Flying insects: model systems in exercise physiology

Insect flight is the most energy-demanding exercise known. It requires very effective coupling of adenosine triphosphate (ATP) hydrolysis and regeneration in the working flight muscles.³¹P nuclear magnetic resonance (NMR) spectroscopy of locust flight muscle in vivo has shown that flight causes only a small decrease in the content of ATP, whereas the free concentrations of inorganic phosphate (P _i ), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were estimated to increase by about 3-, 5- and 27-fold, respectively. These metabolites are potent activators of glycogen phosphorylase and phosphofructokinase (PFK). Activation of glycolysis by AMP and P _i is reinforced synergistically by fructose 2,6-bisphosphate (F2,6P₂), a very potent activator of PFK. During prolonged flight locusts gradually change from using carbohydrate to lipids as their main fuel. This requires a decrease in glycolytic flux which is brought about, at least in part, by a marked decrease in the content of F2,6P₂ in flight muscle (by 80% within 15 min of flight). The synthesis of F2,6P₂ in flight muscle can be stimulated by the nervous system via the biogenic amine octopamine. Octopamine and F2,6P₂ seem to be part of a mechanism to control the rate of carbohydrate oxidation in flight muscle and thus function in the metabolic integration of insect flight.Dedicated to Dr. Ernst Zebe, Emeritus Professor of Zoology (University of Münster) on the occasion of his 70th birthday.     

Effect of L-carnitine and stimulated lipolysis on muscle substrates in the exercising rat

Summary To test the effect of L-carnitine on glycogen sparing when fat oxidation is increased, 100 mg/kg/d were given to rats orally for 3 days, resulting in 1.8-fold higher muscle carnitine levels. Even when FFA were raised by heparin-stimulated lipolysis, the rate of glycogen degradation was not reduced during exercise.     

Carbon tetrachloride modulates the rat hepatic microsomal UDP-glucuronyl transferase activity and membrane fluidity

Summary Modulations in rat hepatic microsomal UDP-glucuronyl transferase activity have been observed during carbon tetrachloride (CCl₄) poisoning, with a large decrease in the enzyme cooperativity and increase in the membrane fluidity, occurring 30 min after administration. The results strengthen the possibility that an increase in microsomal membrane fluidity may be an early key event in liver injury induced by CCl₄.Acknowledgments. This work was supported by funds of the University of Athens.     

miR-194-5p通过Wnt5a抑制肝星状细胞活化

为研究miR-194-5p对肝星状细胞(HSCs)活化的影响及作用机制,采用CCK-8、β-半乳糖苷酶染色、Transwell、划痕、集落形成实验和RT-qPCR、Western blot分别检测miR-194-5p对LX-2细胞生物学特性、细胞活化标志物和靶基因表达的影响,并用生物信息学和双荧光素酶报告实验确定miR-194-5p靶基因.结果显示：miR-194-5p抑制LX-2细胞增殖、细胞集落形成、迁移能力以及LX-2细胞中活化标志物的表达,促进LX-2细胞衰老;Wnt5a为miR-194-5p的直接靶基因.研究表明miR-194-5p通过靶定Wnt5a抑制LX-2细胞活化,miR-194-5p和Wnt5a可能是治疗肝纤维化新的靶点.     

p16基因在原发性肝癌中丢失的研究

为了解抗癌基因Ｐ＾１６在原发性肝癌中的变异情况，采用判别技术研究３４例原发性肝癌及其癌组织。结果显示、１例原发性肝癌存在Ｐ＾１６Ｅｘｏｎｌ纯合子缺失，１５例原发怀肝癌存在Ｐ＾１６Ｅｘｏｎ２纯合子缺失，其余的１９例肝癌及所有的癌周组织无Ｐ＾１６基因纯合子失，研究结果表明Ｐ＾１６基因的缺失与原发性肝癌的发展发展密切相关，并提供了肝癌第９号染色体基因变的依据。     

Hepatic hydroxylation of melatonin in the rat is induced by phenobarbital and 7,12-dimethylbenzy[a]anthracene — implications for cancer etiology

The protective function of the pineal hormone melatonin in the etiology of cancer and carcinogenic activation is increasingly well-established. Low melatonin levels seem to parallel cancer growth. The question arises as to which factors cause the depression of melatonin levels and what the direct effects are. Melatonin is known to be metabolized in the liver by hydroxylation and subsequent conjugation yielding 6-sulfatoxymelatonin as a main product. Nevertheless, the microsomal monoxygenases catalyzing the first step have been poorly investigated. To further characterize these enzymes, typical inducers of three different sub-classes, namely phenobarbital, 7,12-dimethylbenz[a]anthracene, and 17-estradiol, were administered to female Fischer rats. Circadian urinary excretion patterns of melatonin and 6-sulfatoxymelatonin were determined over a 24-hour period on the third (second) day of induction. Liver homogenates were used to monitor the in vitro conversion of melatonin or 6-hydroxymelatonin to 6-sulfatoxymelatonin. Results of both approaches showed the microsomal monoxygenases catalyzing the 6-hydroxylation of melatonin to be strongly inducible by phenobarbital and to a lesser degree by the polyaromatic hydrocarbon 7,12-dimethylbenz[a]anthracene. The dramatic depletion of circulating melatonin as a result of these induction patterns and its possible implications for oncogenesis are discussed.     

能谱CT碘基图对肝细胞癌化疗栓塞术后瘤体血供的分析

目的:探讨能谱CT碘基图对肝癌肝动脉化疗栓塞术(TACE)后肿瘤血供的判断作用.方法:随机抽取65例肝脏肿瘤患者能谱CT成像资料进行回顾分析,均病理诊断为肝细胞性肝癌,且在TACE术后3周进行肝脏能谱CT检查.所有患者均获得常规混合能量图像和能谱图像,通过后处理工作站对能谱图像进行碘基图像重建,再对栓塞术后瘤体进行碘浓度测量、比较.结果:在65例肝癌化疗栓塞术后患者中,5例(第1组)患者动脉期瘤体的IC病灶与周围正常肝组织的IC肝脏之间有统计学意义(P0.05),门脉期的IC病灶与IC肝脏之间没有统计学意义(P0.05),动脉期与门脉期LNR有统计学意义(P0.05);其他60例(第2组)患者动脉期瘤体的IC病灶与周围正常肝组织IC肝脏之间没有统计学意义(P0.05),门脉期的IC病灶与IC肝脏之间没有统计学意义(P0.05),动脉期与门脉期LNR没有统计学意义(P0.05).数字血管减影检查(DSA)复查证实只有5例(第1组)患者瘤体仍有动脉供血,60例(第2组)患者瘤体没有动脉供血.结论:能谱CT碘基图能判断肝细胞性肝癌肝动脉化疗栓塞术后肿瘤瘤体血供情况,为临床进一步治疗提供有价值的影像依据.     

趋化因子IL-8和受体CXCR1,CXCR2在胃肠和肝肿瘤中的表达

为研究趋化因子IL-8和受体CXCR1、CXCR2在胃肠和肝肿瘤中的作用,应用免疫组织化学和RT-PCR的方法检测了趋化因子IL-8和受体CXCR1、CXCR2在食道癌、胃癌、结直肠癌和肝癌中的表达。在胃肠肿瘤中,CXCR1在癌细胞的细胞核膜和细胞质中表达,CXCR2在癌细胞的细胞质中表达。在肝癌中,CXCR1和CXCR2在癌巢中有表达而在邻近的肝组织中无表达。应用RT-PCR的方法检测了受体CXCR1、CXCR2的转录,其结果证实了免疫组织化学的结果。在胃肠和肝肿瘤中检测到了IL-8的表达。进一步分析表明在胃肠和肝肿瘤中IL-8与CXCR1/CXCR2共表达(p=0.0448)。实验结果说明趋化因子IL-8和受体CXCR1、CXCR2可能在胃肠和肝肿瘤的发生和发展中起作用。     

肝硬化肝切除术后肝再生及评估指标研究

原发性肝癌是我国的常见病、多发病,且90%的患者合并有肝硬化,肝切除术是主要的治疗方法,而肝脏在受到损害或切除之后,可以显示出强大的再生能力,这一现象早已被人们所发现并研究.就肝硬化肝切除术后肝再生、肝再生受损机制以及肝再生评估予以综述.     

甲状腺素对雏鸡肝糖原、肌糖原及肝脏脂肪含量的影响

本试验经过对用外科手术去除了甲状腺的雏鸡进行研究,探讨了甲状腺素对鸡肝糖原和肌糖原含量及肝脏脂肪含量的影响,结果表明:甲状腺素对肝脏和肌肉中糖原含量具有调节作用.