bluuebunny/crossref_metadata_2025 huggingface dataset:
Current Distribution on a Cathode Covered by a Thin Film Electrolyte in Crevice Corrosion - An Analytical Model
Authors: Agarwal Arun S. , Landau Uziel , Payer Joe H.
Published: March 2008

Analytical solutions were developed to model the current distribution on an electrode covered by a thin electrolyte layer where the current is fed from the edge. Separate models were developed for the Tafel and the linear kinetics regimes. The model provides the current density profiles and the total current capacity of the cathode in crevice corrosion. Results are shown to be in good agreement with numerical simulations. Conditions for the saturation of the cathodic current as well the trends in the variation of the cathode capacity as a function of electrode length are identified.
EIS Studies of Copper Dissolution in Arginine and Hydrogen Peroxide
Authors: Yerriboina Nagendra Prasad , Venkatakrishnan Vinod Kumar , Srinivasan Ramanathan
Published: March 2008

Anodic dissolution of copper in arginine and hydrogen peroxide based medium suitable for chemical mechanical planarization (CMP) slurry formulation was investigated using Electrochemical Impedance Spectroscopy (EIS). Potentiodynamic polarization and impedance data were acquired for copper dissolving in hydrogen peroxide and arginine. Reaction Mechanism Analysis (RMA) was employed to determine the mechanistic pathway of copper dissolution. The results indicate that there is no stable passivating film formation on the copper surface and direct dissolution was also ruled out. A two step mechanism involving cupric oxide as an intermediate species was proposed. The simulated data for this mechanism captures the essential features of the impedance spectra at various overpotentials.
Influence of Additives on the Transpassive Dissolution of Ferritic Steels in Phosphoric Acid-Acetic Acid Electrolytes
Authors: Tzvetkoff Tzvety B. , Betova Iva G. , Bojinov Martin S.
Published: March 2008

As a continuation of a series of works aimed at disclosing the electropolishing mechanism of ferritic steels, the present paper addresses the influence of additives such as sulphuric acid and glycerol on the transpassive dissolution of industrial ferritic steels in phosphoric acid-acetic acid mixtures. The overall process comprises two parallel pathways: oxidative dissolution of Cr as Cr(VI) via a Cr(IV) intermediate and isovalent dissolution of Fe as Fe(III) mediated by a surface step involving interaction with an electrolyte-originating species. A kinetic model of the process involving surface kinetic steps has been found to reproduce successfully the steady-state and the small amplitude ac response of the studied materials in all electrolyte combinations. The kinetic parameters are estimated via simultaneous fitting of impedance spectra at several potentials and steady state current vs. potential curves for each material-electrolyte combination to the model equations. Relationships between electrolyte composition and electropolishing ability are also discussed.
Effect of Etching Time on Porous Silicon Formation
Authors: Lu Jingmei , Cheng Xuan
Published: March 2008

The electrochemical responses, microstructures and surface species of porous silicon (PS) formed on n (111) silicon at different etching time were investigated by electrochemical polarization, SEM, Raman and FTIR techniques. The kinetic parameters of electrochemical reactions were calculated from the Tafel slopes. The chemical stability was characterized by aging the fresh PS samples stored in the vacuum desiccator. The PS structure of larger pores (∼20 nm) was formed within 1 min, however, the pore sizes decreased with the increase of etching time and became relatively stable up to 10 min. The larger pores were observed afterwards due to the mergence of the small pores. The growth rate of PS was proportional to the etching time. The FTIR spectra revealed that the surface species were mainly identified as SiH and SiH2, and the PS microstructures could be chemically stable for 4 days in the vacuum desiccator.
Band Gap Tuning of Macro-Porous Si Photonic Crystals by Thermally Grown SiO2 Interfacial Layer
Authors: Thitsa Makhin , Albin Sacharia
Published: March 2008

By plane wave expansion method (PWM) we modeled the effects of thermal oxidation and oxide etching on Si photonic crystals (PCs) of triangular lattice and proposed that these two processes can be extremely advantageous methods for tuning the photonic band gap and defect frequency. Two dimensional photonic crystals consisting of air cylinders in silicon background are studied before and after oxidation and partial oxide etching. Before oxidation the absolute band gap can be tuned only in a small range of radii (0.404a-0.48a); a is the lattice constant. Within this range, the band gap changes rapidly with the air cylinder radius due to the high dielectric constant of silicon. When thermal oxide interfacial layers are incorporated, the band gap can be tuned by varying the oxide thickness in the range of (0.26a-0.48a). By supercell method, formation of a defect level inside the band gap by means of the interfacial oxide layer and tuning of the defect frequency by varying the oxide thickness are also studied. A monopole defect mode is observed by oxidizing the center cylinder in a 5x5 suppercell of silicon cylinders with radius 0.28a in air background. The defect frequency is tuned by varying the oxide thickness from 0.15a to 0.3a.
Corrosion Behavior of Parylene-Metal-Parylene Thin Films in Saline
Authors: Li Wen , Rodger Damien , Menon Parvathy , Tai Yu-Chong
Published: March 2008

In this paper, we study the corrosion behavior of parylene-metal-parylene thin films using accelerated-lifetime soak tests. The samples under test are thin film resistors with a 200 nm layer of Au sandwiched by parylene-C on both sides, fabricated with parylene-metal skin technology. The samples are tested in hot saline both passively and actively, and different failure modes are observed using optical and electron-beam metrologies. Bubbles and delamination are first seen in the samples after 2 days of soaking under passive conditions, and followed by metal corrosion. While under active conditions, either bubbles or parylene breakdowns are observed depending on the thickness of parylene packaging. These results contribute to a better understanding of the failure mechanisms of parylene packaging in body fluids.
Voltage Drop Elimination Between the Main and Reference Electrodes in Low Conduction Medium
Authors: Kurbatov Andrey
Published: March 2008

The main source of errors when using relaxation methods and voltage-drop compensation methods between the main and reference electrodes can be the electrochemical cells with high values of RC for the reference electrode circuit and the more complex equivalent circuits of the main electrode, especially in case of surface blockage by the phase films. The use of other elimination methods as microelectrode application or extrapolation to zero current is not practical and labor-consuming. By the example of the corroding lithium electrode it is shown that the use of relaxation IR compensation method between reference and main electrodes leads to the increase of compensation resistance in time, which fully correlates with the growth of the corroding film resistance on the main electrode. The conclusion of impossibility of carrying out IR elimination process correctly in such cases was made.
Estimation of Protective Efficiency of Oil-based Compositions Containing Zinc and Graphite Powders Against Steel Atmospheric Corrosion
Authors: Tsygankova Liudmila , Vigdorovich Vladimir , Kichigin Vladimir , Kim Yaroslava
Published: March 2008

Zinc-containing oil-based compositions containing 75 wt. % zinc powder protect carbon steel in the natural conditions of urban atmosphere for a year with the protective efficiency equal to 96 %. More expedient binding is waste motor oil. The insertion of 4 wt. % graphite dust allows to decrease a content of Zn powder in the composition to 60 wt. % without essential alteration of the protective efficiency. The corrosion potential of the steel electrode covered with the oil composition containing 75 wt. % Zn powder or 60 wt. % Zn powder and 4 wt. % graphite dust in the 3 % NaCl solution is near Zn electrode potential. The polarization curves are close to ones of metal zinc. The properties of the above oil compositions were studied by the electrochemical impedance spectroscopy method too. The values of the equivalent scheme parameters satisfactorily correlate with data of the gravimetrical corrosion tests and the results of the polarization measurements and allow to explain the peculiarities of the zinc-containing oil compositions and an influence of their modification with the graphite powder.
Alternating Pulsed Electrolysis for Fe-Cr Surface Alloying of Conventional Carbon Steel
Authors: Yagi Shunsuke , Oshima Hiroki , Murase Kuniaki , Matsubara Eiichiro , Awakura Yasuhiro
Published: March 2008

Alternating pulsed electrolysis was investigated for the surface modification of carbon steel substrates with carbon contents of 0.2 wt.%, 0.6 wt.% and 0.8 wt.%. This process involves the anodic periodic dissolution of substrates to provide ferrous, or iron(II), ions near the substrate as an electroactive component to form the objective alloy during subsequent cathodic times. The carbon steel substrates dissolved heterogeneously since the substrates had nonuniform texture composed of ferrite, cementite, and pearlite. Although the heterogeneous dissolution tended to provide a rough surface of the iron-chromium alloy layers, which resulted in poor adhesion of the layers, relatively flat and smooth alloy layers were obtained by reducing the amount of dissolved iron during each anodic pulse. Pits and defects that were originally recognized on the carbon steel substrate were gradually infilled and covered with iron-chromium alloy by the pulsed electrolysis.
An Investigation of Commercial Grade 2 Titanium as a Bipolar Plate Material for PEM Fuel Cells
Authors: Wang Yan , Northwood Derek
Published: March 2008

Bipolar plates are one of the most important components in PEM fuel cell stacks. Currently, the commercial bipolar plates are made of non-porous graphite because of its chemical and thermal stability. However, they account for about 80% of the total weight and 45% of stack cost. In this study, commercial grade 2 titanium has been investigated as a possible bipolar plate material because its excellent corrosion resistance and relatively low density. Potentiodynamic, potentiostatic tests and EIS measurements were done to investigate the corrosion resistance in the simulated anode and cathode environments of a PEM fuel cell. SEM metallography was conducted to determine the corrosion morphology. ICP-OES tests were done to determine the metal ion concentrations in solution after corrosion. The Ti ion concentration in solution would be about 20ppm after 5000 hour operation at both the anode and the cathode.
Role of Sp1 and HNF1 transcription factors in SGLT1 regulation during chronic intestinal inflammation
Authors: Kekuda Ramesh , Saha Prosenjit , Sundaram Uma
Published: March 2008

In a rabbit model of chronic intestinal inflammation, we previously demonstrated that the activity of Na-glucose cotransporter (SGLT1), SLC5A1, is inhibited. This inhibition is secondary to a decrease in the number of cotransporters, indicating that the regulation of SGLT1 during chronic inflammation is at the level of transcription. However, the regulation of SGLT1 expression and the transcription factors involved in the regulation are not yet known. In this report, we describe the cloning and characterization of rabbit SGLT1 promoter and the identification of transcription factors affected in villus cells during chronic intestinal inflammation. The promoter sequence for SGLT1 gene was identified by using the publicly available rabbit genomic sequence. Even though rabbit SGLT1 promoter did not have considerable overall homology with other mammalian SGLT1 promoters, two specificity protein 1 (Sp1) and a hepatocyte nuclear factor 1 (HNF1) binding sites were highly conserved among the species. Rabbit SGLT1 cDNA was encoded by 15 exons. Minimal promoter region determination showed that 196 nucleotides upstream of the transcription start site were sufficient for optimal promoter activity. This region encompassed two transcription factor binding sites, Sp1 and HNF1. For maximal SGLT1 promoter activity, these two transcription factor binding sites were essential, and their effect was synergistic, indicating that two separate regulatory pathways might be involved in their regulation. Using mobility shift assays, we further demonstrated that the binding of both Sp1 and HNF1 transcription factors to SGLT1 promoter regions were affected during chronic intestinal inflammation. Thus this report demonstrates that Sp1 and HNF1 transcription factors act in concert to regulate SGLT1 transcription in the chronically inflamed intestine.
Platelet-activating factor-induced chloride channel activation is associated with intracellular acidosis and apoptosis of intestinal epithelial cells
Authors: Claud Erika C. , Lu Jing , Wang Xue Qing , Abe Mark , Petrof Elaine O. , Sun Jun , Nelson Deborah J. , Marks Jeremy , Jilling Tamas
Published: March 2008

Platelet-activating factor (PAF) is a phospholipid inter- and intracellular mediator implicated in intestinal injury primarily via induction of an inflammatory cascade. We find that PAF also has direct pathological effects on intestinal epithelial cells (IEC). PAF induces Cl−channel activation, which is associated with intracellular acidosis and apoptosis. Using the rat small IEC line IEC-6, electrophysiological experiments demonstrated that PAF induces Cl−channel activation. This PAF-activated Cl−current was inhibited by Ca2+chelation and a calcium calmodulin kinase II inhibitor, suggesting PAF activation of a Ca2+-activated Cl−channel. To determine the pathological consequences of Cl−channel activation, microfluorimetry experiments were performed, which revealed PAF-induced intracellular acidosis, which is also inhibited by the Cl−channel inhibitor 4,4′diisothiocyanostilbene-2,2′disulfonic acid and Ca2+chelation. PAF-induced intracellular acidosis is associated with caspase 3 activation and DNA fragmentation. PAF-induced caspase activation was abolished in cells transfected with a pH compensatory Na/H exchanger construct to enhance H+extruding ability and prevent intracellular acidosis. As ClC-3 is a known intestinal Cl−channel dependent on both Ca2+and calcium calmodulin kinase II phosphorylation, we generated ClC-3 knockdown cells using short hairpin RNA. PAF induced Cl−current; acidosis and apoptosis were all significantly decreased in ClC-3 knockdown cells. Our data suggest a novel mechanism of PAF-induced injury by which PAF induces intracellular acidosis via activation of the Ca2+-dependent Cl−channel ClC-3, resulting in apoptosis of IEC.
Design of a new variable-ventilation method optimized for lung recruitment in mice
Authors: Thammanomai Apiradee , Hueser Lauren E. , Majumdar Arnab , Bartolák-Suki Erzsébet , Suki Béla
Published: March 2008

Variable ventilation (VV), characterized by breath-to-breath variation of tidal volume (Vt) and breathing rate (f), has been shown to improve lung mechanics and blood oxygenation during acute lung injury in many species compared with conventional ventilation (CV), characterized by constant Vt and f. During CV as well as VV, the lungs of mice tend to collapse over time; therefore, the goal of this study was to develop a new VV mode (VVN) with an optimized distribution of Vt to maximize recruitment. Groups of normal and HCl-injured mice were subjected to 1 h of CV, original VV (VVO), CV with periodic large breaths (CVLB), and VVN, and the effects of ventilation modes on respiratory mechanics, airway pressure, blood oxygenation, and IL-1β were assessed. During CV and VVO, normal and injured mice showed regional lung collapse with increased airway pressures and poor oxygenation. CVLB and VVN resulted in a stable dynamic equilibrium with significantly improved respiratory mechanics and oxygenation. Nevertheless, VVN provided a consistently better physiological response. In injured mice, VVO and VVN, but not CVLB, were able to reduce the IL-1β-related inflammatory response compared with CV. In conclusion, our results suggest that application of higher Vt values than the single Vt currently used in clinical situations helps stabilize lung function. In addition, variable stretch patterns delivered to the lung by VV can reduce the progression of lung injury due to ventilation in injured mice.
Are skeletal muscles independent actuators? Force transmission from soleus muscle in the cat
Authors: Maas Huub , Sandercock Thomas G.
Published: March 2008

It is unclear if skeletal muscles act mechanically as independent actuators. The purpose of the present study was to investigate force transmission from soleus (SO) muscle for physiological lengths as well as relative positions in the intact cat hindlimb. We hypothesized that force transmission from SO fibers will be affected by length changes of its two-joint synergists. Ankle plantar flexor moment on excitation of the SO was measured for various knee angles (70–140°). This involved substantial length changes of gastrocnemius and plantaris muscles. Ankle angle was kept constant (80°-90°). However, SO ankle moment was not significantly affected by changes in knee angle; neither were half-relaxation time and the maximal rate of relaxation ( P > 0.05). Following tenotomy, SO ankle moment decreased substantially (55 ± 16%) but did not reach zero, indicating force transmission via connective tissues to the Achilles tendon (i.e., epimuscular myofascial force transmission). During contraction SO muscle shortened to a much greater extent than in the intact case (16.0 ± 0.6 vs. 1.0 ± 0.1 mm), which resulted in a major position shift relative to its synergists. If the SO was moved back to its position corresponding to the intact condition, SO ankle moment approached zero, and most muscle force was exerted at the distal SO tendon. Our results also suggested that in vivo the lumped intact tissues linking SO to its synergists are slack or are operating on the toe region of the stress-strain curve. Thus, within the experimental conditions of the present study, the intact cat soleus muscle appears to act mechanically as an independent actuator.
Metabolically Engineered Yeasts: ‘Potential’ Industrial Applications
Authors: Branduardi Paola , Smeraldi Carla , Porro Danilo
Published: March 2008

Industrial biotechnology and metabolic engineering can offer an innovative approach to solving energy and pollution problems. The potential industrial applications of yeast are reviewed here.
ArcA Redox Mutants as a Source of Reduced Bioproducts
Authors: Pettinari M.Julia , Nikel Pablo I. , Ruiz Jimena A. , Méndez Beatriz S.
Published: March 2008

Escherichia coli and other facultative anaerobes can adapt their metabolism according to oxygen availability by means of aerobic and anaerobic respiration and fermentation. ArcAB is a two-component signal transduction system that controls, at the transcriptional level, the choice of energy generation pathway according to the intracellular redox state. High throughput studies on different redox regulator mutants, involving transcriptome analysis, RT-PCR and phenotypic arrays enabled the elucidation of a repertoire of operons coordinated by ArcA which extended beyond respiration control including, among others, those which code for survival, chromosome replication and degradation of fatty acids. Flux analysis by 13C labeling provided new clues to the understanding of the distribution of metabolites mediated by ArcAB. The genetic manipulation of this regulator proved to be useful for the generation of reduced products of commercial value.
Escherichia coli arcA Mutants: Metabolic Profile Characterization of Microaerobic Cultures using Glycerol as a Carbon Source
Authors: Nikel Pablo I. , Pettinari M.Julia , Ramírez M.Cecilia , Galvagno Miguel A. , Méndez Beatriz S.
Published: March 2008

ArcA is a global regulator that switches on the expression of fermentation genes and represses the aerobic pathways when Escherichia coli enters low oxygen growth conditions. The metabolic profile of E. coli CT1062 (ΔarcA)and CT1061 (arcA2) grown in microaerobiosis with glycerol as carbon source were determined and compared with E. coli K1060, the arcA+ parent strain. Both arcA mutants achieved higher biomass yields than the wild-type strain. The production of acetate, formate, lactate, pyruvate, succinate and ethanol were determined in the supernatants of cultures grown on glycerol under microaerobic conditions for 48 h. The yield of extracellular metabolites on glycerol showed lower acid and higher ethanol values for the mutants. The ethanol/acetate ratio was 0.87 for the parent strain, 2.01 for CT1062, and 12.51 for CT1061. Accordingly, the NADH/NAD+ ratios were 0.18, 0.63, and 0.97, respectively. The extracellular succinate yield followed a different pattern, with yield values of 0.164 for K1060, 0.442 for CT1062 and 0.214 for CT1061. The dissimilarities observed can be attributed to the different effects exerted by the deletion and point mutations in a global regulator.
Specific Ethanol Production Rate in Ethanologenic Escherichia coli Strain KO11 Is Limited by Pyruvate Decarboxylase
Authors: Huerta-Beristain Gerardo , Utrilla José , Hernández-Chávez Georgina , Bolívar Francisco , Gosset Guillermo , Martinez Alfredo
Published: March 2008

Modification of ethanol productivity and yield, using mineral medium supplemented with glucose or xylose as carbon sources, was studied in ethanologenic Escherichia coli KO11 by increasing the activity of five key carbon metabolism enzymes. KO11 efficiently converted glucose or xylose to ethanol with a yield close to 100% of the theoretical maximum when growing in rich medium. However, when KO11 ferments glucose or xylose in mineral medium, the ethanol yields decreased to only 70 and 60%, respectively. An increase in GALPEc (permease of galactose-glucose-xylose) or PGKEc (phosphoglycerate kinase) activities did not change xylose or glucose and ethanol flux. However, when PDCZm (pyruvate decarboxylase from Zymomonas mobilis) activity was increased 7-fold, the yields of ethanol from glucose or xylose were increased to 85 and 75%, respectively, and organic acid formation rates were reduced. Furthermore, as a response to a reduction in acetate and ATP yield, and a limited PDCZm activity, an increase in PFKEc (phosphofructokinase) or PYKBs (pyruvate kinase from Bacillus stearothermophilus) activity drastically reduced glucose or xylose consumption and ethanol formation flux. This experimental metabolic control analysis showed that ethanol flux in KO11 is negatively controlled by phosphofructokinase and pyruvate kinase, and positively influenced by the PDCZm activity level.
Testicular Function in Klinefelter Syndrome
Authors: Wikström Anne M. , Dunkel Leo
Published: March 2008

Klinefelter syndrome (KS) is the most common genetic form of male hypogonadism, but the phenotype becomes evident only after puberty. During childhood, and even during early puberty, pituitary-gonadal function in 47,XXY subjects is relatively normal, but from midpuberty onwards, FSH and LH levels increase to hypergonadotropic levels, inhibin B decreases to undetectable levels, and testosterone after an initial increase levels off at a low or low-normal level. Hence, most adult KS males display a clear hypergonadotropism with a varying degree of androgen deficiency; subsequently, testosterone substitution therapy is widely used to prevent symptoms and sequels of androgen deficiency. Testicular biopsies of prepubertal KS boys have shown preservation of seminiferous tubules with reduced numbers of germ cells, but Sertoli and Leydig cells have appeared normal. The testes in the adult KS male are, however, characterized by extensive fibrosis and hyalinization of the seminiferous tubules, and hyperplasia of the interstitium, but the tubules may show residual foci of spermatogenesis. Introduction of testicular sperm extraction in combination with intracytoplasmic sperm injection techniques has allowed non-mosaic KS males to father children.
Extended Hemi-Hepatectomy with Portal Vein Reconstruction in a Patient with Situs Ambiguous
Authors: Sugimachi Keishi , Ikeda Yasuharu , Taketomi Akinobu , Tomikawa Morimasa , Kawasaki Katsumi , Korenaga Daisuke , Maehara Yoshihiko , Takenaka Kenji
Published: March 2008

We report a case of far-advanced hepatocellular carcinoma (HCC) with situs ambiguous, complex visceral and vascular anomalies, who was successfully managed by extended hemi-hepatectomy. A 67-year-old man was referred to our hospital with a large liver mass. Abdominal ultrasonography, computed tomography and angiography revealed HCC with a diameter of 10 cm, with tumor thrombus in the main and first branch of the portal vein. Multiple complex anomalies in the abdomen were determined preoperatively. He had right-sided spleens-stomach-duodenum, liver at midline, inferior vena cava interruption with azygous continuation, and hepatic arterial anomaly. Extended left lobectomy of the liver with reconstruction of the portal vein was performed. Postoperatively, the patient recovered without major complications, and he was discharged on postoperative day 21. We report the first successful extended hepatectomy with portal vein reconstruction for HCC in a patient with rare situs anomalies.
Seronegative Herpes simplex Associated Esophagogastric Ulcer after Liver Transplantation
Authors: Matevossian Edouard , Doll Dietrich , Weirich Gregor , Burian Maria , Knebel Carolin , Thorban Stefan , Hüser Norbert
Published: March 2008

Herpes simplex infection is characterized by acute or subacute infection, often followed by a chronic carrier state. Consecutive recurrences may flare up if immunocompromise occurs. Herpes simplex associated esophagitis or duodenal ulcer have been reported in immunocompromised patients due to neoplasm, HIV/AIDS or therapeutically induced immune deficiency. Here we report the case of an HSV-DNA seronegative patient who developed grade III dysphagia 13 days after allogeneic liver transplantation. Endoscopy revealed an esophageal-gastric ulcer, and biopsy histopathology showed a distinct fibroplastic and capillary ulcer pattern highly suspicious for viral infection. Immunohistochemistry staining revealed a distinct nuclear positive anti-HSV reaction. Antiviral therapy with acyclovir and high-dose PPI led to a complete revision of clinical symptoms within 48 h. Repeat control endoscopy after 7 days showed complete healing of the former ulcer site at the gastroesophageal junction. Although the incidence of post-transplantation Herpes simplex induced gastroesophageal disease is low, the viral HSV ulcer may be included into a differential diagnosis if dysphagia occurs after transplantation even if HSV-DNA PCR is negative.
Management of Duodenal Adenomas Involving the Ampulla of Vater – A Warning against Limited Resection
Authors: Rossaak Jeremy , Bagshaw Philip , Connor Saxon
Published: March 2008

Duodenal adenomas are uncommon, however, when present a proportion have dysplasia associated with the adenoma and therefore require treatment. The options range from less invasive endoscopic treatments to a pancreaticoduodenectomy. This case report describes two patients with adenomas involving the ampulla of Vater. One patient had familial adenomatous polyposis, the other was a renal transplant patient with a large adenoma. Both patients’ adenomas contained high-grade dysplasia. Both patients underwent a pancreaticoduodenectomy. Histology of both specimens demonstrated that the adenoma had migrated up the bile duct for at least 7 mm, and the pancreatic duct for 8 mm in one patient. Limited resection of ampullary adenomas may leave residual adenomatous tissue in the bile duct with the risk of recurrent adenomatous disease and malignant transformation.
ERCP in Total Situs Viscerum Inversus
Authors: Fiocca F. , Donatelli G. , Ceci V. , Cereatti F. , Romagnoli F. , Simonelli L. , Modini C.
Published: March 2008

A 69-year-old cholecystectomized female with known total situs viscerum inversus presented recurrent colicky pain in the left upper abdominal quadrant and jaundice. Laboratory parameters showed increased neutrophils and coniugated bilirubin of 5.53 mg/dl. US and MRCP confirmed total situs viscerum inversus and a dilatation of the intra- and extrahepatic ducts with a peripapillary 13 mm stone. ERCP, sphincterotomy and successful common bile duct stone extraction were performed in the conventional way. ERCP was carried out successfully despite situs inversus maintaining the patient in the prone position with the endoscopist on the right side of the table. Some authors have reported similar cases in whom ERCP was performed in other positions, while this report shows that an experienced endoscopist can achieve the same results in the conventional way as it is possible when anatomical changes, Billroth II or Roux-en-Y, or different positions of the patient, supine or on the left side, are present.
Blood Levels of Brain-Derived Neurotrophic Factor Correlate with Several Psychopathological Symptoms in Anorexia Nervosa Patients
Authors: Mercader Josep M. , Fernández-Aranda Fernando , Gratacòs Mònica , Ribasés Marta , Badía Anna , Villarejo Cynthia , Solano Raquel , González Juan R. , Vallejo Julio , Estivill Xavier
Published: March 2008

Background: Evidence of a role of brain-derived neurotrophic factor (BDNF) in the pathophysiology of eating disorders (ED) has been provided by association studies and by murine models. BDNF plasma levels have been found altered in ED and in psychiatric disorders that show comorbidity with ED. Aims: Since the role of BDNF levels in ED-related psychopathological symptoms has not been tested, we investigated the correlation of BDNF plasma levels with the Symptom Checklist 90 Revised (SCL-90R) questionnaire in a total of 78 ED patients. Methods: BDNF levels, measured by the enzyme-linked immunoassay system, and SCL-90R questionnaire, were assessed in a total of 78 ED patients. The relationship between BDNF levels and SCL-90R scales was calculated using a general linear model. Results: BDNF plasma levels correlated with the Global Severity Index and the Positive Symptom Distress Index global scales and five of the nine subscales in the anorexia nervosa patients. BDNF plasma levels were able to explain, in the case of the Psychoticism subscale, up to 17% of the variability (p = 0.006). Conclusion: Our data suggest that BDNF levels could be involved in the severity of the disease through the modulation of psychopathological traits that are associated with the ED phenotype.
Association of MAO-A Variant with Complicated Grief in Major Depression
Authors: Kersting Anette , Kroker Kristin , Horstmann Julia , Baune Bernhard T. , Hohoff Christa , Mortensen Lena Sünke , Neumann Lisa C. , Arolt Volker , Domschke Katharina
Published: March 2008

Background/Aims: It has been suggested that monoamine oxidase A (MAO-A) activity is involved in the pathogenesis of major depression. Bereavement-related complicated grief significantly increases the risk of major depression and has been shown to be influenced by serotonergic tonus, possibly conferred by MAO-A activity. Complicated grief – whose inclusion in DSM-V as a separate mental disorder is under discussion – has been shown to be a distinct syndrome with symptoms not seen in depression. Therefore, in the present study, genetic variation in the MAO-A gene was investigated for its influence on complicated grief in major depression. Methods: Sixty-six unrelated Caucasian patients (41 female, 25 male) with major depression and a history of bereavement were evaluated for complicated grief using the Inventory of Complicated Grief (ICG), the posttraumatic stress reaction after the loss by means of the Impact of Event Scale (IES-R) and further psychopathological measures. Patients were additionally genotyped for the functional variable number tandem repeat (VNTR) in the promoter region of the MAO-A gene. Results: The more active longer allele of the MAO-A VNTR was significantly associated with complicated grief in the female subgroup of patients (χ2 = 9.471, p = 0.002, OR = 9.208, 95% CI 2.129–38.899, Bonferroni-corrected p = 0.012), whereas there was no such effect in male patients. Higher posttraumatic stress reaction was only nominally associated with the more active longer allele of the MAO-A VNTR in the female subgroup of patients (genotypes: χ2 = 5.939, p = 0.015, OR = 5.333, 95% CI 1.366–20.557, Bonferroni-corrected p = 0.087). No significant associations of MAO-A VNTR with the severity of depressive symptoms (Beck Depression Inventory), anxiety symptoms (Spielberger State-Trait Anxiety Inventory), general mental health (Brief Symptom Inventory), or perceived social support (F-SozU) were found (all p > 0.10). Conclusion: The present pilot study for the first time suggests a gender-specific contribution of the more active MAO-A VNTR variant to an increased vulnerability for complicated grief as a potential intermediate phenotype of major depression.
Effects of Dietary Caffeine on Topographic EEG after Controlling for Withdrawal and Withdrawal Reversal
Authors: Keane Michael A. , James Jack E. , Hogan Michael J.
Published: March 2008

Background/Aims: Despite several decades of research into the effects of caffeine on EEG, few consistent findings have emerged. Notwithstanding the likelihood that differences in methodology may explain some of the inconsistency, confidence in the published findings is undermined by the failure in previous studies to control for the effects of caffeine withdrawal and withdrawal reversal. Methods: Participants (n = 22) alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) 3 times daily for 4 consecutive weeks. EEG activity was measured at 32 sites during eyes closed, eyes open, and performance of a vigilance task. Results: Caffeine was found to have few and modest effects on EEG in the theta and alpha bandwidths, and no effects in the delta and beta bandwidths. Evidence was found of withdrawal, withdrawal reversal, and tolerance in relation to observed increases in theta power during task performance; withdrawal and withdrawal reversal in relation to increases in alpha power during all three behavioural conditions (eyes closed, eyes open, and task performance), and withdrawal-induced adverse effects in relation to aspects of subjective mood. Conclusion: The finding of similar increases in theta power following caffeine challenge and acute caffeine withdrawal casts doubt on whether caffeine may be viewed as having direct stimulant effects. Results could suggest that change in drug state, whether in the form of acute caffeine withdrawal or challenge, may be disruptive to electrophysiological activity in the brain.
Automatic Quantification of Speech Intelligibility of Adults with Oral Squamous Cell Carcinoma
Authors: Windrich M. , Maier A. , Kohler R. , Nöth E. , Nkenke E. , Eysholdt U. , Schuster M.
Published: March 2008

Objective: It has been the aim of the present study to introduce a novel automatic technique for the objective and quantitative assessment of speech intelligibility to the evaluation of postoperative outcome. Patients and Methods: Forty-six patients with oral carcinomas, mean age 59.8 ± 10.1 years, and an age-matched control group of 40 subjects without oral diseases. Recordings of a standard text read by the patients and the control group were analyzed by an automatic speech recognition system. Results: For the patients, automatic speech recognition yielded word recognition rates between 8 and 82% (mean 49 ± 19%), for the control group between 60 and 91% (76 ± 7%). Automatic evaluation closely correlated with the experts’ perceptual evaluation of intelligibility (r = –0.93; p < 0.01). The multi-rater kappa of the experts alone (0.55) differed only slightly from the multi-rater kappa of the experts and the speech recognition system (0.58). Conclusion: For adults with speech disorders, automatic speech recognition may serve as a valuable tool to assess global speech outcome after treatment of oral squamous cell carcinoma objectively and quantitatively for clinical and research purposes.
Changes in Knowledge of Stroke Risk Factors and Warning Signs among Michigan Adults
Authors: Reeves Mathew J. , Rafferty Ann P. , Aranha Alison A.R. , Theisen Velma
Published: March 2008

Background: Increasing the public’s awareness of stroke is a public health priority. Our objective was to assess changes in the public’s knowledge of stroke risk factors and warning signs in Michigan during a 5-year period characterized by a sustained statewide public education effort. Methods: Questions regarding knowledge of stroke risk factors and warning signs were included in the 1999 and 2004 Michigan Behavioral Risk Factor Surveys – random-digit-dialed statewide surveys of adults. Respondents were asked to report up to 3 risk factors and warning signs for stroke. Results: Between 1999 and 2004, the proportion of respondents who reported 3 correct stroke warning signs increased substantially from 14.3 to 27.6% (p < 0.001), whereas the proportion reporting 3 correct risk factors remained almost unchanged (27.9 vs. 29.1%). The reporting of 2 warning signs in particular increased substantially over the 5-year period; ‘any weakness or numbness’ increased from 45.7 to 65.6%, while ‘confusion, trouble speaking or understanding’ increased from 29.9 to 46.5%. Knowledge of stroke warning signs increased across nearly all demographic subgroups, but remained poor for several high-risk groups including the elderly, minorities and those with less education. Conclusions: Knowledge of warning signs increased during this period while there was little change in knowledge of risk factors. The results suggest that these changes occurred in response to the public education campaign which focused primarily on warning signs. The findings further emphasize the need to target those subgroups who are at highest risk of stroke and where knowledge remains poorest.
Platelet Aggregation and Recruitment with Aspirin-Clopidogrel Therapy
Authors: Helgason Cathy M. , Grossi Enzo , Pandey Dilip , Valika Aziz , Cursio John , Brace Larry D.
Published: March 2008

Background: Aspirin-clopidogrel combination therapy inhibits platelet aggregation. The effect on platelet recruitment is unknown. Methods: Thirty chronic ischemic stroke patients taking aspirin alone followed by aspirin-clopidogrel combined therapy had platelet reactivity tests performed over 3 months: ex vivo platelet aggregation, platelet recruitment and urinary 11-dehydro-thromboxane B2 (11-dhTxB2)excretion. Statistical analysis of variance compared platelet aggregation and recruitment between aspirin alone and aspirin-clopidogrel, and longitudinal regression analysis estimated platelet recruitment over time. Nonlinear mapping defined variable connections in each patient. Results: Statistically significant differences were found between aspirin alone and aspirin-clopidogrel for (1) adenosine-diphosphate- and collagen-induced platelet aggregation and maximum inhibition of platelet recruitment and (2) increasing inhibition of platelet recruitment over time. Urinary 11-dhTxB2 excretion did not predict platelet aggregation response. Nonlinear mapping showed patient-unique variable interconnections. Conclusions: Platelet inhibition with aspirin-clopidogrel may increase over time, and future studies should focus on this finding in the context of vascular complications.
Ethnic Differences in the Cerebrovascular Impact of Hypertension
Authors: Birns Jonathan , Morris Robin , Jarosz Jozef , Markus Hugh , Kalra Lalit
Published: March 2008

Background: Small-vessel cerebrovascular disease and vascular cognitive impairment are more prevalent in hypertensive subjects of black African origin compared with Caucasians, but the relationships between blood pressure (BP), regional white matter damage and neuropsychological function have not been studied in well-characterised samples of subjects belonging to different ethnicities. Methods: Twenty-four-hour ambulatory BP, brain white matter lesion volumes on magnetic resonance imaging and executive cognitive function were compared in 41 Caucasian and 47 African-Caribbean subjects on optimal treatment attending a hypertension clinic. Results: African-Caribbean subjects were 4 years younger but had been hypertensive for 3 years longer than Caucasians. Their mean 24-hour systolic (136.6 vs. 129.4 mm Hg, p = 0.011) and diastolic (77.8 vs. 72.6 mm Hg, p = 0.006) BP were also higher despite being well-controlled. In multivariate models, African-Caribbean subjects had a greater parieto-occipital white matter lesion volume [adjusted difference: 319 mm3 (95% CI: 62–575), p = 0.016] and poorer performance on executive function [time difference: 0.375 s (95% CI: 0.191–0.558), p = 0.0001] and verbal fluency [score difference: –6.863 (95% CI: –12.531 to –1.195), p = 0.018] tests after adjusting for covariance in age, gender, vascular risk profile, duration of hypertension and education, and premorbid intelligence. Conclusions: African-Caribbean ethnicity was independently related to increased hypertensive white matter damage and executive cognitive dysfunction, the reasons for which merit further investigation.
Effect of Encoding Condition on Source Memory for Odors in Healthy Young and Older Adults
Authors: Hernandez Rafael J. , Bayer Zach C. , Brushfield Andrea M. , Pirogovsky Eva , Murphy Claire , Gilbert Paul E.
Published: March 2008

Background: Source memory has been shown to be more affected by aging than item memory. Aging also has been shown to result in impairments in odor memory. Objective: The aim of the study is to examine the effects of explicit encoding instructions on source memory for olfactory stimuli in healthy older and young adults. Methods: Source and item memory for odors were assessed in two conditions. In the uninformed condition, young (18–30) and older adults (65+) were presented with 16 odors by two sources (male and female) without instruction at encoding and no warning of a subsequent memory task. In the informed condition, young and older adults were instructed to encode the stimuli and their respective sources. To assess item memory, the participant was presented with an odor from the task and a new odor and was asked to indicate which odor had been presented previously. On source memory trials, the participant was presented with an odor from the task and was asked to indicate whether the male or female presented the odor. Results: A 2 × 2 × 2 analysis of variance revealed that older adults were significantly impaired relative to young adults on the source memory trials in both the uninformed and informed conditions, F(1, 52) = 18.15, p < 0.001. However, older adults matched the performance of young adults on item memory trials, regardless of encoding condition. Conclusions: Even with conscious effort to encode the sources associated with the odors, older adults show significant source memory impairments. The mnemonic processes used to integrate contextual source information with item memory during encoding may fail to initiate due to the amount of effort required to encode the olfactory stimulus. The difficulty of encoding and subsequently retrieving the source may be increased due to the difficulty of encoding the odors. The results demonstrate the robust effects of aging on source memory for odors.
Cholesterol Synthesis Inhibition Elicits an Integrated Molecular Response in Human Livers Including Decreased ACAT2
Authors: Parini Paolo , Gustafsson Ulf , Davis Matt A. , Larsson Lilian , Einarsson Curt , Wilson Martha , Rudling Mats , Tomoda Hiroshi , Ōmura Satoshi , Sahlin Staffan , Angelin Bo , Rudel Lawrence L. , Eriksson Mats
Published: March 2008

Objective—

The purpose of this study was to identify how different degrees of cholesterol synthesis inhibition affect human hepatic cholesterol metabolism.

Methods and Results—

Thirty-seven normocholesterolemic gallstone patients randomized to treatment with placebo, 20 mg/d fluvastatin, or 80 mg/d atorvastatin for 4 weeks were studied. Based on serum lathosterol determinations, cholesterol synthesis was reduced by 42% and 70% in the 2 groups receiving statins. VLDL cholesterol was reduced by 20% and 55%. During gallstone surgery, a liver biopsy was obtained and hepatic protein and mRNA expression of rate-limiting steps in cholesterol metabolism were assayed and related to serum lipoproteins. A marked induction of LDL receptors and 3-hydroxy-3-methylglutaryl (HMG) coenzyme A (CoA) reductase was positively related to the degree of cholesterol synthesis inhibition (ChSI). The activity, protein, and mRNA for ACAT2 were all reduced during ChSI, as was apoE mRNA. The lowering of HDL cholesterol in response to high ChSI could not be explained by altered expression of the HDL receptor CLA-1, ABCA1, or apoA-I.

Conclusions—

Statin treatment reduces ACAT2 activity in human liver and this effect, in combination with a reduced Apo E expression, may contribute to the favorable lowering of VLDL cholesterol seen in addition to the LDL lowering during statin treatment.
Targeted Deletion of PTEN in Smooth Muscle Cells Results in Vascular Remodeling and Recruitment of Progenitor Cells Through Induction of Stromal Cell–Derived Factor-1α
Authors: Nemenoff Raphael A. , Simpson Peter A. , Furgeson Seth B. , Kaplan-Albuquerque Nihal , Crossno Joseph , Garl Pamela J. , Cooper James , Weiser-Evans Mary C.M.
Published: March 2008

We previously showed that changes in vascular smooth muscle cell (SMC) PTEN/Akt signaling following vascular injury are associated with increased SMC proliferation and neointima formation. In this report, we used a genetic model to deplete PTEN specifically in SMCs by crossing PTEN
LoxP/LoxP
mice to mice expressing Cre recombinase under the control of the SM22α promoter. PTEN was downregulated with increases in phosphorylated Akt in major vessels, hearts, and lungs of mutant mice. SMC PTEN depletion promoted widespread medial SMC hyperplasia, vascular remodeling, and histopathology consistent with pulmonary hypertension. Increased vascular deposition of the chemokine stromal cell–derived factor (SDF)-1α and medial and intimal cells coexpressing SM-α-actin and CXCR4, the SDF-1α receptor, was detected in SMC PTEN-depleted mice. PTEN deficiency in cultured aortic SMCs induced autocrine growth through increased production of SDF-1α. Blocking SDF-1α attenuated autocrine growth and blocked growth of control SMCs induced by conditioned media from PTEN-deficient SMCs. In addition, SMC PTEN deficiency enhanced progenitor cell migration toward SMCs through increased SDF-1α production. SDF-1α production by other cell types is regulated by the transcription factor hypoxia-inducible factor (HIF)-1α. We found SMC nuclear HIF-1α expression in PTEN-depleted mice and increased nuclear HIF-1α in PTEN-deficient SMCs. Small interfering RNA–mediated downregulation of HIF-1α reversed SDF-1α induction by PTEN depletion and inhibition of phosphatidylinositol 3-kinase signaling blocked HIF-1α and SDF-1α upregulation induced by PTEN depletion. Our data show that SMC PTEN inactivation establishes an autocrine growth loop and increases progenitor cell recruitment through a HIF-1α–mediated SDF-1α/CXCR4 axis, thus identifying PTEN as a target for the inhibition of pathological vascular remodeling.