STAT-3 overexpression and p21 up-regulation accompany impaired regeneration of fatty livers

Fatty liver is an important cause of morbidity in humans and is linked to impaired liver regeneration after liver injury, but the mechanisms for impaired liver regeneration remain unknown. In the normal liver, the interleukin (IL)-6/STAT-3 pathway is thought to play a central role in regeneration because this pathway is disrupted in IL-6-deficient mice that exhibit impaired liver regeneration after 70% partial hepatectomy (PH). To determine whether inhibition of STAT-3 is involved in fatty liver-related mitoinhibition, regenerative induction of STAT-3 was compared in normal mice and leptin-deficient ob/ob mice that have fatty livers and markedly impaired liver regeneration after PH. In both groups, two waves of STAT-3 activation were observed, the first in endothelia and the second in hepatocytes. Before PH, a significantly higher percentage of ob/ob endothelial and hepatocyte nuclei expressed phosphorylated (activated) STAT-3. After PH, phospho-STAT-3 accumulated in liver nuclei of lean mice and this response was markedly exaggerated in ob/ob mice. Moreover, a striking inverse correlation was noted between hepatocyte nuclear accumulation of phospho-STAT-3 and DNA synthesis (as assessed by bromodeoxyuridine labeling), as well as cyclin D1 mRNA induction and protein expression. In contrast, STAT-3 activation was positively correlated with p21 protein expression in both groups of mice. Because these results link exaggerated STAT-3 activation with impaired hepatocyte proliferation, STAT-3 inhibition cannot be a growth-arrest mechanism in ob/ob fatty livers. Rather, hyperinduction of this factor may promote mitoinhibition by up-regulating mechanisms that impede cell cycle progression.     

In vivo mesenchymal cell recruitment by a scaffold loaded with transforming growth factor beta1 and the potential for in situ chondrogenesis

The objectives of this study were (1) to develop a biphasic implant made of a bioresorbable polymeric scaffold in combination with TGF-beta1-loaded fibrin glue for tissue-engineering applications, and (2) to determine whether the implant made of a polycaprolactone (PCL) scaffold and TGF-beta1-loaded fibrin glue could recruit mesenchymal cells and induce the process of cartilage formation when implanted in ectopic sites. Twenty-four 6-month-old New Zealand White rabbits were used. Scaffolds loaded with various doses of TGF-beta1 in fibrin glue were implanted subcutaneously, intramuscularly, and subperiosteally. The rabbits were killed and implants were removed at 2, 4, and 6 weeks postoperatively. The specimens were subjected to various staining techniques for histological analysis. Light microscopic examination of all specimens revealed that the entire pore space of the scaffolds was filled with various tissues in each group. The entire volume of the scaffolds in the groups loaded with TGF-beta1 and implanted intramuscularly and subcutaneously was populated with mesenchymal cells surrounded with an abundant extracellular matrix and blood vessels. The scaffold loaded with TGF-beta1 and implanted subperiosteally was found to be richly populated with chondrocytes at 2 and 4 weeks and immature bone formation was identified at 6 weeks. We conclude that scaffolds loaded with TGF-beta1 can successfully recruit mesenchymal cells and that chondrogenesis occurred when this construct was implanted subperiosteally.     

Overexpression of monocyte chemotactic protein-1/CCL2 in beta-amyloid precursor protein transgenic mice show accelerated diffuse beta-amyloid deposition

Microglia accumulation at the site of amyloid plaques is a strong indication that microglia play a major role in Alzheimer's disease pathogenesis. However, how microglia affect amyloid-beta peptide (Abeta) deposition remains poorly understood. To address this question, we developed a novel bigenic mouse that overexpresses both amyloid precursor protein (APP) and monocyte chemotactic protein-1 (MCP-1; CCL2 in systematic nomenclature). CCL2 expression, driven by the glial fibrillary acidic protein promoter, induced mononuclear phagocyte (MP; monocyte-derived macrophage and microglial) accumulation in the brain. When APP/CCL2 transgenic mice were compared to APP mice, a fivefold increase in Abeta deposition was present despite increased MP accumulation around hippocampal and cortical amyloid plaques. Levels of full-length APP, its C-terminal fragment, and Abeta-degrading enzymes (insulin-degrading enzyme and neprilysin) in APP/CCL2 and APP mice were indistinguishable. Sodium dodecyl sulfate-insoluble Abeta (an indicator of fibrillar Abeta) was increased in APP/CCL2 mice at 5 months of age. Apolipoprotein E, which enhances Abeta deposition, was also increased (2.2-fold) in aged APP/CCL2 as compared to APP mice. We propose that although CCL2 stimulates MP accumulation, it increases Abeta deposition by reducing Abeta clearance through increased apolipoprotein E expression. Understanding the mechanisms underlying these events could be used to modulate microglial function in Alzheimer's disease and positively affect disease outcomes.     

Model for assessment of proficiency of human immunodeficiency virus type 1 sequencing-based genotypic antiretroviral assays

Use of sequencing-based genotyping as a diagnostic assay for human immunodeficiency virus (HIV) antiretroviral resistance is increasing. Periodic evaluation of the proficiency of laboratories performing this assay should be established. It is important to identify components of the assay that influence the generation of reliable sequencing data and that should and can be monitored. A model was developed to determine what parameters were reasonable and feasible for assessing the performance of genotyping assays. Ten laboratories using the genotyping platform, HIV-1 Genotyping System (HGS) v. 1 and software versions 1.1 or 2.0, participated in two rounds of testing. For each round, each group was sent a panel consisting of three clinical samples to sequence in real time. Six months later, seven laboratories using the TRUGENE HIV-1 Genotyping Kit participated in a separate round, working with both panels at the same time. Analysis of the data showed that one main indicator of genotyping proficiency was achievement of > or =98% sequence homology of a sample tested to a group consensus sequence for that sample. A second was concordant identification of codons at sites identified with resistance mutations in the sample, although scoring of these criteria is still undetermined from this study. These criteria are applicable to all sequence-based genotyping platforms and have been used as a baseline for assessing the performance of genotyping for the determination of antiretroviral resistance in our ongoing proficiency program.     

3～20周人胚和胎儿肾小体的组织发生

应用光、电镜对3～20周22例人胚和胎儿肾小体的组织发生进行了观察.受精后第25天胚肾已有肾小体发生.随着胚龄的增长,肾小体的发生数目增多,肾小体的形成方式是:胚肾内先形成许多厚壁小管,在一部分厚壁小管的诱导下,另一部分厚壁小管的一侧壁呈帽状增厚,分化形成造血干细胞、毛细血管内皮及肾小囊脏层,对侧壁形成肾小囊壁层.即厚壁小管的双侧壁形成肾小体.     

大鼠脊髓缺血再灌注损伤后caspase-12表达与细胞凋亡

目的:观察大鼠脊髓缺血再灌注损伤过程中细胞凋亡、caspase-12的表达变化规律,以探讨其分子机制。方法:采用自制压迫装置制备脊髓压迫缺血再灌注模型。运用形态学、分子生物学等方法,分别于缺血再灌注后3、7、11、23和47h,观察脊髓缺血再灌注损伤后,脊髓的病理变化和内质网的形态学改变、细胞凋亡及caspase-12的表达变化的规律。结果:脊髓缺血再灌注3h后,出现不同程度的细胞肿胀,神经元退行性变及内质网结构变化;随着再灌注时间的延长,神经元和神经胶质细胞凋亡数明显增加,并伴有caspase-12的表达增强;capspase-12表达与细胞凋亡的时空变化规律相一致。结论:在脊髓缺血再灌注过程中神经细胞凋亡是引起脊髓继发性损伤的主要病理因素,caspase-12可能参与了脊髓缺血再灌注损伤所导致的细胞凋亡。     

视黄醇结合蛋白4与代谢综合征的关系

目的 探讨视黄醇结合蛋白4(RBP4)的血清水平及-G 803 A SNP与代谢综合征的关系.方法 收集116名伴2型糖尿病的代谢综合征患者和93名正常体检者,放射免疫法测定RBP4血清水平,聚合酶链式反应及序列分析检测G 803 A多态性基因型.结果 (1)RBP4水平在所有受试者中与体质指数(BMI)、腰围、空腹胰岛素(FINS)、胰岛素抵抗指数(HOMA-IR)、三酰甘油(TG)正相关,对照组中与TG、TC、LDL-C正相关,男性组中与DBP正相关,女性组中与年龄、FINS、HOMA-IR、TG、SBP正相关,多元逐步回归分析发现腰围、BMI、TG和年龄是独立相关因素;RBP4水平在代谢综合征组和男性组显著升高,在有规律运动组显著降低.(2)代谢综合征组与正常对照组的RBP4-G 803 A多态性基因型分布未见显著差异,按不同基因型分组的代谢指标亦无显著性差异.结论 在中国汉族人群中,RBP4水平与多个代谢参数相关,RBP4基因-G 803 A SNP与代谢综合征没有关联.     

前列地尔Lipo-PGE1干预肝脏血流灌注的实验研究

目的： 探讨前列地尔脂微球(liposome prostaglandin E₁,Lipo-PGE₁) 不同用药时间和途径对肝脏血流灌注的作用机制。方法: 选取健康成年犬12只，经左小隐静脉注射Lipo-PGE₁₁ μg/kg，速度均为0.05 μg·kg^-1·min^-1。分别于0 min、5 min、15 min、30 min后行肝脏CT灌注成像（computed tomography perfusion imaging，CTPI）扫描，计算肝动脉灌注量(hepatic arterial perfusion,HAP)、门静脉灌注量 (portal vein perfusion,PVP)、总肝灌注量（total liver perfusion,TLP），对照分析不同时间Lipo-PGE1对肝脏血流灌注的影响。选取健康成年犬24只，随机平均分成4组：对照组、外周静脉用药组、肝动脉组、肠系膜上动脉组。Lipo-PGE₁的用药量均为1 μg/kg、用药速度均为0.05 μg·kg^-1·min^-1，0.9%生理盐水用量为20 mL。各组用药5 min后行肝脏CTPI，比较分析不同途径给予Lipo-PGE₁对肝脏血流灌注的影响。结果: 经外周静脉注射Lipo-PGE10 min、5 min、15 min、30 min后CTPI测量的HAP(mL·min^-1·mL^-1)分别为：0.22 ±0.65、0.24±0.65、0.22±0.69、0.22±0.06；PVP (mL·min^-1·mL^-1)：1.22±0.40、1.88±0.59、1.55±0.55、1.29 ±0.57；TLP (mL·min^-1·mL^-1)分别为：1.44±0.42、2.12±0.61、1.77±0.56、1.51±0.58。方差分析显示HAP组间比较无显著差异（F=0.249，P>0.05），而PVP、TLP组间比较有显著差异（F=3.812，P<0.05）、（F=3.805，P<0.05）。5 min组PVP、TLP增加最为显著，15 min、30 min时两者仍处于高值水平。对照组和外周静脉组、肝动脉组、肠系膜上动脉组的HAP (mL·min^-1·mL^-1)分别为：0.22±0.06、0.24±0.06、0.31±0.07、0.26±0.05；PVP (mL·min^-1·mL^-1)分别为1.28±0.38、2.33±0.41、2.37±0.55、2.83±0.94；TLP (mL·min^-1·mL^-1)分别为：1.50±0.40、2.57±0.42、2.67±0.58、3.09±0.94。方差分析显示HAP组间比较无显著差异（F=2.248，P>0.05），而PVP、TLP组间比较有显著差异（F=6.892，P<0.01）、（F=7.802，P<0.01）。经肠系膜上动脉给药较其它途径给药PVP、TLP增加趋势更为显著。结论: Lipo-PGE₁能显著增强肝脏血流灌注，且主要影响门静脉灌注分量，介入技术可为快速改善肝血流灌注提供有效途径。     

VEGF、ANG-1、ANG-2、TSP-1的表达与胆管细胞性肝癌血管生成和侵润转移的关系

目的：研究血管内皮生长因子（VEGF）、血管生成素-1（ANG-1）、血管生成素-2（ANG-2）、血小板反应蛋白-1（TSP-1）的表达与胆管细胞性肝癌(CCC)血管生成和侵润转移的关系。方法： 对33例手术切除的CCC标本进行CD34、VEGF、 ANG-1、 ANG-2 和TSP-1的免疫组化染色，研究VEGF、ANG-1、ANG-2、TSP-1的表达与胆管细胞性肝癌血管生成和肿瘤门静脉侵犯、肝内转移、淋巴结转移以及肿瘤分化水平之间的关系。 结果： 本组CCC的微血管密度（MVD）为(87.2±52.6)/mm2，VEGF、ANG-1、ANG-2 和TSP-1的阳性率分别为75.6%、36.0%、57.6%和45.5%。VEGF和ANG-2的阳性表达与高MVD相关，TSP-1则与MVD负相关（P<0.01,P<0.05,P<0.01）。阳性TSP-1与肝内转移正相关（46.7% vs 5.6%，P<0.05）。结论： CCC瘤内的血管新生活跃，VEGF和ANG-2的阳性表达与CCC血管生成正相关，TSP-1则与其负相关，TSP-1的阳性表达还与肝内转移相关，VEGF、ANG-1、ANG-2的表达与肿瘤的侵润转移未见显著相关。