased eNOS protein expression, accompanied by activation of KC, reduced perfusion rate, vasoconstriction and elevated sinusoidal blood flow, as well as hepatocellular damage, impaired liver function and impaired survival. ETAR blockade (groups II + IV) improved the ET-1/NO balance, attenuated microcirculatory disorders and improved hepatocellular apoptosis and liver function. Microcirculatory disorders related to an ET-1/NO imbalance may contribute to SFS liver injury. Maintenance of ET-1/NO balance by blocking ETAR reduces SFS injury by protecting liver microcirculation, thus reducing hepatocellular damage.     

Heme breakdown and ischemia/reperfusion injury in grafted liver during living donor liver transplantation

Living donor liver transplantation (LDLT) requires ischemia/reperfusion (I/R), which can cause early graft injury. However, the detailed mechanism of I/R injury remains unknown. Heme oxygenase-1 (HO-1) is a rate-limiting enzyme in heme catabolism and results in the production of iron, carbon monoxide (CO), and biliverdin IXα. Furthermore, in animals, HO-1 has a protective effect against oxidative stress associated with I/R injury. However, in humans, the molecular mechanism and clinical significance of HO-1 remain unclear. We previously demonstrated that exhaled CO levels increase during LDLT, and postulated that this may indicate I/R injury. In this study, we elucidate the origin of increased exhaled CO levels and the role of HO-1 in I/R injury during LDLT. We studied 29 LDLT donors and recipients each. For investigation of HO-1 gene expression by polymerase chain reaction and HO-1 localization by immunohistological staining, liver biopsies from the grafted liver were conducted twice, once before and once after I/R. Exhaled CO levels and HO-1 gene expression levels significantly increased after I/R. In addition, HO-1 levels significantly increased after I/R in Kupffer cells. Furthermore, we found a significant positive correlation between exhaled CO levels and HO-1 gene expression levels. These results indicated that increased heme breakdown in the grafted liver is the source of increased exhaled CO levels. We also found a significant relationship between HO-1 gene expression levels and alanine aminotransferase (ALT) levels; i.e., the higher the HO-1 gene expression levels, the higher the ALT levels. These results suggest that HO-1-mediated heme breakdown is caused by I/R during LDLT, since it is associated with increased exhaled CO levels and liver damage.     

Properties of cryopreserved fetal liver stem/progenitor cells that exhibit long-term repopulation of the normal rat liver

We have previously achieved a high level of long-term liver replacement by transplanting freshly isolated embryonic day (ED) 14 rat fetal liver stem/progenitor cells (FLSPCs). However, for most clinical applications, it will be necessary to use cryopreserved cells that can effectively repopulate the host organ. In the present study, we report the growth and gene expression properties in culture of rat FLSPCs cryopreserved for up to 20 months and the ability of cryopreserved FLSPCs to repopulate the normal adult rat liver. After thawing and placement in culture, cryopreserved FLSPCs exhibited a high proliferation rate: 49.7% Ki-67-positive on day 1 and 34.7% Ki-67-positive on day 5. The majority of cells were also positive for both alpha-fetoprotein and cytokeratin-19 (potentially bipotent) on day 5. More than 80% of cultured cells expressed albumin, the asialoglycoprotein receptor, and UDP-glucuronosyltransferase (unique hepatocyte-specific functions). Expression of glucose-6-phosphatase, carbamyl phosphate synthetase 1, hepatocyte nuclear factor 4alpha, tyrosine aminotransferase, and oncostatin M receptor mRNAs was initially negative, but all were expressed on day 5 in culture. After transplantation into the normal adult rat liver, cryopreserved FLSPCs proliferated continuously, regenerated both hepatocytes and bile ducts, and produced up to 15.1% (mean, 12.0% +/- 2.0%) replacement of total liver mass at 6 months after cell transplantation. These results were obtained in a normal liver background under nonselective conditions. This study is the first to show a high level of long-term liver replacement with cryopreserved fetal liver cells, an essential requirement for future clinical applications.     

Prevention of colorectal cancer liver metastasis by exploiting liver immunity via chitosan-TPP/nanoparticles formulated with IL-12

The development of effective therapies for the prevention of colorectal cancer (CRC) liver metastasis is of great importance. Recently, chitosan (CS) nanoparticles have been utilized as carriers of interluekin-12 (IL-12) administered locally to deliver therapeutic proteins and genes. In this study, we encapsulated IL-12 by incorporation using tripolyphosphate (TPP) as the coacervated crosslinking agent to form CS-TPP/IL-12 nanoparticles. We further characterized the association efficiency, rate of release, liver-targeting, and toxicity, which were predominantly dependent on the factors of particle size, zeta potential, pH of solution, and whether or not modified with TPP. Systemic delivery of CS-TPP/IL-12 nanoparticles significantly reduced the number and volume of CRC liver metastasis foci compared to the CS-TPP treated mouse group. Although delivery of IL-12 alone also inhibited the number of CRC liver metastasis observed, further study of the change in hepatic metastasis volume demonstrated no significant differences between the groups treated with CS-TPP or IL-12 alone. Mechanistically, CS-TPP nanoparticles blocked the toxicity of IL-12 and induced infiltration of NK cells and some T cells, which are most likely the effector cells that mediate tumor metastasis inhibition during CS-TPP/IL-12 immunotherapy. The results obtained from this study demonstrate the potential benefit of using chitosan modification technology as a cytokine delivery system for the successful prevention of CRC liver metastasis by exploiting liver immunity.