Licorice compounds glycyrrhizin and 18beta-glycyrrhetinic acid are potent modulators of bile acid-induced cytotoxicity in rat hepatocytes

The accumulation of hydrophobic bile acids results in cholestatic liver injury by increasing oxidative stress, mitochondrial dysfunction, and activation of cell signaling pathways. Licorice root and its constituents have been utilized as antihepatotoxic agents. The purpose of this study was to evaluate the potential modulation by a primary component of licorice root, glycyrrhizin (GL), and its metabolite, 18beta-glycyrrhetinic acid (GA), in a hepatocyte model of cholestatic liver injury. Preincubation of fresh rat hepatocyte suspensions with GL or GA reduced glycochenodeoxycholic acid (GCDC)-dependent reactive oxygen species generation, with GA more potent than GL. Interestingly, GL and GA had opposing effects toward GCDC-induced cytotoxicity; GA prevented both necrosis and apoptosis, whereas GL enhanced apoptosis. GCDC promoted activation of caspase 10, caspase 3, and PARP; all were inhibited by GA but not GL. Induction of apoptosis by GCDC was also associated with activation of JNK, which was prevented by GA. Activation of caspase 9 and dissipation of mitochondrial membrane potential were prevented by GA but not GL. In liver mitochondrial studies, GL and GA were both potent inhibitors of the mitochondrial permeability transition, reactive oxygen species generation, and cytochrome c release at submicromolar concentrations. Results from this study suggest that GL exhibits pro-apoptotic properties, whereas GA is a potent inhibitor of bile acid-induced apoptosis and necrosis in a manner consistent with its antioxidative effect.     

A role for Wnts in morpho-genesis and tissue polarity

Recent studies have shown that secreted Wnt proteins control morphogenetic movements in fish and frog embryos. The analysis of Dishevelled, a cytoplasmic mediator of Wnt signalling, reveals unexpected similarity between gastrulation in vertebrates and polarization of cells in Drosophila epithelia.     

Quorum-sensing mutations affect attachment and stability of Burkholderia cenocepacia biofilms

Biofilm formation in Burkholderia cenocepacia has been shown to rely in part on acylhomoserine lactone-based quorum sensing. For many other bacterial species, it appears that both the initial adherence and the later stages of biofilm maturation are affected when quorum sensing pathways are inhibited. In this study, we examined the effects of mutations in the cepIR and cciIR quorum-sensing systems of Burkholderia cenocepacia K56-2 with respect to biofilm attachment and antibiotic resistance. We also examined the role of the cepIR system in biofilm stability and structural development. Using the high-throughput MBEC assay system to produce multiple equivalent biofilms, the biomasses of both the cepI and cepR mutant biofilms, measured by crystal violet staining, were less than half of the value observed for the wild-type strain. Attachment was partially restored upon providing functional gene copies via multicopy expression vectors. Surprisingly, neither the cciI mutant nor the double cciI cepI mutant was deficient in attachment, and restoration of the cciI gene resulted in less attachment than for the mutants. Meanwhile, the cciR mutant did show a significant reduction in attachment, as did the cciR cepIR mutant. While there was no change in antibiotic susceptibility with the individual cepIR and cciIR mutants, the cepI cciI mutant biofilms were more sensitive to ciprofloxacin. A significant increase in sensitivity to removal by sodium dodecyl sulfate was seen for the cepI and cepR mutants. Flow cell analysis of the individual cepIR mutant biofilms indicated that they were both structurally and temporally impaired in attachment and development. These results suggest that biofilm structural defects might be present in quorum-sensing mutants of B. cenocepacia that affect the stability and resistance of the adherent cell mass, providing a basis for future studies to design preventative measures against biofilm formation in this species, an important lung pathogen of cystic fibrosis patients.     

The effect of IQGAP1 on Xenopus embryonic ectoderm requires Cdc42

IQGAP1 contains a number of protein recognition motifs through which it binds to targets. Several in vitro studies have documented that IQGAP1 interacts directly with calmodulin, actin, E-cadherin, beta-catenin, and the small GTPases Cdc42 and Rac. Nevertheless, direct demonstration of in vivo function of mammalian IQGAP1 is limited. Using a novel assay to evaluate in vivo function of IQGAP1, we document here that microinjection of IQGAP1 into early Xenopus embryos generates superficial ectoderm lesions at late blastula stages. This activity was retained by the mutated variants of IQGAP1 in which the calponin homology domain or the WW domain was deleted. By contrast, deletion of the IQ (IQGAP1-DeltaIQ), Ras-GAP-related (IQGAP1-DeltaGRD), or C-terminal (IQGAP1-DeltaC) domains abrogated the effect of IQGAP1 on the embryos. None of the latter mutants bound Cdc42, suggesting that the binding of Cdc42 by IQGAP1 is critical for its function. Moreover, overexpression of IQGAP1, but not IQGAP1-DeltaGRD, significantly increased the amount of active Cdc42 in embryonic cells. Co-injection of wild type IQGAP1 with dominant negative Cdc42, but not the dominant negative forms of Rac or Rho, blocked the effect of IQGAP1 on embryonic ectoderm. Together these data indicate that the activity of IQGAP1 in embryonic ectoderm requires Cdc42 function.     

高等植物中的磷酸烯醇式丙酮酸羧激酶

简要介绍了近年来有关高等植物中磷酸烯醇式丙酮酸羧激酶（ＰＥＰＣＫ）的研究进展,并讨论了此酶的结构、功能和调节等方面的问题。     

Differences in need for antihypertensive drugs among those aware and unaware of their hypertensive status: a cross sectional survey

Peripheral arterial disease (PAD) is a common, progressive manifestation of atherothrombotic vascular disease, which should be managed no different to cardiac disease. Indeed, there is growing evidence that PAD patients are a high risk group, although still relatively under-detected and under treated. This is despite the fact that PAD patients are an increased mortality rate comparable to those with pre-existing or established cardiovascular disease [myocardial infarction, stroke]. With a holistic approach to atherothrombotic vascular disease, our management of PAD can only get better.