bluuebunny/crossref_metadata_2025 huggingface dataset:
Gastroschisis: International epidemiology and public health perspectives
Authors: Castilla Eduardo E. , Mastroiacovo Pierpaolo , Orioli Iêda M.
Published: July 2008

Gastroschisis offers the intriguing epidemiological situation of a pandemic, strongly associated with very low maternal age. Identifying gastroschisis, and distinguishing it from the other abdominal wall defects, is theoretically easy but difficult in practice. The baseline birth prevalence of gastroschisis before the pandemic was approximately 1 in 50,000 births and has increased since between 10‐ and 20‐fold. In many populations worldwide, it is still increasing. Such increasing prevalence and the association with very low maternal age are well proven, but the interaction between these two findings remains unknown. Geographic gradients (decreasing prevalence from North to South) are clear in Continental Europe and suggestive in Britain and Ireland. Gastroschisis seems more frequent in Caucasians compared to African Blacks and Orientals, and in Northern compared to Southern Europeans. These observations indicate the need for investigating gene–environment interactions. Since the global human situation is marked by inequalities among as well as within countries, the medical care and public health impact of gastroschisis varies widely among regions and social strata. The postnatal benefits of prenatal diagnosis of gastroschisis include family awareness; adequate planning of delivery with alerted obstetrical, pediatric, and surgical staff; optimal risk categorization, and personalized protocol for action. The increasing prevalence of gastroschisis combined with improved medical techniques to reduce morbidity and mortality are also increasing the burden and costs of this anomaly on health systems. © 2008 Wiley‐Liss, Inc.
Gastroschisis: A gene–environment model involving the VEGF–NOS3 pathway
Authors: Lammer Edward J. , Iovannisci David M. , Tom Lauren , Schultz Kathy , Shaw Gary M.
Published: July 2008

Gastroschisis is a severe major malformation in which an infant is delivered with a portion of intestines and possible other abdominal organs extruding through a defect in the abdominal wall, usually to the right of the umbilical cord. Etiologies of gastroschisis are largely unknown, and even its pathogenesis is poorly understood. Several recent epidemiological studies have identified interactions between maternal smoking during pregnancy, genetic variants of endothelial nitric oxide synthase, and risk for gastroschisis. We present a brief review of the endothelial nitric oxide synthase pathway and its relationship to vasculogenesis, suggesting that disruption of this pathway by environmental exposures or by genetic variation may represent one pathogenetic model for gastroschisis. © 2008 Wiley‐Liss, Inc.
Ancient DNA analysis of human remains from the upper capital city of Kublai Khan
Authors: Fu Yuqin , Xie Chengzhi , Xu Xuelian , Li Chunxiang , Zhang Quanchao , Zhou Hui , Zhu Hong
Published: July 2008

Analysis of DNA from human archaeological remains is a powerful tool for reconstructing ancient events in human history. To help understand the origin of the inhabitants of Kublai Khan's Upper Capital in Inner Mongolia, we analyzed mitochondrial DNA (mtDNA) polymorphisms in 21 ancient individuals buried in the Zhenzishan cemetery of the Upper Capital. MtDNA coding and noncoding region polymorphisms identified in the ancient individuals were characteristic of the Asian mtDNA haplogroups A, B, N9a, C, D, Z, M7b, and M. Phylogenetic analysis of the ancient mtDNA sequences, and comparison with extant reference populations, revealed that the maternal lineages of the population buried in the Zhenzishan cemetery are of Asian origin and typical of present‐day Han Chinese, despite the presence of typical European morphological features in several of the skeletons. Am J Phys Anthropol, 2009. © 2008 Wiley‐Liss, Inc.
Scaling of chew cycle duration in primates
Authors: Ross Callum F. , Reed David A. , Washington Rhyan L. , Eckhardt Alison , Anapol Fred , Shahnoor Nazima
Published: July 2008

The biomechanical determinants of the scaling of chew cycle duration are important components of models of primate feeding systems at all levels, from the neuromechanical to the ecological. Chew cycle durations were estimated in 35 species of primates and analyzed in conjunction with data on morphological variables of the feeding system estimating moment of inertia of the mandible and force production capacity of the chewing muscles. Data on scaling of primate chew cycle duration were compared with the predictions of simple pendulum and forced mass–spring system models of the feeding system. The gravity‐driven pendulum model best predicts the observed cycle duration scaling but isrejected as biomechanically unrealistic. The forced mass–spring model predicts larger increases in chew cycle duration with size than observed, but provides reasonable predictions of cycle duration scaling. We hypothesize that intrinsic properties of the muscles predict spring‐like behavior of the jaw elevator muscles during opening and fast close phases of the jaw cycle and that modulation of stiffness by the central nervous system leads to spring‐like properties during the slow close/power stroke phase. Strepsirrhines show no predictable relationship between chew cycle duration and jaw length. Anthropoids have longer chew cycle durations than nonprimate mammals with similar mandible lengths, possibly due to their enlarged symphyses, which increase the moment of inertia of the mandible. Deviations from general scaling trends suggest that both scaling of the jaw muscles and the inertial properties of the mandible are important in determining the scaling of chew cycle duration in primates. Am J Phys Anthropol, 2009. © 2008 Wiley‐Liss, Inc.
Die Effektivität des Peer‐Review‐Verfahrens: Übereinstimmungsreliabilität und Vorhersagevalidität der Manuskriptbegutachtung bei der Angewandten Chemie
Authors: Bornmann Lutz , Daniel Hans‐Dieter
Published: July 2008

Auf dem Prüfstand: Das Peer‐Review‐Verfahren der Angewandten Chemie wird nach den Kriterien der Reliabilität (Übereinstimmung gutachterlicher Voten) und Vorhersagevalidität (Zusammenhang zwischen Publikationsentscheidung und Zitierhäufigkeit der begutachteten Arbeit) überprüft. Trotz einer drastischen Zunahme der eingereichten Zuschriften und einem deutlichen Rückgang der Annahmequote belegen die Ergebnisse der vorliegenden Studie die nach wie vor hohe Güte des Peer‐Reviews der Angewandten Chemie.
The Effectiveness of the Peer Review Process: Inter‐Referee Agreement and Predictive Validity of Manuscript Refereeing at Angewandte Chemie
Authors: Bornmann Lutz , Daniel Hans‐Dieter
Published: July 2008

Refereeing the referees: The peer review process of Angewandte Chemie has been examined according to the criteria of reliability (agreement between referees) and predictive validity (correlation between publication decision and citation frequency of the reviewed work). Despite the dramatic increase in submitted manuscripts and significant decline in acceptance rate, the results show the unwavering quality of the peer review at Angewandte Chemie.
Effect of temperature‐pressure cycles on structural properties of epoxy‐based composites for printed circuit boards applications
Authors: Fernandes Elizabeth G. , Tramidi Cristiano , Di Gregorio Giordano M. , Angeloni Giacomo , Chiellini Emo
Published: July 2008

During multilayer printed circuit board production, cyclic pressure–temperature (P–T) treatments can give rise to mechanical and thermal stresses with subsequent inner delamination phenomena. These are mainly related to the thermomechanical properties of epoxy resins used in the manufacturing process. In this study, the physical and chemical changes of commercial epoxy‐based prepregs were investigated as a function of P–T treatments by means of thermogravimetric analysis, differential scanning calorimeter, and Fourier transform infrared‐photoacoustic spectroscopy. It was verified that the thermal properties start to decrease after the first P–T treatment. In connection, absorbance spectra indicated that the peaks at 2273 cm−1 and 2235 cm−1 (cyanate group) disappeared after this treatment. Heat transfer as a function of laminate thickness (consequently, as a function of P–T treatment) is one variable that probably contributes to the findings in the work. The results of this study indicated that the analytical methods were satisfactory to determine the beginning of the deterioration of the printed circuit as a function of the P–T treatments. They can be used as a reference for quality controls and to prevent mechanical problems such as interlaminar fractures in the relevant printed circuits. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and curing behavior of a novel ferrocene‐based epoxy compound
Authors: Yu Haojie , Wang Li , Huo Jia , Ding Jianhua , Tan Qiaohua
Published: July 2008

A novel ferrocene‐based epoxy compound of glycidyl ester of 1,1′‐ferrocene dicarboxylate was synthesized by the reaction of 1,1′‐ferrocene dicarboxylate and epichlorohydrin. The resultant epoxy compound showed an irreversible redox process in cyclic voltammetry (CV) measurement. The curing behavior of glycidyl ester of 1,1′‐ferrocene dicarboxylate and dicyandiamide system was investigated by nonisothermal measurement using the Ozawa's approach with the heating rate of 5, 10, 15, and 20°C/min, respectively. It was found that both the diffusion of the compound and the curing temperature have effect on the curing process, and the effect of temperature was greater. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Diffusion of chloride ions in polymer‐mortar composites
Authors: Benosman A. S. , Taibi H. , Mouli M. , Belbachir M. , Senhadji Y.
Published: July 2008

In recent years, the rapid deterioration of various reinforced concrete structures has been a widely recognized problem in the world. Penetration of chloride ions into the concrete structures was found to be the major cause of premature corrosion of reinforcing steel and to promote their deterioration. The present articles deals with the resistance to chloride penetration of polymer‐mortar, which are often used as low‐cost promising materials for preventing or repairing various reinforced concrete structures. To gain more knowledge on the efficiency of polymer‐mortar, four mortar mixtures: one specimen with Portland cement (control sample) and three mixtures with 2.5, 5, and 7.5 wt % of the replacement of cement by polyethylene terephthalate (PET) were tested for chloride ion permeability under immersion in 5% sodium chloride solution. Their chloride ion penetration behavior is discussed by applying Fick's second law. In conclusion, the chloride ion penetration depth and apparent chloride ion diffusion coefficient of the polymer‐mortar composites are smaller than those of unmodified mortar. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Polymeric curing agent reinforced silicone rubber composites with low viscosity and low volume shrinkage
Authors: Dai Lina , Zhang Zhijie , Zhao Yunfeng , Xie Zemin
Published: July 2008

A new type of polymeric curing agent (PCA) was synthesized to improve processing property, increase mechanical properties, and decrease volume shrinkage of silicone rubber. The PCA was prepared by co‐hydrolysis condensation of dimethyldiethoxysilane (DDS) and polyethoxysiloxane, then modified by hexamethylcyclotrisilazane (D3N). Commercial silica and tetraethoxysilane (TEOS) were used as controls simultaneously. The properties of polydimethylsiloxane (PDMS) composites were characterized by shear viscosity measurements, room temperature mass loss, linear volume shrinkage, stress‐strain tests, swelling behaviors and thermogravimetric analysis (TGA). PDMS composites using PCA show lower shear viscosity than those using commercial silica. Compared with the traditional PDMS/TEOS curing systems, PDMS/PCA curing systems behave relatively lower volume shrinkage, better reinforcement and thermal properties. In short, PCA acts as a good compromise in providing the best balance of processing property, volume shrinkage, mechanical properties and thermal stability in silicone rubber composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Influence of high pressure gases on polymer‐solvent thermodynamic and transport behavior
Authors: Jones Adam T. , Danner Ronald P. , Duda J. Larry
Published: July 2008

Removal of residual solvent and monomers from a polymer through devolatilization can be the limiting step in production throughput. The process may be made more efficient by the addition of a cosolvent. In this work, the effects of two soluble gases, carbon dioxide, and ethylene, on the solubility and diffusivity of a number of solvents in poly(vinyl acetate) and poly(styrene) have been evaluated. The results indicate that in general the solubilities are reduced by the presence of the soluble gases and the diffusivity is significantly increased, with ethylene having the most pronounced effect. Larger solvent molecules benefit more by the presence of the added gas. The implications of this work are that replacement of noninteracting gases such as air or nitrogen with soluble gases can reduce solvent removal times and increase production rates. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Studying and increasing light stability of rotomolding grade of polyethylene
Authors: Feyz E. , Sharifi Sanjani N. , Shahraki H. , Ranji A. , Ala N.
Published: July 2008

This article covers the state‐of‐the‐art light stabilizer for rotational molding and the influence of synergistic effects between light and thermal stabilizers, which improve physical and mechanical properties. Different formulations of polyethylene (PE) with light stabilizer, thermal stabilizer, and acid scavenger have been produced in twin‐screw extruder. To study the light stability, sheets that produced by injection‐molding machine have been put in weather‐ometer instrument for 1000 h. After and before that, physical and mechanical properties have been evaluated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Cyclic extrusion of poly(butylene terephthalate)/organo‐montmorillonite nanocomposites: Thermal and mechanical retention properties
Authors: Chow Wen Shyang
Published: July 2008

Poly(butylene terephthalate) (PBT) containing 3 wt % of organo‐montmorillonite (OMMT) was prepared using twin screw extrusion followed by injection molding. The effects of thermal cycles (two times extrusion followed by injection molding) were studied on both PBT and PBT/OMMT nanocomposites. The samples were characterized by using tensile tests, flexural tests, field‐emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and dynamic mechanical thermal analysis (DMTA). The intercalation of the OMMT silicate layers in the PBT was confirmed using XRD. Both tensile and flexural modulus of PBT was improved by addition of OMMT. DSC results revealed that OMMT improved the crystallinity of PBT. The percentage retention in tensile and flexural properties of PBT/OMMT(E2) intercalated nanocomposites (i.e. two times extrusion followed by injection molding) is more than 96%. The melting temperature, crystallization temperature, and degree of crystallinity of PBT/OMMT(E2) is comparable with PBT/OMMT(E1) (i.e. one time extrusion followed by injection molding). This indicates that PBT/OMMT intercalated nanocomposites exhibit good retention‐ability in mechanical and thermal properties after subjecting to two times twin‐screw extrusion followed by injection molding. From the TGA results, it was observed that the thermal stability (e.g. Tonset) of PBT was reduced by the addition of OMMT. However, the addition of OMMT assists in the char formation of PBT. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The complicated influence of branching on crystallization behavior of poly(ethylene terephthalate)
Authors: Li Guang , Yang Shenglin , Jiang Jianming , Jin Junhong , Wu Chengxun
Published: July 2008

The randomly branched poly(ethylene terephthalate) (BPET) was prepared by bulk polycondensation from dimethyl terephthalate (DMT) and ethylene glycol (EG), with 0.4–5.0 mol % (with respect to DMT) of glycerol (GL) as a branching agent. The glass transition and crystallization behavior was studied by differential scanning calorimetry (DSC). It was found that the glass transition temperature of BPET reduced with the increasing content of GL until 1.2 mol %, and then increases a little at high degrees of branching. When compared with a linear PET, the crystallization temperature of BPET from the melt shifted to higher temperature as GL content was smaller than 1.2 mol %, and then became lower while GL load was added. Nonisothermal crystallization kinetics was studied through the modified Avrami analysis. It was revealed that the overall crystallization rate parameter of BPET became larger when the GL content was less than 1.2 mol %, then turned to lower at higher branching degree. This indicated that low degree of branching could enhance the overall crystallization of poly(ethylene terephthalate) (PET), whereas high degree of branching in the range of 3.5–5.0 mol % would block the development of crystallization. On the basis of Hoffman's secondary crystallization theory, the product σσe of the free energy of formation per unit area of the lateral and folding surface was calculated. According to the change of the product σσe with the degree of branching, a possible explanation was presented to illuminate this diverse effect of different degrees of branching on crystallization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The shift towards multi‐disciplinarity in information science
Authors: Chua Alton Y.K. , Yang Christopher C.
Published: July 2008

This article analyzes the collaboration trends, authorship and keywords of all research articles published in the Journal of American Society for Information Science and Technology (JASIST). Comparing the articles between two 10‐year periods, namely, 1988–1997 and 1998–2007, the three‐fold objectives are to analyze the shifts in (a) authors' collaboration trends (b) top authors, their affiliations as well as the pattern of coauthorship among them, and (c) top keywords and the subdisciplines from which they emerge. The findings reveal a distinct tendency towards collaboration among authors, with external collaborations becoming more prevalent. Top authors have grown in diversity from those being affiliated predominantly with library/information‐related departments to include those from information systems management, information technology, businesss, and the humanities. Amid heterogeneous clusters of collaboration among top authors, strongly connected cross‐disciplinary coauthor pairs have become more prevalent. Correspondingly, the distribution of top keywords' occurrences that leans heavily on core information science has shifted towards other subdisciplines such as information technology and sociobehavioral science.
Folate‐related gene polymorphisms as risk factors for cleft lip and cleft palate
Authors: Mills James L. , Molloy Anne M. , Parle‐McDermott Anne , Troendle James F. , Brody Lawrence C. , Conley Mary R. , Cox Christopher , Pangilinan Faith , Orr David J. A. , Earley Michael , McKiernan Eamon , Lynn Ena C. , Doyle Anne , Scott John M. , Kirke Peadar N.
Published: July 2008

BACKGROUND:

Cleft lip with or without cleft palate (CLP) and cleft palate only (CPO) have an inherited component and, many studies suggest, a relationship with folate. Attempts to find folate‐related genes associated with clefts have, however, often been inconclusive. This study examined four SNPs related to folate metabolism (MTHFR 677 C→T, MTHFR 1298 A→C, MTHFD1 1958 G→A, and TC II 776 C→G) in a large Irish population to clarify their relationship with clefts.

METHODS:

Cases and their parents were recruited from major surgical centers performing cleft repairs in Ireland and a support organization. Data on risk factors, medical history, and DNA were collected. Controls were pregnant women from the greater Dublin area (n = 1,599).

RESULTS:

CLP cases numbered 536 and CPO cases 426 after exclusions. CPO mothers were significantly more likely than controls to be MTHFR 677 TT, OR 1.50 (95% CI: 1.05–2.16; p = .03). Log‐linear analysis showed a borderline association (p = .07). Isolated CPO case mothers were significantly more likely than controls to be homozygous for the MTHFD1 1958 G→A variant, OR 1.50 (95%CI: 1.08–2.09; p = .02). When multiple cases were added, both CPO cases and case mothers were significantly more likely to be AA (p = .02 and p = .007, respectively). The CLP case‐control and mother‐control analyses also showed significant effects, ORs 1.38 (95% CI: 1.05–1.82; p = .03) and 1.39 (95% CI: 1.04–1.85; p = .03), respectively.

CONCLUSIONS:

Associations were found for both CPO and CLP and MTHFD1 1958 G→A in cases and case mothers. MTHFR 677 C→T could be a maternal risk factor for clefts but the association was not strong. Because multiple comparisons were made, these findings require additional investigation. Given the known association between MTHFD1 1958 G→A and NTDs, these findings should be explored in more detail. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.
Optimized evolution in the cytostat: A Monte Carlo simulation
Authors: Gilbert Alan , Srienc Friedrich
Published: July 2008

Rational genetic alterations of a microorganism for a specific purpose are not possible in many situations where our knowledge of the relationship between phenotype and genotype is limited. In such cases evolutionary techniques must be applied. Evolutionary methods are usually time consuming; therefore, more efficient techniques are highly desirable. In this work we present the optimization of strain development in a cytostat. The time required for mutant strain isolation is dependent on the total cells present, the wild‐type specific growth rate, the beneficial mutation probability, the mutant specific growth rate, and several bioreactor operating conditions. These parameters are highly related, and a theoretical model, as developed here, is needed to define the conditions that optimize the isolation. The model is based on a discrete, stochastic description of mutant formation and selection in the background of abundant wild‐type cells. Using the model, we determined the optimal cytostat operating strategy for mutant isolation that varies according to the probability of beneficial mutations. It is also shown that mutants with as little as a 5% growth advantage can be isolated in less than 15 days which is significantly faster than in a chemostat. The described optimal mutant isolation procedure is expected to be particularly useful for the generation of industrial strains that are robust in challenging growth conditions. Biotechnol. Bioeng. 2009;102: 221–231. © 2008 Wiley Periodicals, Inc.
Precipitation and recovery of metal sulfides from metal containing acidic wastewater in a sulfidogenic down‐flow fluidized bed reactor
Authors: Gallegos‐Garcia Marisol , Celis Lourdes B. , Rangel‐Méndez René , Razo‐Flores Elías
Published: July 2008

This study reports the feasibility of recovering metal precipitates from a synthetic acidic wastewater containing ethanol, Fe, Zn, and Cd at an organic loading rate of 2.5 g COD/L‐day and a COD to sulfate ratio of 0.8 in a sulfate reducing down‐flow fluidized bed reactor. The metals were added at increasing loading rates: Fe from 104 to 320 mg/L‐day, Zn from 20 to 220 mg/L‐day, and Cd from 5 to 20 mg/L‐day. The maximum COD and sulfate removals attained were 54% and 41%, respectively. The biofilm reactor was operated at pH as low as 5.0 with stable performance, and no adverse effect over COD consumption or sulfide production was observed. The metals precipitation efficiencies obtained for Fe, Zn, and Cd exceeded 99.7%, 99.3%, and 99.4%, respectively. The total recovered precipitate was estimated to be 90% of the theoretical mass expected as metal sulfides. The precipitate was mainly recovered from the bottom of the reactor and the equalizer. The analysis of the precipitates showed the presence of pyrite (FeS2), sphalerite (ZnS) and greenockite (CdS); no metal hydroxides or carbonates in crystalline phases were identified. This study is the first in reporting the feasibility to recover metal sulfides separated from the biomass in a sulfate reducing process in one stage. Biotechnol. Bioeng. 2009;102: 91–99. © 2008 Wiley Periodicals, Inc.
Sterilization of ginseng using a high pressure CO2 at moderate temperatures
Authors: Dehghani Fariba , Annabi Nasim , Titus Mamata , Valtchev Peter , Tumilar Aldric
Published: July 2008

The aim of this study was to determine the feasibility of using high pressure CO2 for sterilization of Ginseng powder, as an alternative method to conventional techniques such as γ‐irradiation and ethylene oxide. The Ginseng sample used in this study was originally contaminated with fungi and 5 × 107 bacteria/g that was not suitable for oral use. This is the first time that high pressure CO2 has been used for the sterilization of herbal medicine to decrease the total aerobic microbial count (TAMC) and fungi. The effect of the process duration, operating pressure, temperature, and amount of additives on the sterilization efficiency of high pressure CO2 were investigated. The process duration was varied over 15 h; the pressure between 100 and 200 bar and the temperature between 25 and 75°C. A 2.67‐log reduction of bacteria in the Ginseng sample was achieved after long treatment time of 15 h at 60°C and 100 bar, when using neat carbon dioxide. However, the addition of a small quantity of water/ethanol/H2O2 mixture, as low as 0.02 mL of each additive/g Ginseng powder, was sufficient for complete inactivation of fungi within 6 h at 60°C and 100 bar. At these conditions the bacterial count was decreased from 5 × 107 to 2.0 × 103 TAMC/g complying with the TGA standard for orally ingested products. A 4.3 log reduction in bacteria was achieved at 150 bar and 30°C, decreasing the TAMC in Ginseng sample to 2,000, below the allowable limit. However, fungi still remained in the sample. The complete inactivation of both bacteria and fungi was achieved within 2 h at 30°C and 170 bar using 0.1 mL of each additive/g Ginseng. Microbial inactivation at this low temperature opens an avenue for the sterilization of many thermally labile pharmaceutical and food products that may involve sensitive compounds to γ‐radiation and chemically reactive antiseptic agents. Biotechnol. Bioeng. 2009;102: 569–576. © 2008 Wiley Periodicals, Inc.
In situ magnetic separation for extracellular protein production
Authors: Käppler Tobias , Cerff Martin , Ottow Kim , Hobley Timothy , Posten Clemens
Published: July 2008

A new approach for in situ product removal from bioreactors is presented in which high‐gradient magnetic separation is used. This separation process was used for the adsorptive removal of proteases secreted by Bacillus licheniformis. Small, non‐porous bacitracin linked magnetic adsorbents were employed directly in the broth during the fermentation, followed by in situ magnetic separation. Proof of the concept was first demonstrated in shake flask culture, then scaled up and applied during a fed batch cultivation in a 3.7 L bioreactor. It could be demonstrated that growth of B. licheniformis was not influenced by the in situ product removal step. Protease production also remained the same after the separation step. Furthermore, degradation of the protease, which followed first order kinetics, was reduced by using the method. Using a theoretical modeling approach, we could show that protease yield in total was enhanced by using in situ magnetic separation. The process described here is a promising technique to improve overall yield in bio production processes which are often limited due to weak downstream operations. Potential limitations encountered during a bioprocess can be overcome such as product inhibition or degradation. We also discuss the key points where research is needed to implement in situ magnetic separation in industrial production. Biotechnol. Bioeng. 2009;102: 535–545. © 2008 Wiley Periodicals, Inc.
Generation of human embryonic stem cell‐derived mesoderm and cardiac cells using size‐specified aggregates in an oxygen‐controlled bioreactor
Authors: Niebruegge Sylvia , Bauwens Céline L. , Peerani Raheem , Thavandiran Nimalan , Masse Stephane , Sevaptisidis Elias , Nanthakumar Kumar , Woodhouse Kim , Husain Mansoor , Kumacheva Eugenia , Zandstra Peter W.
Published: July 2008

The ability to generate human pluripotent stem cell‐derived cell types at sufficiently high numbers and in a reproducible manner is fundamental for clinical and biopharmaceutical applications. Current experimental methods for the differentiation of pluripotent cells such as human embryonic stem cells (hESC) rely on the generation of heterogeneous aggregates of cells, also called “embryoid bodies” (EBs), in small scale static culture. These protocols are typically (1) not scalable, (2) result in a wide range of EB sizes and (3) expose cells to fluctuations in physicochemical parameters. With the goal of establishing a robust bioprocess we first screened different scalable suspension systems for their ability to support the growth and differentiation of hESCs. Next homogeneity of initial cell aggregates was improved by employing a micro‐printing strategy to generate large numbers of size‐specified hESC aggregates. Finally, these technologies were integrated into a fully controlled bioreactor system and the impact of oxygen concentration was investigated. Our results demonstrate the beneficial effects of stirred bioreactor culture, aggregate size‐control and hypoxia (4% oxygen tension) on both cell growth and cell differentiation towards cardiomyocytes. QRT‐PCR data for markers such as Brachyury, LIM domain homeobox gene Isl‐1, Troponin T and Myosin Light Chain 2v, as well as immunohistochemistry and functional analysis by response to chronotropic agents, documented the impact of these parameters on cardiac differentiation. This study provides an important foundation towards the robust generation of clinically relevant numbers of hESC derived cells. Biotechnol. Bioeng. 2009;102: 493–507. © 2008 Wiley Periodicals, Inc.
Effect of enzyme supplementation at moderate cellulase loadings on initial glucose and xylose release from corn stover solids pretreated by leading technologies
Authors: Kumar Rajeev , Wyman C.E.
Published: July 2008

Moderate loadings of cellulase enzyme supplemented with β‐glucosidase were applied to solids produced by ammonia fiber expansion (AFEX), ammonia recycle (ARP), controlled pH, dilute sulfuric acid, lime, and sulfur dioxide pretreatments to better understand factors that control glucose and xylose release following 24, 48, and 72 h of hydrolysis and define promising routes to reducing enzyme demands. Glucose removal was higher from all pretreatments than from Avicel cellulose at lower enzyme loadings, but sugar release was a bit lower for solids prepared by dilute sulfuric acid in the Sunds system and by controlled pH pretreatment than from Avicel at higher protein loadings. Inhibition by cellobiose was observed to depend on the type of substrate and pretreatment and hydrolysis times, with a corresponding impact of β‐glucosidase supplementation. Furthermore, for the first time, xylobiose and higher xylooligomers were shown to inhibit enzymatic hydrolysis of pure glucan, pure xylan, and pretreated corn stover, and xylose, xylobiose, and xylotriose were shown to have progressively greater effects on hydrolysis rates. Consistent with this, addition of xylanase and β‐xylosidase improved performance significantly. For a combined mass loading of cellulase and β‐glucosidase of 16.1 mg/g original glucan (about 7.5 FPU/g), glucose release from pretreated solids ranged from 50% to75% of the theoretical maximum and was greater for all pretreatments at all protein loadings compared to pure Avicel cellulose except for solids from controlled pH pretreatment and from dilute acid pretreatment by the Sunds pilot unit. The fraction of xylose released from pretreated solids was always less than for glucose, with the upper limit being about 60% of the maximum for ARP and the Sunds dilute acid pretreatments at a very high protein mass loading of 116 mg/g glucan (about 60 FPU). Biotechnol. Bioeng. 2009;102: 457–467. © 2008 Wiley Periodicals, Inc.
Expression of merA, amoA and hao in continuously cultured Nitrosomonas europaea cells exposed to zinc chloride additions
Authors: Radniecki Tyler S. , Semprini Lewis , Dolan Mark E.
Published: July 2008

The effects of ZnCl2 additions on a mercuric reductase, merA, ammonia monooxygenase, amoA, and hydroxylamine (NH2OH) oxidoreductase, hao, gene expression were examined in continuously cultured Nitrosomonas europaea cells. The reactor was operated for 85 days with a 6.9 d hydraulic retention time and with four successive additions of ZnCl2 achieving maximum concentrations from 3 to 90 µM Zn2+. Continuously cultured N. europaea cells were more resistant to Zn2+ inhibition than previously examined batch cultured cells due to the presence of Mg2+ in the growth media, suggesting that Zn2+ enters the cell through Mg2+ import channels. The maximum merA up‐regulation was 45‐fold and expression increased with increases in Zn2+ concentration and decreased as Zn2+ concentrations decreased. Although Zn2+ irreversibly inactivated ammonia oxidation in N. europaea, the addition of either 600 µM CuSO4 or 2250 µM MgSO4 protected N. europaea from ZnCl2 inhibition, indicating a competition between Zn2+ and Cu2+/Mg2+ for uptake and/or AMO active sites. Since ZnCl2 inhibition is irreversible and amoA was up‐regulated at 30 and 90 µM additions, it is hypothesized that de novo synthesis of the AMO enzyme is needed to overcome inhibition. The up‐regulation of merA during exposure to non‐inhibitory Zn2+ levels indicates that merA is an excellent early warning signal for Zn2+ inhibition. Biotechnol. Bioeng. 2009;102: 546–553. © 2008 Wiley Periodicals, Inc.
High‐level cell‐free synthesis yields of proteins containing site‐specific non‐natural amino acids
Authors: Goerke Aaron R. , Swartz James R.
Published: July 2008

We describe an E. coli‐based cell‐free system for the production of proteins with a non‐natural amino acid (nnAA) incorporated site‐specifically (modified protein). The mutant Methanococcus jannaschii tyrosyl‐tRNA synthetase (mTyrRS) and tRNATyr pair were used as orthogonal elements. The mTyrRS experienced proteolysis and modified protein yields improved with higher synthetase addition (200–300 µg/mL). Product yields were also improved by increasing levels of total protein to 20 mg protein/mL and available vesicle surface area to 0.5 m2/mL. This new E. coli‐based cell‐free procedure produced up to 400 µg/mL of eCAT109pAz, 660 µg/mL of eDHFR10pAz, and 210 µg/mL of mDHFR31pAz with p‐azido‐L‐phenylalanine (pAz) incorporated site‐specifically at the amber nonsense codon. O‐methyl‐L‐tyrosine and p‐acetyl‐L‐phenylalanine were incorporated by similar protocols. The desired specificity for incorporation of the nnAA by the cell‐free system was confirmed. Additionally, the modified proteins were enzymatically active and reactive for copper(I)‐catalyzed (3 + 2) cycloadditions (click chemistry). Biotechnol. Bioeng. 2009;102: 400–416. © 2008 Wiley Periodicals, Inc.
Endoscopic ultrasonography-detected low-volume ascites as a predictor of inoperability for oesophagogastric cancer
Authors: Sultan J , Robinson S , Hayes N , Griffin S M , Richardson D L , Preston S R
Published: July 2008

Background

Endoscopic ultrasonography (EUS) can detect low-volume ascites (LVA) not apparent on computed tomography. The aim of this study was to assess the importance of LVA for management of patients with oesophagogastric (OG) cancer.

Methods

Patients with LVA were identified from a prospective OG cancer unit database between January 2002 and January 2006.

Results

Of 1118 patients staged with OG cancer, 802 had EUS. The incidence of LVA was 8·4 per cent overall but fell to 6·5 per cent when those with metastases on computed tomography were excluded. Only patients with gastric and OG junction carcinoma had LVA. Staging laparoscopy in the 21 patients with LVA revealed that 11 (52 per cent) were inoperable. The remainder had laparotomy and complete (R0) resection was possible in only five (50 per cent). In 106 patients who had staging laparoscopy after EUS without LVA, 37 (34·9 per cent) were inoperable and 56 of the remaining 69 (81 per cent) had R0 resection.

Conclusion

The presence of LVA on EUS is uncommon in patients with OG cancer but very important, being indicative of incurable disease in 76 per cent. This information will be helpful in counselling patients regarding management options and the low likelihood of potentially curative treatment.
Systematic review of randomized controlled trials of the effectiveness of biofeedback for pelvic floor dysfunction
Authors: Koh C E , Young C J , Young J M , Solomon M J
Published: July 2008

Background

Pelvic floor dysfunction (PFD) is a type of functional constipation. The effectiveness of biofeedback as a treatment remains unclear.

Methods

A systematic review of all randomized controlled trials evaluating the effectiveness of biofeedback in adults with PFD was carried out. All online databases from 1950 to 2007 were searched. This was supplemented by hand searching references of retrieved articles.

Results

Seven trials fulfilled the inclusion criteria. Three compared biofeedback with non-biofeedback treatments and four compared different biofeedback modalities. Electromyography feedback was most widely utilized. The trials were heterogeneous with varied inclusion criteria, treatment protocols and definitions of success. Most had methodological limitations. Quality of life and psychological morbidity were assessed rarely. Meta-analysis of the studies involving any form of biofeedback compared with any other treatment suggested that biofeedback conferred a sixfold increase in the odds of treatment success (odds ratio 5·861 (95 per cent confidence interval 2·175 to 15·794); random-effects model).

Conclusion

Although biofeedback is the recommended treatment for PFD, high-quality evidence of effectiveness is lacking. Meta-analysis of the available evidence suggests that biofeedback is the best option, but well designed trials that take into account quality of life and psychological morbidity are needed.
A laboratory demonstration illustrating bioseparations using colorful proteins
Authors: Cohen Theodore M. , Rohs Amanda E. , Lefebvre Brian G.
Published: July 2008

A simple in class laboratory illustrating the principles of ion exchange chromatography as a bioseparation technique is described. A protein's isoelectric point as a driving force for ion exchange chromatography is easily demonstrated by using combinations of proteins with natural color or fluorescence, such as DsRed2, enhanced green fluorescent protein (EGFP), and flavodoxin. Simple equipment is required for this separation which can be performed on a desk top. The experiment can stimulate a range of discussion about process parameters that would create a more efficient separation of the proteins, other types of chromatography, and bioseparations in general.
Primordial soup, fool's gold, and spontaneous generation
Authors: McNichol Jesse
Published: July 2008

This study provides a concise background to the biochemical search for the origin of life, as grounded in the field of prebiotic chemistry. It is intended to provide a good summary of competing theories and place them in a broader context, raising questions about weaknesses in any particular theory. This material is relevant for science educators at all levels, and will stimulate interest in a wide variety of students.
Teaching noncovalent interactions using protein molecular evolution
Authors: Fornasari María Silvina , Parisi Gustavo , Echave Julián
Published: July 2008

Noncovalent interactions and physicochemical properties of amino acids are important topics in biochemistry courses. Here, we present a computational laboratory where the capacity of each of the 20 amino acids to maintain different noncovalent interactions are used to investigate the stabilizing forces in a set of proteins coming from organisms adapted to different environments. Using protein sequence and structure information it is possible to evaluate the noncovalent contributions to the stabilization of a given protein fold. As a case study, we use the protein lumazine synthase from three different organisms adapted to live in extreme temperatures: one psychrophilic (optimal growth temperature, 0–20 °C), one mesophilic (optimal growth temperature, 20–50 °C), and one thermophilic (optimal growth temperature, 80–110 °C). We found that this computational laboratory for biochemistry and molecular biology courses enhances student amino acid noncovalent interaction understanding and how these interactions are involved in protein stability.
Design‐based learning for biology
Authors: Ellefson Michelle R. , Brinker Rebecca A. , Vernacchio Vincent J. , Schunn Christian D.
Published: July 2008

Gene expression is a difficult topic for students to learn and comprehend, at least partially because it involves various biochemical structures and processes occurring at the microscopic level. Designer Bacteria, a design‐based learning (DBL) unit for high‐school students, applies principles of DBL to the teaching of gene expression. Throughout the 8‐week unit, students genetically engineer bacteria to meet a need in their own lives. Through a series of investigations, discussions, and design modifications, students learn about the molecular processes and structures involved in gene expression, and how these processes and structures are dependent upon various environmental variables. This article is intended to describe the Designer Bacteria unit and report preliminary results of student progress and performance on pre‐unit and post‐unit assessments. Teacher experiences and student progress indicate that Designer Bacteria successfully taught core aspects of gene expression through DBL.
Pedagogies of engagement in science
Authors: Eberlein Thomas , Kampmeier Jack , Minderhout Vicky , Moog Richard S. , Platt Terry , Varma‐Nelson Pratibha , White Harold B.
Published: July 2008

Problem‐based learning, process‐oriented guided inquiry learning, and peer‐led team learning are student‐centered, active‐learning pedagogies commonly used in science education. The characteristic features of each are compared and contrasted to enable new practitioners to decide which approach or combination of approaches will suit their particular situation.
Problem‐solving test: Targeted gene disruption
Authors: Szeberényi József
Published: July 2008

Terms to be familiar with before you start to solve the test: mutation, vector, plasmid, origin of replication, promoter, introns/exons, open reading frame, transfection, circular and linear DNA, DNA integration, homologous recombination, DNA replication, gene expression, heterozygote, homozygote.
Bridging the educational research‐teaching practice gap
Authors: Anderson Trevor R. , Schönborn Konrad J.
Published: July 2008

The term “conceptual understanding” has been used rather loosely over the years in educational practice, with a tendency to focus on a few aspects of an extremely complex phenomenon. In this first article of a two‐part miniseries on conceptual understanding, we describe the nature of expert (versus novice) knowledge and show how the conceptual understanding of experts is multifaceted in nature requiring competence in a wide range of cognitive skills. We then discuss five such facets of conceptual understanding that require competence in the cognitive skills of memorization, integration, transfer, analogical reasoning, and system thinking. We also argue for the importance of explicitly teaching and assessing such facets of understanding as part of all molecular life science curricula so as to better prepare our students to become experts in the field. Examples of the assessment tasks that can be used to promote the development of multifaceted conceptual understanding in students are presented in Part 2 of this series.
A simple HPLC method for the quantification of mizoribine in human serum: pharmacokinetic applications
Authors: Choi Su Jin , Hur Hye Jung , Lee Sang‐Bong , Choi Mi‐Sun , Kuh Hyo‐Jeong , Shin Young‐Hee , Lee Hwa Jeong
Published: July 2008

A simple high‐performance liquid chromatographic (HPLC) method was developed and validated for the quantification of mizoribine in human serum. After the addition of 70% perchloric acid and 3‐methylxanthine (50 µg/mL, internal standard) to human serum, the samples were mixed and centrifuged at 12,000 rpm (1432g) for 10 min. The supernatant was injected onto a C18 column eluted with a mobile phase of 20 mm Na2HPO4 and methanol (93:7, v/v, pH 3) containing 0.04% octanesulfonic acid and detected utilizing an ultraviolet detector at 275 nm. The linear calibration curve was obtained in the concentration range of 0.1–4.0 µg/mL and the lower limit of quantification was 0.1 µg/mL. This method was validated with selectivity, linearity, precision and accuracy. In addition, the method was successfully applied to estimate the pharmacokinetic parameters of mizoribine in Korean subjects following an oral administration of 100 mg mizoribine (two Bredinine® 50 mg tablets). The maximum serum concentration (Cmax) of 2.30 ± 0.83 µg/mL was reached 2.27 ± 0.66 h after an oral dose. The mean AUC0–12h and the elimination half‐life (t1/2) were 13.2 ± 4.79 µg h/mL and 3.10 ± 0.74 h, respectively. Copyright © 2008 John Wiley & Sons, Ltd.
Development and validation of a HPLC method for simultaneous quantitation of gatifloxacin, sparfloxacin and moxifloxacin using levofloxacin as internal standard in human plasma: application to a clinical pharmacokinetic study
Authors: Srinivas Nimmagadda , Narasu Lakshmi , Shankar B. Prabha , Mullangi Ramesh
Published: July 2008

A highly selective, sensitive and accurate HPLC method has been developed and validated for the estimation of three fluoroquinolones (FQs) viz., gatifloxacin (GFC), sparfloxacin (SFC) and moxifloxacin (MFC) with 500 µL human plasma using levofloxacin (LFC) as an internal standard (IS). The sample preparation involved simple liquid–liquid extraction of GFC, SFC, MFC and IS from human plasma with ethyl acetate. The resolution of peaks was achieved with phosphate buffer (pH 2.5)–acetonitrile (80:20, v/v) at a flow rate of 1 mL/min on a Kromasil C18 column. The total chromatographic run time was 18.0 min and the simultaneous elution of GFC, SFC, MFC and IS occurred at approximately 10.8, 12.8, 17.0 and 6.0 min, respectively. The method proved to be accurate and precise at linearity range of 100–10,000 ng/mL with a correlation coefficient (r) of ≥0.999. The limit of quantitation for each of the FQs studied was 100 ng/mL. The intra‐ and inter‐day precision and accuracy values found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers following oral administration of 400 mg GFC tablet. Copyright © 2008 John Wiley & Sons, Ltd.