The role of helium ion microscopy in the characterisation of complex three-dimensional nanostructures

This work addresses two major issues relating to Helium Ion Microscopy (HeIM). First we show that HeIM is capable of solving the interpretation difficulties that arise when complex three-dimensional structures are imaged using traditional high lateral resolution techniques which are transmission based, such as scanning transmission electron microscopy (STEM). Secondly we use a nano-composite coating consisting of amorphous carbon embedded in chromium rich matrix to estimate the mean escape depth for amorphous carbon for secondary electrons generated by helium ion impact as a measure of HeIM depth resolution.

Abstract 119: Stabilization of hypoxia-inducible factor-1α by the human rhomboid family-1 gene product RHBDF1

Hypoxia inducible factor 1α (HIF1α) is a key transcription factor in the maintenance of oxygen and energy homoeostasis. Increased levels of HIF1α in cancer cells are often associated with increased tumor angiogenesis, metastasis, drug resistance, and poor prognosis. We reported recently that the human rhomboid family-1 gene (RHBDF1) plays a critical role in facilitating tumor growth. Here, we show that RHBDF1 interacts with and stabilizes HIF1α. RHBDF1 gene-silencing with siRNA leads to markedly decreased HIF1α protein stability and down-regulation of HIF1α-targeted genes. However, HIF1α gene transcription and translation is unaffected. RACK1 and HSP90 are protein factors that compete for binding to HIF1α, causing either oxygen-independent degradation or stabilization of the latter. Protection of HIF1α from degradation by RHBDF1 is the result of a switch of HIF1α binding from RACK1 to HSP90. Stabilization of HIF1a can be abolished by using 17-allylaminogeldanamycin, an inhibitor of HSP90. Moreover, engineered over-expression of RHBDF1 leads to hypoxia-induced resistance of cancer cells to apoptosis-inducing agent Etoposide, an anticancer drug, apparently due to high HIF1α levels. These findings are consistent with the view that RHBDF1 may function as a chaperone to maintain HIF-1α stability.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 119.

Altered global gene expressions of human placentae subjected to assisted reproductive technology treatments

BACKGROUND

Researchers are more and more concerning the safety of fetus or offspring derived from assisted reproductive technology (ART) treatment. As the placenta is a critical organ that sustains and protects the fetus, we hypothesize that altered global gene expression of the placenta subjected to ART manipulation may reflect changes associated with ART procedures and subsequently causal related to offspring health.

METHODS

Three term placenta samples were obtained from patients undergone in vitro fertilization and embryo transfer due to oviductal factors only. Other three control placentae were from those underwent normal pregnancy. A GeneChip Affymetrix HG-U133 Plus 2.0 Array was utilized to analyze the genes. Using qRT-PCR we certified microarray data from 10 dysregulated genes. Five genes were localized precisely in the placenta as per immunohistochemistry.

RESULTS

Twenty-six differentially expressed genes were identified in the ART-treated placentae: 17 up-regulated; 9 down-regulated. Eighteen of these were classified into six groups according to critical placental function: immune response; transmembrane transport; metabolism; oxidative stress; cell differentiation; and other functions. Genes involved in immune response, such as ERAP2 and STAT4, and those regulating cell differentiations, such as MUC1, were discerned to be differentially expressed. These gene products were expressed in the placental villus tissues, either in the cytoplasm or in the membrane of syncytiotrophoblastic cells.

CONCLUSION

To our knowledge, this is the first study in comparing differentially expressed genes in placentae from patients undergone ART treatment vs. those underwent normal pregnancy. Abnormal profiles of critical placental functioning genes, such as ERAP2, STAT4 and MUC1, may be valuable biomarkers to understand how the placenta affects fetal development and ART-derived offspring's health problems.

Interleukin-6 increases intracellular Ca2+ concentration and induces catecholamine secretion in rat carotid body glomus cells

Although abundant evidence indicates mutual regulation between the immune and the central nervous systems, how the immune signals are transmitted to the brain is still an unresolved question. In a previous study we found strong expression of proinflammatory cytokine receptors, including interleukin (IL)-1 receptor I and IL-6 receptor alpha in the rat carotid body (CB), a well-known arterial chemoreceptor that senses a variety of chemostimuli in the arterial blood. We demonstrated that IL-1 stimulation increases intracellular calcium ([Ca(2+)](i)) in CB glomus cells, releases ATP, and increases the discharge rate in carotid sinus nerve. To explore the effect of IL-6 on CB, here we examine the effect of IL-6 on [Ca(2+)](i) and catecholamine (CA) secretion in rat CB glomus cells. Calcium imaging showed that extracellular application of IL-6 induced a rise in [Ca(2+)](i) in cultured glomus cells. Amperometry showed that local application of IL-6 evoked CA release from glomus cells. Furthermore, the CA secretory response to IL-6 was blocked by 200 microM Cd(2+), a well-known Ca(2+) channel blocker. Our experiments provide further evidence for the responsiveness of the CB to proinflammatory cytokines and indicate that the CB might play a role in inflammation sensing and transmission of such information to the brain.