bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and kinetics of gas hydrates from methane/ethane/propane mixtures relevant to the design of natural gas hydrate storage and transport facilities
Authors: Kumar Rajnish , Linga Praveen , Moudrakovski Igor , Ripmeester John A. , Englezos Peter
Published: June 2008

The kinetics of gas hydrate growth from binary CH4/C2H6 and CH4/C3H8 and ternary CH4/C2H6/C3H8 gas mixtures were obtained by the gas uptake method in a semibatch stirred vessel at constant pressure and a temperature of 273.7 K. These data are of interest for the design of facilities for natural gas storage and transportation in the solid (hydrate) state. During hydrate formation, samples from the gas phase were taken and analyzed by gas chromatography. It was found that the molar composition of CH4 in the vapor phase increased as hydrate crystallization progressed. The observed fractionation effect (enrichment of the hydrate phase with propane) complicates the natural gas storage process. The fractionation effect was also confirmed with molecular‐level studies where hydrate from the CH4/C2H6/C3H8 gas mixture was characterized by powder X‐ray diffraction (PXRD), NMR, and Raman spectroscopy. The hydrate phase composition and cage occupancy of each gas were calculated with the help of information obtained by Raman spectroscopy, gas chromatography, and PXRD. The results were consistent with those obtained by NMR. The composition of the gas phase and the hydrate are found to evolve over time, suggesting that kinetic and transport factors contribute in addition to thermodynamics. © 2008 American Institute of Chemical Engineers AIChE J, 2008
A parallel plate wet denuder for acidic gas measurement
Authors: Tsai Chuen‐Jinn , Lin Guan‐Yu , Chen Sheng‐Chieh
Published: June 2008

A parallel plate wet denuder (PPWD) was designed and tested for acidic gas absorption in this study. The PPWD is composed of two frosted glass plates coated with nano‐TiO2 particles. The gap of the plates is 4 mm, the active surface is 7.5 cm in width and 15 cm in height. The DI water is flowing downward along the surfaces to form a uniform water film to absorb the gas flowing upward along the gap. The gas absorption efficiency and memory effect were tested using test gases of HF (3.57–3.80 ppb), HCl (0.48–15.63 ppb), and HNO3 (8.43–20.92 ppb) generated from permeation tubes at the flow rate of 5–10 L/min, scrubbing DI water flow rate of 1.0 mL/min/plate, and pH = 6.8 ± 0.3. The experiment was also conducted for HF and HCl with scrubbing water pH value of 3.08 and 4.10 to examine the effect of pH on the absorption efficiency. The experimental data at different flow rates match with the theoretical values very well assuming perfect absorption condition at the water film when the scrubbing water pH = 6.8 ± 0.3. The absorption efficiency of the three gases at the sampling flow rate of 5 L/min was nearly 100% when the scrubbing water pH value was 6.8 ± 0.3, but was found to decrease slightly when the pH value of scrubbing water was reduced from 6.8 to 3.08, which indicates slight modification of perfect absorption condition at the water film. The memory effect test showed that the rise time was 15 to 25 min and the fall time was 10 to 25 min for the three gases. Good uniformity of the water film was observed during the 9‐day ambient air sampling for HF, HCl, and HNO3, which indicates the applicability of the present PPWD for ambient air sampling. © 2008 American Institute of Chemical Engineers AIChE J, 2008
A numerical model for predicting diffusivity in a biocatalyst particle with heterogeneous reactions
Authors: Wu Binxin , Liu Yan , Liao Wei , Chen Shulin
Published: June 2008

Determination of effective diffusivity of a substrate in biocatalyst particles is a key requirement in modeling heterogeneous reactions. The diffusivity is mainly controlled by the molecular‐diffusion characteristics of the substrate, the tortuousness of the diffusion path within the biocatalyst, and the void fraction of particle volume available for diffusion. A general numerical model describing reactions in a biocatalyst particle following zero‐order, first‐order, and Michaelis‐Menten kinetics was developed. Finite volume method was used to discretize the nonlinear second‐order differential equation, and tridiagonal matrix algorithm was applied to solve the algebraic equation iteratively after discretization. Computer codes were written for calculating the diffusivity under specified boundary conditions. The numerical solution of the diffusion‐reaction equations was validated against the experimental data from literatures. The model was further calibrated with experimental data obtained from fungal pellet experiments and then verified using additional data. The results show that the inverse methodology developed in this study was capable of predicting diffusivity in biocatalyst particles. Based on the predicted diffusivity, oxygen consumption by an individual pellet was simulated, oxygen consumptions by small versus large pellets were compared, and the effect of reaction rate on oxygen consumption was evaluated. © 2008 American Institute of Chemical Engineers AIChE J, 2008
A multivariate statistical process control procedure for BIAS identification in steady‐state processes
Authors: Sánchez Mabel C. , Alvarez Carlos R. , Brandolin Adriana
Published: June 2008

In this article, a multivariate statistical process control (MSPC) strategy, devoted to bias identification and estimation for processes operating under steady‐state conditions, is presented. The technique makes use of the D statistic to detect the presence of biases. Besides, it uses a new decomposition of this statistic to identify the faulty sensors. The strategy is based only on historical process data. Neither process modeling nor assumptions about the probability distribution of measurement errors are required. In contrast to methods based on fundamental models, both redundant and nonredundant measurements can be examined to identify the presence of biases. The performance of the proposed technique is evaluated using data‐reconciliation benchmarks. Results indicate that the technique succeeds in identifying single and multiple biases and fulfills three paramount issues to practical implementation in commercial software: robustness, uncertainty, and efficiency. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Continuous distribution kinetics for microwave‐assisted oxidative degradation of poly(alkyl methacrylates)
Authors: Marimuthu A. , Madras Giridhar
Published: June 2008

The microwave‐assisted oxidative degradation of poly(alkyl methacrylates) namely poly(methyl methacrylate), poly(ethyl methacrylate) (PEMA), and poly(butyl methacrylate) was investigated. The kinetic parameters were compared to that obtained by thermal oxidative degradation. The molecular weight distributions (MWDs) were simulated using continuous distribution kinetic models. The MWD of polymer was expressed as a γ‐distribution, and the mathematical solutions were developed in terms of γ‐distribution parameters. The MWD of degradation mixture approaches an exponential distribution under both oxidative thermal degradation and microwave‐assisted oxidative degradation of poly(alkyl methacrylates), indicating random chain scission. The degradation of PEMA was investigated in the presence of three different oxidizers. The hydrogen abstraction from polymer and the oxidative random chain scission of polymer radicals were found to be the important steps in the overall mechanism of microwave‐assisted oxidative degradation of poly(alkyl methacrylates). The model developed can be used to predict degradation rate of the polymer in the presence of any oxidizers by knowing only the dissociation rate constant of the oxidizer. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Multilayered patella: Similar radiographic findings in pseudoachondroplasia and recessive multiple epiphyseal dysplasia
Authors: Vatanavicharn Nithiwat , Lachman Ralph S. , Rimoin David L.
Published: June 2008

A multilayered patella is a characteristic radiographic finding of recessive multiple epiphyseal dysplasia (rMED) caused by DTDST mutations. However it has been recently reported in a dominant MED case with a COL9A2 mutation. We report on a new radiographic patellar finding in a patient with pseudoachondroplasia and a heterozygous COMP mutation. It is similar to the radiographic appearance of fusing multilayered patellae in rMED cases. This led us to search the International Skeletal Dysplasia Registry for similar abnormalities. We did not observe this finding in other skeletal dysplasias or other pseudoachondroplasia cases. However we found an accessory ossification center of the patella in another pseudoachondroplasia case. Thus, we hypothesize that variable defects of cartilage extracellular matrix can result in similar abnormal patellar ossifications, and emphasize the importance of a lateral knee radiograph in patients with the pseudoachondroplasia‐MED bone dysplasia group of disorders. © 2008 Wiley‐Liss, Inc.
Mucopolysaccharidoses in Brazil: What happens from birth to biochemical diagnosis?
Authors: Vieira Taiane , Schwartz Ida , Muñoz Verónica , Pinto Louise , Steiner Carlos , Ribeiro Márcia , Boy Raquel , Ferraz Victor , de Paula Ana , Kim Chong , Acosta Angelina , Giugliani Roberto
Published: June 2008

Mucopolysaccharidoses (MPS) form a group of inherited metabolic disorders characterized by intralysosomal storage of glycosaminoglycans. This study aimed to investigate the path followed by Brazilian patients from birth to diagnosis. An interview was conducted with patient's parents or guardians with subsequent review of patient's medical records. One hundred thirteen patients with MPS were included (MPS I: 18, MPS II: 43, MPS IIIA: 2, MPS IIIB: 3, MPS IIIC: 1, MPS IVA: 15, MPS IVB: 1, MPS VI: 29, MPS VII: 1) from 97 families. Median age at the onset of signs/symptoms was 18 months (MPS I: 18, MPS II: 24, MPS IVA: 8, MPS VI: 8). Skeletal abnormalities (for MPS IVA and MPS VI), joint contractures (for MPS II), and typical facial features (for MPS I) were the most frequently reported first signs/symptoms. Several health professionals were involved in patient's care as of the onset of symptoms until biochemical diagnosis was established. Median age at diagnosis was 76 months (MPS I: 75, MPS II: 95, MPS IVA: 75, MPS VI: 52). Considering the group as a whole, there was a 4.8‐year delay between the onset of signs/symptoms and the establishment of the diagnosis. Considering that specific therapies are available for some of these disorders and that early treatment is likely to change more favorably the natural history of the disease, efforts should be made to minimize this delay. We believe that this situation can be improved by measures that both increase awareness of health professionals about MPS and improve access to diagnostic tests. © 2008 Wiley‐Liss, Inc.
Long‐term follow‐up in Stuve–Wiedemann syndrome: A clinical report
Authors: Gaspar Isabel Mendes , Saldanha Tiago , Cabral Pedro , Vilhena M. Manuel , Tuna Madalena , Costa Cristina , Dagoneau Nathalie , Daire Valerie Cormier , Hennekam Raoul C.M.
Published: June 2008

Stuve–Wiedemann syndrome (SWS) is an autosomal recessively inherited disorder that is usually associated with high mortality in the neonatal period. Eleven cases have been published with prolonged survival, the oldest being 16 years. This phenotype is characterized by progressive skeletal anomalies including short stature, severe spinal deformities, bowing of the long bones, contractures and spontaneous fractures, and by neurological features that resemble dysautonomia. Here we report on the natural history of a Portuguese girl from birth till 12 years. The diagnosis was molecularly confirmed by the detection of a homozygous 4 bp deletion (167_170 del TAAC) in exon 3 of LIFR. We compare the findings in this patient to other patients with prolonged survival from the literature. © 2008 Wiley‐Liss, Inc.
Beckwith‐Wiedemann syndrome in adults: Observations from one family and recommendations for care
Authors: Greer Kimberly J. , Kirkpatrick Susan J. , Weksberg Rosanna , Pauli Richard M.
Published: June 2008

Literature review and clinical findings in four affected adult males from one family suggest that there are serious and currently ill‐defined health risks in adults with Beckwith‐Wiedemann syndrome (BWS). These may include male subfertility, vascular anomalies, renal abnormalities, hearing loss and, possibly, an increased risk for adult‐onset malignancy. Given present knowledge, recommendations in caring for adults with this disorder remain tentative but likely should include counseling for possible infertility in males, screening echocardiography, renal sonogram and renal function testing, and counseling about possible increased risk for adult onset malignancy. © 2008 Wiley‐Liss, Inc.
Mitochondrial DNA haplogroup analysis in patients with bipolar disorder
Authors: Kazuno An‐a , Munakata Kae , Mori Kanako , Nanko Shinichiro , Kunugi Hiroshi , Nakamura Kazuhiko , Mori Norio , Yamada Kazuo , Yoshikawa Takeo , Kato Nobumasa , Kato Tadafumi
Published: June 2008

Several lines of evidence support mitochondrial dysfunction in bipolar disorder. Elevated calcium level in platelets is reported in this disease. To verify mitochondrial DNA (mtDNA) haplogroups characteristic to bipolar disorder, we sequenced mtDNA of seven regions and performed haplogroup analysis in 195 patients with bipolar disorder and 255 controls. They belonged to 16 major mtDNA haplogroups, A, B4, B5, C, D4, D5, F, G, M7, M8, M9, M10‐12, N9a, N9b, Y, and Z. The logistic regression analysis revealed that the haplogroup N9a was over‐represented in bipolar disorder. We also performed a case–control study for two functional mtDNA polymorphisms, mtDNA5460G > A and 12358A > G, that altered intracellular calcium dynamics. While the mtDNA5460G > A polymorphism was not associated with bipolar disorder, the mtDNA12358A > G polymorphism was associated with bipolar disorder in 199 patients with bipolar disorder and 260 controls. However, this association was not replicated in an independent sample set. Possible significances of these findings are discussed. © 2008 Wiley‐Liss, Inc.
Botulinum toxin type a induces direct analgesic effects in chronic neuropathic pain
Authors: Ranoux Danièle , Attal Nadine , Morain Francoise , Bouhassira D.
Published: June 2008

Objective

Botulinum toxin type A (BTX‐A) has been reported to have analgesic effects independent of its action on muscle tone, possibly by acting on neurogenic inflammation. Such a mechanism may be involved in peripheral neuropathic pain.

Methods

A possible direct analgesic effect of BTX‐A pain processing was investigated in 29 patients with focal painful neuropathies and mechanical allodynia using a randomized, double‐blind, placebo‐controlled design. Patients received a one‐time intradermal administration of BTX‐A (20–190 units) into the painful area. Outcome measures, evaluated at baseline, then at 4, 12, and 24 weeks, included average spontaneous pain intensity, quantified testing of thermal and mechanical perception and pain, allodynia to brushing (area, intensity), neuropathic symptoms, clinical global impression, and quality of life.

Results

BTX‐A treatment, relative to placebo, was associated with persistent effects on spontaneous pain intensity from 2 weeks after the injection to 14 weeks. These effects correlated with the preservation of thermal sensation at baseline (p < 0.05). BTX also improved allodynia to brush and decreased pain thresholds to cold, without affecting perception thresholds. There were sustained improvements in the proportion of responders (number needed to treat for 50% pain relief: 3.03 at 12 weeks), neuropathic symptoms, and general activity. Most patients reported pain during the injections, but there were no further local or systemic side effects.

Interpretation

These results indicate for the first time that BTX‐A may induce direct analgesic effects in patients with chronic neuropathic pain independent of its effects on muscle tone and suggest novel indications for BTX‐A in analgesia. Ann Neurol 2008
Effect of poly(styrene‐co‐maleic anhydride) imidization on the miscibility and phase‐separation temperatures of poly(styrene‐co‐maleic anhydride)/poly(vinyl methyl ether) and poly(styrene‐co‐maleic anhydride)/ poly(methyl methacrylate) blends
Authors: Fang Haixia , Mighri Frej , Ajji Abdellah
Published: June 2008

The objective of this work was to study the miscibility and phase‐separation temperatures of poly(styrene‐co‐maleic anhydride) (SMA)/poly(vinyl methyl ether) (PVME) and SMA/poly(methyl methacrylate) (PMMA) blends with differential scanning calorimetry and small‐angle light scattering techniques. We focused on the effect of SMA partial imidization with aniline on the miscibility and phase‐separation temperatures of these blends. The SMA imidization reaction led to a partially imidized styrene N‐phenyl succinimide copolymer (SMI) with a degree of conversion of 49% and a decomposition temperature higher than that of SMA by about 20°C. We observed that both SMI/PVME and SMI/PMMA blends had lower critical solution temperature behavior. The imidization of SMA increased the phase‐separation temperature of the SMA/PVME blend and decreased that of the SMA/PMMA blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Modeling of ethylene polymerization with difunctional initiators in tubular reactors
Authors: Khazraei P. K. F. , Dhib R.
Published: June 2008

The severe thermodynamic conditions of the high‐pressure ethylene polymerization process hinder ethylene from going to full conversion. One remedy to improve the monomer conversion is to make effective use of difunctional peroxides. Multifunctional peroxides can accelerate the polymerization rate, produce branching, and modify the rheological properties of molten polymers. This article proposes a kinetic model based on a postulated reaction mechanism for ethylene polymerization initiated by difunctional initiators in a high‐pressure tubular reactor. Three peroxides suitable for ethylene polymerization were compared for their effectiveness. Compared to dioctanoyl peroxide, the two difunctional peroxides considered performed much better for the higher temperature regions of the reactor and gave ethylene conversions nearly twice as high for only half of the initial amount of dioctanoyl. They also generated low‐density polyethylene polymer with a broader molecular weight distribution and longer chain branching. These two important polymer characteristics can influence the end‐product rheological properties. Injecting fresh ethylene at different points along the reactor improved the conversion and produced more branched polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Bamboo is a suitable template for polymerizations
Authors: Eastman Scott A. , Lesser Alan J. , McCarthy Thomas J.
Published: June 2008

In situ hydrosilation reactions and ring‐opening metathesis polymerizations were demonstrated to occur in bulk samples of bamboo. Bamboo was infused with silicone precursors or cyclodiene monomers with the assistance of supercritical CO2 and subsequently crosslinked or polymerized, respectively. Bending stiffness, energy release rate, and specific fire resistance properties of the bamboo‐polymer composites were measured and compared with unmodified bamboo. Bamboo‐silicone composites showed an increase in fire resistance and a slight increase in mechanical properties. The bamboo‐poly(alkenamer) composites showed significant increases in mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Microstructural parameters in electron‐irradiated hydroxypropyl methylcellulose films using X‐ray line profile analysis
Authors: Sangappa  , Demappa T. , Mahadevaiah  , Ganesh S. , Divakara S. , Somashekar R.
Published: June 2008

The changes in microstructural parameters in hydroxypropyl methylcellulose (HPMC) polymer films irradiated with 8 MeV electron beam have been studied using wide‐angle X‐ray scattering (WAXS) method. The crystal imperfection parameters such as crystal size , lattice strain (g in %), and enthalpy (α*) have been determined by line profile analysis (LPA) using Fourier method of Warren. Exponential, Lognormal, and Reinhold functions for the column length distributions have been used for the determination of these parameters. The goodness of the fit and the consistency of these results suggest that the exponential distribution gives much better results, even though lognormal distribution has been widely used to estimate the similar stacking faults in metal oxide compounds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Determination of Mark–Houwink parameters of ethylene–norbornene copolymers and molecular characteristics estimation
Authors: Yao Zhen , Liu Shao‐jie , Lv Fei , Cao Kun
Published: June 2008

Ethylene–norbornene copolymers (ENC) with ∼ 50%, ∼ 25% and ∼ 15% norbornene (NB) fraction in a wide range of molecular weight were produced by metallocene catalysts. By coupling the gel permeation chromatography (GPC) with the intrinsic viscosity data in 1,2,4‐trichlorobenzene (TCB)at 150°C, the Mark–Houwink parameters of ENC were determined and compared with previous classical analysis using polyethylene's relative parameters. The results indicated that parameter K was considerably increased with decreasing NB fraction in ENC but parameter α was only increased slightly. Furthermore, the structure characteristics and correlative rheological parameters of resultant ENC were also calculated and discussed by the Stockmayer–Fixman analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of poly(methyl methacrylate) polymerized by microwave energy or conventional water bath
Authors: Acosta‐Torres L. S. , Barceló‐Santana F. H. , Álvarez‐Gayosso C. A. , Reyes‐Gasga J.
Published: June 2008

In this work, the influence of three different suspension agents (agar, sodium alginate, and gelatin) in the synthesis of poly(methyl methacrylate) (PMMA) particles is reported. Sodium alginate was the best suspension agent, obtaining characteristics closer to commercial denture base resins. Synthesized particles and two commercial acrylic resins (Acron MC and Lucitone 199) were characterized by light microscopy, scanning electron microscopy, characteristic X‐ray energy dispersive spectroscopy, thermogravimetric analysis, and molecular weight measurements. Mechanical tests (transverse deflection behavior) were done using two heat‐polymerizing techniques. The results indicated that both the PMMA particles and the commercial acrylic resins have similar characteristics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
When “personhood” begins in the embryo: Avoiding a Syllabus of Errors
Authors: Gilbert Scott F.
Published: June 2008

The following essay was delivered at the conference “Ontogeny and Human Life” at the Ponifical Athenaeum “Regina Apostolorum,” November, 2007. Sponsored by the Legion of Christ, the Pontifical Academy for Life, and the John Templeton Foundation, the sessions focused on when the conceptus became a “person.” My essay focused on the scientific conclusions that could aid such discussions. Moreover, after listening to the philosophical, legal, and theological discussions that ensued, I responded theologically as well. New concepts in modern embryology have made scientists revise their views concerning the autonomy of embryos and the mechanisms that generate such embryos. There are interactions between the sperm and the female reproductive tract and egg which had never been known until recently. There are also interactions between the developing organism and its environment that had been unsuspected a decade ago. Gut bacteria induce the development of the mammalian digestive system and immune system by changing the gene expression patterns in the mammalian intestine. Conversely, chemicals in our technological society can adversely affect the embryo, rendering it sterile or prone to tumors later in life. While there is no consensus among scientists as to when human life begins, both Church and science can become allies in persuading governments to regulate or ban the production and use of these fetotoxic chemicals. These new views of embryonic development change many of the stories told about human embryos and fetuses, and they have implications concerning the use of science as evidence for theological positions. Birth Defects Research (Part C) 84:164–173, 2008. © 2008 Wiley‐Liss, Inc.
Cell biology of embryonic migration
Authors: Kurosaka Satoshi , Kashina Anna
Published: June 2008

Cell migration is an evolutionarily conserved mechanism that underlies the development and functioning of uni‐ and multicellular organisms and takes place in normal and pathogenic processes, including various events of embryogenesis, wound healing, immune response, cancer metastases, and angiogenesis. Despite the differences in the cell types that take part in different migratory events, it is believed that all of these migrations occur by similar molecular mechanisms, whose major components have been functionally conserved in evolution and whose perturbation leads to severe developmental defects. These mechanisms involve intricate cytoskeleton‐based molecular machines that can sense the environment, respond to signals, and modulate the entire cell behavior. A big question that has concerned the researchers for decades relates to the coordination of cell migration in situ and its relation to the intracellular aspects of the cell migratory mechanisms. Traditionally, this question has been addressed by researchers that considered the intra‐ and extracellular mechanisms driving migration in separate sets of studies. As more data accumulate researchers are now able to integrate all of the available information and consider the intracellular mechanisms of cell migration in the context of the developing organisms that contain additional levels of complexity provided by extracellular regulation. This review provides a broad summary of the existing and emerging data in the cell and developmental biology fields regarding cell migration during development. Birth Defects Research (Part C) 84:102–122, 2008. © 2008 Wiley‐Liss, Inc.
Regulation of cartilage formation and maturation by mitogen‐activated protein kinase signaling
Authors: Bobick Brent E. , Kulyk William M.
Published: June 2008

The majority of bones comprising the adult vertebrate skeleton are generated from hyaline cartilage templates that form during embryonic development. A process known asendochondral ossificationis responsible for the conversion of these transient cartilage anlagen into mature, calcified bone. Endochondral ossification is a highly regulated, multistep cell specification program involving the initial differentiation of prechondrogenic mesenchymal cells into hyaline chondrocytes, terminal differentiation of hyaline chondrocytes into hypertrophic chondrocytes, and finally, apoptosis of hypertrophic chondrocytes followed by bone matrix deposition. Recently, extensive research has been carried out describing roles for the three major mitogen‐activated protein kinase (MAPK) signaling pathways, the extracellular signal‐regulated kinase 1/2 (ERK1/2), p38, and c‐jun N‐terminal kinase (JNK) pathways, in the successive stages of chondrogenic differentiation. In this review, we survey this research examining the involvement of ERK1/2, p38, and JNK pathway signaling in all aspects of the chondrogenic differentiation program from embryonic through postnatal stages of development. In addition, we summarize evidence from in vitro studies examining MAPK function in immortalized chondrogenic cell lines and adult mesenchymal stem cells. We also provide suggestions for future studies that may help ameliorate existing confusion concerning the specific roles of MAPK signaling at different stages of chondrogenesis. Birth Defects Research (Part C) 84:131–154, 2008. © 2008 Wiley‐Liss, Inc.
Fluid dynamics of establishing left–right patterning in development
Authors: Cartwright Julyan H. E. , Piro Nicolas , Piro Oreste , Tuval Idan
Published: June 2008

How does the clockwise motion of tens of monocilia drive a leftward flow in the node? And, as the observed flow is leftward, how is the fluid recirculating within the node, as it must, because the node is a closed structure? How does the nodal flow lead to left–right symmetry breaking in the embryo? These questions are within the realm of fluid physics, whose application to the problem of left–right symmetry breaking in vertebrates has led to important advances in the field. Birth Defects Research (Part C) 84:95–101, 2008. © 2008 Wiley‐Liss, Inc.
Genetisches Screening im Unterricht. Was Gene anmacht
Authors: Nikolay Rainer , Wiederkehr Thomas
Published: June 2008

Mit dem Hefe‐2‐Hybrid‐Screening kann nach Bindungspartnern für ein Protein und damit nach Anhaltspunkten für weitere Forschungen nach der Funktion dieses Proteins gesucht werden. Außerdem ist diese Art des Screenings eine elegante Methode, um den komplexen Zusammenhang zwischen Gen und Phän und das Prinzip von Reportergenen an der Schule zu vermitteln.
Das Geheimnis eines guten Kaffees. Biochemische Grundlagen der Nacherntebehandlung
Authors: Selmar Dirk , Bytof Gerhard
Published: June 2008

Traditionell gibt es zwei unterschiedliche Verfahren der Nacherntebehandlung des Arabica‐Kaffees: die “trockene” und die “nasse” Aufbereitung, die zu einem unterschiedlichen Geschmack und unterschiedlicher Qualität führen. Analysen der Expression keimungsspezifischer Enzyme sowie der Zellteilungsaktivität haben gezeigt, dass in Kaffeesamen während dieser Aufbereitung Keimungsprozesse stattfinden, deren Ausprägung von der Art der Nachernte‐Behandlung abhängig ist. Darüber hinaus finden in den trocknenden Kaffeebohnen stressinduzierte Prozesse statt, wie beispielsweise die Akkumulation von γ‐Aminobuttersäure. Diese Erkenntnisse, die erstmalig belegt haben, dass die bekannten Qualitätsunterschiede der Rohkaffees auch auf Unterschiede im Metabolismus der Kaffeesamen zurückzuführen sind, haben zu einem Paradigmenwechsel geführt: Rohkaffee wird nicht mehr als “totes Handelsgut” angesehen, sondern als ein lebendiger Rohstoff verstanden, dessen Stoffwechselkapazität genutzt werden kann, um modulierend in die Qualitätsausprägung einzugreifen.
Das Ubiquitin‐Proteasom‐System. Konsequente Erforschung und therapeutische Nutzung
Authors: Fuchs Dominik , Berges Carsten , Naujokat Cord
Published: June 2008

Das Ubiquitin‐Proteasom‐System ist eines der wichtigsten zellulären Regulationssysteme. In weniger als 25 Jahren wurde es systematisch und vollständig charakterisiert. Heute bietet es eine umfassende molekulare Basis für die Therapie bösartiger, entzündlicher und immunologischer Erkrankungen.
Sanddollar: doppelt hält besser
Authors: Wendler Silke
Published: June 2008

Die erwachsenen Tiere des Sandseeigels (Dendraster excentricus, “Sanddollar”) leben im sandigen Untergrund küstennaher Regionen, wo sie sich von feinen organischen Partikeln ernähren. Der Nachwuchs hingegen verbringt seine Larvalzeit im Zooplankton treibend. Das Phyto‐ und Zooplankton wird von vielen Meeresbewohnern als Hauptnahrungsquelle genutzt. Die Meeresbiologin Dawn Vaughn und ihr Kollege Richard Strathmann haben jetzt beobachtet, dass die Larven des Sanddollars durch Klonierung ihre Überlebenschancen verbessern.
Tauziehen beim Transport in der Zelle
Authors: Feil Sylvia
Published: June 2008

Betrachtet man die Mikrotubuli des Cytoskeletts als Straßen, gleiten die zu transportierenden Substanzen auf ihnen entlang. Die Richtung entscheidet sich in einem Tauziehen zweier Gruppen von Motorproteinen, wie aktuelle Forschungsergebnisse zeigen.
Antibiotika als Nahrung für Bodenbakterie
Authors: Hille‐Rehfeld Annette
Published: June 2008

Bodenbakterien können nicht nur gegen ganz unterschiedliche Antibiotika Resistenzen entwickeln – einige von ihnen sind sogar in der Lage, ihre potenziellen Gegenspieler als Kohlenstoffquelle zu nutzen. Die Entwicklung von Resistenzen gegen therapeutisch eingesetzte Antibiotika, die die medizinische Versorgung zunehmend vor Probleme stellt, beruht demnach auf dem natürlichen genetischen Potenzial der Mikroorganismen.
Die Struktur der DNA – ein Modell‐Projekt
Authors: Quadbeck‐Seeger H.‐J.
Published: June 2008

Die menschliche DNA besteht aus circa 3,2 Milliarden Basenpaaren und ist etwa 1,8 m lang. Vorstellen können wir uns den “Faden des Lebens” nicht wirklich. Abhilfe schafft der Nachbau eines einfachen Modells, das sowohl die Verdrillung als auch die Festigkeit der Doppelhelix wiedergibt. Vor allem zu Unterrichtszwecken ist dieses anschauliche Erbgut im Eigenbau bestens geeignet.
Heinrich Boie
Authors: Irsch Wilhelm
Published: June 2008

Coenraad Jacob Temminck war ein bekannter Pionier und Wegbereiter moderner naturhistorischer Sammlungen (BIUZ 1/2008). Nicht ganz so bekannt, aber dennoch nicht vergessen ist Heinrich Boie, ein bewährter Mitarbeiter Temmincks – sozusagen seine rechte Hand. Der zukunftsweisende Naturforscher und Ornithologe (1794–1827) wuchs an der deutschen Nordseeküste auf. Er starb vor mehr als 150 Jahren auf einer Reise in die Tropen.
Antagonistic effect of EGF on FAK phosphorylation/dephosphorylation in a cell
Authors: Kim Sang‐Heon , Kim Soo Hyun
Published: June 2008

Focal adhesion kinase (FAK) plays a key role in the crosstalk of growth factor‐ and cell adhesion‐mediated signaling pathway. In this study, we found that the quantitative change of phosphorylated FAK was bell‐shaped time‐dependently by EGF stimulation in immortalized human keratinocyte (HaCaT). EGF enhanced FAK phosphorylation and cell spreading in adhering HaCaT cells with low‐phosphorylated FAK. On the other hand, spread HaCaT cells having high‐phosphorylated FAK changed to round shapes with FAK dephosphorylation 15 min after EGF stimulation. Pharmacological agents, U0126 and PD98059 (mitogen‐activated protein kinases (MAPK) kinases (MEK) inhibitors), and AG1478 (an EGF receptor kinase inhibitor) blocked the cell rounding and FAK dephosphorylation. In addition, the EGFR‐MAPK signaling pathway had an influence on cell migration by regulating FAK dephosphorylation of keratinocytes in response of EGF, since the MEK inhibitors and AG1478 suppressed EGF‐induced cell migration. However, FAK phosphorylation and HaCaT cell spreading were inhibited only by the antagonist of EGF–EGFR binding but not by the MEK inhibitors and AG1478. Taken together, we suggest that EGF is antagonistically involved in both FAK phosphorylation and dephosphorylation with different mechanisms in a cell. Copyright © 2008 John Wiley & Sons, Ltd.
Isolation and characterization of novel phenotype CHO cell mutants defective in peroxisome assembly, using ICR191 as a potent mutagenic agent
Authors: Ghaedi Kamran , Fujiki Yukio
Published: June 2008

To elucidate molecular and cellular mechanisms of peroxisome biogenesis, we have isolated Chinese hamster ovary (CHO) cell mutants defective in peroxisome biogenesis by making use of enhanced green fluorescent protein (EGFP) and a frameshift‐inducing mutagen ICR191. CHO‐TKa cells stably expressing Pex2p were transformed with a cDNA encoding EGFP fused with peroxisomal targeting signal type 2 (PTS2‐EGFP), termed Tka/EG2. TKa/EG2 cells were mutagenized with ICR191 and cultured in the presence of P9OH (9‐(1′‐pyrene) nonanol) followed by an exposure to UV. P9OH/UV‐resistant and morphologically peroxisome‐deficient mutant cells were isolated by directly observing cytosolic localization of EGFP, without cell staining. By a combination of cell‐fusion and PEX transfection, we determined complementation groups (CGs) of 16 cell mutants isolated here. The mutants were classified into five CGs, including pex2, pex3, pex5, pex6, and pex7 cell mutants. In contrast to typical pex6 mutants with the impaired import of both PTS1‐ and PTS2‐proteins, two clones, ZPEG236 and ZPEG244, showed a distinct, novel phenotype where PTS1‐protein import was normal despite the abrogated PTS2 import. Dysfunction of Pex3p in pex3 ZPEG 238 was due to one base (G) insertion in the codon for Asn7 resulting in a frameshift, thereby inducing a distinct 31 amino‐acid sequence and a termination. pex2 ZPEG239 showed a mutation in codon GAG for Glu201 to a nonsense mutation, TAG. Thus, the method developed here using ICR191 could be useful for isolation of further novel cell mutants impaired in peroxisome biogenesis. Copyright © 2008 John Wiley & Sons, Ltd.
The practice of Interventional Cardiovascular Medicine: “Evidence‐based” or “Judgment‐based”?
Authors: Moussa Issam D.
Published: June 2008

Evidence‐based medicine has emerged in response to empiric clinical decision‐making with the quest of infusing more “science” into the process of caring for the sick. Yet, evidence‐based medicine today is being applied to clinical practice in a rigid and, paradoxically, unscientific manner. The perception that evidence‐based medicine is the “ultimate and unquestionable biologic truth” that should supersede all other components of clinical decision‐making at the individual patient level needs to be critically reexamined. The practice of Interventional Cardiovascular Medicine should represent a bottom‐up approach that integrates the best external evidence—that has been critically analyzed—with individual clinical expertise and patient choice; it cannot result in cookbook approaches to patient care. External clinical evidence should inform, not replace, individual clinical expertise, and it is this expertise that decides whether the external evidence applies to the individual patient at all and, if so, how it should be integrated into a clinical decision. © 2008 Wiley‐Liss, Inc.
Concordant improvements in coronary flow reserve and ST‐segment resolution during percutaneous coronary intervention for acute myocardial infarction: A benefit of postconditioning
Authors: Laskey Warren K. , Yoon Sam , Calzada Norberto , Ricciardi Mark J.
Published: June 2008

Objective: To assess the effect of ischemic postconditioning on indices of coronary microvascular function during percutaneous coronary intervention (PCI) for acute ST segment elevation myocardial infarction (STEMI). Background: Myocardial tissue level perfusion remains suboptimal in many patients with STEMI despite restoration of antegrade flow in the epicardial coronary artery. Methods: Twenty‐four patients with an evolving anterior STEMI were randomized to undergo a previously‐validated ischemic postconditioning protocol or usual care during PCI. The extent of resolution of ST segment elevation along with Doppler‐tip catheter velocimetry was used as indices of myocardial reperfusion and microvascular function, respectively. Results: Postconditioned patients exhibited a greater, and therefore more rapid, extent of ST segment resolution (postconditioning, 70% ± 15%; control, 48% ± 16%; P = 0.0002) by the end of the procedure. Postconditioned patients also exhibited a greater hyperemic coronary vasodilator response at the completion of the procedure (coronary flow velocity reserve, CFVR: postconditioning, 2.2 ± 0.1; control, 1.5 ± 0.1; P < 0.0001). The end‐procedure CFVR was directly related to the extent of the ST segment resolution (r = 0.85) but inversely related to the absolute magnitude of ST segment elevation at end procedure (r = −0.76). Peak serum creatine kinase was significantly lower in postconditioned patients (postconditioning, 1,524 ± 435 IU/l; control, 1,862 ± 561 IU/l; P = 0.03). Conclusions: Ischemic postconditioning, as described, can be expeditiously performed during PCI for STEMI. Concordant changes in coronary flow reserve and ST segment resolution, measures of microcirculatory function, and myocardial perfusion, were greater in postconditioned patients. © 2008 Wiley‐Liss, Inc.
Efficacy and safety of argatroban in patients with heparin induced thrombocytopenia undergoing endovascular intervention for peripheral arterial disease
Authors: Baron Suzanne J. , Yeh Robert W. , Cruz‐Gonzalez Ignacio , Healy Josephine L. , Pomerantsev Eugene , Garasic Joseph , Drachman Douglas , Rosenfield Kenneth , Jang Ik‐Kyung
Published: June 2008

Objectives: This study aimed to evaluate the efficacy and safety of argatroban during percutaneous interventions for peripheral arterial disease (PAD). Background: Endovascular interventions are commonly used in patients with peripheral arterial disease. Heparin is routinely administered during these procedures, but cannot be used in patients with a history of heparin‐induced thrombocytopenia (HIT). Argatroban is an approved direct thrombin inhibitor for treatment of patients with HIT. There are currently few data on the efficacy and safety of argatroban during endovascular interventions for PAD. Methods: Patients who underwent endovascular interventions for PAD on argatroban between 2002 and 2005 were identified from out database. Efficacy was evaluated using a composite of death, urgent revascularization, and amputation, while safety was assessed by TIMI major bleeding during the index hospitalization. Results: A total of 48 patients undergoing lower extremity revascularization on argatroban were identified. Thirty two of these patients (67%) had antibody‐confirmed HIT and the other 16 (33%) had suspected HIT. A mean dose of argatroban was 173.5 ± 143 μg/kg bolus, followed by a 10.7 ± 9.64 μg/kg/min infusion during the procedure. Twelve patients (25%) met the composite end point (two deaths, one urgent revascularization, nine amputations because of progressive peripheral arterial disease). TIMI major bleeding occurred in three (6%) patients. Conclusion: In patients with confirmed or suspected HIT undergoing endovascular intervention for PAD, argatroban appears to be effective and safe. A larger study is warranted to confirm these findings from a single center. © 2008 Wiley‐Liss, Inc.
Serial late dilatations of expanded polytetrafluoroethylene‐covered stents in porcine aorta
Authors: Gordon Brent M. , Fishbein Michael C. , Levi Daniel S.
Published: June 2008

Background: Covered stents may be desirable for stenting of coarctations. Objectives: To evaluate the ability of Atrium expanded polytetrafluoroethylene (ePTFE)‐covered stents to be implanted and then serially dilated to the size of the adjacent aorta during a rapid growth period in swine. Methods: Eight Yorkshire pigs (7 females) with a mean weight of 18.3 ± 0.7 kg had an Atrium ePTFE‐covered stent deployed in the descending aorta. Five of these animals also had an identical Atrium bare metal stent (BMS) control deployed in the descending aorta. All swines were recatheterized with the first dilatation of the stents to 14 mm at day 100. Four of these animals were recatheterized at day 145 and euthanized, and the remaining four swine were recatheterized with a second dilatation to 18–20 mm, 195 days after initial implantation. Results: All stents were deployed without device malfunction, and both uncovered and covered stents were successfully dilated from 10 to 11 mm to the size of the adjacent aorta (16–20 mm). There was no gradient across either type of stent on recatheterization and all stents were well sized to the native aorta. Only the size of the aorta limited the degree of stent dilatation. The Atrium covered stents consistently recoiled after maximal dilatation and required higher pressures for further expansion. Gross damage to the aorta was noted in two animals in which stents were dilated to >20% the diameter of the native aorta. In stent neointimal thickness was equivalent for both types of stent. Conclusions: Atrium ePTFE‐covered stents can be implanted at 10–11 mm and serially dilated to accommodate for rapid aortic growth. High pressure balloons are required for dilatation of ePTFE‐covered stents. Atrium covered stents exhibited more recoil and foreshortening at larger diameters. © 2008 Wiley‐Liss, Inc.
Percutaneous closure of a complex posttraumatic muscular ventricular septal defect
Authors: Muyskens Steve , Lasala John , Balzer David
Published: June 2008

We report the percutaneous closure of a complex traumatic ventricular septal defect resulting from a stab wound to the anterior chest. The patient presented with heart failure 3 months after the initial trauma. Evaluation revealed a new large ventricular septal defect with diminished cardiac function. Closure was accomplished with a combination of an Amplatzer muscular ventricular septal defect occluder and two Amplatzer vascular plugs. © 2008 Wiley‐Liss, Inc.
Postnatal reorganization of primary afferent terminal fields in the rat gustatory brainstem is determined by prenatal dietary history
Authors: Mangold Jamie E. , Hill David L.
Published: June 2008

Dietary manipulation has been used as an experimental strategy to gain insight into the normal development of the gustatory system. Institution of a diet low in sodium chloride (NaCl) from embryonic day 3 (E3) to E12 (E3–E12 sodium‐restricted rats) yields dramatically enlarged terminal fields of the chorda tympani (CT), greater superficial petrosal (GSP), and glossopharyngeal (IX) nerves in the rostral pole of the nucleus of the solitary tract (NTS) at adulthood. To examine how this early, limited dietary manipulation affects postnatal terminal field development, we used a triple anterograde nerve label procedure at postnatal day 15 (P15), P25, P35, and ≥P40 (adults) in two groups: rats fed a commercial diet replete in sodium (controls) and E3–E12 sodium‐restricted rats. Results showed an age‐related decrease in terminal field volumes of all three nerves during normal development. In contrast, E3–E12 sodium‐restricted rats displayed age‐related increases of the CT and IX terminal fields, with the terminal field volume of the GSP remaining unchanged throughout development. NTS volume did not grow after P15; therefore, alterations in terminal field volumes are not due to parallel alterations in the size of the NTS. Our data suggest that the age‐related decrease in terminal fields observed in controls may reflect activity‐dependent pruning of afferent terminals, whereas terminal field increases seen in E3–E12 sodium‐restricted rats may reflect cellular/molecular differences in the NTS induced predominantly by activity‐independent mechanisms. These findings predict a significant difference in the development of neural coding and sensory‐guided behaviors between E3–E12 sodium‐restricted rats and controls. J. Comp. Neurol. 509:594–607, 2008. © 2008 Wiley‐Liss, Inc.
Differential reaction of outgrowing olfactory neurites monitored in explant culture
Authors: Luxenhofer Georg , Breer Heinz , Strotmann Joerg
Published: June 2008

Olfactory sensory neurons (OSNs) send their axons to distinct glomeruli in the olfactory bulb. On the way to their target, outgrowing axons are guided, fasciculated, and resorted before they extend in homotypic bundles to the glomerulus. The molecular mechanisms underlying these complex processes supposedly involve multiple intrinsic and extrinsic cues. Although the contribution of typical guidance molecules has been proposed, a detailed understanding of the olfactory wiring process remains elusive. By using in vitro cultures of the olfactory epithelium (OE) from gene‐targeted mice, which allowed visualization of mature OSN and their axons, the impact of distinct molecular and cellular cues on defined OSN populations could be studied. The differentiating factor retinoic acid induced a heterogeneous response pattern of OMP expression and axon elongation. Cocultures with forebrain explants revealed that tissue from the presumptive olfactory bulb of embryonic stage E14 exhibited nonpermissive, repellent effects on outgrowing neurites, whereas precultured bulb tissue strongly attracted them, even from distantly located OE explants. A selective attraction of fibers from OSNs expressing defined odorant receptor types to distinct bulb explants was observed. These data indicate a differential reaction of OSNs to their target tissue. J. Comp. Neurol. 509:580–593, 2008. © 2008 Wiley‐Liss, Inc.