bluuebunny/crossref_metadata_2025 huggingface dataset:
Maturation of phagosomes is accompanied by specific patterns of small GTPases
Authors: Meyer Markus , Mayer Thomas , Tiedtke Arno
Published: May 2005

In this study we purified phagosomes of the ciliated protozoan Tetrahymena thermophila to analyze aspects of the maturation pathway of phagocytotic vesicles. Phagosomes were labeled with magnetic microparticles and then purified in high amounts with the help of a permanent magnet. By combining a pulse‐chase labeling protocol with the magnetic separation procedure we were able to isolate phagosomes of defined ages, which represent distinct stages of their maturation pathway. GTP‐overlay assays showed that a set of small GTPases of the ras superfamily is associated with these phagosomes. Phagosomes isolated at different stages of maturation revealed a change in the pattern of the small GTPases. Some small GTPases identified by the GTPase overlay assays could be aligned to India ink stained protein spots in two‐dimensional gels of isolated phagosomes. The results presented here are a first step to identify the members of small GTPases associated with phagosomes during their maturation pathway. Microsequencing of pooled polypeptides by mass‐spectrometric techniques will identify the primary structure of these small GTPases.
A tabulated review of capillary electrophoresis of carbohydrates
Authors: Suzuki Shigeo , Honda Susumu
Published: May 2005

This review summarizes publications on capillary electrophoresis (CE) of carbohydrates, covering almost all hitherto published papers on this topic. It is designed to be a convenient tool for the literature search by providing a comprehensive table. Since CE analysis of carbohydrates is generally complicated due to the structural diversity of carbohydrate species, an attempt is made in this table to supply detailed information on the analyzed form (underivatized or derivatized, type of derivative) and analytical conditions (capillary size, state of the inner wall, composition of the electrophoretic solution, applied voltage, detection method, etc.), for each combination of carbohydrate species to be analyzed. In addition, a brief overview is presented to help in the literature search.
Separation of disaccharides by affinity capillary electrophoresis in lectin‐containing electrophoretic solutions
Authors: Taga Atsushi , Yabusako Yukiko , Kitano Atsuko , Honda Susumu
Published: May 2005

Separation of the 1‐phenyl‐3‐methyl‐5‐pyrazolone (PMP) derivatives of simple disaccharides (maltose, cellobiose, gentiobiose, lactose, and melibiose) by affinity capillary electrophoresis was investigated using lectin‐containing neutral phosphate buffers, filled in a linear polyacrylamide‐coated capillary. When Lens culinaris agglutinin (LCA) was added, the derivatives of glucobioses were retarded with varying magnitudes depending on the amount of LCA and were well separated from each other and from galactosyl glucose under optimized conditions. Addition of Ricinus communis 60 kDa agglutinin (RCA60) to the phosphate buffer gave a different migration profile, in which the derivatives of galactosyl glucoses were more retarded than those of glucobioses. However, addition of either lectin did not accomplish complete separation of the derivatives of all these disaccharides even under optimum conditions. The addition of two kinds of lectins in appropriate proportions improved separation. Thus, the binary system composed of LCA and RCA60, as well as LCA and soybean agglutinin from Glycine max (SBA), gave better separation of these derivatives, giving peak tops for all derivatives.
Mapping and identification of Corynebacterium glutamicum proteins by two‐dimensional gel electrophoresis and microsequencing
Authors: Hermann Thomas , Wersch Gregor , Uhlemann Eva‐Maria , Schmid Roland , Burkovski Andreas
Published: May 2005

As a prerequisite for proteome analyses of Corynebacterium glutamicum separation of the cytoplasm and the membrane fraction was optimized and two‐dimensional (2‐D) gel electrophoresis was established. The resulting 2‐D protein maps revealed over 1000 silver‐stained protein spots separated by isoelectric point and molecular mass for cytoplasmic proteins and approximately 700 silver‐stained spots for proteins of the membrane fraction. Proposing a mean size of 1 kbp per gene the complete C. glutamicum genome of 3 Mbp encodes 3000 different proteins; more than half of these can be located using the maps which are presently available. In this study 10 proteins were identified by N‐terminal microsequencing, namely the 35 kDa antigen, antigen 84, ATP synthase subunits α, γ and δ, cysteine synthase, elongation factor G and Ts, enolase, and rotamase. For seven sequences, corresponding proteins could not be identified. Additionally, two proteins were specifically detected by immunoblotting, a corynebacterial porin and the cytoplasmic protein threonine dehydratase. The methods and 2‐D maps established in this study will be the basis for comparative studies of protein expression and a detailed proteome analysis of C. glutamicum.
On the use of generalized linear models for interpreting climate variability
Authors: Chandler Richard E.
Published: May 2005

Many topical questions in climate research can be reduced to either of two related problems: understanding how various different components of the climate system affect each other, and quantifying changes in the system. This article aims to justify the addition of generalized linear models to the climatologist's toolkit, by demonstrating that they offer an intuitive and flexible approach to such problems. In particular, we provide some suggestions as to how ‘typical’ climatological data structures may be represented within the GLM framework. Recurring themes include methods for space–time data and the need to cope with large datasets. The ideas are illustrated using a dataset of monthly U.S. temperatures. Copyright © 2005 John Wiley & Sons, Ltd.
Assessing the impacts of grazing levels on bird density in woodland habitat: a Bayesian approach using expert opinion
Authors: Kuhnert Petra M. , Martin Tara G. , Mengersen Kerrie , Possingham Hugh P.
Published: May 2005

Many studies on birds focus on the collection of data through an experimental design, suitable for investigation in a classical analysis of variance (ANOVA) framework. Although many findings are confirmed by one or more experts, expert information is rarely used in conjunction with the survey data to enhance the explanatory and predictive power of the model.

We explore this neglected aspect of ecological modelling through a study on Australian woodland birds, focusing on the potential impact of different intensities of commercial cattle grazing on bird density in woodland habitat.

We examine a number of Bayesian hierarchical random effects models, which cater for overdispersion and a high frequency of zeros in the data using WinBUGS and explore the variation between and within different grazing regimes and species. The impact and value of expert information is investigated through the inclusion of priors that reflect the experience of 20 experts in the field of bird responses to disturbance.

Results indicate that expert information moderates the survey data, especially in situations where there are little or no data. When experts agreed, credible intervals for predictions were tightened considerably. When experts failed to agree, results were similar to those evaluated in the absence of expert information. Overall, we found that without expert opinion our knowledge was quite weak. The fact that the survey data is quite consistent, in general, with expert opinion shows that we do know something about birds and grazing and we could learn a lot faster if we used this approach more in ecology, where data are scarce. Copyright © 2005 John Wiley & Sons, Ltd.
Spatiotemporal models in the estimation of area precipitation
Authors: Severino Eduardo , Alpuim Teresa
Published: May 2005

Since area precipitation measurements are difficult to obtain because of the large spatial and time variability of the precipitation field, the development of statistical methods for the optimal combination of weather radar and rain gauge measurements is a matter of great importance. This work presents area rainfall prediction methods based on kriging and cokriging techniques modified to account for the autoregressive temporal structure of the gauge measurement process. Hence, the suggested kriging‐type predictor includes spatial observations both at the present time and at k lagged time instants. Such predictors are called of kth‐order. Cokriging‐type predictors developed in this article include the mixed cokriging and linkage cokriging predictors. Mixed cokriging combines 1st‐order prediction and observations of a co‐process. The linkage cokriging predictor is appropriate to deal with observations from any two different processes with proportional, yet unknown, expected values. This will be the case for the spatiotemporal models adopted in this work to describe rain gauges and radar measurements. Its expression is the same as the simple cokriging, but the usual conditions are replaced by a single linkage condition. Finally, we apply these methods to a storm of mixed type that occurred in 1992, for 99 h, over the Alenquer River basin region located north of Lisbon. Copyright © 2005 John Wiley & Sons, Ltd.
Signature‐forecasting and early outbreak detection system
Authors: Naumova Elena N. , MacNeill Ian B.
Published: May 2005

Daily disease monitoring via a public health surveillance system provides valuable information on population risks. Efficient statistical tools for early detection of rapid changes in the disease incidence are a must for modern surveillance. The need for statistical tools for early detection of outbreaks that are not based on historical information is apparent. A system is discussed for monitoring cases of infections with a view to early detection of outbreaks and to forecasting the extent of detected outbreaks. We propose a set of adaptive algorithms for early outbreak detection that does not rely on extensive historical recording. We also include knowledge of infection disease epidemiology into forecasts. To demonstrate this system we use data from the largest water‐borne outbreak of cryptosporidiosis, which occurred in Milwaukee in 1993. Historical data are smoothed using a loess‐type smoother. Upon receipt of a new datum, the smoothing is updated and estimates are made of the first two derivatives of the smooth curve, and these are used for near‐term forecasting. Recent data and the near‐term forecasts are used to compute a color‐coded warning index, which quantify the level of concern. The algorithms for computing the warning index have been designed to balance Type I errors (false prediction of an epidemic) and Type II errors (failure to correctly predict an epidemic). If the warning index signals a sufficiently high probability of an epidemic, then a forecast of the possible size of the outbreak is made. This longer term forecast is made by fitting a ‘signature’ curve to the available data. The effectiveness of the forecast depends upon the extent to which the signature curve captures the shape of outbreaks of the infection under consideration. Copyright © 2005 John Wiley & Sons, Ltd.
Flame retardant synergism between molybdenum and halogen‐containing compounds in unsaturated polysters
Authors: Skinner G. A. , Parker L. E. , Marshall P. J.
Published: May 2005

Oxygen index results for a series of unsaturated polysters, containing molybdenum oxide and various halogenated compounds, have provided definite evidence for some form of flame retardant synergistic effect between molybdenum and halogen. With the halogenated compounds used, the magnitude of the effect was greater in the presence of bromine but was dependent on the type of compound. When dibromoneopentyl glycol was used as the bromine source, the synergistic effect exhibited by molybdenum oxide was comparable to that shown by antimony oxide. Since molybdenum oxide also acts as a smoke suppressant, it could offer a useful alternative to antimony oxide particularly in the light of probable changes in standards and regulatory control regarding smoke emission.
Inorganic elements in the tracheas of fire fatalities
Authors: Wiletts Paul , Anderson Robert A. , Farmer John G. , Watson Alan A. , Harland W. Arthur , Dale Ian M.
Published: May 2005

Concentrations of elements were determined in tracheal specimeans of fatal fire casualties and of non‐fire fatalities. Elevated concentrations of antimony, bromine, zinc, chromium, cobalt, iron, lead, cadmium and gold found in the group exposed to the fire environment were associated with deposition of soot. The presence of raised concentrations of antimony in fatalities was found to occur in association with increased content of carboxyhaemoglobin in blood and was greatest in fires involving major destruction of property. A relationship between the increased concentration of this element and the use of antimony containing fire‐retardants in construction materials could not be demonstrated.
Action of phosphorus compounds on fire‐retardancy of cellulosic materials: A review
Authors: Kishore K. , Mohandas K.
Published: May 2005

Owing to their low cost phosphorus fire‐retardants find vast application in making fire‐retardant cellulosic compostions. They have been used both as a physical additive as well as part of the polymer structure. Acid forming phosphorus compounds are generally effective in cotton and other cellulosic. Acidic retardants produce char via a dehydration process and this brings about the final fire‐retardancy in phosphate‐containing composition. High efficiency of phosphorus fire retardants in polyurethane foam has also been suggested to be the result of stable char formation. The char affects the flammability in the three following ways: reduction of flammable fuel, insulation by the char and coating by the non‐volatile thermally stable phosphorous acids which screen the hot carbon from the oxygen. Nitrogen‐phosphorus synergism in cellulose in controversial and evidence indicates that it is non existent in polymers.
An appraisal of standard methods for determination of flame spread behaviour of materials
Authors: Bhatnagar Subodh Kumar , Varshney B. S. , Mohanty B.
Published: May 2005

Salient features of the standard apparatuses and the methodology adopted by various countries for determination of flame spread behaviour of materials are analysed and discussed with a view to obtain a perspective of the performance of these apparatuses. This study was undertaken to investigate the possible reasons for anamolies in the results obtained using these apparatuses. A need is established for development of a new technique for direct determination of flame spread rate of materials under steady‐state conditions which has the potential of overcoming the inherent limitations of the existing apparatuses.
Non‐dimensional heat of gasification measurements in the intermediate scale rate of heat release apparatus
Authors: Urbas Joe
Published: May 2005

Wall‐fire spread models require heat of gasification or non‐dimensional heat of gasification to calculate mass loss rate or rate of heat release from the wall material. An intermediate scale rate of heat release apparatus was used to measure all the parameters needed to calculate non‐dimensional heat of gasification for wood materials. An infra‐red pyrometer was used to measure surface temperature. The results of measurements on six wood materials indicate that non‐dimensional heat of gasification, if plotted against mass remaining, does not change significantly with external heat flux, but is material dependent.
Evaluation of polymer combustion and fire retardance by using thermography
Authors: Bertelli G. , Benassi R. , Marchini R. , Camino G. , Costa L. , Luda M. P.
Published: May 2005

The temperature distribution in the condensed and gas phase during combustion of polymer materials in fire tests was measured by means of thermography. It is shown that these data are very useful for mechanistic rationalization of the diagnostically poor, fail‐pass rating of most of these tests. Preliminary data were obtained for polymer materials, fire retarded or not, burning in the widely used Glow Wire and UL 94 tests. It is shown that the relative fire hazard and test rating may depend strongly on the combustion parameter on which the rating is based. Furthermore, detailed data on temperature distribution are helpful in eliminating intrinsic ambiguity of the UL 94 classification in the case of fire‐retarded materials burning with dripping.
Designing information technology products with flame retarded plastics with special emphasis on current flammability safety and environmental concerns
Authors: Wadehra Inder
Published: May 2005

This paper discusses the requirements and challenges associated with the selection of plastic resins for information technology (IT) products. The discussion includes a review of presently used fire retardant systems in plastics in relation to the current flammability safety and environmental concerns and cost pressures as well as suggestions for the development of new flame retardant systems and/or resins for IT applications with optimum performance, safety, cost and environmental attributes. Copyright © 2004 John Wiley & Sons, Ltd.
The new employment relationship versus the mutual investment approach: Implications for human resource management
Authors: Tsui Anne S. , Wu Joshua B.
Published: May 2005

With increasing globalization and hypercompetitive markets, most employers have resorted to headcount management to gain flexibility, remain competitive, and ensure survival. A new employment relationship has emerged. The bond between employer and employee no longer is a long‐term relationship involving loyalty and commitment, but a contractlike economic exchange. The authors take a closer look at this new employee relationship in the context of the more traditional employer‐employee relationship still found in many organizations. The economic value of the new employee relationship may be less attractive than previously perceived. © 2005 Wiley Periodicals, Inc.
Changing mental models: HR's most important task
Authors: Pfeffer Jeffrey
Published: May 2005

In the “managerial knowledge” marketplace, there is little evidence of much diffusion of ideas, innovative business models, or management practices. In organizations not implementing what they know they should be doing based on experience and insight, and in companies not acting on the basis of the best available evidence, one main factor explains the difficulties—the mental models or mind‐sets of senior leaders. How they are formed, what they are about, and a multitude of examples that show how those mind‐sets can be improved are presented here. © 2005 Wiley Periodicals, Inc.
Talentship, talent segmentation, and sustainability: A new HR decision science paradigm for a new strategy definition
Authors: Boudreau John W. , Ramstad Peter M.
Published: May 2005

Two paradigm shifts are discussed here: talentship and sustainability. First, the traditional service‐oriented HR focus must be extended to a “decision science” that enhances decisions about human capital. We call this decision science talentship. It includes talent segmentation, or identifying pivotal talent pools where the quality and/or availability of human capital makes the biggest difference to strategic success. Second, HR and business leaders increasingly define organizational effectiveness beyond traditional financial outcomes to encompass sustainability—achieving success today without compromising the needs of the future. A common strategic human capital decision science can reveal pivotal talent under both traditional and sustainability‐based definitions, and thus uncover important insights about the talent implications of the shifting definition of strategic success. © 2005 Wiley Periodicals, Inc.
HR's new ROI: Return on intangibles
Authors: Ulrich Dave , Smallwood Norm
Published: May 2005

A new human resource ROI has been identified: return on intangibles. Intangibles represent the hidden value of a firm and are becoming an increasingly important portion of a firm's total market capitalization. Six actions that HR professionals can take to create sustainable intangible value are presented in great detail. The emerging focus on intangibles opens the way for HR professionals to more readily link their work to shareholder value. © 2005 Wiley Periodicals, Inc.
Will there really be a labor shortage?
Authors: Cappelli Peter
Published: May 2005

HR challenges have more to do with changes in employment relationships than a shortfall of workers caused by demographic changes. But there are serious problems with forthcoming labor shortages as well, especially now that the baby boomers are beginning to leave the labor market. An immense change in the labor market from many perspectives—economic growth, demographics, labor supply trends, and other metrics—is investigated in this article. © 2005 Wiley Periodicals, Inc.
Managing integration through cooperation
Authors: Gratton Lynda
Published: May 2005

In profiles of Nokia, BP, OgilvyOne, and Royal Bank of Scotland, all high‐performing companies, the author shows how the executive team in each company believed the capacity to work cooperatively across borders was one key to the success of its company. Cooperative working within teams and across internal and external boundaries of a company provides much of the value‐creation opportunities within an organization. © 2005 Wiley Periodicals, Inc.
From business partner to driving business success: The next step in the evolution of HR management
Authors: Cascio Wayne F.
Published: May 2005

In the 1980s, a combination of economic and political factors led to the demand for greater accountability in all functional areas of business, including HR. The massive restructuring of organizations in the 1990s led to the outsourcing of many of HR's basic transactional functions. In order for HR to add value to an organization, it must have several key competencies. “Influence in leadership is all about understanding the business well enough so that what you recommend adds value to the organization,” says one HR vice president. This article shows how this is done through the example of SYSCO Corporation. © 2005 Wiley Periodicals, Inc.
From human resource management to organizational effectiveness
Authors: Lawler Edward E.
Published: May 2005

It is nearly unanimous that HR can and should add more value to corporations. The best way to do this is by being a business partner—by directly improving the performance of the business. This can be accomplished by effective talent management, helping with change management, influencing strategy, and a host of other value‐added activities that impact effectiveness. But HR does not seem able to position itself as a business partner in many cases. To analyze the problem HR has in transitioning to a new role, think of HR as a business and what products it should offer. © 2005 Wiley Periodicals, Inc.
Evolution and revolution in the twenty‐first century: Rules for organizations and managing human resources
Authors: Roberts Russ , Hirsch Paul
Published: May 2005

Changing organizational critical success factors, new expectations for human resources, and the changing roles and capabilities of HR professionals are discussed here. The authors envision that today's top HR job encompasses: enabling capable and courageous leadership; building a very strong and adaptive organizational culture; strengthening organizational productivity and performance; fostering creative innovations, products, and solutions; and building exceptionally high customer loyalty. They explain why and show you how this is done. © 2005 Wiley Periodicals, Inc.
Partner or guardian? HR's challenge in balancing value and values
Authors: Wright Patrick M. , Snell Scott A.
Published: May 2005

Will HR professionals continue on their journey to be business leaders, with full sway and equal influence in organizational decision making, or will they take the shortcut by sacrificing professional ethics and values for a “seat at the table”? The first challenge refers to value creation. Creating value in a global economy requires HR executives to clearly understand the confluence of economic, social, and technological forces that drive industry competition. The second challenge, value delivery, deals with the pressing need for HR to demonstrate its tangible impact by aligning with and driving the issues critical to the business. Finally, living values asks us to rediscover that we are the guardians of our organizations. We guard and preserve strategic capability, people, and values. These challenges are examined and a model is provided for understanding how the competing demands placed on HR create both organizational and professional conflict. © 2005 Wiley Periodicals, Inc.
In pursuit of marketplace agility: Applying precepts of self‐organizing systems to optimize human resource scalability
Authors: Dyer Lee , Ericksen Jeff
Published: May 2005

Presented here is an in‐depth look at human resources scalability—an organization's capacity to get the right numbers of the right types of people to the right places at the right times. The authors pose Guiding Principles to Promote Freedom and Flexibility and Guiding Principles to Promote Discipline and Order, and discuss how HR and other business functions can work together to build a far more flexible and effective workplace. © 2005 Wiley Periodicals, Inc.
The four Cs of the HR profession: Being competent, curious, courageous, and caring about people
Authors: Meisinger Susan R.
Published: May 2005

The Society for Human Resource Management has conducted research to determine how the HR profession is perceived by other, non‐HR executives. The results present a mixed acceptance of HR professionals. The author contends that successful HR professionals today and in the future must be competent, curious, courageous, and caring about people—the four Cs. Each area is broken down into separate components, and examples from various companies' HR roles are used to demonstrate how each quality works to make the HR function an inherent valuable asset. © 2005 Wiley Periodicals, Inc.
Differentiation through people: How can HR move beyond business partner?
Authors: Armstrong Geoff
Published: May 2005

Today's employers must use their resources as efficiently as possible. This includes continuous improvement in products, processes, and productivity, as well as sound procedures for compliance, risk management, and accountability. But customer satisfaction depends on employee discretionary behavior. The HR profession has the lead responsibility to design the policies and practices that elicit behavior leading to sustainable success. This article presents what HR has to do to prove it is a sound business partner, as well as the steps it can take to stimulate the essential employee of today. © 2005 Wiley Periodicals, Inc.
Conclusion: Reality, impact, and professionalism
Authors: Losey Michael , Meisinger Susan R. , Ulrich Dave
Published: May 2005

The authors of each article in this special issue of Human Resource Management offer a personal perspective about the future of HR. In this concluding article, we cull common themes that emerge from these thoughtful syntheses. We have identified eight major trends these observers believe will affect HR in the future. Three themes shape a new reality for HR (what it is), two define the impact of HR (what it means), and three suggest the profile of the future HR professional (who it is). No one can fully characterize the future, but with the help of the authors in this issue, we can begin to envision it. The themes proposed in this article propose that the reality, impact, and professionalism will change as HR evolves. © 2005 Wiley Periodicals, Inc.
The future of HR management: Research needs and directions
Authors: Roehling Mark V. , Boswell Wendy R. , Caligiuri Paula , Feldman Daniel , Graham Mary E. , Guthrie James P. , Morishima Motohiro , Tansky Judith W.
Published: May 2005

The contributors to this special issue provide unique perspectives and insights about the future of human resource management, and many of their ideas present opportunities for future research. Our intent is to focus on identifying and briefly discussing the key needs and directions suggested by these articles. The discussion is organized around four general themes: the HR function and its impact, the roles of HR professionals, the value of HR competencies, and the HR implications of globalization. © 2005 Wiley Periodicals, Inc.
Role of protein kinase C in the monocyte‐derived macrophage‐mediated biodegradation of polycarbonate‐based polyurethanes
Authors: McBane Joanne E. , Santerre J. Paul , Labow Rosalind S.
Published: May 2005

Polycarbonate‐polyurethanes (PCNUs) elicit a foreign body reaction during the initial tissue contact, partly mediated by the respiratory burst in monocytes, during which protein kinase C (PKC) activates NADPH (nicotinamide adenine dinucleotide phosphate) oxidase. Using an in vitro cell system, monocytes were differentiated into monocyte‐derived macrophages (MDMs) and then reseeded onto three PCNUs (HDI431, HDI321, or MDI321): hexane (HDI) or 4,4′‐methylene bis‐phenyl (MDI) diisocyanates synthesized with poly(1,6‐hexyl 1,2‐ethyl carbonate) diol (PCN) and 14C‐labeled butanediol (BD) in the ratios 4:3:1 or 3:2:1 (diisocyanate/PCN/BD). MDM‐mediated degradation was assessed by radiolabel release in the presence of a PKC activator (phorbol myristate acetate), inhibitor (H7), and a catalase/peroxidase inhibitor (NaN3). Activating PKC decreased biodegradation and esterase activity in MDMs on HDI431 and HDI321 but not MDI321, whereas H7 and NaN3 inhibited the MDM degradation of MDI321 only. Pretreatment of the PCNUs with H2O2 inhibited esterase‐mediated radiolabel release from HDI431 and HDI321 but stimulated radiolabel release from MDI321. The difference in the effect of H2O2 on the HDI versus MDI PCNUs contributes to explaining the effect of PKC activation on material degradation. Understanding the mechanism by which this pathway is linked to PCNU chemistry may assist in designing materials with tailored biodegradation rates. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Direct measurement of interactions between adsorbed vitronectin layers: The influence of ionic strength and pH
Authors: Zhang Hailong , Bremmell Kristen E. , Smart Roger St. C.
Published: May 2005

Vitronectin (Vn) is an adhesive protein in the plasma serum and plays an important role in cell attachment, spreading, and proliferation. The interactions between protein bovine vitronectin layers adsorbed onto a silica probe and a mica surface have been investigated with the use of atomic force microscopy (AFM). Adsorption of vitronectin was confirmed by XPS surface analysis. The force‐separation curves and pull‐off forces were measured as a function of ionic strength and solution pH. The pull‐off force (adhesion force) decreased as the salt concentration increased, which suggests that some binding domains of this protein may associate with the ionic species and reduce its binding ability. Discrete jumps, or discontinuities, in the separation force curve were observed to extend to a maximum of 300 nm, evidence that the protein molecules bridge between the surfaces. As a function of pH, the adhesion force on separation of the protein‐coated surfaces showed a maximum at pH 5 (i.e.p. of vitronectin), decreasing in magnitude at lower and higher pH values. At pH 5, the approaching curves illustrated a jump‐in force; whereas for pH values away from 5, the approaching force curves were repulsive. Correlation of the interaction forces with Vn conformational changes in different pH environments, directly visualized with the use of AFM imaging, was developed. In its i.e.p. region, the Vn molecular conformation appeared to be dense and compact. Significantly, at wounds/injured sites the pH is low (approximately 5) which this study discovered to facilitate adsorption and formation of vitronectin aggregates, known to trigger their subsequent biological functions. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Fibrinogen and von Willebrand's factor adsorption are both required for platelet adhesion from sheared suspensions to polyethylene preadsorbed with blood plasma
Authors: Kwak Dean , Wu Yuguang , Horbett Thomas A.
Published: May 2005

Previous studies showed that platelet adhesion to biomaterials from static suspensions was greatly increased by the adsorption of even very small amounts (<5 ng/cm2) of fibrinogen (Fg). In this study, the sensitivity of platelet adhesion to Fg was reexamined by measuring platelet adhesion under flow conditions. The role of adsorbed von Willebrand's factor (vWf) was also studied. Polyethylene (PE) tubing was preadsorbed with Fg, vWf, vWf‐deficient plasma, and Fg‐deficient plasma or serum with added Fg, and Fg adsorption measured with 125I Fg. Platelets in a red blood cell suspension were passed through the tubes at either low (50 s−1) or high (500 or 1000 s−1) shear rates and adhesion measured with an improved LDH assay. Adhesion from flowing suspensions measured after preadsorption with afibrinogenemic plasma or serum was very low, but increased greatly with addition of Fg. Less than 10 ng/cm2 of adsorbed Fg was enough to greatly enhance platelet adhesion. Adhesion at high shear was also strongly affected by vWf, as platelet adhesion at 500 s−1 to PE preadsorbed with vWf‐deficient plasma decreased by more than tenfold compared to adhesion at 50 s−1, but platelet adhesion to PE preadsorbed with normal plasma increased about eightfold when shear rate was increased. The results show that very low amounts of adsorbed Fg are able to support platelet adhesion under shear flow. However, adsorbed vWf also appears to play an important cofactor role in platelet adhesion to biomaterials, as its presence greatly augments platelet adhesion under high shear. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Biocompatible oligochitosans as cationic modifiers of alginate/Ca microcapsules
Authors: Orive G. , Bartkowiak A. , Lisiecki S. , De Castro M. , Hernández R. M. , Gascòn A. R. , Pedraz J. L.
Published: May 2005

In the past, it has been proven that by properly adjusting the molecular mass of the oligochitosan samples, it is possible to optimize the formation of rigid, biocompatible capsules with semipermeable membranes under physiological conditions. In this study, the feasibility of four oligochitosan samples, with varying molar masses (Mn in range 3–5 kDa), as biocompatible coatings of alginate/Ca capsules was investigated. By selection of appropriate depolymerization and purification methods we obtained oligochitosan samples that appeared to be noncytotoxic for C2C12 myoblasts and did not influence the mammalian cell metabolism especially in relative short time during the process of capsule formation. Furthermore, oligochitosans can be used as a tool to reduce the membrane cut‐off of the alginate capsules. However, such reduction, as well as mechanical resistance of formed microcapsules, depend on MM of the cationic polysaccharide and the chemical composition of the alginate (mannuronic/guluronic acid ratio). Here, we address that the use of low molar mass chitosan (< 5000 g/mol) permits the formation of mechanical stable capsules at physiological pH, which represents a strong advantage over other chitosan‐based chemistries. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Controlled release of EGF and bFGF from dextran hydrogels in vitro and in vivo
Authors: Doǧan Alper K. , Gümüşderelioǧlu Menemşe , Aksöz Erol
Published: May 2005

In the present study, dextran‐epichlorohydrin hydrogels were employed as carriers for the controlled release of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). The hydrogels were synthesized from 50% (by weight) monomeric cross‐linker, epichlorohydrin, containing dextran mixtures by intermolecular side‐chain reaction of dextran‐hydroxyl groups with epichlorohydrin‐epoxy groups. The hydrogel disks of 3‐mm diameter and 1.5‐mm thickness have a high swelling capacity (EWC = 650%) and enough mechanical stability for the studies in vivo. Impregnation of EGF and bFGF into the dried hydrogels was carried out by use of phosphate buffered saline solution (PBS, pH =7.4) containing 0.5 μg mL−1 EGF and 0.1 μg mL−1 bFGF, respectively. The in vitro release of growth factors was detected by fluorescence spectroscopy. The prolonged release of EGF is continued up to the 14th day, in comparison with a 26‐day release of bFGF. The in vivo studies were realized with subcutaneously implanted hydrogels in Wistar albino rats. The rate of neovascularization was analyzed statistically using one‐way analysis of significance with EGF and bFGF incorporated hydrogels. In conclusion, dextran‐epichlorohydrin hydrogels were shown to be an alternative delivery system for the release of growth factors. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Poly(D,L‐lactide) coating is capable of enhancing osseous integration of Schanz screws in the absence of infection
Authors: Partale K. , Klein P. , Schell H. , Schmidmaier G. , Wildemann B. , Bail H. , Schiller R. , Bragulla H. , Duda G.N.
Published: May 2005

Pin loosening is a major complication in external fixation. Biological and mechanical conditions play an important role in the maintenance and enhancement of the implant–bone interface in fracture fixation. It is thought that biodegradable coatings may be capable of preventing pin track infection and pin loosening. The goal of this study was therefore to analyze the influence of a biodegradeable coating on the osseous integration of Schanz' screws during fracture treatment. Standardized osteotomies (3‐mm fracture gap) of the right tibiae were performed on 16 sheep and stabilized by an AO mono‐lateral external fixator. Additional, mechanically less loaded Schanz' screws were also mounted. All screws were randomly coated with biodegradable poly(D,L‐lactide). The sheep were sacrificed after 9 weeks. All screws were removed and rolled on blood agar plates for microbiological analysis. Histological sections of the pin tracks were histochemically and morphometrically analyzed. Clinically, no signs of severe infection were visible. Microbiological analysis revealed 14.8% colonization by Staphylococcus aureus in the coated and 29% in the uncoated screws. Histomorphometry of the bone surrounding the Schanz' screws revealed that significantly more osseous integration had occurred on poly(D,L‐lactide)‐coated screws in the absence of bacterial colonization. Significantly more bone remodeling and a higher osteoclastic activity was seen near the screw–bone interface in the uncoated screw group. Up to a threefold increase in new bone formation and more severe remodeling was observed around the screw entry compared to the pin exit in all groups. Loaded screws showed significantly more callus formation around the exit sites than their less loaded counterparts. In the present study, poly(D,L‐lactide) coating of Schanz' screws was found to enhance osseous integration in the absence of bacterial colonization in sheep by causing less cortical remodeling and less osteoclastic activity in the cortices compared to uncoated screws. Additionally, the coating appeared to reduce the instances of pin track infections. Mechanical loading showed an adverse effect on bone formation and remodeling. It has been shown that both biological and mechanical factors play an important role in the maintenance of osseous integrity of the pin–bone interface. Poly(D,L‐lactide) coating of Schanz' screws does not prevent osseous destruction and severe bacterial colonization along the pin tracts, but can improve osseous integration of Schanz' screws in the absence of infection. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Vascular graft infections: In vitro and in vivo investigations of a new vascular graft with long‐term protection
Authors: Ueberrueck Torsten , Zippel Roland , Tautenhahn Joerg , Gastinger Ingo , Lippert Hans , Wahlers Thorsten
Published: May 2005

We investigated a polyester vascular prosthesis (PET) coated with elemental silver (SC). Measurement of silver release over a period of 52 weeks by means of inductively coupled plasma atomic emission spectrometry of PET with (PET‐G) and without (PET‐N) gelatine impregnation revealed a silver release on the first day of 1.2 ± 0.2μg (PET‐N) and 1.2 ± 0.1 μg (PET‐G) (calculated for 1 g of prosthesis); from the 90th day onward, it was between 0.22 ± 0.14μg (PET‐N) and 0.18 ± 0.12 μg (PET‐G) per day. The prostheses were incubated with Staphylococcus aureus (S.a.), Staphylococcus epidermidis (S.e.), or Escherichia coli (E.c.) to investigate in vitro antibacterial efficacy. After 6 h of incubation, no colony‐forming units were to be seen for any of the bacterial suspensions for PET with SC (p < 0.001). To investigate in vivo antibacterial efficacy, PET‐G rings with and without SC contaminated with S.a., S.e., or E.c. were implanted in 18 albino rabbits and examined 7 days after agar culture for 48 h. The silver coating was associated with a significant reduction in bacterial growth (S.a., p = 0.001; S.e., p < 0.005; E.c., p < 0.001). The silver‐coated prosthesis, with and without gelatine impregnation, had a significantly antibacterial effect with continuous release of silver. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Manufacture of porous polymer nerve conduits through a lyophilizing and wire‐heating process
Authors: Huang Yi‐Cheng , Huang Yi‐You , Huang Chun‐Chieh , Liu Hwa‐Chang
Published: May 2005

We have developed a method for nerve tissue regeneration using longitudinally oriented channels within biodegradable polymers created by a combined lyophilizing and wire‐heating process. This type of cell‐adhesive scaffold provides increased area to support and guide extending axons subsequent to nerve injury. Utilizing NiCr wires as mandrels to create channels in scaffold increased safety, effectiveness, and reproducibility. The scaffolds tested were made from different biodegradable polymers, chitosan and poly(D,L‐lactide‐co‐glycolide) (PLGA), because of their availability, ease of processing, low inflammatory response, and approval by the FDA. According to our experimental results, the high permeability and the characteristic porous structure of chitosan proved to be a better material for nerve guidance than PLGA. The scanning electron micrographs revealed that the scaffolds were consistent along the longitudinal axis with channels being distributed evenly throughout the scaffolds. There was no evidence to suggest merging or splitting of individual channels. The diameter of the channels was about 100 μm, similar to the 115 μm diameter of the NiCr wire. Regulating the size and quantity of the NiCr wires allow us to control the number and the diameter of the channels. Furthermore, the neutralizing processes significantly influenced the porous structure of chitosan scaffolds. Using weak base (NaHCO3 1M) to neutralize chitosan scaffolds made the porous structure more uniform. The innovative method of using NiCr wires as mandrels could be easily tailored to other polymer and solvent systems. The high permeability and the characteristic porous structure of chitosan made it a superior material for nerve tissue engineering. These scaffolds could be useful for guiding regeneration of the peripheral nerve or spinal cord after a transection injury. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Novel intramedullary plug with sliding mechanism used in revision total knee arthroplasty
Authors: Fujita H. , Kitaori T. , Iida H. , Shimizu K. , Hiroshima Y. , Kawanabe K. , Nakamura T.
Published: May 2005

A novel intramedullary plug with sliding mechanism has been developed and evaluated clinically in the settings of revision total knee arthroplasty (TKA). The new plug consists of a pair of specially designed components. Each component is shaped like an obliquely cut cylinder. Postoperative plain radiographs of 8 arthroplasties that include 7 stemmed femoral components and 6 stemmed tibial components (total 13 regions) were examined. No radiolucent line between the cement and the cortical bone was observed. Plugging was complete in 11 regions. No migration of the plug was observed. Slight leak of the cement was observed in 2 of 7 femoral components, but not found in tibial components. Our study demonstrated the efficacy of the plug in occluding the femoral and tibial canal completely in 11 out of 13 regions in revision TKAs. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
The large‐scale separation of fluids from fibrous pulps
Authors: Pirie N. W.
Published: May 2005

Most of the free fluid can generally be expressed from fibrous pulps in a few seconds at 50 lb/in2 if the layer of pulp is kept thinner than 1 in. after it has been pressed, and if the fluid is allowed to run away freely. The need for this time and the frictional properties of many pulps are serious obstacles to the design of any strictly continuous press. Roller presses do not allow enough time, screw expellers create too much friction, continuous centrifuges and some other arrangements are intricate and vulnerable.

An intermittent but automatic press which avoids these defects is described. In this the material on a perforated conveyor is pressed by a ram and then moved forward as the ram lifts. One such machine has already been made. An outline is given of the principles on which an improved design will depend.
Development of Streptomyces aureofaciens in submerged culture
Authors: Doskočil J. , Hošťálek Z. , Kašparová J. , Zajíček J. , Herold M.
Published: May 2005

During the biosynthetic production of chlortetracycline on a medium with sucrose, soy meal, corn steep extract, sodium chloride, ammonium sulphate, calcium carbonate and beet molasses, the amount of nucleic acids synthesized by the culture and the maximum respiration of the culture is determined by the amount of inorganic phosphate in the original medium. Chlortetracycline production does not start until all the inorganic phosphate has been consumed. The adverse influence of increased amounts of inorganic phosphate upon production of chlortetracycline is more apparent in flasks on a shaking machine than in agitated and aerated fermentation tanks with higher oxygen transfer numbers.
Surface culture in the mass growth of bacteria
Authors: Porter F. E. , Nack H.
Published: May 2005

The present study was conducted to determine the feasibility of growing bacteria in quantity on solid media in closed vessels. Five techniques were investigated in the laboratory, including growth on agar, growth on packing in beds, growth on solids in a fluidized bed, growth in foamed medium, and growth on semipermeable membranes. Data obtained from the laboratory experiments were used to scale up these techniques on paper and compare the projected plants with a conventional submerged fermentation production. All the techniques compared unfavourably with submerged culture on the basis of plant and operating costs, operating complexity, equipment complexity, and safety. One technique of surface culture, growth on semipermeable membranes, appears to offer a decided advantage over submerged culture, in that the cell product can be recovered directly as a paste. Further work on this technique is recommended.