Recycle or die: the role of autophagy in cardioprotection

Autophagy is a highly conserved cellular process responsible for the degradation of long-lived proteins and organelles. Autophagy occurs at low levels under normal conditions, but is upregulated in response to stress such as nutrient deprivation, hypoxia, mitochondrial dysfunction, and infection. Upregulation of autophagy may be beneficial to the cell by recycling of proteins to generate free amino acids and fatty acids needed to maintain energy production, by removing damaged organelles, and by preventing accumulation of protein aggregates. In contrast, there is evidence that enhanced autophagy can contribute to cell death, possibly through excessive self-digestion. In the heart, autophagy has an essential role for maintaining cellular homeostasis under normal conditions and increased autophagy can be seen in conditions of starvation, ischemia/reperfusion, and heart failure. However, the functional significance of autophagy in heart disease is unclear and controversial. Here, we review the literature and discuss the evidence that autophagy can have both beneficial and detrimental roles in the myocardium depending on the level of autophagy, and discuss potential mechanisms by which autophagy provides protection in cells.     

Gene and antisense delivery in alcoholism research

This article represents the proceedings of a symposium at the 2001 annual meeting of the Research Society on Alcoholism in Montreal, Canada. Drs. Yedy Israel and Fulton Crews were organizers and co-chairpersons. The presentations were (1) Introduction to the symposium, by Yedy Israel; (2) Gene delivery to the brain, by Fulton T. Crews; (3) Gene therapy in alcoholic liver injury, by Ronald Thurman; and (4) Antisense oligonucleotides and antisense-gene delivery, by Yedy Israel.     

Changes in body composition, brown adipose tissue activity and thermogenic capacity in BN/BiRij rats undergoing senescence

Metabolic rate, thermogenesis, brown adipose tissue (BAT) activity, and body composition were followed in ageing rats (female BN/BiRij) at 3 to 35.5 months of age. Colonic temperatures were similar in rats at 3 to 23 months of age (37.1–37.6°C), but significantly reduced (36.3°C) in those aged 36 months. Resting oxygen consumption (VO₂), corrected for body size, was comparable in all groups, but the thermogenic response to noradrenaline was significantly reduced with age. BAT mass was unaffected by age, but brown fat protein content, specific mitochondrial cytochrome oxidase activity and thermogenic activity (assessed from mitochondrial purine nucleotide binding) all declined markedly with age.

Carcass analysis revealed a fall in body protein in very old (35.5 month) rats, but body fat content increased up to 23 months of age and thereafter declined.     

Lifespan and reproduction in Drosophila: New insights from nutritional geometry

Modest dietary restriction (DR) prolongs life in a wide range of organisms, spanning single-celled yeast to mammals. Here, we report the use of recent techniques in nutrition research to quantify the detailed relationship between diet, nutrient intake, lifespan, and reproduction in Drosophila melanogaster. Caloric restriction (CR) was not responsible for extending lifespan in our experimental flies. Response surfaces for lifespan and fecundity were maximized at different protein-carbohydrate intakes, with longevity highest at a protein-to-carbohydrate ratio of 1:16 and egg-laying rate maximized at 1:2. Lifetime egg production, the measure closest to fitness, was maximized at an intermediate P:C ratio of 1:4. Flies offered a choice of complementary foods regulated intake to maximize lifetime egg production. The results indicate a role for both direct costs of reproduction and other deleterious consequences of ingesting high levels of protein. We unite a body of apparently conflicting work within a common framework and provide a platform for studying aging in all organisms.     

维甲酸、三氧化二砷诱导NB4细胞TRAIL基因表达的研究

目的：研究全反式维甲酸(ATRA)或三氧化二砷(As2O3)诱导急性早幼粒细胞白血病(APL)NB4细胞肿瘤坏死因子相关的凋亡诱导配体(TRAIL)基因的表达及其治疗APL的机制。方法：采用RT—PCR检测TRAIL基因表达的变化。结果：10^-6mol／L的ATRA作用6h或10^-6mol／L的As2O3作用12h，即可诱导TRAIL基因表达。结论：ATRA或As2O3能诱导NB4细胞TRAIL基因表达，TRAIL基因可能以类似“旁分泌”的作用方式杀伤NB4细胞。诱导TRAIL基因介导的细胞凋亡可能是ATRA或As2O3治疗APL的机制之一。     

Long recovery times improve the detection of cellular resistance in vitro

In vitro cytotoxicity testing is used increasingly during the development of clinical treatment protocols. These tests are influenced by many variables, not all of which have been assessed systematically yet. We analyzed the influence of the recovery time between the end of treatments and measurements on the detection of cellular resistance. The development of resistance to cisplatin and radiation was chosen as a model since the schedule of these treatments is the objective of several ongoing clinical trials. C6 rat glioma, T98G, 86HG-39, A172 human glioma and TE671 human rhabdomyosarcoma cells were pretreated with radiation or cisplatin. The cellular resistance was then compared in pretreated and wild-type cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. In all cell lines, apparent drug concentrations killing 50% of the cells were dependent on the recovery time. In A172 cells this concentration was 10.3 ± 02.1 μM after 48 h but decreased to 3.56 ± 0.44 μM after 120 h recovery time (P < 0.001). After recovery times of more than 168 h, 53% of all pretreated cell lines were resistant to cisplatin or radiation, 25% were unchanged and 22% were more sensitive. However, only half the resistant cells could be identified when the MTT test was done with only 48 h recovery time. The sensitivity of detection increased from 0.46 to 0.83 when the recovery time of the test system was extended from 48 h to 168 h. The specificity was not dependent on the recovery time. Experi-ments showing resistance after short recovery times are reliable, but lack of resistance can only be shown in experiments with long recovery times. Cisplatin treatment can result in resistance to radiation in glioma cells. Received: 7 March 1997 / Accepted: 18 March 1998     

Insights into the mechanisms of alveolarization - Implications for lung regeneration and cell therapies

Although the lung has extensive regenerative capacity, some diseases affecting the distal lung result in irreversible loss of pulmonary alveoli. Hitherto, treatments are supportive and do not specifically target tissue repair. Regenerative medicine offers prospects to promote lung repair and regeneration. The neonatal lung may be particularly receptive, because of its growth potential, compared to the adult lung. Based on our current understanding of neonatal lung injury, the ideal therapeutic approach includes mitigation of inflammation and fibrosis, and induction of regenerative signals. Cell-based therapies have shown potential to prevent and reverse impaired lung development. Their mechanisms of action suggest effects on both, mitigating the pathophysiological processes and promoting lung growth. Here, we review our current understanding of normal and impaired alveolarization, provide some rationale for the use of cell-based therapies and summarize current evidence for the therapeutic potential of cell-based therapies for pulmonary regeneration in preterm infants.     

老年肺炎患者IFN-γ和IL-4在CD8^＋T细胞中的表达及临床意义

目的探讨免疫衰老在老年肺炎中的作用。方法随机选择青年、老年健康志愿者各15人,青年、老年肺炎患者各20例,采用流式细胞分析技术检测各组样本外周血CD4 /CD8 的比值,CD3 、CD4 和CD8 T细胞胞内IFN-γ和IL-4的表达。结果①老年组外周血CD4 /CD8 的比值高于青年组,而肺炎和非肺炎组之间差异无显著性。②各组外周血CD3 、CD4 T细胞胞内IFN-γ和IL-4表达的差异无显著性,而CD8 T细胞胞内IFN-γ的表达,老年组高于青年组(P<0.05),而相同年龄组的肺炎和非肺炎组之间差异无显著性。CD8 T细胞胞内IL-4的表达老年肺炎组高于其他3组(P<0.05),青年健康组、青年肺炎组、老年健康组之间差异无显著性。③在4组之间IFN-γ/IL-4的比值差异无显著性。结论免疫衰老在CD4 、CD8 T细胞明显不同,CD4 T细胞胞内分泌IFN-γ和IL-4差异无显著性,而CD8 T细胞IFN-γ的产生在老年人显著增加,IL-4的产生仅在老年肺炎组增加。CD8 T细胞的增龄性改变可能在老年人肺炎中发挥重要作用。     

双萘酰亚胺类化合物诱导SMMC-7721细胞凋亡的研究

目的 观察双萘酰亚胺类化合物(C8)对人肝癌细胞株SMMC-7721细胞的作用. 方法 四甲基偶氮唑盐法检测C8对SMMC 7721细胞的抑制情况;流式细胞术检测细胞周期和凋亡率;Western blot检测Bcl 2蛋白表达量;流式细胞术分析细胞内Bcl 2蛋白量;酶联免疫法检测Caspase9和Caspase 3表达量. 结果 C8抑制SMMC 7721细胞增殖,半数抑制浓度为15 umol/L.C8作用浓度在10,15、20 umol/L时,SMMC 7721细胞的凋亡比例分别为16.8%、29.4%和35.8%,对照组为2.1%,SMMC 7721细胞的凋亡率明显高于对照组,P<0.01.细胞内Bcl-2蛋白表达水平下降.酶联免疫检测结果表明Caspase 9和Caspase 3被活化.结论 C8可诱导人肝癌SMMC 7721细胞的凋亡,为抗肿瘤药物的研究提供新的化合物.     

胰岛素样生长因子1受体抗体对大鼠血管平滑肌细胞增殖的影响

目的观察胰岛素样生长因子1受体抗体对大鼠血管平滑肌细胞增殖的影响。方法球囊导管损伤大鼠一侧颈总动脉,7天后体外培养受损血管的中膜平滑肌细胞,以损伤侧血管细胞为实验组,以对侧正常血管中膜平滑肌细胞为对照组;采用-αactin免疫细胞化学法进行细胞鉴定;在细胞的培养悬液中加入不同浓度的胰岛素样生长因子1受体抗体作用24 h,然后采用5-溴-2脱氧尿苷细胞增殖检测法检测细胞的增殖程度。结果大鼠颈总动脉球囊损伤后,体外培养的中膜平滑肌细胞表现出显著的增殖性(与对照组比较,P<0.01);胰岛素样生长因子1受体抗体可以显著抑制大鼠平滑肌细胞的增殖,呈现出浓度依赖性特征(组间比较,P<0.01)。结论胰岛素样生长因子1受体抗体具有抑制平滑肌细胞增殖的作用,有望用于治疗平滑肌细胞增殖性疾病。