bluuebunny/crossref_metadata_2025 huggingface dataset:
New Insights into the Genetics of Familial Chromaffin Cell Tumors
Authors: KOCH CHRISTIAN A. , VORTMEYER ALEXANDER O. , ZHUANG ZHENGPING , BROUWERS FREDERIEKE M. , PACAK KAREL
Published: July 2009

Abstract: We review genetic aspects and recent advances in our understanding of the molecular pathogenesis of familial chromaffin cell tumors (pheochromocytoma, paraganglioma). About 10 percent of pheochromocytomas are familial and occur as part of multiple endocrine neoplasia type 2 (MEN 2), von Hippel‐Lindau (VHL) disease, and neurofibromatosis type 1 (NF 1). A subset of paragangliomas, tumors that can also produce and secrete catecholamines, are also familial and occur in patients with germline mutations in genes that encode subunits of the mitochondrial complex II. The precise molecular mechanisms underlying the pathogenesis of chromaffin cell tumors remain widely unknown, although recent studies in hereditary tumors help elucidate their development. In MEN 2, overrepresentation of mutant RET in selected adrenomedullary cells may be an important mechanism in initiating the formation of a pheochromocytoma. In VHL disease, pheochromocytoma development appears to occur according to Knudson's two‐hit model, a VHL germline mutation and wildtype allelic deletion. Tumorigenesis of NF1‐associated pheochromocytomas remains unknown, as does tumor formation (i.e., carotid body tumor) in patients with germline mutations in SDHB, SDHC, and SDHD, genes that encode subunits of the mitochondrial complex II, the smallest complex in the respiratory chain. Many genetic alterations have been found in sporadic chromaffin cell tumors. However, at present such genetic changes are difficult to place into context with regard to tumor formation and progression.
Primary Aldosteronism
Authors: YOUNG WILLIAM F.
Published: July 2009

Abstract:Since its initial description in 1955, primary aldosteronism was thought to be a rare cause of hypertension. However, improved screening methods show that primary aldosteronism is a common form of secondary hypertension. Diagnosis of this disorder results in improved or cured hypertension or targeted pharmacotherapy. Patients with hypertension and hypokalemia and most patients with treatment‐resistant hypertension should undergo screening for primary aldosteronism. A random and ambulatory ratio of plasma aldosterone concentration (PAC) to plasma renin activity (PRA) that is elevated and a PAC higher than a set cutoff is a positive screen for primary aldosteronism. An increased PAC/PRA ratio alone is not diagnostic of primary aldosteronism; primary aldosteronism must be confirmed by demonstrating inappropriate aldosterone secretion with either the intravenous saline suppression test or measurement of 24‐hr urinary aldosterone while the patient is on a high‐sodium diet. The two major subtypes of primary aldosteronism are unilateral aldosterone‐producing adenoma (APA) and bilateral idiopathic hyperplasia (IHA). Patients with APA are usually treated with unilateral adrenalectomy, and patients with IHA are treated medically. The subtype evaluation may require one or more tests, the first of which is imaging the adrenals with computerized tomography (CT). When a solitary unilateral macroadenoma (> 1 cm) and normal contralateral adrenal morphologic pattern are found on CT in a young patient with primary aldosteronism, unilateral laparoscopic adrenalectomy is a reasonable therapeutic option. However, in many cases, CT imaging may reveal normal‐appearing adrenals or ambiguous findings. Adrenal venous sampling helps to resolve these clinical dilemmas.
Diagnostic Tests for Cushing's Syndrome
Authors: NIEMAN LYNNETTE K.
Published: July 2009

Abstract: The diagnosis of Cushing's syndrome rests on the demonstration of clinical features and biochemical abnormalities that reflect hypercortisolism. If a patient presents with typical clinical features such as weight gain with truncal obesity and supraclavicular fat deposition, wide purple striae, and proximal muscle weakness, the diagnosis is clear‐cut and is nearly always substantiated by a 24‐hour urine free cortisol excretion value more than four times the normal level. However, many patients present with signs and symptoms that are common in the general population, such as hypertension, generalized weight gain, reproductive abnormalities, and depression. Many of these patients have normal cortisol excretion and do not have Cushing's syndrome. Others have mild hypercortisolism caused by psychiatric disorders, obligate exercise, morbid obesity, sleep apnea, or uncontrolled diabetes mellitus. These patients may be confused with those with the true Cushing's syndrome, and thus are considered to have a “pseudo‐Cushing” state. Additional observation over time, and testing with midnight cortisol measurements, the 2‐day‐2‐mg dexamethasone suppression test, or the dexamethasone suppression‐CRH stimulation test may be useful to identify true Cushing's syndrome in these patients.
Cholinergic and Peptidergic Regulation of PhenylethanolamineN‐Methyltransferase Gene Expression
Authors: WONG DONA LEE , ANDERSON LEAH J. , TAI TZE‐CHUN
Published: July 2009

Abstract:The splanchnic nerve, innervating the adrenal medulla, releases a variety of neurotransmitters that stimulate genes involved in catecholamine biosynthesis. In particular, cholinergic agonists have been shown to induce phenylethanolamineN‐methyltransferase (PNMT) gene expression through activation of both nicotinic and muscarinic receptorsin vivoandin vitro. By contrast, the role of peptidergic neurotransmitters in adrenal medullary PNMT gene expression remains unclear. Using transient transfection assays, we demonstrate that rat PNMT promoter‐luciferase reporter gene constructs are markedly activated by 10 nM PACAP when expressed in PC12 cells. PACAP appears to mediate its effects primarily through PAC1 receptors and, subsequently, cAMP‐protein kinase A (PKA) and extracellular Ca2+signaling mechanisms. Activation of these signal transduction pathways markedly increases nuclear levels of the immediately early gene transcription factor Egr‐1 and the developmental factor AP2. A slight decrease in Sp1 expression may also occur, whereas MAZ and glucocorticoid receptor expression remains unaltered. Although PACAP stimulates rapid changes in transcription factor expression and PNMT promoter activity, its effects are long lasting. PNMT promoter induction continues to rise and is sustained for ≥48 hours. By contrast, while muscarine, nicotine, or carbachol (100 μM) also evoke rapid increases in rat PNMT promoter activity, peak activity is observed at 6 hours, followed by a decline and restoration to basal levels by 24 hours. Cholinergic activation of the PNMT promoter also seems to involve the cAMP‐PKA signaling mechanism. However, the magnitude of stimulation and antagonist blockade with H‐89 or the polypeptide inhibitor PKI suggests that the extent of activation is much less than that with PACAP.
In Situ Chelation of Ca2+ in Intracellular Stores Induces Capacitative Ca2+ Entry in Bovine Adrenal Chromaffin Cells
Authors: POWIS DAVID A. , ZERBES MARIANN
Published: July 2009

Abstract: Reduction of intracellular Ca2+ stores (by chelation with the EDTA structural analogue, TPEN) is itself a sufficient trigger of capacitative Ca2+ entry. TPEN may be a useful tool in studies to investigate the mechanism of capacitative Ca2+ entry, since potential confounders, such as changes in cytosolic Ca2+ and second messenger levels, are obviated and the use of pharmacological modifiers of SERCA pumps and Ca2+ release channels is avoided.
Regulated Secretion in Chromaffin Cells
Authors: VITALE NICOLAS , CHASSEROT‐GOLAZ SYLVETTE , BADER MARIE‐FRANCE
Published: July 2009

Abstract: ARFs constitute a family of structurally related proteins that forms a subset of the ras GTPases. In chromaffin cells, secretagogue‐evoked stimulation triggers the rapid translocation of ARF6 from secretory granules to the plasma membrane and the concomitant activation of PLD in the plasma membrane. Both PLD activation and catecholamine secretion are strongly inhibited by a synthetic peptide corresponding to the N‐terminal domain of ARF6. ARNO, a potential guanine nucleotide exchange factor for ARF6, is expressed and localized in the plasma membrane of chromaffin cells. Using permeabilized cells, we found that the introduction of anti‐ARNO antibodies into the cytosol inhibits both PLD activation and catecholamine secretion. Chromaffin cells express PLD1 at the plasma membrane. We found that microinjection of the catalytically inactive PLD1(K898R) dramatically reduces catecholamine secretion monitored by amperometry, most likely by interfering with a late postdocking step of calcium‐regulated exocytosis. We propose that ARNO‐ARF6 participate in the exocytotic reaction by controlling the plasma membrane‐bound PLD1. By generating fusogenic lipids at the exocytotic sites, PLD1 may represent an essential component of the fusion machinery in neuroendocrine cells.
Large Dense‐Core Secretory Granule Biogenesis Is under the Control of Chromogranin A in Neuroendocrine Cells
Authors: KIM TAEYOON , TAO‐CHENG JUNG‐HWA , EIDEN LEE E. , LOH Y. PENG
Published: July 2009

Abstract: The large dense‐core secretory granule is an organelle in neuroendocrine/endocrine cells, where prohormones and proneuropeptides are stored, processed, and secreted in a regulated manner. Here we present evidence that chromogranin A (CgA), one of the most abundant acidic glycoproteins ubiquitously present in neuroendocrine/endocrine cells, regulates dense‐core secretory granule biogenesis. Specific depletion of CgA expression by antisense RNAs in PC12 cells led to a profound loss of secretory granule formation. An exogenously expressed prohormone, pro‐opiomelanocortin, was neither stored nor secreted in a regulated manner in CgA‐deficient PC12 cells. Overexpression of bovine CgA into CgA‐deficient PC12 cells rescued regulated secretion. Other secretory granule proteins, such as chromogranin B (CgB), carboxypeptidase E, and synaptotagmin, were rapidly degraded, whereas nongranule proteins were not affected in CgA‐deficient PC12 cells. Unlike CgA, another granin protein CgB could not substitute for the role of CgA in secretory granule biogenesis. Thus, we conclude that CgA is a master “on/off” switch regulating the formation of the dense‐core secretory granule in neuroendocrine cells.
Circle of Life of Secretory Vesicles in Gastric Enterochromaffin‐Like Cells
Authors: ZANNER ROBERT , GRATZL MANFRED , PRINZ CHRISTIAN
Published: July 2009

Abstract: Enterochromaffin‐like (ECL) cells are neuroendocrine cells in the gastric epithelium characterized by numerous electron‐empty, histamine‐containing secretory vesicles. The antral hormone gastrin is the key stimulus of histamine secretion from this cell type, thereby controling acid secretion. Following receptor binding, gastrin activates a biphasic calcium signal in ECL cells that involves activation of inositol triphosphate receptors and calcium entry across the plasma membrane. Dihydropyridines block gastrin‐induced histamine secretion. However, no depolarization was observed following stimulation with gastrin. Elevation of intracellular calcium by gastrin is an important prerequisite for exocytosis. In permeabilized ECL cells, addition of calcium results in histamine release, which can be inhibited by tetanus toxin and botulinum neurotoxin A, underlining the functional importance of the synaptosome‐associated protein of 25 kDa (SNAP‐25) and synaptobrevin. Immunocytochemistry also confirmed the presence of these SNAP receptor (SNARE) proteins, as well as synaptophysin, synaptotagmin, and syntaxin. Following 3‐6 h of incubation in isolated cells, several transcription factors are induced by gastrin, such as ERK1/2, Sp1, and CRE. Gastrin thereby directly stimulates transcription of the vesicular monoamine transporter subtype 2 (VMAT‐2) and chromogranins. Gene expression of histidine decarboxylase (HDC) appears to be stimulated by a putative “gastrin‐responsive” element adjacent to the HDC exon 1 gene. ECL cells thereby share several similarities with adrenal chromaffin cells and neurons, but have their own functional properties. Gastrin coordinates secretion, synthesis, and storage by activating diverging signal transducers, leading to a functional synergy in this cell type.
Protein Trafficking to Chromaffin Granules and Proteolytic Processing within Regulated Secretory Vesicles of Neuroendocrine Chromaffin Cells
Authors: HOOK VIVIAN , METZ‐BOUTIGUE MARIE‐HÉLÈNE
Published: July 2009

Abstract: Proteolytic processing within secretory vesicles is required for the production and secretion of biologically active peptide neurotransmitters and hormones, known collectively as neuropeptides. This chapter addresses several new aspects of proteolysis in secretory vesicles, chromaffin granules, with respect to sorting proneuropeptides or prohormones into such regulated secretory vesicles that use specific prohormone sorting signals. Concomitant with prohormone sorting, evidence for the role of chromogranin A in secretory granule biogenesis is presented. Secretory vesicle function involves endogenous serpin protease inhibitors for the regulation of proteolysis. The novel serpins endopin 1 and endopin 2 possess high homology to a1‐antichymotrypsin, yet they possess distinct target protease specificities. The serpins PAI‐1 and neuroserpin are also localized to chromaffin granules. In addition, regulation of secretory vesicle function involves cytochrome b561 that regulates reducing equivalents to maintain the intravesicular redox state. These studies demonstrate multiple components as regulatory factors in the control of secretory vesicle function for the biosynthesis and secretion of neuropeptides and catecholamines.
Novel Chromaffin Granule Serpins, Endopin 1 and Endopin 2
Authors: HOOK VIVIAN Y.H. , YASOTHORNSRIKUL SUKKID , HWANG SHIN‐RONG
Published: July 2009

Abstract: Endopin 1 and endopin 2 represent two novel serpin protease inhibitors localized within chromaffin granules, secretory vesicles of adrenomedullary chromaffin cells that represent a model neuroendocrine cell for synthesis and secretion of peptide neurotransmitters. This chapter describes the molecular features of the primary sequences of endopin 1 and endopin 2 that provided prediction of their distinct target protease specificities. Endopin 1 inhibits trypsin that cleaves at basic residues. In contrast, endopin 2 possesses cross‐class inhibition of papain and elastase that represent cysteine and serine proteases, respectively. Cell biological studies indicate that endopin 1 and endopin 2 are localized within chromaffin granules. These results implicate endopin 1 inhibition in vivo of trypsin‐like proteases in secretory vesicles, and endopin 2 inhibition of papain‐ or elastase‐like proteases. Indeed, endopin 2 inhibits the endogenous cysteine protease PTP (prohormone thiol protease), present in chromaffin granules, that participates in the proteolytic processing of proenkephalin. These findings indicate the presence of endogenous endopin 1 and endopin 2 in secretory vesicle function.
Fast‐Breaking Results on the PACAP/VIP/Secretin Peptide Family in Chromaffin Cells
Authors: VAUDRY DAVID , TAUPENOT LAURENT
Published: July 2009

Abstract:The neuropeptide pituitary adenylyl cyclase‐activating polypeptide (PACAP) has been reported to be a potent regulator of chromaffin cell activity. In particular, PACAP stimulates catecholamine biosynthesis as well as the expression of various genes, including chromogranin A, neuropeptide Y, enkephalins, vasoactive intestinal polypeptide, and PACAP itself. The mechanisms involved in the effects of PACAP on chromaffin cells have been investigated using rat pheochromocytoma PC12 cells. This cell line turned out to be a suitable model in which to study the neurotrophic activities of PACAP. Recent studies using transgenic mice have shown that in the sympathoadrenal system, PACAP acts as an “emergency response” cotransmitter involved in the regulation of insulin‐induced hypoglycemia.
Regulation of Catecholamine Synthesis by Leptin
Authors: SHIBUYA IZUMI , UTSUNOMIYA KENSUKE , TOYOHIRA YUMIKO , UENO SUSUMU , TSUTSUI MASATO , CHEAH TAT BENG , UETA YOICHI , IZUMI FUTOSHI , YANAGIHARA NOBUYUKI
Published: July 2009

Abstract:Obesity is often associated with cardiovascular and metabolic disorders such as hypertension and hyperglycemia. Leptin, a protein product of the obese gene, regulates satiety and energy expenditure through its receptors in the hypothalamus. Recent studies have shown that leptin has extrahypothalamic and peripheral actions. The presence of leptin receptors has been reported in the adrenal medulla. In the present study, we examined the effects of leptin on catecholamine synthesis in cultured bovine adrenal medullary cells. Leptin (3‐30 nM) caused a significant increase in14C‐catecholamine synthesis from [14C] tyrosine, but not from [14C] DOPA. Incubation of cells with leptin resulted in an activation and phosphorylation of tyrosine hydroxylase. Leptin caused a transient activation of mitogen‐activated protein kinases (MAPKs). U0126, an inhibitor of MAPK kinase, abolished the effect of leptin on14C‐catecholamine synthesis. High concentrations of leptin (10‐100 nM) produced an increase in intracellular Ca2+concentration, which was blocked by Cd2+, an inhibitor of voltage‐dependent Ca2+channels. Concurrent treatment of cells with leptin (10 nM) and acetylcholine (0.3 mM) potently enhanced the stimulatory effect of acetylcholine on14C‐catecholamine synthesis. Leptin, however, failed to enhance the stimulatory effect of acetylcholine on the phosphorylation and activity of tyrosine hydroxylase. Acetylcholine (0.3 mM) decreased the intracellular pH (pHi). Leptin (10 nM) affected neither the basal pHi nor the acetylcholine‐induced fall in pHi. These findings suggest that leptin phosphorylates and activates tyrosine hydroxylase and subsequently stimulates catecholamine synthesis through MAPK and probably Ca2+pathways in the adrenal medulla.
Pathfinder and Other Tools for Analyzing Signal Transduction Networks
Authors: LOK LARRY
Published: July 2009

Abstract: Many electronic design tools are, at their core, tools for analyzing interacting networks of components in which there is a definite causal sense of direction in each interaction: outputs affect inputs, but not vice versa. Simplifying or restricting a network of protein interactions so that this kind of directedness holds makes the same category of software tools applicable. In signal transduction cascades the direction is usually given by “kinase phosphorylates substrate.” This paper examines a few kinds of directed network analysis tools in the context of signal transduction.
Simultaneous Velocity and Concentration Measurements of a Turbulent Jet Mixing Flow
Authors: HU HUI , SAGA TETSUO , KOBAYASHI TOSHIO , TANIGUCHI NOBUYUKI
Published: July 2009

Abstract: A method for the simultaneous measurement of velocity and passive scalar concentration fields by means of particle image velocimetry (PIV) and planar laser induced florescence (PLIF) techniques is described here. An application of the combined PIV‐PLIF system is demonstrated by performing simultaneous velocity and concentration measurements in the near field of a turbulent jet mixing flow. The distributions of the ensemble‐averaged velocity and concentration, turbulent velocity fluctuation, concentration standard deviation, and the correlation terms between the fluctuating velocities and concentration in the near field of the turbulent jet flow are presented as the measurement results of the simultaneous PIV‐PLIF system.
PIV Measurement and Numerical Analysis of a New Refrigeration Compartment of a Refrigerator
Authors: CHO SEONG‐HO , LEE IN‐SEOP , CHOI JAY‐HO , NAM YOUNG‐SOK
Published: July 2009

Abstract: A new cooling duct system was developed in order to increase the refrigerator performance in terms of uniform temperature distribution particle image velocimetry (PIV) and the commercial software FLUENT was used to compare the performance of the conventional cooling system with the new cooling system. The new cooling system effectively cooled the door basket region, thus increasing the uniformity of the temperature distribution in the refrigeration compartment.
Visualization of Blood Microcirculation Parameters in Human Tissues by Time‐Integrated Dynamic Speckles Analysis
Authors: GONIK MARIA M. , MISHIN ALEXANDER B. , ZIMNYAKOV DMITRY A.
Published: July 2009

Abstract: Statistical analysis of images of time‐integrated non‐stationary speckle patterns is a tool for diagnostics and imaging of in vivo dynamics of blood microcirculation in superficial layers of tissues and organs. The approach to monitoring blood microcirculation using the contrast analysis of time‐averaged speckle images is known as the laser speckle contrast analysis (LASCA) technique. This paper presents a modified version of LASCA, based on the application of a localized light source in combination with the speckle contrast analysis of time‐integrated dynamic speckle patterns. This method adds possibilities for the analysis of depth distributions of the blood microcirculation parameters. A theoretical background for the depth‐resolved analysis of blood microcirculation parameters is considered here on the basis of the concept of effective optical path distributions for a multiply scattered probe light.
Treating Crohn's Disease by Inducing T Lymphocyte Apoptosis
Authors: VAN DEN BRANDE JAN M. H. , PEPPELENBOSCH MAIKEL P. , VAN DEVENTER SANDER J. H.
Published: July 2009

Abstract: Apoptosis is one of the most important regulatory mechanisms in immunological homeostasis. Disturbances in the apoptotic pathways lead to autoimmune disease. Crohn's disease is a chronic inflammatory bowel disease of unknown origin, which seems to be mediated by excessive T cell‐mediated immunity. Recently, disturbances in apoptotic pathways of lamina propria T lymphocytes of patients with Crohn's disease have been identified. In the uninflamed, normal intestinal mucosa, lamina propria (LP) T cells are susceptible to activation‐induced cell death, but these cells show a resistance to apoptosis based on several disturbances compared to controls. Recently, intriguing data were published using cytokine‐targeted therapy (anti‐IL12, anti‐IL6 receptor, anti‐TNF). Actually, these medications restored mucosal immunological imbalance by inducing apoptosis of the LP T cells and seemed to be beneficial in models of Crohn's disease. In this review, mechanisms of immunological homeostasis will be discussed. We will also discuss the fascinating new results of cytokine‐targeted therapy in animal models of Crohn's disease and the effects of these drugs in patients with Crohn's disease.
Increased in Vitro Cytotoxicity of TNF‐α Analog LK‐805 Is Based on the Interaction with Cell Surface Heparan Sulfate Proteoglycan
Authors: MENART VIKTOR , FONDA IRENA , KENIG MAJA , POREKAR VLADKA GABERC
Published: July 2009

Abstract: Our tumor necrosis factor‐alpha (TNF‐α) analog LK‐805 (E107K) exhibited twofold higher specific cytotoxicity on the mouse fibroblast L‐929 cell line than its native counterpart. In addition, significantly lowered systemic toxicity was observed in tumor‐bearing mouse models treated with this analog. Due to a charge reversal and clustering of three lysines in the exposed tip region of LK‐805, we assumed that additional ionic interactions between the positively charged TNF analog and the negatively charged components of the cell surface were created, which might contribute to improved properties of LK‐805. To prove this hypothesis, we designed truncated forms of TNF‐α and analog LK‐805 and performed three independent sets of experiments: measurement of cytotoxic activity in the presence of excess heparan sulfate, determination of cytotoxic activity on heparinase‐treated L‐929 cells, and binding of various TNF‐α proteins onto the heparin‐sepharose affinity column. Cytotoxicity studies of both kinds confirmed the pivotal role of the E107K mutation for interaction with heparan sulfate proteoglycans on the cell surface of L‐929 cells. However, heparin‐binding studies revealed that intact, full‐length N‐termini of TNF‐α or its analogs were necessary for high retention on the heparin affinity column, whereas the three‐lysine containing tip of LK‐805 by itself was not enough for binding. Obviously, immobilized heparin does not represent an adequate model for membrane‐bound heparan sulfate proteoglycans of L‐929 cells.
Potential Intervention by Vaccinia Virus Complement Control Protein of the Signals Contributing to the Progression of Central Nervous System Injury to Alzheimer's Disease
Authors: KOTWAL GIRISH J. , LAHIRI DEBOMOY K. , HICKS RAMONA
Published: July 2009

Abstract: Traumatic brain injury (TBI) is one of the few known risk factors for Alzheimers disease (AD) and for depression. The mechanisms by which trauma causes delayed cognitive deficits are largely unknown. In recent studies, it was demonstrated that the complement system (an important component of the immune system and a mediator of inflammation) is activated both in human AD and following experimental TBI in rats. Amyloid proteins are also present in AD and following TBI, and are known to activate complement in vitro. Based on these and other previous studies, it was hypothesized that regulation of the complement system will attenuate the long‐term consequences of TBI. Vaccinia virus complement control protein (VCP) is a protein encoded by vaccinia virus. It blocks both the classic and alternative pathways of complement activation in vitro, and by doings so prevents the generation of proinflammatory chemotactic factors. Based on in vitro studies VCP can block the complement activation by the amyloid beta peptide. Using a fluid percussion rat model that causes traumatic brain injury (TBI), it was found that VCP significantly enhances functional recovery as determined by the Morris Water Maze test. Taken togther these studies indicate that potentially VCP could block molecular signals such as the formation of amyloid beta or the activation of complement to inhibit formation of AD following TBI.
Regulation of Promoter Activity of the APP Gene by Cytokines and Growth Factors
Authors: GE Y.‐W. , LAHIRI D. K.
Published: July 2009

Abstract: One of the major pathological hallmarks of Alzheimer's disease (AD) is the presence of brain depositions of senile plaques that are primarily composed of potentially toxic amyloid β‐peptide (Aβ), which is generated from a family of Aβ‐containing precursor proteins (APP; 695–770 amino acids). The role of inflammatory cytokines and growth factors has been implicated in the pathogenesis of AD. Our goal is to study the effects of these factors on the regulation of APP gene expression. Here we compared APP promoter activity in the presence of different growth factors and cytokines such as brain‐derived neurotrophic factor (BDNF), interleukin (IL‐1), nerve growth factor (NGF), neurotrofin‐3 (NT‐3), transforming growth factor (TGF‐β1), and tumor necrosis factor (TNF‐α1). PC12 neuronal cells, which were treated separately with these agents, were transfected with the construct containing either 190 bp APP proximal promoter region (−46 to 144 bp with respect to the transcription start site [+1]), 94 bp APP 5′‐untranslated region (UTR, +50 to 144) or other 5′‐UTR‐deleted regions. Each construct was cloned upstream of a reporter chloramphenicol acetyl transferase gene (CAT). The treatment of PC12 cells with NGF stimulated reporter activity in all constructs tested. The treatment of cells with BDNF, NT3, TGF‐β1, or TNF‐α stimulated reporter activity in a promoter/UTR‐specific manner. Transfection with the complete −46 to 144 region retained the maximum stimulatory activity for any treatment tested in PC12 cells. These results suggest that the regulatory elements of the APP gene respond to the stimulation of different growth factors, cytokines, and interleukins. This is consistent with the effects of the different growth factors, cytokines, and interleukins on APP message and protein levels.
Transcriptional Regulation by Thiol Compounds in Helicobacter pylori‐Induced Interleukin‐8 Production in Human Gastric Epithelial Cells
Authors: SEO JEONG YEON , KIM HYEYOUNG , KIM KYUNG HWAN
Published: July 2009

Abstract: Reactive oxygen species (ROS) have been counted among the potential toxic factors involving Helicobacter pylori (H. pylori)‐induced gastric injury. Transcription nuclear factor‐κB (NF‐κB) is activated by ROS and regulates inflammatory gene expression. Thiol compounds, such as glutathione and N‐acetylcysteine, scavenge hydrogen peroxide and are reported to prevent oxidative damage in various cells. The present study aims to investigate whether thiol compounds could affect H. pylori‐induced IL‐8 production by regulating transcription factor NF‐κB in human gastric epithelial AGS cells. AGS cells were incubated with H. pylori (NCTC 11637) at a ratio of 1:100 in the presence or absence of thiol compounds. ROS generation was determined by confocal microscopy using ROS‐sensitive dichlorofluorescein diacetate dye. Levels of hydrogen peroxide and IL‐8 in the medium and DNA binding activity of NF‐κB were determined by enzyme‐linked immunosorbent assay, colorimetric assay, and electrophoretic mobility shift assay. Results indicated both thiol compounds inhibited H. pylori‐induced hydrogen peroxide production, in accordance with their inhibition on NF‐κB activation and IL‐8 production induced by H. pylori in AGS cells. In conclusion, ROS may be a signaling molecule triggering NF‐κB activation and the expression of inflammatory genes such as IL‐8.
Type I Insulin‐like Growth Factor Receptor Expression on Colorectal Adenocarcinoma Cell Lines Is Decreased in Response to the Chemopreventive Agent N‐Acetyl‐l‐Cysteine
Authors: KELLY RAYMOND G. , NALLY KENNETH , SHANAHAN FERGUS , O'CONNELL JOE
Published: July 2009

Abstract: Increased expression of the type I insulin‐like growth factor receptor (IGF‐1R) is associated with colon cancer, while the antioxidant N‐acetyl‐l‐cysteine (NAC) is known to suppress colonic proliferation. We demonstrate that NAC down‐regulates the expression of IGF‐1R on three colorectal adenocarcinoma cell lines (HT29, SW480, and LoVo). NAC also abrogates the proliferative effect of IGF‐I on HT29 cells. This indicates a novel mechanism for the therapeutic effects of NAC.
Paraoxonase 1 Activity: A New Vascular Marker of Dementia?
Authors: DANTOINE THIERRY F. , DEBORD JEAN , MERLE LOUIS , LACROIX‐RAMIANDRISOA HANTA , BOURZEIX LAURENCE , CHARMES JEAN‐PIERRE
Published: July 2009

Abstract:Paraoxonase 1 (PON1), an A‐esterase with peroxidase‐like activity present on the surface of HDL, decreases the peroxidation of LDL. Serum PON1 activity (PON1a) decreases with aging and in disorders associated with a high risk of adverse cardiovascular events (acute myocardial infarction, diabetes mellitus, and chronic renal failure). The implication of vascular factors in Alzheimer‐type dementia (ATD) is strongly suspected. We measured PON1a by spectrophotometry using the paraoxon substrate in 180 healthy subjects (controls; mean age: 75.3 ± 8.9 years; 98 women) and 154 patients admitted for cognitive testing. According to criteria, 45 patients had mild cognitive impairments (MCI; mean age: 75.6 ± 9.3 years; 28 women), 60 had ATD (mean age: 75.6 ± 8.3 years; 47 women), and 49 had vascular dementia (VaD; mean age: 77.5 ± 7.2 years; 33 women). Mean PON1a was lower in VaD (0.25 ± 0.1 U/mL) than in controls or ATD (both 0.41 ± 0.2 U/mL,p< 0.01). Mean PON1a values in MCI (0.34 ± 0.2 U/mL) and ATD (0.41 ± 0.2 U/mL) were not significantly different. In multiple linear regression, PON1a was negatively correlated with male sex, age, and VaD, and positively correlated with ATD (each correlationp< 0.001). As shown in other high‐risk cardiovascular disorders, PON1a seems to be a reliable marker of VaD. Its modification in Alzheimer's disease supports the implication of vascular risk factors in this type of dementia.
Pathologies and Pathological Mechanisms for White Matter Hyperintensities in Depression
Authors: THOMAS ALAN J. , PERRY ROBERT , BARBER ROBERT , KALARIA RAJ N. , O'BRIEN JOHN T.
Published: July 2009

Abstract: Signal hyperintensities on magnetic resonance imaging (MRI) are increased in the white matter (WMH) and deep gray matter in dementia and depression and may have similar pathologies. However, no previous study has examined WMH in subjects with major depression. We carried out in vitro MRI on brain tissue from elderly subjects who had suffered major depression and elderly control subjects to identify and rate WMH. The tissue was subsequently prepared for histopathological analysis using a number of conventional and immunohistochemical stains, and the WMH were examined to identify their underlying pathological causes. Cerebral microvessels were also assessed and the findings compared with assessments of atheromatous disease in these subjects. PVH were found to be due to one of three causes: dilated perivascular spaces (with and without ischemia in the perivascular area), oligemic demyelination, and ischemic demyelination. DWMH also showed three types of causes: dilated perivascular spaces (with and without ischemia in the perivascular area), oligemic demyelination, and ischemic demyelination. Cerebral microvascular disease only contributed to a few of the lesions and atheromatous disease did not show associations with WMH in these subjects. These findings are similar to previous reports in other diseases and demonstrate WMH in elderly depression to be a manifestation of cerebrovascular disease. However, since large vessel and small vessel disease were not associated with WMH, our findings suggest hypotensive disease might be an important and unrecognized mechanism underlying WMH in late‐life depression.
Lipid Metabolism, Epidemiology, and the Mechanisms of Alzheimer's Disease
Authors: FRIEDLAND ROBERT P.
Published: July 2009

Abstract: Global variations in the incidence and prevalence of Alzheimer's disease (AD) have not been explained. Patterns of dietary intake of fats and other nutrients may be partly responsible. Recent work with transgenic mice overexpressing the β‐amyloid precursor protein suggests that anti‐Aβ antibodies enhance clearance of the Aβ protein from the brain and reduce plaque burden. This has been shown even with anti‐Aβ antibodies that do not enter the brain. Many factors other than circulating anti‐Aβ antibodies may influence this important process of Aβ clearance, including the Aβ‐binding elements, apolipoproteins E and J, circulating LDL, HDL, and LRP, alpha‐2‐macroglobulin, and transthyretin. Also important may be clearance of antibody‐antigen complexes from the circulation, as well as complement, metals, and estrogen. Dietary intake of lipids may influence the ability of Aβ‐binding proteins to enhance clearance of Aβ from the brain to blood. Understanding processes of Aβ clearance from brain may aid in determining the causes of AD in individuals, as well as the causes of global variations in incidence and prevalence of the disease.
Placental Growth Factor (PlGF) and Its Receptor Flt‐1 (VEGFR‐1)
Authors: LUTTUN AERNOUT , TJWA MARC , CARMELIET PETER
Published: July 2009

Abstract: Efforts to therapeutically stimulate or inhibit vessel growth have been primarily focused on vascular endothelial growth factor (VEGF) and its receptor VEGFR‐2 (Flk‐1), while little attention has been devoted to the therapeutic potential for angiogenic disorders of placental growth factor (PlGF), a VEGF family member, and its receptor VEGFR‐1 (Flt‐1). However, recent developments and insights could shift that focus to P1GF and Flt‐1. Indeed, PlGF stimulated angiogenesis and collateral growth in ischemic heart and limb with at least a comparable efficiency to VEGF and did not cause side effects associated with VEGF, such as edema or hypotension. An anti‐Flt‐1 antibody suppressed neovascularization in tumors and ischemic retina, and angiogenesis and inflammatory joint destruction in arthritis. The anti‐Flt‐1 antibody also reduced atherosclerotic plaque growth and vulnerability, but the atheroprotective effect was not due to reduced plaque neovascularization. The anti‐inflammatory effects of the anti‐Flt‐1 antibody were attributable to a reduced mobilization of bone marrow‐derived myeloid progenitors into the peripheral blood, a reduced mobilization/differentiation (and impaired infiltration) of Flt‐1‐expressing leukocytes into inflamed tissues, and a defective activation of myeloid cells. Thus, PlGF and Flt‐1 constitute potential candidates for therapeutic modulation of angiogenesis and inflammation.
Automated Biological Sequence Description by Genetic Multiobjective Generalized Clustering
Authors: ZWIR I. , ZALIZ R. ROMERO , RUSPINI E. H.
Published: July 2009

Abstract:Recent advances in the accessibility of databases containing representations of complex objects—exemplified by repositories of time‐series data, information about biological macromolecules, or knowledge about metabolic pathways—have not been matched by availability of tools that facilitate the retrieval of objects of particular interest and aid understanding their structure and relations. In applications, such as the analysis of DNA sequences, on the other hand, requirements to retrieve objects on the basis of qualitative characteristics are poorly met by descriptions that emphasize precision and detail rather than structural features. This paper presents a method for identification of interesting qualitative features in biological sequences. Our approach relies on a generalized clustering methodology in which the features being sought correspond to the solutions of a multivariable, multiobjective optimization problem with features generally corresponding to fuzzy subsets of the object being represented. Foremost among the optimization objectives being considered are measures of the degree by which features resemble prototypical structures deemed to be interesting by database users. Other objectives include feature size and, in some cases, performance criteria related to domain‐specific constraints. Genetic‐algorithm methods are employed to solve the multiobjective optimization problem. These optimization algorithms discover candidate features as subsets of the object being described and that lie in the set of all Pareto‐optimal solutions—of that problem. These candidate features are then summarized, employing again evolutionary‐computation methods, and interrelated by employing domain‐specific relations of interest to the end users. We present results of the application of this two‐step method to the recognition and summarization of interesting features in DNA sequences ofTripanosoma cruzi.
The Influence of Gravity on the Precise Measurement of Solute Diffusion Coefficients in Dilute Liquid Metals and Metalloids
Authors: SMITH REGINALD W. , ZHU XIAOHE , TUNNICLIFFE MARK C. , SMITH TIMOTHY J.N. , MISENER LOWELL , ADAMSON JOSEE
Published: July 2009

Abstract: It is now well known that the diffusion coefficient (D) measured in a laboratory in low earth orbit (LEO) is less than the corresponding value measured in a terrestrial laboratory. However, all LEO laboratories are subject to transient accelerations (g‐jitter) superimposed on the steady reduced gravity environment of the space platform. In measurements of the diffusion coefficients for dilute binary alloys of Pb‐(Ag, Au,Sb), Sb‐(Ga,In), Bi‐(Ag,Au,Sb), Sn‐(Au,Sb), Al‐(Fe, Ni,Si), and In‐Sb in which g‐jitter was suppressed, it was found that D∝T (temperature) if g‐jitter was suppressed, rather than D∝ T2 as observed by earlier workers with g‐jitter present. Furthermore, when a forced g‐jitter was applied to a diffusion couple, the value measured for D increased. The significance of these results is reviewed in the light of recent work in which ab initio molecular dynamics simulations predicted a D∝T relationship.
The Influence of Marangoni Flows on Crack Growth in Cast Metals
Authors: YANG B. J. , SMITH R. W. , SAHO M. , SADAYAPPAN M.
Published: July 2009

Abstract: In previous work with copper‐based alloys, the authors showed that a necessary part of the hot‐tearing process is the creation of a void in association with an inclusion and its subsequent growth to form the crack observed in the as‐cast state. The work reported here is an examination of hot tearing in aluminum alloy A201 and various similar Al‐based aerospace alloys to determine (1) if a similar process to that seen in copper alloys takes place; (2) the extent to which buoyancy forces influence the movement of solute‐enriched liquid and so contribute to the development of voids which are subsequently observed as hot tears; and (3) the influence of the local variations in liquid/void surface tension arising due to local composition and temperature changes on interdendritic fluid flow—that is, the effects of Marangoni convection on void size and movement during solidification. Hot cracking of aluminum alloy A201 has been examined under standardized experimental conditions. In addition, experiments were conducted in which fluid flow in test castings was controlled by magnetic fields. The results from these various investigations are presented in this paper. Similar experiments are planned for reduced gravity aircraft parabolic flights. To assist in the planning and interpretation of the results, numerical modeling simulations have been developed for Al‐Cu alloys.
ATEN
Authors: TURNBULL WAYNE N.O. , MISENER DONALD L. , SMITH TIMOTHY J.N. , ORAM GUY R.J. , SMITH REGINALD W.
Published: July 2009

Abstract: Since the beginning of microgravity materials research, studies of diffusion in liquids have been performed as the typical research that efficiently uses the microgravity environment. Successful experiments in microgravity have demonstrated the ability of the Canadian Microgravity Program (QUEST I, QUELDs I and II) to make significant contributions to this field of international microgravity research. Recently, Millenium Biologix was selected to develop and build the advanced thermal environment facility (ATEN) for the International Space Station. The design of this new processing facility builds on the considerable experience gained in designing and building the QUELD II furnace and developing sealed samples for use on board a manned space platform. The system requirements for ATEN are presented, along with preliminary test data from a prototype furnace.
Gravity‐Induced Anomalies in Interphase Spacing Reported for Binary Eutectics
Authors: SMITH REGINALD W.
Published: July 2009

Abstract: It has been reasoned that desirable microstructural refinement in binary eutectics could result from freezing in reduced‐gravity. It is recognized that the interphase spacing in a binary eutectic is controlled by solute transport and that, on Earth, buoyancy‐driven convection may enhance this. Hence, it has been presumed that the interphase spacing ought to decrease when a eutectic alloy is frozen under conditions of much‐reduced gravity, where such buoyancy effects would be largely absent. The result of such speculation has been that many workers have frozen various eutectics under reduced gravity and have reported that, although some eutectics became finer, others showed no change, and some even became coarser. This reported varied behavior will be reviewed in the light of long term studies by the author at Queen's University, including recent microgravity studies in which samples of two eutectic alloy systems, MnBi‐Bi and MnSb‐Sb, were frozen under very stable conditions and showed no change in interphase spacing.
Experimental Investigation of the Liquid Interface Reorientation upon Step Reduction in Gravity
Authors: MICHAELIS MARK , DREYER MICHAEL E. , RATH HANS J.
Published: July 2009

Abstract: Experiments have been carried out to investigate the settling behavior of a free liquid/gas interface in a partly filled right circular cylinder upon step reduction in gravity. Microgravity conditions were obtained within milliseconds after the release of a drop capsule in the drop tower facility in Bremen. In the experiments the cylinder radius was varied from 10 mm to 20mm with static contact angles of 2° to 60°. In addition to a series of silicone fluids, two different test liquids with a refractive index matched with the value of the cylinder material were used for experiments. The use of a digital high‐speed recording system with a recording frequency of up to 500 fps allowed both an observation of the entire free liquid interface and a detail view on the moving contact line. Digital image processing techniques were applied to detect the contour of the free surface. For the initial condition the system is dominated by hydrostatic forces. In this case the equilibrium of the free liquid surface is characterized by a high Bond number yielding a flat surface and a small liquid ascent at the cylinder wall depending on the static contact angle. After transition to reduced gravity with a very low Bond number, capillary forces govern the flow and a capillary driven reorientation of the liquid to the new equilibrium position is established in a damped oscillation. The particular interest of this study is the investigation of the initial behavior of the free surface reorientation. It was found that the initial rise velocity of the contact point is determined by the Morton number and the static contact angle. Experimental results are presented that show an increasing rise velocity for decreasing Morton numbers. Further results characterize the initial behavior of the free surface at the center point as a function of characteristic time scales.
Origin and Effect of Thermocapillary Convection in Subcooled Boiling
Authors: STRAUB JOHANNES
Published: July 2009

Abstract: During the past two decades we have performed pool boiling experiments under microgravity conditions with saturated and subcooled liquids using various fluids, mostly fluorinated hydrocarbons, and various shapes of heaters. The common observation at subcooled boiling is the development of thermocapillary convection around bubbles. This convection forms jet streams above the head of the bubbles that carry the heat from the bubbles into the ambient liquid. Heat transfer measurements demonstrate that this flow does not directly contribute to the overall heat transfer itself, but that it is an important transport mechanism in subcooled boiling, not only at microgravity, but also under terrestrial conditions. The development of a thermocapillary flow is surprising, because it is well known that for this convection a temperature gradient along the interface of a bubble is necessary. However, it is also well known that the interfacial kinetics of evaporation and condensation is very strong. Thus, small temperature differences generate strong mass flow rates across the interface, coupled with high heat transfer rates that immediately equalize even moderate temperature gradients appearing along the bubble interface. This is confirmed by the observation that, during boiling in saturated liquids under microgravity conditions, thermocapillary convection was never observed, thus indicating uniformity of the temperature along the interface. From this we must conclude that the temperature difference of wall superheat, which generates boiling, cannot be the driving force for the observed thermocapillary flow even in subcooled liquids. Therefore, the question about the origin of this flow arises and is discussed in this paper.