bluuebunny/crossref_metadata_2025 huggingface dataset:
Collagen-IV and laminin-1 regulate estrogen receptor α expression and function in mouse mammary epithelial cells
Authors: Novaro Virginia , Roskelley Calvin D. , Bissell Mina J.
Published: June 2003

The expression level and functional activity of estrogen receptor αis an important determinant of breast physiology and breast cancer treatment. However, it has been difficult to identify the signals that regulate estrogen receptor because cultured mammary epithelial cells generally do not respond to estrogenic signals. Here, we use a combination of two- and three-dimensional culture systems to dissect the extracellular signals that control endogenous estrogen receptor α. Its expression was greatly reduced when primary mammary epithelial cells were placed on tissue culture plastic; however, the presence of a reconstituted basement membrane in combination with lactogenic hormones partially prevented this decrease. Estrogen receptor αexpression in primary mammary fibroblasts was not altered by these culture conditions, indicating that its regulation is cell type specific. Moreover,estrogen receptor-dependent reporter gene expression, as well as estrogen receptor α levels, were increased threefold in a functionally normal mammary epithelial cell line when reconstituted basement membrane was added to the medium. This regulatory effect of reconstituted basement membrane was reproduced by two of its components, collagen-IV and laminin-1, and it was blocked by antibodies against α2, α6 and β1 integrin subunits. Our results indicate that integrin-mediated response to specific basement membrane components, rather than cell rounding or cell growth arrest induced by reconstituted basement membrane, is critical in the regulation of estrogen receptor α expression and function in mammary epithelial cells.
Numerical simulation of unsteady compressible flows induced by a high-speed train passing through a tunnel
Authors: Kwon H-B , Kim T-Y , Lee D-H , Kim M-S
Published: June 2003

The unsteady flow fields induced by a high-speed train travelling through a tunnel have been numerically simulated. In order to present the relative motion between a train and a tunnel, a modified patched-grid scheme based on the structured grid system has been developed and employed for an axisymmetric unsteady Euler solver using Roe's flux difference splitting method. In this paper, the innovative zonal method, named the hybrid dimension method, is proposed and applied to the train-tunnel interaction problems. The basic idea of this method is to maximize the efficiency of numerical calculations by minimal assumption of spatial dimensions. The numerical results from the modified patched-grid scheme showed good agreement with the inviscid compressible phenomena of the experimental result, i.e. the entry compression wave and the micropressure wave. The hybrid dimension method is successfully applied to the present modified patched-grid method, hardly losing the numerical accuracy. Moreover, the hybrid dimension method is expected to reduce the huge computation time of the train-tunnel interaction problems especially for the cases of long tunnels.
Optimization of circular hydrostatic axial journal bearings using a multicriteria approach
Authors: Solmaz E , Babalik F C , Öztürk F
Published: June 2003

The solutions that best optimize the design process must be determined using single-criterion and multicriteria approaches. In this research, a multicriteria optimization approach is carried out to determine the circular hydrostatic journal bearing design parameters based on the power requirement, the bearing coefficient and the minimization of the temperature rise of the oil, so that the total performance of the system is optimal. The optimization results of more than two criteria are presented and compared with previous research outcomes. Computational experimental results are given to demonstrate the effectiveness of the present approach.
Finite difference automatically generated non-uniform grids in the numerical solution of the Reynolds' compressible one-dimensional squeeze-film equation
Authors: Almas E. A. M. , De Silva F. A. P.
Published: June 2003

With the Reynolds equation, for compressible squeeze-film thrust bearings, the use of a finite difference discretization with a grid of nodes having a non-uniform spacing can result in a more efficient computation of the solution. Comparative tests of two variable spatial grid models against a uniform model were conducted with the classical finite difference methods for chosen combinations of squeeze number and excursion ratio values. For problems with a high value of σ, one of the non-uniform grid models has shown some advantages over the uniform model, requiring a smaller number of nodes and less computation time with the same solution accuracy.
Review of Drug War Heresies by MacCoun and Reuter
Authors: Levitt Steven D
Published: June 2003

MacCoun and Reuter's primary goal is to understand how current U.S. drug policies can be improved. They carefully describe the facts and trends regarding drug usage, criminal justice enforcement, and the harms associated with drug use, then discuss the public debate surrounding drug prohibition and give an informal treatment of the theory underlying the competing positions. The authors study policies towards other vices like gambling, cigarettes, alcohol, and prostitution, as well as drug policies in other times and places. The broader implication that emerges is that there is a desperate need for better data and increased research if there is any hope for making truly informed policy on illicit drugs.
On Networks and Markets by Rauch and Casella, eds.
Authors: Zuckerman Ezra W
Published: June 2003

This essay reviews Networks and Markets, edited by James E. Rauch and Alessandra Casella. This book provides a useful vehicle for clarifying the main conceptual and operational issues facing the growing study of economic networks. Three types of networks are discussed: networks as concentrated or patterned exchange; as primordial relations; and, the most general, networks as structures of mutual orientation. An overview is provided of the challenges faced by research on the economic implications of three types of networks. The strengths and weaknesses of current research on economic networks are examined via a review of the contributions in the book.
Corporate Earnings: Facts and Fiction
Authors: Lev Baruch
Published: June 2003

Manipulated earnings played a central role in the slew of corporate scandals which surfaced during the last three years. This article focuses on the vulnerability of earnings to manipulation by managers: it surveys the empirical record of manipulation, their major objectives, and the means of manipulation. It then focuses on the major source of earnings manipulation--the multitude of estimates and subjective judgments underlying the comutation of earnings. The article accordingly concludes with a proposal to curb manipulation by requiring managers to routinely compare key estimates with ex post realizations, and revise earnings in case of large deviations.
Perspectives from the President's Commission on Social Security Reform
Authors: Cogan John F , Mitchell Olivia S
Published: June 2003

Recently we were asked to serve on the President's Commission to Strengthen Social Security (CSSS) along with 14 other members drawn equally from both major political parties. The Commission's charge was to provide recommendations to modernize the Social Security system, restore its fiscal soundness, and develop a workable system of Personal Retirement Accounts. This paper explains how the Commission arrived at some of its recommendations and the role that economics played in contributing to these recommendations. We describe the key institutional constraints confronting efforts to reform Social Security and how these constraints influenced Commission decisions. We also illustrate how economics research influenced the Commission's analysis of how to structure personal accounts, ways to enhance traditional Social Security program finances, and means of measuring the extent of financial progress achieved through reform.
History Lessons Sanctions: Neither War nor Peace
Authors: Davis Lance , Engerman Stanley
Published: June 2003

This paper surveys the increasing international use of sanctions over the past century. Sanctions are a form of action taken by one state or by collective action to influence another state to change its behavior, as a substitute for welfare. They generally involve restrictions on foreign trade, either of all goods or of specific commodities. Sanctions have generally been imposed by larger countries on smaller countries. Sanctions have had a mixed success rate, depending on the costs imposed on the targeted nation, their response to these costs, and the impact on the economy and public opinion in other nations.
Expression of cVg1 mRNA during chicken embryonic development
Authors: Somi Semir , Houweling Arjan C. , Buffing Anita A.M. , Moorman Antoon F.M. , Van Den Hoff Maurice J.B.
Published: June 2003

Using degenerated PCR‐primers to identify known and novel BMPs that are expressed in the developing chicken heart, we identified not only BMP2, ‐4, and ‐7 mRNA, but also the TGFβ superfamily member cVg1. The expression pattern of cVg1 mRNA was determined during chicken development from HH4 to HH44. In early developmental stages, cVg1 mRNA is expressed in the primitive streak, paraxial mesoderm, developing somites, and developing neural tube. Subsequently, cVg1 mRNA is expressed in the developing central and peripheral nervous system, retina, auditory vesicle, notochord, lung alveoli, and olfactory mucosa. In the heart, cVg1 is initially expressed through the linear heart tube, but becomes restricted to the forming chamber myocardium, in an expression domain similar to that of atrial natriuretic factor (ANF) mRNA. Anat Rec Part A 273A:603–608, 2003. © 2003 Wiley‐Liss, Inc.
Ontogenetic and regional morphologic variations in the turkey ulna diaphysis: Implications for functional adaptation of cortical bone
Authors: Skedros John G. , Hunt Kenneth J. , Hughes Paul E. , Winet Howard
Published: June 2003

This study examines relationships between bone morphology and mechanically mediated strain/fluid‐flow patterns in an avian species. Using mid‐diaphyseal transverse sections of domestic turkey ulnae (from 11 subadults and 11 adults), we quantified developmental changes in predominant collagen fiber orientation (CFO), mineral content (%ash), and microstructure in cortical octants or quadrants (i.e., %ash). Geometric parameters were examined using whole mid‐diaphyseal cross‐sections. The ulna undergoes habitual bending and torsion, and demonstrates nonuniform matrix fluid‐flow patterns, and high circumferential strain gradients along the neutral axis (cranial‐caudal) region at mid‐diaphysis. The current results showed significant porosity differences: 1) greater osteocyte lacuna densities (N.Lac/Ar) (i.e., “non‐vascular porosity”) in the caudal and cranial cortices in both groups, 2) greater N.Lac/Ar in the pericortex vs. endocortex in mature bones, and 3) greater nonlacunar porosity (i.e., “vascular porosity”) in the endocortex vs. pericortex in mature bones. Vascular and nonvascular porosities were not correlated. There were no secondary osteons in subadults. In adults, the highest secondary osteon population densities and lowest %ash occurred in the ventral‐caudal, caudal, and cranial cortices, where shear strains, circumferential strain gradients, and fluid displacements are highest. Changes in thickness of the caudal cortex explained the largest proportion of the age‐related increase in cranial‐caudal breadth; the thickness of other cortices (dorsal, ventral, and cranial) exhibited smaller changes. Only subadult bones exhibited CFO patterns corresponding to habitual tension (ventral) and compression (dorsal). These CFO variations may be adaptations for differential mechanical requirements in “strain‐mode‐specific” loading. The more uniform oblique‐to‐transverse CFO patterns in adult bones may represent adaptations for shear strains produced by torsional loading, which is presumably more prevalent in adults. The micro‐ and ultrastructural heterogeneities may influence strain and fluid‐flow dynamics, which are considered proximate signals in bone adaptation. Anat Rec Part A 273A:609–629, 2003. © 2003 Wiley‐Liss, Inc.
Anatomy and motor pathways of the electric organ of skates
Authors: Koester David M.
Published: June 2003

The electric organ of skates is a paired structure within the tail consisting of two longitudinal columns of electrocytes contained within the lateral musculature on each side of the vertebral column. The electrocytes develop from hypaxial skeletal muscle fibers, and, depending upon the species, are generally classified as either cup‐shaped or disc‐shaped. The disc‐shaped electrocytes are considered to be the more derived type. Regardless of the morphology of the electrocyte, the electric organ discharge of all skates is characterized as a weak asynchronous and long‐lasting signal. Although recent behavioral investigations have revealed a communicative function for the electric organ, details as to which specific behaviors utilize this motor system remain uncertain. The electric organ is innervated by segmental motor nerves that branch from the ventral root of caudal spinal nerves at all levels of the electric organ. The cells of origin of the electromotor nerves, or electromotoneurons (EMNs), are large multipolar neurons with extensive dendrites located within the ventral gray matter of the spinal cord. The EMNs are uniformly distributed among the somatic motoneurons at levels corresponding to the rostrocaudal extent of the electric organ, and therefore do not form a discrete nucleus. The medullary command nucleus is comprised of neurons located within the nucleus raphe magnus, and forms a descending spinal pathway to the EMNs. Anat Rec Part A 273A:648–662, 2003. © 2003 Wiley‐Liss, Inc.
Portal vein resection and reconstruction prior to hepatic dissection during right hepatectomy and caudate lobectomy for hepatobiliary cancer
Authors: Kondo S , Katoh H , Hirano S , Ambo Y , Tanaka E , Okushiba S
Published: June 2003

Background

Hepatobiliary cancer invading the hilar bile duct often involves the portal bifurcation. Portal vein resection and reconstruction is usually performed after completion of the hepatectomy. This retrospective study assessed the safety and usefulness of portal vein reconstruction prior to hepatic dissection in right hepatectomy and caudate lobectomy plus biliary reconstruction, one of the common procedures for radical resection.

Methods

Clinical characteristics and perioperative results were compared in patients who underwent right hepatectomy and caudate lobectomy plus biliary reconstruction with (ten patients) and without (11 patients) portal reconstruction from September 1998 to March 2002.

Results

All ten portal vein reconstructions were completed successfully before hepatic dissection; the portal cross-clamp time ranged from 15 to 41 (median 22) min. Blood loss, blood transfusion during the operation, postoperative liver function, morbidity and length of hospital stay were similar in the two groups. No patient suffered postoperative hepatic failure or death.

Conclusion

This study demonstrates that portal vein reconstruction does not increase the morbidity or mortality associated with right hepatectomy and caudate lobectomy with biliary reconstruction. This approach facilitates portal vein reconstruction for no-touch resection of hepatobiliary cancer invading the hilar bile duct.
Temporary closure of open abdominal wounds by the modified sandwich–vacuum pack technique
Authors: Navsaria P H , Bunting M , Omoshoro-Jones J , Nicol A J , Kahn D
Published: June 2003

Background

A 5-year experience with the modified sandwich–vacuum pack technique, using an opened 3-litre urological irrigation bag and continuous high-pressure suction, for temporary abdominal wall closure is presented.

Methods

The records of all patients who underwent temporary abdominal wall closure using this method from January 1996 to December 2000 were examined.

Results

The modified sandwich–vacuum pack was used 139 times in 55 patients. Forty patients sustained penetrating trauma while 15 patients sustained blunt trauma. The mean Injury Severity Score was 19 (range 9–34). Intra-abdominal sepsis (51 per cent) was the commonest indication, followed by visceral oedema (18 per cent), abdominal compartment syndrome (16 per cent), intra-abdominal packing (11 per cent) and abdominal wall defects (4 per cent). The overall mortality rate was 45 per cent. Three patients (5 per cent) developed enterocutaneous fistula. Of the 30 survivors, 16 patients underwent primary fascial closure.

Conclusion

The modified sandwich–vacuum pack technique of temporary abdominal wall closure is easy and rapid, cost effective and provides an effective means of containing abdominal wall contents.
Randomized clinical trial of the effect of interferon α on survival in patients with disseminated midgut carcinoid tumours
Authors: Kölby L , Persson G , Franzén S , Ahrén B
Published: June 2003

Background

Midgut carcinoid tumours often present with widespread disease making curative surgery impossible. Medical treatment therefore plays a major role in the treatment of these patients.

Methods

In this prospective randomized study, the effect of interferon (IFN) α on survival and risk of tumour progression was evaluated in 68 patients with midgut carcinoid tumours metastatic to the liver. All patients had undergone primary surgical treatment and hepatic arterial embolization of liver metastases before randomization. Patients were randomized to treatment with either octreotide alone (n = 35) or octreotide in combination with IFN-α (n = 33).

Results

Forty-one of the 68 patients died during a follow-up period of 33–120 months, equivalent to a 5-year survival rate of 46·5 per cent. There was no significant difference in survival between patients treated with octreotide alone (5-year survival rate 36·6 per cent) and those given octreotide in combination with IFN-α (56·8 per cent). However, patients treated with IFN-α had a significantly reduced risk of tumour progression during follow-up (P = 0·008).

Conclusion

Addition of IFN-α to octreotide may retard tumour growth in patients with midgut carcinoid tumours.
Image-directed parathyroidectomy under local anaesthesia in the elderly
Authors: Biertho L , Chu C , Inabnet W B
Published: June 2003

Background

Surgical morbidity and mortality rates are increased in elderly patients. The aim of this study was to evaluate the outcome of targeted parathyroid operations in patients over the age of 70 years.

Methods

Forty patients aged over 70 years underwent targeted parathyroidectomy for primary hyperparathyroidism (HPT). Data were collected prospectively and reviewed retrospectively.

Results

There were 33 women and seven men with a mean age of 78 (range 70–92) years, all of whom had symptoms attributable to HPT. A solitary parathyroid adenoma was detected by ultrasonography and/or sestamibi scintigraphy before operation in all patients. Six patients had a history of neck surgery, including two with persistent or recurrent HPT. Thirty-three patients underwent neck exploration under local anaesthesia with intravenous sedation. Following parathyroidectomy, intraoperative parathyroid hormone levels normalized in 39 of 40 patients and accurately predicted postoperative eucalcaemia. Intraoperative findings included 37 solitary adenomas, one double adenoma and two carcinomas. One patient with persistent HPT developed severe hypoparathyroidism following targeted parathyroid exploration with autotransplantation. Twenty-nine patients were discharged from hospital on the day of surgery. Nineteen of 21 patients for whom data were available reported an improvement in symptoms.

Conclusion

A focused neck exploration provides a safe and effective alternative to bilateral neck exploration in elderly patients in whom a solitary parathyroid adenoma has been localized before operation. Targeted parathyroidectomy under local anaesthesia is recommended in most elderly patients with HPT.
Limits and drawbacks of video-assisted parathyroidectomy
Authors: Berti P , Materazzi G , Picone A , Miccoli P
Published: June 2003

Background

Minimally invasive video-assisted parathyroidectomy (MIVAP) is a novel minimally invasive approach to primary hyperparathyroidism (PHPT). It is a gasless operation characterized by a single central incision and external retraction. This paper describes the drawbacks and limitations of this procedure based on a 5-year experience and 260 operations.

Methods

Of 364 patients with PHTP, 260 were selected for MIVAP. In most patients a unilateral minimally invasive exploration was performed.

Results

MIVAP was carried out successfully in 239 patients with a mean operating time of 40 (range 20–180) min. Conversion to cervicotomy was required in 21 patients (8·1 per cent). Complications included recurrent nerve palsy in two patients (0·8 per cent), haemorrhage that required reoperation 6 h after parathyroidectomy in one patient (0·4 per cent) and transient hypoparathyroidism in six patients (2·5 per cent). In five patients (2·1 per cent) persistent PHPT developed shortly after surgery.

Conclusion

After 5 years of experience, MIVAP appears to be feasible, safe and applicable to the majority of patients with PHPT.
Laparoscopic liver resection
Authors: Cherqui D
Published: June 2003

certainly feasible; possibly effective
Letter 1: Systemic inflammatory response predicts survival following curative resection of colorectal cancer (Br J Surg 2003; 90: 215–219)
Authors: Shankar J , Mathew J , Saklani A
Published: June 2003

The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses can be sent electronically via the BJS website (http://www.bjs.co.uk) or by post. All letters will be reviewed and, if approved, appear on the website. A selection of these will be edited and published in the Journal. Letters must be no more than 250 words in length. Letters submitted by post should be typed on A4-sized paper in double spacing and should be accompanied by a disk.
Issues and considerations regarding the use of assessment instruments in the evaluation of competency to stand trial
Authors: Zapf Patricia A. , Viljoen Jodi L.
Published: June 2003

Since the early 1960s, a number of instruments, reflecting a broad range of assessment methods, have been developed to assist in the evaluation of competency to stand trial. These instruments have taken various forms including checklists, self‐report questionnaires, sentence‐completion tasks, and interview‐based instruments with and without criterion‐based scoring. This article reviews these assessment instruments with a specific focus on their contribution to the competency evaluation process. Furthermore, relevant issues and considerations regarding the use of these instruments are outlined, including a comparison of screening versus assessment applications of these instruments, balancing standardized approaches with individualized assessments, the integration of instrumentally derived data with other components of a competency evaluation, and the communication of results to the fact finder. Each of these issues is discussed in relation to specific competency assessment instruments. Overall, we argue that each of the competency assessment instruments developed to date can make a contribution to the competency evaluation process and this article serves to delineate those areas in which these contributions are made. Copyright © 2003 John Wiley & Sons, Ltd.
Competency to stand trial: rationalism, “contextualism” and other modest theories
Authors: Jan Brakel S.
Published: June 2003

Determinations of competency to stand trial in criminal cases are complicated and rendered unpredictable by two sub‐surface issues that are rarely articulated: (i) the place of the defendant's rationality in the substantive standard(s) for competency and (ii) the level or degree of incompetency required to stop the criminal process. The rare references to these issues, mostly indirect, that are made in the cases, commentary, and competency testing instruments devised (including those civil as well as criminal) are examined. The conclusion that emerges is that the level of capacity and rationality required of the defendant depends much on context—the type of case, its relative complexity, and the values and stakes implicated in the outcome. Copyright © 2003 John Wiley & Sons, Ltd.
Beyond Dusky and Godinez: competency before and after trial
Authors: Perlin Michael L.
Published: June 2003

Scholars have carefully considered all aspects of the incompetency to stand trial process, questions involving incompetency to confess, questions involving incompetency to be executed, and, to a lesser extent, questions related to incompetency to plead guilty or to waive counsel, but little attention has been paid to the relationship between incompetency and the full range of other criminal procedure issues: sentencing, appeals, consent to searches, and others. This article discusses this range of issues, assesses the factors relied upon by courts in deciding these cases and attempts to offer an agenda for future scholarly developments in this area. Copyright © 2003 John Wiley & Sons, Ltd.
Pre‐adjudicative and adjudicative competence in juveniles and young adults
Authors: Redlich Allison D. , Silverman Melissa , Steiner Hans
Published: June 2003

There are several different types of legal competence, such as competence to waive Miranda rights, competence to confess, and competence to stand trial. Although it can be surmised that many of the underlying factors that influence the different legal competencies are similar, little research has been conducted to empirically test this hypothesis. In the present study, juveniles' and young adults' understanding and appreciation of their Miranda rights and their ability to stand trial were measured. Age, suggestibility, average grades in school, and frequency of previous police involvement were also examined as possible factors that influence both types of legal knowledge. Results indicated that Miranda competence and adjudicative competence are indeed strongly related, especially for juveniles. Also, age and suggestibility were found to predict Miranda competence, whereas suggestibility and average school grades predicted competence to stand trial. Patterns of findings often diverged for juveniles and young adults. Implications for legal policy are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Hospitalization of criminal defendants for evaluation of competence to stand trial or for restoration of competence: clinical and legal issues
Authors: Miller Robert D.
Published: June 2003

The clinical and legal literature abounds with articles dealing with competence to stand trial; while most agree that criminal defendants must be capable of defending themselves before the state can bring them to trial, a number of articles are quite critical of the procedures by which these concepts are operationalized, some even going so far as to suggest abolishing the requirement for competence altogether. One of the major problems leading to the criticisms is the unnecessary loss of liberty involved. Although the length of incarceration has decreased significantly since the 1970s, the majority of states still permit, or require, hospitalization for evaluation of competence, and even more so for treatment to restore competence.

The author reviews case law and presents data from his survey of current state statutes and responses from state forensic mental health program directors, to demonstrate the rarity of outpatient treatment to restore competence. He argues that outpatient treatment for defendants who do not require hospitalization on clinical or public safety grounds should be available, on both clinical and legal grounds, and provides recommendations for establishing such programs in the community. Copyright © 2003 John Wiley & Sons, Ltd.
New Modular Integral Pilot Reactors for Information Retrieval on Fixed‐Bed Catalytic Gas‐Phase Reactions
Authors: Hennig T. , Bauer M. , Schröder F. , Schreier M. , Adler R.
Published: June 2003

The integral reactor is most critical for experimental reaction engineering. However, its design does not come up to current requirements. Based on a tested modular construction principle, new modules for multifunctional integral pilot reactors with a wide range of applications were developed. These modules allow to configure both single and combination reactors for implementing varied methodical objectives. Two examples illustrate the advantages for the user.
CFD Simulation of Preparative HPLC Columns with Consideration of Nonlinear Isotherms
Authors: Boysen H. , Wozny G. , Laiblin T. , Arlt W.
Published: June 2003

The simulation of chromatography increasingly becomes an important tool for process design. For this purpose, one‐dimensional simulations usually are sufficient. For the simulation of today’s preparative HPLC columns with extreme geometries (length/diameter ratio less than 1), at least two dimensions in space have to be considered so that radial influences are taken into account. A two‐dimensional CFD model has been developed using the commercial software FLUENT.
Isolation of Carbohydrate Carboxylic Acids from Aqueous Solutions by Reactive Extraction
Authors: Hirth J. , Bicker M. , Vogel H.
Published: June 2003

Until now the separation of carbohydrate carboxylic acids from aqueous solutions obtained by reaction or fermentation represents an economic barrier. Hydroxycarboxylic acids are poorly extractable with conventional solvents. To reach good extraction results, i.e., high distribution ratios and selectivities with respect to the resource, combined, highly synergistic extractant systems were used. Hydroxycarboxylic acids, which have been extracted with trialkylamines, primarily with tri‐n‐octylamine, can frequently show a poor coalescence behavior and form stable emulsions. Thus, different methods to accelerate the separation of phases were investigated.
Steady‐State Modeling and Simulation of an Axial‐Radial Ammonia Synthesis Reactor
Authors: Panahandeh M.R. , Fathikaljahi J. , Taheri M.
Published: June 2003

A two‐dimensional model was developed for an axial‐radial ammonia synthesis reactor of the Shiraz petrochemical plant. In this model, momentum and continuity equations as well as mass and energy balance equations are solved simultaneously by orthogonal collocation on the finite element method to obtain pressure, velocity, concentration and temperature profiles in both axial and radial directions. For the catalyst particle, the effectiveness factor is calculated by solving a two‐point boundary value differential equation. The boundary conditions for the Navier‐Stokes and continuity equations are obtained by using equations representing the phenomena of gases splitting or joining in different streams and going through holes in a thin wall. The results of the mathematical model have been compared with the plant data and a good agreement is obtained.
Incorporation of Flexibility in the Design of a Methanol Synthesis Loop in the Presence of Catalyst Deactivation
Authors: Rahimpour M.R. , Ghader S. , Baniadam M. , Fathi Kalajahi J.
Published: June 2003

This paper presents the incorporation of process flexibility into a methanol synthesis loop operating under catalyst deactivation. A design methodology is discussed with regard to catalyst deactivation, and some limitations are identified. In the current flexibility study the size of the reactor and recycle ratio have been fixed. Attempts to maintain methanol production at the rates observed with fresh catalyst included increased pressure, increased make up gas flow rate, and the injection of carbon dioxide into the make up gas at optimized inlet temperature. In order to provide flexibility and produce a design compatible with increased production rates, the effect of interrelating equipment had to be considered. As a result of catalyst deactivation, an increased flow rate is necessary and the altered process streams entering the preheater disturb the reactor inlet temperature. These issues should be considered in the design stage and may be resolved by the flexible designs presented.
Modeling of Kinetic Expressions for the Reduction of NOx by Hydrogen in Oxygen‐Rich Exhausts Using a Gradient‐Free Loop Reactor
Authors: Frank E. , Oguz H. , Weisweiler W.
Published: June 2003

The reduction of NOx by hydrogen under lean conditions is investigated in a gradient‐free loop reactor. Using this computer‐controlled reactor, the reaction rates can be measured under exact isothermal conditions. Systematic variation of the input concentrations of hydrogen, nitric oxide, oxygen as well as reaction temperature provides a complete data set of reaction rates for the given reaction system. A number of kinetic rate expressions were evaluated for their ability to fit the experimental data by using toolboxes of MATLAB. The temperature influence on reaction rate constants and adsorption equilibrium constants were correlated simultaneously using Arrhenius and van’t Hoff equations, respectively. The kinetic rate expression based on a Langmuir‐Hinshelwood‐type model describes the data and the model can be improved by introducing a correction term in square root of hydrogen partial pressure over the range of conditions investigated.
The Partial Oxidation of Isobutene in Sub‐ and Supercritical Water
Authors: Richter T. , Vogel H.
Published: June 2003

The task of this work was to investigate which kind of reaction pathway takes place under supercritical water conditions in the oxidation of isobutene with molecular oxygen. The reaction was examined at temperatures of 350–20 °C, pressures of 25–35 MPa, uncatalyzed and under platinum‐catalyses. Isobutyraldehyde was the main product. Tert‐butanol was used as a source for isobutene, which dehydrates to isobutene quantitatively under the conditions used.
Investigation of Heavy Metal Release during Thermal Waste Treatment on a Forward‐Acting Grate by Means of Radiotracers
Authors: Jentsch T. , Beckmann M. , Davidovic M. , Biollaz S.
Published: June 2003

This paper deals with the determination of location, time and quantity of the release of heavy metals in a pilot‐scale grate system by means of short‐lived radioactive isotopes during the incineration of municipal waste. The isotopes 69mZn (half life: 13.8 hours) and 64Cu (half life: 12.7 hours) were used to represent heavy metals which can be released relatively well and more difficultly, respectively. Due to the implementation of isotopes which emit gamma rays, all measured values could be acquired without direct contact and without the need to take samples. The location of release was determined by means of NaI(Tl)‐scintillation detectors positioned alongside the outer walls of the grate. The time and the quantity of the release were measured with a detector located in a special absorption vessel for the purification of a partial flow of the exhaust gases.
Eigenvector‐free indicator, pinpointing and branch‐switching for bifurcation
Authors: Noguchi H. , Fujii F.
Published: June 2003

The authors have already proposed in their previous papers an innovative eigenanalysis‐free idea to extract the buckling mode for bifurcation instability from the LDLT‐decomposed stiffness matrix. The present study first outlines this basic idea very briefly for a review purpose. The idea will then be applied to eigenvector‐free procedures for identifying and pinpointing the stability point and branch‐switching for post‐bifurcation analysis. Numerical examples will examine the versatility and robustness of the proposed eigenvector‐free procedures in computational bifurcation theory. It is illustrated that the proposed procedures are robust enough for multiple as well as simple bifurcation. Copyright © 2003 John Wiley & Sons, Ltd.
Exacerbation of experimental autoimmune encephalomyelitis in rodents infected with murine gammaherpesvirus‐68
Authors: Peacock James W. , Elsawa Sherine F. , Petty Cynthia C. , Hickey William F. , Bost Kenneth L.
Published: June 2003

Viral infections have long been suspected to play a role in the pathogenesis of multiple sclerosis. In the present study, two different rodent models of experimental autoimmune encephalomyelitis (EAE) were used to demonstrate the ability of murine gammaherpesvirus‐68 (γHV‐68) to exacerbate development of neurological symptoms. SJL mice received UV‐inactivated γHV‐68 or intranasalγHV‐68, followed by immunization against proteolipid‐protein peptide 139–151. Infected mice became moribund within 10 days post‐immunization, whereas mice exposed to UV‐inactivated γHV‐68 recovered. In the second model, Lewis rats were exposed to UV‐inactivated γHV‐68 or to γHV‐68, followed by passive transfer of encephalitogenic T lymphocytes specific for myelin basic protein. Consistently, infected rats had higher clinical scores, and this result was observed during acute or latent γHV‐68 infection. It is unlikely that this γHV‐68‐induced exacerbation was due to significant viral replication within the central nervous system since nested PCR, viral plaque assays, and infectious‐centers assays demonstrated no detectable virus in spinal cords or brains of infected rodents undergoing EAE. Taken together, these studies demonstrate increased clinical symptoms of EAE in rodents infected by a gammaherpesvirus that has a limited ability to invade the central nervous system.
Development of protective immunity against cutaneous leishmaniasis is dependent on STAT1‐mediated IFN signaling pathway
Authors: Rosas Lucia E. , Keiser Tracy , Pyles Ryan , Durbin Joan , Satoskar Abhay R.
Published: June 2003

Although STAT1‐dependent signaling mediates biological functions of IFN‐α/β and IFN‐γ, recent reports indicate that STAT1‐independent IFN signaling also regulates expression of several genes. To determine the roles of STAT1‐dependent and ‐independent IFN signaling in the regulation of immunity during cutaneous leishmaniasis, we studied the course of Leishmania major infection in resistant C57BL/6 mice lacking the STAT1 gene. While L. major‐infected STAT1+/+ mice resolved their lesions, STAT1–/– mice developed large lesions containing significantly more parasites. Moreover, the inability of STAT1–/– mice to control L. major infection was due to the lack of Th1 development associated with reduced production of IL‐12, IFN‐γ and nitric oxide. Although STAT1–/– mice produced more IL‐4 and total IgE than STAT1+/+ mice later during infection, these differences were not significant. Nevertheless, at these time points lymph node cells from STAT1–/– mice produced significantly more IL‐10. Finally, STAT1–/– mice were also susceptible to low dose L. major infection. Thesefindings demonstrate that STAT1‐mediated IFN signaling is indispensable for the development of protective immunity against cutaneous L. major infection. Moreover, they also suggest that the protective role of STAT1‐mediated signaling is due to its ability to induce Th1 development during infection with this parasite.
Naive and memory B cells respond differentially to T‐dependent signaling but display an equal potential for differentiation toward the centroblast‐restricted CD77/globotriaosylceramide phenotype
Authors: Gagro Alenka , Toellner Kai‐Michael , Grafton Gillian , Servis Dražen , Branica Srećko , Radojčić Vedran , Kosor Ela , Hrabak Maja , Gordon John
Published: June 2003

Resting (CD38low) tonsillar B cells differentiate to express the centroblast‐restricted CD77/globotriaosylceramide antigen on high‐level engagement of CD154. As the CD38low population comprises both naive and memory subsets, we wished to compare the propensity of each to develop this germinal center phenotype; particularly as the capacity of memory B cells to re‐enter afollicular reaction remains unclear. Resting B lymphocytes were therefore separated into CD27–IgA–IgG– and IgD– fractions to generate subsets enriched for naive and memory cells, respectively. Following stimulation via BCR and/or CD40 – surrogate signals for B cells engaged in T‐dependent signaling – differences between the two subsets were seen in the kinetics and/or magnitude of responses such as entry into DNA synthesis, induction of the costimulatory molecules CD80 and CD86; up‐regulation of CD23, and changes in BCL‐6 mRNA expression. Nevertheless, naive and memory cells revealed a nigh identical capacity for acquiring CD77: both appeared equally sensitive in this regard, with high‐level CD40 engagement via cell‐bound CD154 being required for both subsets to achieve the hallmark centroblast phenotype. These findings suggest that, provided with the opportunity to encounter cell membrane CD154 in abundance, both naive and memory B cells display the potential to be diverted towards a germinal center pathway of differentiation.
‘Bystander polarization’ of CD4+ T cells: activation with high‐dose IL‐2 renders naive T cells responsive to IL‐12 and/or IL‐18 in the absence of TCR ligation
Authors: Chakir Habiba , Lam Debbie Ka Yee , Lemay Anne‐Marie , Webb John R.
Published: June 2003

Responsiveness of CD4+ T cells to the IFN‐γ‐inducing cytokines IL‐12 and IL‐18 is generally thought to be acquired only after stimulation via the TCR. We report herein that stimulation of naive CD4+ T cells with high‐dose IL‐2 (1000 U/ml) renders these cells responsive to IL‐12 and/or IL‐18 without a requirement for TCR ligation. Naive CD4+CD62L+ Tcells from normal C57BL/6 mice or from DO11.10/Rag2–/– OVA‐specific TCR‐transgenic mice secreted substantial amounts of IFN‐γ when stimulated concurrently with high‐dose IL‐2 plus IL‐12 or IL‐18. mRNA encoding both chains of the IL‐12 and the IL‐18 receptors was expressed by CD4+ T cells after stimulation with high‐dose IL‐2. Furthermore, anti‐CD3‐induced IL‐12/IL‐18 responsiveness was fully abrogated in the presence of cyclosporin A whereas IL‐2‐induced IL‐12/IL‐18 responsiveness was not, reminiscent of the previously reported IL‐12+IL‐18 innate pathway of T cell activation. Lastly, after stimulation with IL‐2+IL‐12, naive CD4+ T cells from DO11.10/Rag2–/– mice exhibited polarization towards a Th1 phenotype (high IFN‐γ but no IL‐4) during secondary stimulation with immobilized anti‐CD3. We have coined the term ‘bystander polarization’ to describe this phenomenon and we speculate that bystander polarization of naive CD4+ T cells may occur in vivo during strong antigen‐specific immune responses.
"Bystander" recruitment of systemic memory T cells delays the immune response to respiratory virus infection
Authors: Ostler Tobias , Pircher Hanspeter , Ehl Stephan
Published: June 2003

The concept of heterologous T cell immunity postulates that nonspecific memory T cells recruited and reactivated in the context of an unrelated virus infection may contribute to protective antiviral immunity. Pulmonary infection with respiratory syncytial virus (RSV) of mice immune to lymphocytic choriomeningitis virus (LCMV) leads to substantial recruitment of systemic LCMV‐specific memory CD8 T cells to the lung. Using a sensitive TCR‐transgenic model, we show that such "bystander" recruitment to the RSV‐infected lung could induce a single round of cell division among LCMV‐specific T cells. However, it did not change their activation status as assessed by expression of surface markers, the extent or kinetics of IFN‐γ production and cytolytic effector function. Moreover,recruitment of LCMV‐specific bystander T cells not only failed to enhance immunity to RSV, but significantly delayed virus elimination and slightly enhanced RSV‐induced weight loss in non‐transgenic BALB/c mice. This correlated with a delay in the recruitment of RSV‐specific T cells to the lung. These data show that bystander recruitment of heterologous T cells is not necessarily accompanied by bystander activation. More importantly, bystander recruitment of systemic memory T cells can impair antiviral immunity, presumably by interference with the recruitment of specific T cells.
Induction of T‐cell‐mediated skin disease specific for antigen transgenically expressed in keratinocytes
Authors: Azukizawa Hiroaki , Kosaka Hiroshi , Sano Shigetoshi , Heath William R. , Takahashi Isao , Gao Xing‐Hua , Sumikawa Yasuyuki , Okabe Masaru , Yoshikawa Kunihiko , Itami Satoshi
Published: June 2003

Transgenic mice were generated to establish an animal model for T‐cell‐mediated autoimmune skin disease. A membrane‐bound form of OVA (mOVA) was specifically expressed under the control of thekeratin 5 (K5) promoter in the epidermal and hair follicular keratinocytes of mice. Syngeneic, wild‐type mice rejected the skin grafts of K5‐mOVA mice with the generation of OVA‐specific CTL. To study the CTL response against K5‐mOVA skin, we used OT‐I transgenic mice, which produce Kb‐restricted, OVA‐specific CD8+ T cells. Accelerated rejection of K5‐mOVA skin was demonstrated when transplanted onto OT‐I mice. Furthermore, OT‐I cells, when adoptively transferred into K5‐mOVA mice, underwent activation and vigorous proliferation in the skin‐draining lymph nodes. A bone‐marrow‐reconstitution assay demonstrated that Kb presentation by bone‐marrow‐derived cells, but not epithelial cells, was required for this response, indicating that cross‐priming was the basis for immunity in this model. Finally, transferred OT‐I cells, activated by cross‐priming, targeted the skin of K5‐mOVA mice, resulting in development of skin lesions that were reminiscent of toxic epidermal necrolysis. We conclude that our system provides a useful model for autoimmune skin diseases and will aid understanding of the pathomechanism of drug eruption, viral exanthema, and graft‐versus‐host disease.
Paradoxical effects of arthritis‐regulating chromosome 4 regions on myelin oligodendrocyte glycoprotein‐induced encephalomyelitis in congenic rats
Authors: Becanovic Kristina , Bäckdahl Liselotte , Wallström Erik , Aboul‐Enein Fahmy , Lassmann Hans , Olsson Tomas , Lorentzen Johnny C.
Published: June 2003

Immunoregulatory gene loci in different organ‐specific inflammatory diseases often co‐localize. We here studied myelin oligodendrocyte glycoprotein (MOG)‐induced EAE in rat strains congenic for arthritis‐regulating genome regions on chromosome 4. We used congenic rats with a 70‐centimorgan (cM) fragment from the EAE‐ and arthritis‐resistant PVG.1AV1 rat strain on the arthritis‐ and EAE‐permissive Dark Agouti (DA) rat background. In addition, we evaluated three recombinant strains, C4R1–C4R3, which overlap with arthritis‐linked loci. PVG.1AV1 alleles in the C4R1 recombinant did not affect arthritis, but conferred protection against MOG‐EAE. PVG.1AV1 alleles in the C4R2 recombinant down‐regulated arthritis but had no effect in MOG‐EAE. Paradoxically, PVG.1AV1 alleles in the C4R3 recombinant down‐regulated arthritis, but the same fragment increased serum levels of anti‐MOG Ab and aggravated clinical MOG‐EAE. Thus, we provide original evidence that the same genome regions can have opposite effects in different organ‐specific inflammatory diseases. Interestingly, no apparent difference in the MOG‐EAE phenotype was observed in full‐length congenic rats and parental DA rats, suggesting that the disease amelioration in C4R1 and aggravation in C4R3 functionally counteract each other. The data set the stage for definition of the mechanisms and positioning of the genes regulating two organ‐specific inflammatory diseases differently.