bluuebunny/crossref_metadata_2025 huggingface dataset:
Wearable Medical Devices
Authors: Fotiadis Dimitrios I. , Glaros Constantine , Likas Aristidis
Published: April 2006

The termwearable medical devicesdescribes autonomous devices that are worn by a person and provide medical monitoring or support over a prolonged period of time. Their distinguishing characteristic is that they are worn either as an accessory or are embedded into clothing. Such devices normally incorporate noninvasive physiological sensors, data processing modules, medical feedback, and wireless data transmission capabilities. They are small, light, unobtrusive, and designed for operation by unskilled users. Current developments include real‐time feedback, alerting mechanisms, medical decision support, and wireless access to information. Wearable medical devices offer the supporting hardware for dealing with the emerging medical trend of delivering point‐of‐care service, unconfined medical monitoring and support, and assisting in the remote management of medical conditions for rehabilitating patients, the chronically ill, and the disabled.
Cognitive Assistive Technology
Authors: Mihailidis Alex , LoPresti Edmund F.
Published: April 2006

Cognitive assistive technology (AT) attempts to compensate for existing impairments by using devices, tools, or techniques that either partially take the place of a person's impaired ability, including attempting to rehabilitate those impairments if possible, or translate a problem into one that matches the user's strengths. This chapter will provide an introduction to the field of cognitive AT. The reader will be presented with a review of the current and previous research trends in this field, key aspects on the design of these devices and tools, and a discussion of future work and trends. As the field of cognitive AT is quite diverse, this overview will focus primarily on those devices that are considered compensatory tools, specifically devices developed to assist users with memory, planning, and problem‐solving impairments.
Functional Electrical Stimulation (FES) for Stroke Rehabilitation
Authors: Raymond Tong Kai Yu
Published: April 2006

Functional electrical stimulation (FES) is generally referred to as the artificial electrical stimulation of a muscle that has diminished nervous control, with the aim of providing a muscular contraction and producing a functionally useful movement. FES is a technique that uses bursts of short electrical pulses to generate muscle contractions by stimulating motor‐neurons or reflex pathways. FES aims to generate functional movements that mimic normal voluntary movements and to restore functions that have been lost after the impairment on the nervous system. From the first successful FES application on the peroneal nerve of patients with hemiplegia for walking by Liberson et al. in 1961, various types of FES have been applied in stroke rehabilitation. The common FES applications for the rehabilitation of lower limbs and upper limbs are the drop foot stimulator and hand grasp system, respectively. The general aim of applying FES on patients after stroke is to help the person by optimizing functional motor performance and facilitating neurorehabilitation.
Biomolecular Layers: Quantification of Mass and Thickness
Authors: Fulga Florin , Nicolau Dan V.
Published: April 2006

The approach of building biomolecular devices starts with the preparation of thin biomolecular films with a structural control. The first question regarding a biomolecular film is how many molecules are deposited on the substrate, or equivalently, what is the mass of the film. The optical methods, like ellipsometry and surface plasmon resonance (SPR), which describe the film in terms of experimentally measurable optical parameters, allow a precise determination of the thickness and the mass of the film. Other methods like quartz crystal microbalance (QCM) allow the determination of other parameters of the film, like viscosity and water content. A combination of these methods would allow a better characterization of the parameters of the biomolecular film.
Arthroscopic Fixation Devices
Authors: Gabriel Stefan M. , Lipchitz John M. , Brunelle John E.
Published: April 2006

Arthroscopic fixation devices enable surgeons to repair ligament and tendon damage at the joints of the body without creating larger incisions or tissue retractions for access to the repair site. Until recently, surgical procedures, such as anterior cruciate ligament (ACL) and meniscal repair in the knee and rotator cuff repair in the shoulder, were done exclusively through large incisions, which was necessary to allow a surgeon's fingers to reach the repair site. Visualization instruments such as the arthroscope provide a window into the joint for diagnostic and visual guidance purposes. Small suture anchors and tissue anchors and their associated insertion and access instruments used under arthroscopic visualization now make it possible for the same procedures to be done through 10‐mm diameter and smaller access portals. The development of novel materials such as absorbable copolymers along with continued innovation in design will continue to provide the surgeon and the patient with better and better solutions, expanding the number of procedures and their efficacy in the challenging area of arthroscopic surgery.
Myoelectric Control of Powered Upper‐Limb Prostheses
Authors: Englehart Kevin , Hudgins Bernard , Bush Greg
Published: April 2006

The surface myoelectric signal has found many important applications in research and clinical application. Its use as a system input for the control of powered upper‐limb prostheses was first proposed almost 60 years ago. This control approach, referred to as myoelectric control, has been a clinically significant option for limb‐deficient individuals for 30 years. Myoelectric control has gained widespread use, with many fitting centers worldwide. The sophistication of myoelectric control continues to improve, offering users improvements in dexterity and ease of use.
Electromyography (EMG) of Pelvic Floor Muscles
Authors: Merletti Roberto , Enck Paul
Published: April 2006

This contribution analyses the anatomy and neurophysiology of the pelvic floor muscles as well as the multichannel electromyogram (EMG) of the anal sphincter, urethral sphincter and puborectalis muscles. Cylindrical probes carrying one or more circumferential arrays of electrodes are used to detect the generation (at the end‐plates), propagation (along the muscle fibers) and extinction (at the fiber endings) of individual action potentials generated by motor units of the sphincters.

A linear array of electrodes printed on a plastic band glued on the tip of the index finger of a surgical glove allows is used to detect signals from the puborectalis muscles. The anatomical features (fiber length, orientation, location of innervation zone) of motor units of these muscles can be observed with this technique. The application to the anal sphincter is particularly useful for the identification of innervation zones and the proper planning of episiotomy to reduce the risk of anal sphincter damage during child birth.
Bone, Mechanical Testing of
Authors: Horan M.P. , An Y.H.
Published: April 2006

Bone is a complex heterogeneous material or structure that in the animal or human body serves the function of support, movement and protection, body mineral homeostasis, and hematopoesis. The mechanical properties of bone, expressed as strength, stiffness or elastic modulus, depend on its hierarchical structure at the macro, micro, sub‐micro, nano and sub‐nano levels. There are numerous methods for testing the mechanical properties of bone at its different structural levels. A laboratory equipped with basic tools, devices, and mechanical testing machines is essential for mechanical testing of bone. This chapter presents basic concepts and principles of bone biomechanics and introduces basic methodologies of mechanical testing of bone at the macro level. The importance and basic design of testing fixtures are included. Common errors and precautions for mechanical testing of bone are also discussed.
Computer‐Assisted Radiation Therapy (CART)
Authors: Giannouli Stavroula
Published: April 2006

Radiation therapy is mostly a computer‐based technique. From the first days of using radiation to treat cancer, it was obvious that automatic procedures are important, because implication of technicians was dangerous. All kinds of radiation therapy have evolved over the last decades because of the use of computers. New imaging techniques like computed tomagraphy and magnetic resonance imaging, new treatment machines like accelerators and afterloaders, and treatment planning software have been based totally on the evolution of computers. The whole procedure of radiation therapy is now more safe and accurate after the use of new imaging modalities and simulators, three‐dimensional algorithms for dose calculation, and various optimization methods.
Diffusion Tensor Imaging
Authors: Zhou Xiaohong Joe
Published: April 2006

Diffusion tensor imaging (DTI), or diffusion tensor magnetic resonance imaging (DT‐MRI), is a technique that measures the orientation dependence (i.e., anisotropy) of the diffusion process. This technique relies on diffusion‐induced MRI signal loss as a function of diffusion‐weighting gradient orientations. With DTI, the diffusion tensor at each spatial location can be characterized, and a series of parameters can be obtained to describe various aspects of the diffusion process in biological tissues. Typical parameters calculated from DTI include apparent diffusion coefficients (ADC), diffusion anisotropy indices, and the principal diffusion direction. These parameters (e.g., fractional anisotropy, or FA) can be used to reveal specific tissue structures, such as white‐matter fiber tracts in the brain, and detect their changes during disease progression and regression.
Artificial Heart Valves
Authors: Simionescu Dan T.
Published: April 2006

A significant article in the study of cardiovascular diseases must necessarily address the degeneration of natural heart valves. As the anticipated mission of cardiovascular biomedical engineering is to develop devices and approaches to safely and effectively treat heart disease, substantial efforts have been made in the last 35 years to develop artificial heart valves and pioneer exciting research in heart valve tissue regeneration. This chapter gives an overview on these efforts describing the biology and pathology of heart valves, the status of current replacement devices, and the trends of future research.
Artificial Heart
Authors: Takatani Setsuo
Published: April 2006

The artificial heart (AH) is a mechanical pump that partially or completely replaces the pumping function of the native heart. Two types of AH exist depending on use. The first is called ventricular assist device (VAD) and consists of a single pump to help the pumping function of the left or right ventricle, or both ventricles by combining two VADs without removing the native heart. The second AH is called total artificial heart (TAH) and is comprised of two pumps to maintain both lung circulation and systemic circulation after removal of the native heart.
Atrial Fibrillation and Atrial Flutter
Authors: Hornero Fernando
Published: April 2006

Nonpharmacologic treatments of atrial fibrillation and atrial flutter potentially offer therapy, sparing patients the long‐term risks of antiarrhythmic drug therapy. For patients with typical atrial flutter, contemporary catheter ablation techniques afford cure rates in excess of 85%. For patients with atrial fibrillation, surgical Maze procedure and catheter‐based procedures emulating aspects of the surgical Maze technique can today offer cure rates around 75%. However, additional research and technological development is necessary to further define and refine the best effective procedure. For the present, because each therapeutic alternative carries its own unique set of risks, side effects, and benefits, patients selection remains of critical importance.
Back‐Propagation
Authors: Najarian Kayvan , Eichelberger Christopher N.
Published: April 2006

A summary of multilayer, feed‐forward sigmoid artificial neural networks and the backpropagation algorithm that trains them.
Electrocardiogram (ECG) Signal Processing
Authors: Sörnmo Leif , Laguna Pablo
Published: April 2006

Signal processing of electrocardiographic signals has a long and rich history and has greatly helped to enhance the diagnostic capability, especially when signals are recorded in noisy environments. This article gives an introductory presentation of the basic set of algorithms used for conditioning the ECG with respect to different types of noise and artifacts, detecting heartbeats, extracting basic ECG measurements, and performing data compression. Signal processing in clinical applications is exemplified by the high‐resolution ECG and T wave alternans.
Cardiac Electromechanical Coupling
Authors: Nickerson David
Published: April 2006

Cardiac electromechanical coupling is the process that enables electrical excitation of cardiac cells and tissue to result in mechanical contraction of the cell and, hence, the tissue. The mechanisms involved in this process are discussed here and reference is made to the mathematical modeling and computational simulation of these mechanisms.
Titanium and Titanium Alloys
Authors: Zardiackas Lyle D.
Published: April 2006

Because of the high level of biocompatibility, low level of corrosion, and excellent mechanical properties, titanium and many of its alloys have found extended use as the metal of choice for many implant applications. In addition, because of these properties there continues to be research on the properties of these alloys as well as prolific research and development of new titanium alloy systems. The newerβ‐titanium alloys have shown promise for applications where a lower modulus of elasticity is desirable. Newer alloys being developed must meet the primary requirement of biocompatibility as well as having the desired mechanical properties
Nonlinear observer of crystal‐size distribution during batch crystallization
Authors: Bakir T. , Othman S. , Fevotte G. , Hammouri H
Published: April 2006

A high‐gain observer was designed to estimate the crystal‐size distribution (CSD) in batch crystallization processes. The observer is based on the discretization of population balance equations describing the evolution of the CSD using finite difference method. Due to process impurities and other batch‐to‐batch variations, the kinetic parameters involved in the dynamic model of the crystallization, relating primary and secondary nucleation in particular, are subject to significant variations. In order to avoid any estimation divergence, an on‐line parameter identification algorithm was added to the observer. Assuming that measurements of the nuclei particles are available, the observer is shown to provide a discretized reconstruction of the entire CSD which can be used for control purposes or process supervision. © 2006 American Institute of Chemical Engineers AIChE J, 2006
The genetic tyrosinemias
Authors: Scott C. Ronald
Published: April 2006

The genetic tyrosinemias are characterized by the accumulation of tyrosine in body fluids and tissues. The most severe form of tyrosinemia, Type I, is a devastating disorder of childhood that causes liver failure, painful neurologic crises, rickets, and hepatocarcinoma. This disorder is caused by a deficiency of fumarylacetoacetate hydrolase (FAH). If untreated, death typically occurs at less than 2 years of age, with some chronic forms allowing longer survival. It has a prevalence of about 1 in 100,000 newborns in the general population. Oculocutaneous tyrosinemia, Type II, is caused by a deficiency of tyrosine aminotransferase (TAT). It clinically presents with hyperkeratotic plaques on the hands and soles of the feet and photophobia due to deposition of tyrosine crystals within the cornea. Tyrosinemia Type III is an extremely rare disorder caused by a deficiency of 4‐hydroxyphenylpyruvic dioxygenase. It has been associated with ataxia and mild mental retardation. These disorders are diagnosed by observing elevated tyrosine by plasma amino acid chromatography and characteristic tyrosine metabolites by urine organic acid analysis. In tyrosinemia Type I, methionine is also elevated, reflecting impaired hepatocellular function. Urine organic acids show elevated p‐hydroxy‐phenyl organic acids in each type of tyrosinemia, and the pathognomic succinylacetone in tyrosinemia Type I. Diagnosis can be confirmed by enzyme or molecular studies in tyrosinemia Type I. Therapy consists of a diet low in phenylalanine and tyrosine for each of the tyrosinemias and 2‐(2‐nitro‐4‐trifluoromethylbenzoyl)‐1,3‐cyclohexanedione (NTBC) for tyrosinemia Type I. © 2006 Wiley‐Liss, Inc.
Tetracyanoethylene (TCNE): The Characteristic Geometries and Vibrational Absorptions of Its Numerous Structures
Authors: Miller Joel S.
Published: April 2006

Tetracyanoethylene (TCNE) undergoes numerous reactions and is reported to exist in many structural motifs. Identification of these forms and motifs can be challenging. Nonetheless, the number of $\tilde \nu $CN absorptions and their frequencies provide insight with respect to the specific forms and charge on the TCNE fragment. Particularly informative is the average of the fundamental $\tilde \nu $CN bands, as well as the length of the central CC bond. This Review discusses the assignment of structure and formal charge for TCNE‐containing compounds. Scrutiny of previous assignments reveals some discrepancies which are discussed, and provides a basis for further study of TCNE structure–function relationships. Several multimetal complexes with bridging [TCNE]z units exhibit mixed valency and extensive delocalization. The scarcity of suitable model compounds, especially those with M backbonding to the CN groups, have thwarted the detailed description of these valence ambiguous compounds; thus, new well‐characterized polynuclear compounds are needed.
Cover Picture: Synthesis and Characterization of a Multicomponent Rhenium(I) Complex for Application as an OLED Dopant (Angew. Chem. Int. Ed. 16/2006)
Authors: Lundin Natasha J. , Blackman Allan G. , Gordon Keith C. , Officer David L.
Published: April 2006

Modular molecules designed to act as efficient dopants for organic light‐emitting diodes (OLEDs) encourage directional transport of electrons and holes, causing them to recombine at the emitting center. In their Communication on page 2582 ff., K. C. Gordon and co‐workers describe such a molecule, a phosphorescent dye that comprises an emissive center bound on either side by an electron‐transport group and a hole‐transport group, as shown in the cover picture.
Calix[4]arene‐filled poly dimethylsiloxane (PDMS) membranes for the pervaporative removal of benzene from dilute aqueous solution
Authors: Liu Liang , Jiang Zhongyi , Pan Fusheng
Published: April 2006

In this article, tert‐butylcalix [4]arene (CA)‐filled poly dimethylsiloxane (PDMS) membranes (CA‐f‐PDMS) were prepared for pervaporative removal of benzene from aqueous solution. In comparison with unfilled PDMS membrane, CA‐f‐PDMS membranes showed higher permselectivity towards benzene due to the inclusion interaction between benzene and CA. The separation factor increased from 3275 to 5604 when the CA content varies from 0 to 3 wt % in the PDMS membrane. On the other hand, the normalized permeation rate of benzene (NPRb) decreased with the increase of the degree of crystallization of the membranes due to the crystallinity of CA. The membrane with 1 wt % CA content had the highest degree of crystallization and thus the lowest NPRb, whereas the membrane with 3 wt % CA content was the opposite. Furthermore, the addition of CA increased the elastic modulus of membranes slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 90–100, 2006
Simulation dynamisch‐thermischen Langzeitverhaltens in Gebäuden mittels CFD
Authors: Zitzmann Tobias , Pfrommer Peter , Cook Malcolm
Published: April 2006

Die Planung komplexer Gebäude erfordert immer häufiger den Einsatz von Simulationsprogrammen. Die hierfür derzeit verwendeten dynamischen Gebäudesimulationsprogramme sind jedoch nicht in der Lage, die Luftströmungen und die Temperaturverteilung innerhalb eines Raumes zu erfassen. Eine Lösung der Problematik besteht in der Verlagerung der Gebäudesimulation auf eine CFD‐Plattform, deren Berechnung derzeit allerdings noch mit extrem langen Rechenzeiten und großen Datenmengen verbunden ist. Um diese Rechenzeiten zu verringern, wurde für ANSYS CFX‐5 eine neue Freeze‐Flow‐Methode entwickelt, die auf der periodischen Einfrierung der hydrodynamischen Gleichungen basiert und so dynamische Langzeitsimulationen erlaubt. Zudem wurden die CFD‐Simulationen für die in Räumen vorherrschende freie Konvektion validiert. Im Ergebnis ergaben Freeze‐Flow‐Simulationen einfacher Testmodelle schließlich eine erhebliche Reduzierung der Simulationszeit ohne einhergehenden Verlust an Genauigkeit im Vergleich zur volldynamischen CFD‐Simulation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Verringerung der Feuchtigkeitsbelastung geschädigter Bauteile durch Temperierung
Authors: Dreyer Jürgen
Published: April 2006

Wenn der Feuchtigkeitsgehalt in Baustoffen kritische Werte überschreitet, können verschiedenartige Schädigungsmechanismen auftreten. Der sich einstellende Feuchtigkeitsgehalt ist ein Gleichgewichtszustand aus Befeuchtungs‐ und Trocknungsprozessen und hängt somit von deren Intensität und Häufigkeit ab. Zur Verbesserung der Feuchtebilanz kann man durch Sperrschichten oder Dampfbremsen die Feuchtigkeitszufuhr vermindern oder durch diffusionsoffene Schichten die Feuchtigkeitsabfuhr erhöhen. Zur Feuchtigkeitsentlastung werden bei aufsteigender Feuchtigkeit häufig Dränagen und Lüftungskanäle verwendet. Umstritten ist eine Methode, die unter dem Namen “Temperierung von Bauteilen” an einigen Objekten eingesetzt wurde. Die Bauteilbeheizung soll die Verdunstung fördern und so die Feuchtigkeitsbelastung verringern. Bei höheren Temperaturen sinkt die Viskosität stärker als die Oberflächenspannung, so daß Wasser in erwärmten Stoffen schneller kapillar transportiert wird. Allerdings wird dadurch die Verdunstung wesentlich erhöht, so daß in Abhängigkeit von den Geometrien und den klimatischen Bedingungen durchaus der Verdunstungseffekt überwiegen kann und sich der Feuchtigkeitsgehalt verringert. Die durchgeführten Untersuchungen haben gezeigt, daß bei Kalksandstein, Porenbeton, Sand‐ und Kalkstein diese Methode erfolgreich sein kann. Bei Wänden aus Ziegelstein ist diese Methode nicht ohne Einschränkungen zu empfehlen, da hier die Wirkungen sehr unterschiedlich ausfallen können. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gültigkeit thermischer Behaglichkeitsmodelle
Authors: Hellwig Runa Tabea , Bischof Wolfgang
Published: April 2006

Zur Zeit führen fehlende Richtlinien für das Raumklima zu Planungsunsicherheit bei frei belüfteten Bürogebäuden in Deutschland. Eine interdisziplinäre Forschungsarbeit wurde durchgeführt, um anhand von Befragungs‐ und Meßdaten zu untersuchen, ob es Unterschiede in der thermischen Behaglichkeit von Personen in frei belüfteten und mechanisch belüfteten Gebäuden gibt. Es werden Befragungs‐ und Meßdaten von 14 Bürogebäuden aus dem ProKlimA‐Projekt verwendet. Die relevante Literatur nennt vier bedeutende Methoden zur Bewertung und Vorhersage der thermischen Behaglichkeit. Auf der einen Seite werden das PMV‐Modell von Fanger sowie eine Modifizierung dieses Modells von Mayer betrachtet. Auf der anderen Seite stehen zwei Ansätze – eine niederländische Richtlinie und ein Ansatz aus einer ASHRAE‐Studie. Im Gegensatz zum PMV‐Modell wird die optimale Raumtemperatur bei diesen zwei Ansätzen in Abhängigkeit von einer mittleren Außentemperatur bestimmt. Die vier Methoden werden auf ihre Eignung für die Bewertung thermischer Behaglichkeit in frei und mechanisch belüfteten Gebäuden untersucht. Der Ansatz nach Mayer erzielt für Personen in mechanisch belüfteten Gebäuden die beste Übereinstimmung mit der Beobachtung. Für frei belüftete Gebäude ist dies der ASHRAE‐Ansatz. Die Ergebnisse zeigen, daß sowohl für freie als auch für mechanische Lüftung neue, bisher in Deutschland und Europa nicht genormte Modelle zur Planung von Behaglichkeit in Räumen erforderlich sind. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Brandschutz in Lüftungsanlagen – die neue Muster‐Lüftungsanlagenrichtlinie M‐LüAR vom September 2005
Authors: Czepuck Knut
Published: April 2006

Seit 1984 gibt es die “Lüftungsanlagenrichtlinie”: Richtlinie über brandschutztechnische Anforderungen an Lüftungsanlagen – eine anerkannte technische Baubestimmung. Das Bauordnungsrecht hat sich in der Zwischenzeit deutlich weiterentwickelt. Die zu erwartenden Brände und deren Verläufe sind zwar physikalisch unverändert, aber die Produktentwicklungen und deren weitere Anwendungen sowie die Ausführungen der Gebäude in der Praxis führen zu neuen Lösungswegen. Auch die Erfahrungen aus Bränden der jüngeren Vergangenheit und die veränderte Beurteilung von Risiken und von Einschätzungen zur Brandausbreitung waren zu berücksichtigen. Die M‐LüAR mußte daher auf Aktualität geprüft und an die heutigen Rahmenbedingungen angepaßt werden. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A newly established mutant strain with mild‐type ocular coloboma (retinochoroidal coloboma without microphthalmia) in albino mice
Authors: Matsuura Tetsuro , Kodama Yasushi , Ozaki Kiyokazu , Shirai Shoichiro , Hirasawa Tsutomu , Aoyama Hiroaki , Narama Isao
Published: April 2006

BACKGROUND

A complicated malformation of the fundus accompanied by typical ocular coloboma was detected in albino fatty liver Shionogi (FLS) mice. We elucidated a new type of 3‐dimensional anomalous structure inside the eye in this mouse strain.

METHODS

The fundi of FLS mice aged 1, 3, 5, and 20 weeks were observed intensively, both macroscopically and by light microscopy. For the prenatal study, coronal serial sections of eyes of FLS embryos were examined by light microscopy on gestation day (GD) 15.0.

RESULTS

The frequency of ocular coloboma was almost 70% in FLS mice, and the inheritance mode of this anomaly is suggested to be autosomal recessive with incomplete penetrance. Stereoscopic observation and light microscopy revealed that the mice had characteristic fundus features at any age during the postnatal period. Following ectopic ciliary epithelia, the surface of the retina protruded like a roof, and on the opposite side of the “roof,” a translucent membrane without retinal tissue and choroidal tissue was also consistently detected in the inferior part of the fundus. On GD 15.0, the inner layer and the outer layer were not normally fused at the optic fissure, where a part of the outer layer was absent and the irregular fold of the inner layer was conspicuous in the colobomatous eye of the FLS embryo.

CONCLUSIONS

The characteristics of the ocular coloboma in FLS mice are thought to be similar to a mild‐type malformation in humans. These ocular defects seem to be situated along the failed fetal optic fissure. Birth Defects Research (Part A), 2006. © 2006 Wiley‐Liss, Inc.
An anthocyanin/polyphenolic‐rich fruit juice reduces oxidative DNA damage and increases glutathione level in healthy probands
Authors: Weisel Tamara , Baum Matthias , Eisenbrand Gerhard , Dietrich Helmut , Will Frank , Stockis Jean‐Pierre , Kulling Sabine , Rüfer Corinna , Johannes Christian , Janzowski Christine
Published: April 2006

Oxidative cell damage is involved in the pathogenesis of atherosclerosis, cancer, diabetes and other diseases. Uptake of fruit juice with especially high content of antioxidant flavonoids/polyphenols, might reduce oxidative cell damage. Therefore, an intervention study was performed with a red mixed berry juice [trolox equivalent antioxidative capacity (TEAC): 19.1 mmol/L trolox] and a corresponding polyphenol‐depleted juice (polyphenols largely removed, TEAC 2.4 mmol/L trolox), serving as control. After a 3‐week run‐in period, 18 male probands daily consumed 700 mL juice, and 9 consumed control juice, in a 4‐week intervention, followed by a 3‐week wash‐out. Samples were collected weekly to analyze DNA damage (comet assay), lipid peroxidation (plasma malondialdehyde: HPLC/fluorescence; urinary isoprostanes: GC‐MS), blood glutathione (photometrically), DNA‐binding activity of nuclear factor‐κB (ELISA) and plasma carotenoid/α‐tocopherol levels (HPLC‐DAD). During intervention with the fruit juice, a decrease of oxidative DNA damage (p<5×10–4) and an increase of reduced glutathione (p<5×10–4) and of glutathione status (p<0.05) were observed, which returned to the run‐in levels in the subsequent wash‐out phase. The other biomarkers were not significantly modulated by the juice supplement. Intervention with the control juice did not result in reduction of oxidative damage. In conclusion, the fruit juice clearly reduces oxidative cell damage in healthy probands.
Essential fatty acids: biochemistry, physiology and pathology
Authors: Das Undurti N.
Published: April 2006

Essential fatty acids (EFAs), linoleic acid (LA), and α‐linolenic acid (ALA) are essential for humans, and are freely available in the diet. Hence, EFA deficiency is extremely rare in humans. To derive the full benefits of EFAs, they need to be metabolized to their respective long‐chain metabolites, i.e., dihomo‐γ‐linolenic acid (DGLA), and arachidonic acid (AA) from LA; and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from ALA. Some of these long‐chain metabolites not only form precursors to respective prostaglandins (PGs), thromboxanes (TXs), and leukotrienes (LTs), but also give rise to lipoxins (LXs) and resolvins that have potent anti‐inflammatory actions. Furthermore, EFAs and their metabolites may function as endogenous angiotensin‐converting enzyme and 3‐hdroxy‐3‐methylglutaryl coenzyme A reductase inhibitors, nitric oxide (NO) enhancers, anti‐hypertensives, and anti‐atherosclerotic molecules. Recent studies revealed that EFAs react with NO to yield respective nitroalkene derivatives that exert cell‐signaling actions via ligation and activation of peroxisome proliferator‐activated receptors. The metabolism of EFAs is altered in several diseases such as obesity, hypertension, diabetes mellitus, coronary heart disease, schizophrenia, Alzheimer's disease, atherosclerosis, and cancer. Thus, EFAs and their derivatives have varied biological actions and seem to be involved in several physiological and pathological processes.
Yoghurt fermentation at elevated temperatures by strains of Streptococcus thermophilus expressing a small heat‐shock protein: application of a two‐plasmid system for constructing food‐grade strains of Streptococcus thermophilus
Authors: El Demerdash Hassan A. , Oxmann Julian , Heller Knut J. , Geis Arnold
Published: April 2006

Streptococcus thermophilus S4 expressing a small heat‐shock protein from the plasmid pSt04‐encoded copy of shsp, is able to carry out fermentation at elevated temperature, i.e., at 50°C. In yoghurt culture together with Lactobacillus delbrueckii subsp. bulgaricus, fermentation at elevated temperature results in a mild yoghurt with low post‐acidification and improved stability of the starter bacteria during storage at 4°C. To transfer pSt04 into commercial S. thermophilus yoghurt starter strains, a two‐plasmid system was constructed. A helper plasmid providing a selectable antibiotic marker, but relying on the repA gene of pSt04, was transformed together with pSt04. After isolation of transformants, the helper plasmid was readily lost upon incubation of transformants in antibiotic‐free medium, thus yielding food‐grade strains carrying pSt04 only. Successful application of the system was demonstrated.
Model‐based analysis and design of a microchannel reactor for tissue engineering
Authors: Mehta Khamir , Linderman Jennifer J.
Published: April 2006

Recently developed perfusion micro‐bioreactors offer the promise of more physiologic in vitro systems for tissue engineering. Successful application of such bioreactors will require a method to characterize the bioreactor environment required to elicit desired cell function. We present a mathematical model to describe nutrient/growth factor transport and cell growth inside a microchannel bioreactor. Using the model, we first show that the nature of spatial gradients in nutrient concentration can be controlled by both design and operating conditions and are a strong function of cell uptake rates. Next, we extend our model to investigate the spatial distributions of cell‐secreted soluble autocrine/paracrine growth factors in the bioreactor. We show that the convective transport associated with the continuous cell culture and possible media recirculation can significantly alter the concentration distribution of the soluble signaling molecules as compared to static culture experiments and hence needs special attention when adapting static culture protocols for the bioreactor. Further, using an unsteady state model, we find that spatial gradients in nutrient/growth factor concentrations can bring about spatial variations in the cell density distribution inside the bioreactor, which can result in lowered working volume of the bioreactor. Finally, we show that the nutrient and spatial limitations can dramatically affect the composition of a co‐cultured cell population. Our results are significant for the development, design, and optimization of novel micro‐channel systems for tissue engineering. © 2006 Wiley Periodicals, Inc.
Model of the mass transport to the surface of animal cells cultured in a rotating bioreactor operated in micro gravity
Authors: Rivera‐Solorio Ivan , Kleis Stanley J.
Published: April 2006

A mathematical model is used to investigate the transport of dissolved oxygen from the bulk fluid to the surface of aggregates of animal cells cultured in a rotating bioreactor. These aggregates move through different regions of the bioreactor with a local flow field and concentration distribution that vary with time. The time variation of the Sherwood number and the surface concentration for a range of parameters typical of a cell science experiment executed in the Rotating Wall Perfused Vessel (RWPV) bioreactor in space are investigated. The Reynolds numbers experienced by the aggregate are generally low (Re < 1) and the Peclet numbers range from O(1) to O(100). Comparison of the results from the numerical solution of the mathematical model with those from a quasi‐steady model, using a steady‐state correlation for mass transport on a sphere, indicate that the quasi‐steady assumption is not a good model to compute the instantaneous Sherwood number. This indicates a significant history effect in the Sherwood number response to the variations of acceleration of the aggregates in the bioreactor. A high resistance to the mass transport from the bulk fluid to the surface of the aggregate exists for the bioreactor operated in micro gravity. The difference between the surface concentration and the free stream concentration was as high as 30% for aggregates larger than 3 mm. Diffusion reduces the variations of the free stream concentration resulting in a nearly constant value for the concentration at the surface of the aggregates. © 2006 Wiley Periodicals, Inc.
Responses of defense signals, biosynthetic gene transcription and taxoid biosynthesis to elicitation by a novel synthetic jasmonate in cell cultures of Taxus chinensis
Authors: Hu Fengxian , Huang Junhai , Xu Yufang , Qian Xuhong , Zhong Jian‐Jiang
Published: April 2006

Recently novel synthetic jasmonate derivatives were shown to have very powerful stimulating effects on the biosynthesis of taxuyunnanine C (Tc) by Taxus chinensis cells (Biotech Bioeng, 86:595; ibid. 86: 809, 2004). To provide an insight into the elicitation mechanism of the newly synthesized elicitors, by taking 2‐hydroxyethyl jasmonate (HEJ, at 100 µM) as a typical example, in this work the defense signals were detected and their influences on the expression of important genes in taxoid biosynthetic pathway were examined in cell cultures of T. chinensis. The oxidative burst (induced H2O2 production) was confirmed, and the induction of lipoxygenase (LOX) activity and intracellular jasmonate acid (JA) synthesis was found. The gene transcription of geranylgeranyl diphosphate synthase (GGPPs) and taxa‐4(5),11(12)‐diene synthase (TS) was up‐regulated by HEJ elicitation compared to control. Inhibition of JA biosynthesis by a putative LOX inhibitor, ibuprofen (IBU), effectively depressed the HEJ‐induced up‐regulation of GGPPs and TS gene transcription levels. In contrast, the inhibition of H2O2 production by membrane NADPH oxidase inhibitor, diphenylene iodonium (DPI), did not affect the transcriptions of those genes. For the HEJ‐induced Tc production, it was suppressed with addition of DPI or IBU. The results suggest that both H2O2 and JA signals were involved in HEJ‐induced Tc biosynthesis, and JA mediated the induction of GGPPs and TS genes expression, but H2O2 was not essential to activate them. Finally, a signal transduction cascade from defense signal response to activated transcription of taxoid biosynthetic genes and enhanced Tc production is proposed. © 2006 Wiley Periodicals, Inc.
Assaying CO2 release for determination of formate dehydrogenase activity in entrapment matrices and aqueous‐organic two‐phase systems
Authors: Ansorge‐Schumacher Marion B. , Steinsiek Sonja , Eberhard Werner , Keramidas Nikolaos , Erkens Klaus , Hartmeier Winfried , Büchs Jochen
Published: April 2006

Formate dehydrogenase is an important enzyme for NADH‐regeneration in enzyme‐catalysed reductions. Methods to determine the activity of this biocatalyst during reaction in aqueous‐organic two‐phase systems or after immobilisation were therefore investigated. Determination of gaseous CO2 in the headspace of reaction vessels either by gas chromatography or by pressure sensors was found to be a suitable way for deduction of FDH‐activity in either of these reaction systems. In the presence of organic solvents, gas chromatography yielded more precise data than pressure sensors, while pressure measurements offer the opportunity to assay continuously the activity of entrapped FDH throughout the whole course of reaction. © 2006 Wiley Periodicals, Inc.
Engineering of protein thermodynamic, kinetic, and colloidal stability: Chemical Glycosylation with monofunctionally activated glycans
Authors: Solá Ricardo J. , Al‐Azzam Wasfi , Griebenow Kai
Published: April 2006

In this work we establish the relationship between chemical glycosylation and protein thermodynamic, kinetic, and colloidal stability. While there have been reports in the literature that chemical glycosylation modulates protein stability, mechanistic details still remain uncertain. To address this issue, we designed and coupled monofunctional activated glycans (lactose and dextran) to the model protein α‐chymotrypsin (α‐CT). This resulted in a series of glycoconjugates with variations in the glycan size and degree of glycosylation. Thermodynamic unfolding, thermal inactivation, and temperature‐induced aggregation experiments revealed that chemical glycosylation increased protein thermodynamic (ΔG(25°C)), kinetic (t1/2(45°C)), and colloidal stability. These results highlight the potential of chemical glycosylation with monofunctional activated glycans as a technology for increasing the long‐term stability of liquid protein formulations for industrial and biotherapeutic applications. © 2006 Wiley Periodicals, Inc.
Siderophore production by using free and immobilized cells of two pseudomonads cultivated in a medium enriched with Fe and/or toxic metals (Cr, Hg, Pb)
Authors: Braud Armelle , Jézéquel Karine , Léger Marie‐Anne , Lebeau Thierry
Published: April 2006

Pseudomonads are serious candidates for siderophore production applied to toxic metal (TM) solubilization. The bioaugmentation of contaminated soils by these TM‐solubilizing bacteria combined with phytoextraction is an emerging clean‐up technology. Unfortunately, siderophore synthesis may be drastically reduced by soluble iron in soils and bacteria can suffer from TM toxicity. In this study, we compared siderophore production by Pseudomonas aeruginosa and Pseudomonas fluorescens by using free and immobilized cells in Ca‐alginate beads incubated in a medium containing Fe and/or TM (mixture of Cr, Hg, and Pb in concentrations which represented the soluble fraction of a contaminated agricultural soil). Free cell growth was stimulated by Fe, whatever the microorganism, the inoculum size and the presence or not of TM might have been. P. aeruginosa was less sensitive to TM than P. fluorescens. By comparison with free cells, immobilization with the high inoculum size showed less sensitivity to TM most probably because of lower metal diffusion in beads. Indeed, a maximum of 99.1% of Cr, 57.4% of Hg, and 99.6% of Pb were adsorbed onto beads. The addition of iron in the culture medium reduced significantly siderophore production of free cells while it led only to a low decrease with their immobilized counterparts, in particular with P. aeruginosa. In culture medium enriched with Fe and/or TM, siderophore‐specific production of immobilized cells was higher than for free cells. © 2006 Wiley Periodicals, Inc.
Claudication secondary to Perclose use after percutaneous procedures
Authors: Jang James J. , Kim Michael , Gray Bruce , Bacharach J. Michael , Olin Jeffrey W.
Published: April 2006

The use of suture‐mediated arterial closure devices has dramatically increased with the increased number of percutaneous procedures being performed. Complications from suture‐mediated closure devices have been underreported. Specifically, arterial stenosis resulting in claudication has not been previously described in detail. We present nine patients who presented with various leg symptoms after Perclose was used to achieve arterial hemostasis following percutaneous procedures. All cases were found to have significant arterial stenoses from the Perclose sutures. Once diagnosis was correctly made, the patients either underwent surgical repair or percutaneous balloon angioplasty and in all cases the symptoms abated. © 2006 Wiley‐Liss, Inc.
Percutaneous replacement of pulmonary valve using the Edwards‐Cribier percutaneous heart valve: First report in a human patient
Authors: Garay Francisco , Webb John , Hijazi Ziyad M.
Published: April 2006

We report on the use of the Edwards‐Cribier percutaneous heart valve (PHV) in a stenotic right ventricle to pulmonary artery homograft in a 16‐year old patient who underwent the Ross operation. Initially, the homograft was stented and at the same procedure, the PHV was deployed inside it. This is the first human case of the application of this valve in the pulmonary valve position. © 2006 Wiley‐Liss, Inc.
A Challenge to Chemical Intuition: Donor–Acceptor Interactions in H3BL and H2B+L (L=CO; EC5H5, E=N–Bi)
Authors: Erhardt Stefan , Frenking Gernot
Published: April 2006

The equilibrium geometries and bond energies of the complexes H3BL and H2B+L (L=CO; EC5H5: E=N, P, As, Sb, Bi) have been calculated at the BP86/TZ2P level of theory. The nature of the donor–acceptor bonds was investigated by energy decomposition analysis (EDA). The bond strengths of H3BL have the order CO>N>P>As>Sb>Bi. The calculated values are between De=37.1 kcal mol−1 for H3BCO and De=6.9 kcal mol−1 for H3BBiC5H5. The bond dissociation energies of the cations H2B+CO and H2B+EC5H5 are larger than for H3BL, particularly for complexes of the heterobenzene ligands. The calculated values are between De=51.9 kcal mol−1 for H2B+CO and De=122.1 kcal mol−1 for H2B+NC5H5. The trend of the BDE of H2B+CO and H2B+EC5H5 is N>P>As>Sb>Bi>CO. A surprising result is found for H2B+CO, which has a significantly stronger and yet substantially longer bond than H3BCO. The reason for the longer but stronger bond in H2B+CO compared with that in H3BCO comes mainly from the change in electrostatic attraction and π bonding at shorter distances, which increases more in the neutral system than in the cation, and to a lesser extent from the deformation energy of the fragments. The H2B+←NC5H5 π⊥ donation plays an important role for the stronger interactions at shorter distances compared with those in H3BNC5H5. The attractive interaction in H2B+CO further increases at bond lengths that are shorter than the equilibrium value, but this is compensated by the energy which is necessary to deform BH2+ from its linear equilibrium geometry to the bent form in the complex. The EDA shows that the contributions of the orbital interactions to the donor–acceptor bonds are always larger than the classical electrostatic contributions, but the latter term plays an important role for the trend in bond strength. The largest contributions to the orbital interactions come from the σ orbitals. The EDA calculations suggest that heterobenzene ligands may become moderately strong π donors in complexes with strong Lewis acids, while CO is only a weak π donor. The much stronger interaction energies in H2B+EC5H5 compared with those in H3BEC5H5 are caused by the significantly larger contribution of the π⊥ orbitals in H2B+EC5H5 and by the increase of the binding interactions of the σ+π∥ orbitals.
In Search of Ionic Liquids Incorporating Azolate Anions
Authors: Katritzky Alan R. , Singh Shailendra , Kirichenko Kostyantyn , Smiglak Marcin , Holbrey John D. , Reichert W. Matthew , Spear Scott K. , Rogers Robin D.
Published: April 2006

Twenty‐eight novel salts with tetramethyl‐, tetraethyl‐, and tetrabutylammonium and 1‐butyl‐3‐methylimidazolium cations paired with 3,5‐dinitro‐1,2,4‐triazolate, 4‐nitro‐1,2,3‐triazolate, 2,4‐dinitroimidazolate, 4,5‐dinitroimidazolate, 4,5‐dicyanoimidazolate, 4‐nitroimidazolate, and tetrazolate anions have been prepared and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and single‐crystal X‐ray crystallography. The effects of cation and anion type and structure on the physicochemical properties of the resulting salts, including several ionic liquids, have been examined and discussed. Ionic liquids (defined as having m.p.<100 °C) were obtained with all combinations of the 1‐butyl‐3‐methylimidazolium cation ([C4mim]+) and the heterocyclic azolate anions studied, and with several combinations of tetraethyl or tetrabutylammonium cations and the azolate anions. The [C4mim]+ azolates were liquid at room temperature exhibiting large liquid ranges and forming glasses on cooling with glass‐transition temperatures in the range of −53 to −82 °C (except for the 3,5‐dinitro‐1,2,4‐triazolate salt with m.p. 33 °C). Six crystal structures of the corresponding tetraalkylammonium salts were determined and the effects of changes to the cations and anions on the packing of the structure have been investigated.
Quantification of Ultrasound‐Induced Chain Scission in PdII–Phosphine Coordination Polymers
Authors: Paulusse Jos M. J. , Huijbers Jeroen P. J. , Sijbesma Rint P.
Published: April 2006

A kinetically inert, reversible coordination polymer (3) was obtained through complexation of dicyclohexylphosphine telechelic poly(tetrahydrofuran) with palladium(II) dichloride. This coordination polymer is unreactive towards palladium(II) dichloride bis(1‐diphenylphosphino)dodecane (4), because ligand dissociation in the coordination polymer is slow. However, upon ultrasonication of solutions of 3 in toluene in the presence of 4, formation of palladium(II) heterocomplexes was observed with 31P NMR spectroscopy. Heterocomplex formation, the consumption of 4, and changes in molecular weight were used to quantify the scission process. In the presence of 60 equivalents of the alkyldiphenylphosphine stopper complex, the reduction in molecular weight was strongly enhanced; over a period of eight hours the weight‐averaged molecular weight was reduced from 1.1×105 to 2.3×104 g mol−1 while 47 % of the palladium(II) complexes in the coordination polymer had been converted into heterocomplexes. These results show that the system of 3 in combination with scavenger 4 is a suitable system to study the efficiency of ultrasound‐induced chain scission of coordination polymers.