bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of thrombomodulin release and endothelial cell injury by neutrophil‐derived proteases and oxygen radicals
Authors: Boehme Michael W. J. , Galle Peter , Stremmel Wolfgang
Published: March 2003

Thrombomodulin is a transmembranous glycoprotein of endothelial cells. In vitro it is a marker of endothelial cell injury. In vivo the levels of serum thrombomodulin are regarded as a parameter of activity in vasculitides. The latter are pathophysiologically determined by neutrophil‐derived inflammation and endothelial cell injury caused by secretion of proteases and hydrogen peroxide. It was the objective of this study to determine whether thrombomodulin is only a late marker of advanced endothelial cell injury or whether it indicates also earlier stages of cell alterations. Over 24 hr endothelial cell cultures were incubated with hydrogen peroxide or the neutrophil proteases proteinase‐3, elastase and cathepsin G. The time‐dependent increase of thrombomodulin in the supernatant was determined by enzyme‐linked immunosorbent assay and immunoblot. In addition the viability (eosin, tetrazolium dye assay), detachment (crystal‐violet assay), and apoptosis (4′,6‐diamine‐2′‐phenylindole‐dihydrochloride assay) of the respective endothelial cells were determined for adherent and non‐adherent cells. A rapid thrombomodulin increase was found under all experimental conditions. The additional immunoblotting analysis showed the pattern of proteolytic cleavage caused by the protease reactivity. In case of hydrogen peroxide the thrombomodulin increase was closely correlated with the loss of cell viability and lysis. The incubation of endothelial cells with the different proteases resulted in a time‐dependent detachment of primarily viable cells. In addition to cell necrosis apoptotic cell death was found in the subgroup of detached endothelial cells after prolonged incubation over 24 hr with proteinase‐3 (23%), elastase (31%), and cathepsin G (19%). In contrast, still adhering cells did not show any signs of necrosis or apoptosis. In summary these studies confirm in vitro that soluble thrombomodulin is not only a parameter of advanced endothelial cell destruction itself but also in addition an early marker of initial endothelial cell membrane changes induced by neutrophil derived proteases and oxygen radicals.
The haemopoietic growth factor, Flt3L, alters the immune response induced by transcutaneous immunization
Authors: Baca‐Estrada Maria E. , Ewen Catherine , Mahony Donna , Babiuk Lorne A. , Wilkie Darryl , Foldvari Marianna
Published: March 2003

Topical application of antigen induces antigen‐specific humoral and cellular immune responses. In this study we examined whether expansion of dendritic cells (DC) by Flt3 ligand (Flt3L) treatment influences the induction of immune responses following transcutaneous immunization. Mice were treated intraperitoneally with Flt3L or phosphate‐buffered saline (PBS) and immunized transcutaneously with hen egg lysozyme (HEL). Flt3L‐treated mice developed lower HEL‐specific cellular and humoral immune responses than PBS‐treated mice. However, in the presence of cholera toxin (CT), a potent adjuvant for mucosal and transcutaneous immunization, Flt3L‐treated mice developed significantly higher cellular and humoral immune responses to HEL when compared to PBS‐treated mice. We assessed whether the immunomodulatory effects of CT were a result of activation of epidermal dendritic cells (Langerhans' cells; LC). Our results indicate that within 8–12 hr of topical application of CT, epidermal LC cells lose their dendritic morphology and become rounder in appearance. In addition, we observed enhanced expression of major histocompatibility complex (MHC) class II, and of adhesion molecules CD11c and intracellular adhesion molecule‐1 (ICAM‐1). Our observations support the concept that the state of activation of DC in the skin is central to the regulation of immune responses. This information is relevant to the design of effective transcutaneous vaccination strategies.
Flavoxobin, a serine protease from Trimeresurus flavoviridis (habu snake) venom, independently cleaves Arg726‐Ser727 of human C3 and acts as a novel, heterologous C3 convertase
Authors: Yamamoto Chieko , Tsuru Daisuke , Oda‐Ueda Naoko , Ohno Motonori , Hattori Shosaku , Kim Sung‐Teh
Published: March 2003

We have recently shown that crude Trimeresurus flavoviridis (habu snake) venom has a strong capability for activating the human alternative complement system. To identify the active component, the crude venom was fractionated and purified by serial chromatography using Sephadex G‐100, CM‐cellulose C‐52, diethylaminoethyl‐Toyopearl 650M, and Butyl‐Toyopearl, and the active fractions were evaluated by the C3a‐releasing and soluble membrane attack complex‐forming activities. Two peak fractions with the highest activities were detected after gel filtration and ion exchange chromatography, and the first fraction was purified to homogeneity. The homogeneous protein was examined for its N‐terminal amino acid sequence by Edman degradation. The determined sequence of 25 amino acids completely coincided with that of a previously reported serine protease with coagulant activity, flavoxobin, purified from the same snake venom. To elucidate the molecular mechanism of the complement activation, the reactive products of the mixture of the purified human C3 and flavoxobin were examined by sodium dodecyl sulphate–polyacrylamide gel electrophoresis. The digesting pattern revealed that flavoxobin cleaves the α chain of the C3 molecule into two fragments. The N‐terminal amino acid sequences for the remnant fragments of C3 disclosed that flavoxobin severs the human C3 at the Arg726‐Ser727 site to form C3b and C3a the way C3bBb, the human alternative C3 convertase, does. In conclusion, flavoxobin acts as a novel, heterologous C3 convertase that independently cleaves human C3 and kick‐starts the complement cascade.
G1/S cell cycle arrest provoked in human T cells by antibody to CD26
Authors: Ohnuma Kei , Ishii Tomonori , Iwata Satoshi , Hosono Osamu , Kawasaki Hiroshi , Uchiyama Masahiko , Tanaka Hirotoshi , Yamochi Tadanori , Dang Nam H. , Morimoto Chikao
Published: March 2003

CD26 is T cell costimulatory molecule with dipeptidyl peptidase IV (DPPIV) enzyme activity located in its extracellular region. The expression of CD26 is enhanced after activation of T cells, while it is preferentially expressed on a subset of CD4+ memory T cells in the resting state. In this paper, we demonstrate that binding of the soluble anti‐CD26 monoclonal antibody (mAb) 1F7 inhibits human T‐cell growth and proliferation in both CD26‐transfected Jurkat T‐cell lines and human T‐cell clones by inducing G1/S arrest, which is associated with enhancement of p21Cip1 expression. This effect depends on the DPPIV enzyme activity of the CD26 molecule. Moreover, we show that expression of p21Cip1 after treatment with the anti‐CD26 mAb 1F7 appears to be induced through activation of extracellular signal‐regulated kinase (ERK) pathway. These data thus suggest that anti‐CD26 treatment may have potential use in the clinical setting involving activated T cell dysregulation, including autoimmune disorders and graft‐vs.‐host disease.
Opposing roles of activator protein‐1 and CCAAT/enhancer binding protein β in the regulation of inducible granulysin gene expression in a human monocytic cell line, THP‐1
Authors: Kida Yutaka , Shimizu Takashi , Kuwano Koichi
Published: March 2003

We previously reported that inducible granulysin gene expression in a human monocytic cell line, THP‐1 is dominantly dependent on transcription factor activator protein‐1 (AP‐1). Here, we further examined the precise regulatory mechanisms underlying granulysin gene expression using THP‐1 cells treated with Acholeplasma laidlawii. Transfection of reporter gene constructs into THP‐1 cells indicated that the presence of a positive regulatory element(s) is located from −329 to −85 base pairs, containing two distinct AP‐1 binding sites and one nuclear factor‐κB (NF‐κB) binding site. Deletion or mutation of the NF‐κB binding site failed to affect inducible promoter activity, whereas deletion or mutation of both the AP‐1 binding sites abrogated the promoter activity. Interestingly, deletion of the putative CCAAT/enhancer binding protein β (C/EBPβ) binding site upstream of the positive regulatory element induced the augmentation of granulysin promoter activity. Electrophoretic mobility shift assays demonstrated that nuclear extract prepared from A. laidlawii‐treated THP‐1 cells generated a specific binding to oligonucleotides, including AP‐1, C/EBPβ, and NF‐κB element. Furthermore, over‐expression of liver‐enriched transcriptional activator protein, a subunit of C/EBPβ, augmented A. laidlawii‐induced granulysin promoter activity, whereas over‐expression of liver‐enriched transcriptional inhibitory protein inhibited the promoter activity. NF‐κB p50 homodimer had no transactivation property, although it bound to the NF‐κB site. These results indicate that AP‐1 and C/EBPβ, but not NF‐κB participate in the regulation of inducible granulysin gene expression in THP‐1 cells. Moreover, the Toll‐like receptor 2‐dependent signalling pathway may be involved in A. laidlawii‐induced transactivation of the granulysin promoter. Thus, these results suggest that the gene expression of granulysin in macrophages would be exquisitely regulated by positive and negative transcription factors when microbial invasion occurs.
B‐cell repertoire specific for an unfolded self‐determinant of mouse lysozyme escape tolerance and dominantly participate in the autoantibody response
Authors: Tsujihata Yoshiyuki , Mizukami Yousuke , Ueda Tadashi , So Takanori , Imoto Taiji
Published: March 2003

We previously found that autoantibodies against mouse lysozyme (ML) were strongly induced in normal BALB/c mice when immunized with mutant ML that has triple mutations rendering the dominant T‐cell epitope of hen egg lysozyme (HEL), HEL 107–116. As T cells specific for HEL 107–116 were primed in these mice, the anti‐ML immunoglobulin G (IgG) responses would be the result of collaborations between autoreactive B cells specific for ML and T cells specific for HEL 107–116. Serum IgG responses against ML were dominantly focused on the ML 14–69 region, indicating that B cells responding to the epitope escape tolerance. In the present study, we prepared several monoclonal antibodies (mAbs) specific for ML 14–69 and examined their antigen specificities in detail, to characterize the nature of the remaining B‐cell repertoire specific for ML. mAbs specific for ML 14–69 interacted weakly with soluble, native ML, but the interactions were strengthened by denaturation of ML. The apparent affinity constants between these mAbs and ML showed an increase, ranging from six‐ to 80‐fold, by denaturation of ML. Therefore, these mAbs were more specific for the denatured determinant than for the determinant in the native structure. These results indicate that a substantial number of autoreactive B cells, specific for the unfolded conformation of ML, escape tolerance and are dominantly involved in the autoantibody response to ML. Our finding provides important information to understand the naturally occurring autoreactive B‐cell repertoire in normal mice.
Respiratory syncytial virus infection and virus‐induced inflammation are modified by contaminants of indoor air
Authors: Foster Serene , Bedford Kirk J. , Gould Melanie E. L. , Coward William R. , Hewitt Colin R. A.
Published: March 2003

The airway epithelium is the first cellular component of the lung to be encountered by the particles and pathogens present in inhaled air. In addition to its role as a physical barrier, the immunological activity of the airway epithelium is an essential part of the pulmonary immune system. This means that the symptoms of lung diseases that involve immunological mechanisms are frequently exacerbated by infection of the airway epithelium with respiratory viruses. The virus‐induced enhancement of immunological activity in infected epithelial cells is well characterized. However, the effects that contaminants of inhaled air have upon the infectivity and replication of respiratory viruses and the inflammation they cause, are comparatively unknown. In this study, we have shown that pre‐exposure of airway epithelial cells to bacterial lipopolysaccharides or a proteolytically active house dust mite allergen, is able to, respectively, inhibit or enhance the level of cellular infection with respiratory syncytial virus and similarly alter virus‐induced expression of the inflammatory chemokine interleukin‐8. These results suggest that respiratory syncytial virus infection and the inflammation caused by respiratory syncytial virus may be modified by the biologically active contaminants of indoor air.
Roles for CD40, B7 and major histocompatibility complex in induction of enhanced immunity by cryptococcal polysaccharide‐pulsed antigen‐presenting cells
Authors: Blackstock Rebecca
Published: March 2003

Immunization of mice with activated antigen‐presenting cells (APC) pulsed ex vivo with cryptococcal capsular polysaccharide, a glucuronoxylomannan (GXM‐APC) results in prolongation of survival and delayed‐type hypersensitivity (DTH) responsiveness following infection with Cryptococcus neoformans (NU‐2). GXM‐APC has both non‐specific and GXM‐specific effects that influence the immune responses that develop in mice after infection with NU‐2. Type 1 cytokine responses are augmented after immunization with APC alone, while GXM must be present for the vaccine to influence survival and DTH reactions. This investigation evaluated the role that major histocompatibility complex (MHC) and co‐stimulatory molecules play in the non‐specific and GXM‐specific responses induced by GXM‐APC. APC from CD40 knockout mice were as effective as wild‐type APC for the induction of non‐specific and GXM‐specific responses. Blocking activity of B7‐1 and B7‐2 by treatment of immunized mice with monoclonal antibodies specific for these molecules just before and for 6 days following GXM‐APC immunization decreased the splenic interferon‐γ response of mice subsequently infected with NU‐2, but only in mice that were treated with both antibodies. These antibody treatments had no effect on DTH reactivity in similarly treated animals. MHC class I molecules were not involved in the antigen non‐specific or GXM‐specific activities of the vaccine. MHC class II molecules were not required for augmentation of type 1 cytokine responses but were needed for induction of the GXM‐specific response that regulates the expression of DTH reactivity. This investigation has shown that an MHC class II‐restricted, GXM‐specific response is responsible for altering DTH responsiveness which is the correlate of immunity in this model.
Knowledge, legitimacy and progress? Requirements as inscriptions in information systems development
Authors: Westrup Christopher
Published: March 2003

Given the importance placed on requirements analysis for success in systems development, this paper seeks to illuminate some of the underlying issues common to requirements techniques. This view is offered as a contrast to frameworks that identify an apparent diversity of requirements techniques, on the one hand, and those that portray differences in requirements techniques based on a progressive improvement of these techniques. The central argument of the paper is that most requirements techniques share common characteristics with inscription devices, by translating problematic organizational situations into agreed representations on paper or on computer. These inscriptions are commonly seen as providing legitimate knowledge of the organization that cannot be shown to be ‘correct’ but which act as resources to resolve tensions in requirements formulation and enable information technologies to be implemented successfully in organizations. A consequence of this argument is that portrayals of progressive improvement in requirements techniques have more rhetorical force than historical accuracy, and this assertion is illustrated by comparing SOP (Study Organization Plan), a 1960s requirements methodology, with ‘state‐of‐the‐art’ object‐oriented analysis. Finally, given the problematic role of requirements techniques as inscription devices, guidance is given to those engaged in requirements analysis that focuses as much on the context of the application of the requirements technique as the requirements technique itself.
The missing link between systems analysts' actions and skills
Authors: Jiang James J. , Klein Gary , Means Tom
Published: March 2003

System analysts approach tasks with different orientations to their actions. Likewise, they exhibit a variety of skills. A study is conducted to explore the links, or similarities, between these orientations and skills. The findings indicate that analysts do indeed have orientations corresponding to their skills. This trait enables information systems management to select project teams appropriate to the development context. The variety of skills and orientations needed for success can be chosen based on one trait. Training of analysts can be targeted more effectively to consider missing skills based on current orientations.
Learning failure in information systems development
Authors: Lyytinen Kalle , Robey Daniel
Published: March 2003

Abstract. Abstract. Information systems development is a high‐risk undertaking, and failures remain common despite advances in development tools and technologies. In this paper, we argue that one reason for this is the collapse of organizational intelligence required to deal with the complexities of systems development. Organizations fail to learn from their experience in systems development because of limits of organizational intelligence, disincentives for learning, organizational designs and educational barriers. Not only have many organizations failed to learn, but they have also learned to fail. Over time they accept and expect poor performance while creating organizational myths that perpetuate short‐term optimization. This paper illustrates learning failure in systems development and recommends tactics for overcoming it.
Impact of the quality of information products on information system users’ job satisfaction: an empirical investigation
Authors: Joshi Kailash , Rai Arun
Published: March 2003

Abstract. In recent years, researchers and practitioners have paid increasing attention to the effects of information systems on work‐related outcomes. The purpose of the reported research is to investigate the influence of information systems on work‐related outcomes. A model is derived from prior research that considers direct effects of quality of information product on job satisfaction along with indirect effects through role conflict and role ambiguity. Results from a field study of 368 users indicated that quality of information product has a positive relationship with job satisfaction. However, role ambiguity and role conflict mediated this relationship. A causal path model identified that quality of information product influenced job satisfaction through role conflict and role ambiguity. Role conflict and role ambiguity fully mediated the relationship between quality of information product and job satisfaction. The results identify the role of information systems in influencing users’ work related outcomes. In view of the importance of job satisfaction in motivating employees, IS designers and researchers should pay greater attention to the need for designing quality systems that not only meet their primary information delivery objectives, but also take into account the task and organizational design issues that may influence the work environment of users.
Dismantling the silos: extracting new value from IT investments in public administration
Authors: Bannister Frank
Published: March 2003

The drive for information technology‐led organizational and operational change in public administration has lagged behind that in the private sector. For good reasons, central public administrations are conservative by nature. Most public administrations are bureaucracies and bureaucracies tend to resist change. Nevertheless the pressure to obtain better value from public administration information technology investments is growing and the debate as to how to achieve this is increasingly important. Part of this debate is concerned with how best to confront the formidable and specific challenges faced by the sector. These include cultural, structural, resource and technical problems as well as a legacy of isolated developments which do not interrelate. The difficulties are compounded by the problems of evaluation generally in public administration – problems which are reflected in the evaluation of public sector information systems. This drive for change is reviewed and discussed in the context of the Irish civil service, in which there is a growing awareness of the strategic importance of breaking down specialized vertical systems and providing an integrated service to the citizen. A new approach to the problem, based on adapting the concept of business objects, is suggested.
Educating reflective systems developers
Authors: Mathiassen Lars , Purao Sandeep
Published: March 2003

Abstract. Systems development research shows that practitioners seldom follow methods and that the competencies required for successful development of computer‐based systems go well beyond those represented in contemporary methods. These insights make us question the role that methods should play in educating would‐be developers. Pedagogical theories, such as situated learning and double‐loop learning, complement these insights. Integrating the two, we argue that students need to complement the simplified accounts that methods express, with reflections on methods‐in‐use and on development practice in general. We present operationalizations of this idea in two quite different academic settings. Based on a retrospective analysis of our experiences in these settings, and a comparison and evaluation of the two approaches, we propose a number of lessons that can be used to improve the education of would‐be developers.
Reliability factors in business software: volatility, requirements and end‐users
Authors: Bowen Paul L , Heales Jon , Vongphakdi Monthira T
Published: March 2003

Abstract. Many business‐oriented software applications are subject to frequent changes in requirements. This paper shows that, ceteris paribus, increases in the volatility of system requirements decrease the reliability of software. Further, systems that exhibit high volatility during the development phase are likely to have lower reliability during their operational phase. In addition to the typically higher volatility of requirements, end‐users who specify the requirements of business‐oriented systems are usually less technically oriented than people who specify the requirements of compilers, radar tracking systems or medical equipment. Hence, the characteristics of software reliability problems for business‐oriented systems are likely to differ significantly from those of more technically oriented systems.
The value of certification: an empirical assessment of the perceptions of end‐users of local area networks
Authors: Cegielski Casey G. , Rebman Carl M. , Reithel Brian J.
Published: March 2003

Abstract. Certification is one criterion that employers seek when hiring network professionals. Many employers assume a certified network professional is better able to manage networked resources than is a non‐certified counterpart. Therefore, employers often offer a monetary premium to attract certified network professionals. By measuring end‐user perceptions, the current study empirically assesses the popular industry assumption that certified network professionals are more adept managers of network resources than those individuals who are not certified network professionals. Analyses of a data derived from 299 end‐users of 11 separate local area networks indicate no statistically significant difference exists between the capabilities of certified network professionals and non‐certified network professionals.
Two‐dimensional gel analysis of midgut proteins of Anopheles stephensi lines with different susceptibility to Plasmodium falciparum infection
Authors: Prévot G. I. , Laurent‐Winter C. , Feldmann A. M. , Rodhain F. , Bourgouin C.
Published: March 2003

Little is known about the composition of the mosquito midgut which plays a central role in the development and subsequent transmission of malaria parasites. As a first step towards the characterization of mosquito midgut molecules involved in the transmission of malaria parasites, we analysed two‐dimensional gel electrophoresis patterns of the midgut proteins of sugar‐fed and blood‐fed Anopheles stephensi lines of different susceptibility to P. falciparum infection. Two lines fully susceptible and one line (Pb3‐9A) of reduced susceptibility were used. In the refractory line ookinetes do develop but are only inefficiently transformed into oocysts (Feldmann & Ponnudurai, 1989). The protein profiles of midguts from all sugar‐fed mosquito lines were similar. However, after blood feeding, the midgut of the fully susceptible lines contained proteins not found in the midgut of line Pb3‐9A. Twenty‐nine such proteins were detected and are candidates for involvement in the interaction between the mosquito midgut and P. falciparum.
Genetic differentiation in the yellow fever virus vector, Aedes simpsoni complex, in Africa: Sequence variation in the ribosomal DNA internal transcribed spacers of anthropophilic and non‐anthropophilic populations
Authors: Mukwaya L. G. , Kayondo J. K. , Crabtree M. B. , Savage H. M. , Biggerstaff B. J. , Miller B. R.
Published: March 2003

Mosquitoes of the Aedes simpsoni complex are important vectors of yellow fever virus in Africa. We examined the ribosomal DNA sequence divergence in the internal transcribed spacer regions (ITS‐1 and ITS‐2) for populations of mosquitoes that were determined to be anthropophilic or non‐anthropophilic in their bloodmeal host preference. A neighbour‐joining tree produced two clades: one contained all of the individual mosquitoes from anthropophilic populations and the other contained all of the individual mosquitoes from non‐anthropophilic populations. There was no segregation of the taxa within each of the two clades based on geographical origin. The data suggest the exisf′tence of two distinct species of Ae. simpsoni s.l. in Uganda that correlates with their host blood‐feeding preference. The current taxonomic status of the complex is discussed in relation to these findings.
Cloning of a catalytic subunit of cAMP‐dependent protein kinase from the honeybee (Apis mellifera) and its localization in the brain
Authors: Eisenhardt D. , Fiala A. , Braun P. , Rosenboom H. , Kress H. , Ebert P. R. , Menzel R.
Published: March 2003

In the honeybee the cAMP‐dependent signal transduction cascade has been implicated in processes underlying learning and memory. The cAMP‐dependent protein kinase (PKA) is the major mediator of cAMP action. To characterize the PKA system in the honeybee brain we cloned a homologue of a PKA catalytic subunit from the honeybee. The deduced amino acid sequence shows 80–94% identity with catalytic subunits of PKA from Drosophila melanogaster, Aplysia californica and mammals. The corresponding gene is predominantly expressed in the mushroom bodies, a structure that is involved in learning and memory processes. However, expression can also be found in the antennal and optic lobes. The level of expression varies within all three neuropiles.
Leveraging genomic databases: from an Aedes albopictus mosquito cell line to the malaria vector Anopheles gambiae via the Drosophila genome project
Authors: Eccleston E. D. , Gerenday Anna , Fallon Ann M.
Published: March 2003

An important justification for genome sequencing efforts is the anticipation that data from model organisms will provide a framework for the more rapid analysis of other, less studied genomes. In this investigation, we sequenced an internal region of 25 amino acids from a 52 kDa protein that was differentially expressed in 20‐hydroxyecdysone‐treated Aedes albopictus cells in culture. Within the GenBank non‐mouse and non‐human expressed sequence tag (EST) database, this ‘Aedes peptide’ uncovered a putative homology to hypothetical translation products from Anopheles gambiae, Caenorhabditis elegans and Drosophila melanogaster. The hypothetical translation product from D. melanogaster, which included 462 amino acids, uncovered five expressed sequence tags (ESTs) from the malaria vector, Anopheles gambiae. When the Anopheles ESTs were aligned against the hypothetical Drosophila protein, we found that in aggregate they covered 324 amino acids, with gaps measuring 19, 30, and 87 amino acids. To approximate the complete amino acid sequence, gaps between translation products from Anopheles ESTs were replaced with corresponding amino acids from Drosophila to arrive at a calculated mass of 51 104 and a pI of 5.84 for the mosquito protein, consistent with the position of the Ae. albopictus protein on two‐dimensional polyacrylamide gels. Finally, tandem mass spectrometry of a tryptic digest of the 52 kDa Ae. albopictus protein revealed 33 peptides with masses within 1 Dalton of those predicted from an in silico digestion of the reconstructed Anophleles protein. In addition to providing the first direct evidence that a hypothetical protein in Drosophila is in fact translated, this analysis provides a general approach for maximizing recovery, from existing databases, of information that can facilitate prioritization of efforts among several candidate proteins.
Transgenic Drosophila reveals a functional in vivo receptor for the Bacillus thuringiensis toxin Cry1Ac1
Authors: Gill Michael , Ellar David
Published: March 2003

The bacterium Bacillus thuringiensis synthesizes toxins (δ‐endotoxins) that are highly specific for insects. Once ingested, the activated form of the toxin binds to a specific receptor(s) located on the midgut epithelial cells, inserts into the membrane causing the formation of leakage pores and eventual death of the susceptible insect larvae. Manduca sexta larvae are highly susceptible to Cry1Ac1, a toxin that is believed to bind M. sexta Aminopeptidase N, a glycoprotein located on the apical membrane. However, the binding data obtained to date only support the interaction of Cry1Ac1 with APN in vitro. To explore the in vivo role of APN, we have utilized the GAL4 enhancer trap technique to drive the expression of M. sexta APN in both midgut and mesodermal tissues of Cry1Ac1 insensitive Drosophila larvae. Transgenic Drosophila fed the toxin were now killed, demonstrating that APN can function as a receptor for Cry1Ac1 in vivo.
External and internal macromorphology in 3D‐reconstructed maxillary molars using computerized X‐ray microtomography
Authors: Bjørndal L. , Carlsen O. , Thuesen G. , Darvann T. , Kreiborg S.
Published: March 2003

Aim The aim of this study was to perform a qualitative analysis of the relationship between the external and internal macromorphology of the root complex and to use fractal dimension analysis to determine the correlation between the shape of the outer surface of the root and the shape of the root canal.

Methodology On the basis of X‐ray computed transaxial microtomography, a qualitative and quantitative analysis of the external and internal macromorphology of the root complex in permanent maxillary molars was performed using well‐defined macromorphological variables and fractal dimension analysis. Five maxillary molars were placed between a microfocus X‐ray tube with a focal spot size of 0.07 mm, a Thomson‐SCF image intensifier, and a CCD camera compromising a detector for the tomograph. Between 100 and 240 tomographic 2D slices were made of each tooth. Assembling slices for 3D volume was carried out with subsequent median noise filtering. Segmentation into enamel, dentine and pulp space was achieved through thresholding followed by morphological filtering. Surface representations were then constructed. A useful visualization of the tooth was created by making the dental hard tissues transparent and the pulp chamber and root‐canal system opaque. On this basis it became possible to assess the relationship between the external and internal macromorphology of the crown and root complex.

Results There was strong agreement between the number, position and cross‐section of the root canals and the number, position and degree of manifestation of the root complex macrostructures. Data from a fractal dimension analysis also showed a high correlation between the shape of the root canals and the corresponding roots.

Conclusions It is suggested that these types of 3D volumes constitute a platform for preclinical training in fundamental endodontic procedures.
Comparison of measurements obtained with hand files or the Canal Leader attached to electronic apex locators: an in vitro study
Authors: Steffen H. , Splieth CH. , Behr K.
Published: March 2003

Aim The aim of the present in‐vitro study was to combine directly the Canal Leader handpiece (SET, Olching, Germany) with the electronic apex locators ROOT ZX (Morita, Kyoto, Japan) and JUSTY (Yoshida, Tokyo, Japan) to find out whether the working length values thus obtained were identical to those resulting from the combination of the same electronic devices with hand files.

Methodology A total of 50 natural extracted teeth with single canals and mature apices were used. A radiograph was used as a control and the distance from the radiographic apex to the tip of the file was measured and compared with the results of the electronic length determination.

Results For both electronic devices the differences amongst the distribution of the measurements were not statistically significant under the specified conditions (P > 0.05), indicating that the measurements with hand files and with the Canal Leader were identical for the majority of the cases.

Conclusions Under the conditions of this study the working length of canals obtained with electronically assisted hand files were similar to those obtained with the electronically assisted mechanical handpiece Canal Leader.
In vitro evaluation of the reliability of the Root ZX electronic apex locator
Authors: Ounsi H. F. , Naaman A.
Published: March 2003

Aim An experimental comparison of the Root ZX apex locator with the real measurement of the root canal length was carried out using a saline gel to simulate the periodontium.

Methodology Lengths were taken when the needle reached the 0.5 mark and the Apex mark on the meter. These measurements were then compared with a calculated reference length representing the real length of the root canal. Reliability was assessed using Student’s t‐test. Precision was assessed using the mean and standard deviation of differences.

Results The Root ZX gave measurements within a range of 0.5 mm in 84.72% of the cases. The intra‐operator and inter‐operator variabilities were not statistically significant (P > 0.05).

Conclusions The Root ZX is not capable of detecting the ‘0.5 mm from the foramen’ position and thus, should only be used to detect the foramen (major diameter).
Root canal anatomy of anterior and premolar teeth in Down’s syndrome
Authors: Kelsen A. E. , Love R. M. , Kieser J. A. , Herbison P.
Published: March 2003

Aim The aim of this study was to examine tooth length and root canal anatomy of 281 anterior and premolar teeth from 66 DS individuals using a standard protocol.

Results The results indicated that root canals in DS are relatively simple and that there is a significant reduction in root and crown length.

Conclusions We propose that these observations are commensurate with the suggestion that trisomy 21 exerts its effect by slowing the mitotic cycle and rate of cell proliferation, resulting in generalized retardation of growth.
A comparison of root fracture resistance using two root canal sealers
Authors: Apicella M. J. , Loushine R. J. , West L. A. , Runyan D. A.
Published: March 2003

Aim The aim of this study was to compare in vitro root fracture resistance following root canal filling with either Ketac‐Endo or Roth's root canal sealer.

Methodology The roots of 40 teeth with single canals were instrumented and placed randomly into four groups of 10 teeth. The prepared canals were obturated with lateral compaction using gutta‐percha and Roth's 801 sealer, lateral compaction and Ketac‐Endo sealer or with a single cone and Ketac‐Endo sealer; the fourth group acted as unfilled controls. The roots were stored for 2 weeks in 100% humidity priorto being mounted in acrylic resin blocks. A steel tipped rod attached to an Instron testing machine was positioned against the canal opening and a slowly increasing force was applied until root fracture occurred. The results were subjected to statistical analysis using Kruskal–Wallis one‐way ANOVA.

Results There were no significant differences between the groups in terms of force required to vertically fracture the roots.

Conclusions Under the conditions of this study, the use of Ketac‐Endo sealer in conjunction with lateral compaction or single‐cone obturation techniques does not increase the fracture resistance of root‐filled teeth.
Development of a method to detect and quantify prostaglandin E2 in pulpal blood from cariously exposed, vital primary molar teeth
Authors: Waterhouse P. J. , Whitworth J. M. , Nunn J. H.
Published: March 2003

Aim The aim of this in vitro study was to detect and quantify an established marker of inflammation, prostaglandin E2 (PGE2), in blood samples harvested from radicular pulp stumps after coronal pulp amputation.

Methodology Harvesting was achieved by a paper strip ‘dip‐stick’ method and the volume of each sample estimated before storage at − 808C. A competitive, plate‐based enzyme immunoassay technique (EIA) was developed for detection and quantification of the inflammatory mediator assumed to be present in bloodsamples. Since this technique had not previously been used to assess pulp blood, steps in the development of harvesting, storage, extraction and validation of this sensitive assay are described.

Results Thirty‐nine single‐blood samples were assayed and yielded detectable amounts of PGE2 ranging from 1.0 to 2641 ng mL − 1.

Conclusions The results of this investigation indicate that the inflammatory mediator, PGE2 can be detected and quantified in small blood samples from pulp stumps. Further development may derive quantitative tests for determining the condition of pulp tissue in primary molar pulp treatment.
Periapical health related to the quality of root canal treatment in a Belgian population
Authors: De Moor R. J. G. , Hommez G. M. G. , De Boever J. G. , Delmé K. I. M. , Martens G. E. I.
Published: March 2003

Aim  The aim of this study was to collect data on the prevalence and technical standard of root canal treatment as well as the prevalence of apical periodontitis in Belgium.

Methodology The panoramic radiographs of 206 Belgian adults attending the Dental School of the University Hospital of Gent were examined for endodontic treatment, periapical conditions and coronal restorations.

Results  Of the 4617 teeth examined, 6.8% were endodontically treated. Periapical radiolucencies were found in 6.6% of all teeth and in 40.4% of the endodontically treated teeth. More than half of the root‐filled teeth (56.7%) were scored inadequate on the basis of a criterion evaluating the level of the root canal filling.

Conclusion  The endodontic treatment need of this Belgian subpopulation was great and the technical standard of root canal treatment disappointing. The findings indicate that there is still a substantial need for postgraduate endodontic education in Belgium and a need for specialists in endodontology.
A primary observation on the preparation and obturation of oval canals
Authors: Wu M‐K. , Wesselink P. R.
Published: March 2003

Aim

The aim of this study was to observe the existence and assess the quality of obturation of uninstrumented recesses in oval canals.

Methodology

The balanced force technique was used in two groups of oval canals in human mandibular incisors. The canals in group 1 were enlarged to conventional sizes, whereas canals in group 2 were enlarged more widely. All canals were obturated with cold laterally condensed gutta‐percha. Two horizontal sections were cut in the apical portion of each filled root. Images of the cross‐sections were scanned and analysed using the KS100 Imaging system.

Results

Uninstrumented recesses appeared in 13 (65%) oval canals. The recesses in five of these 13 canals were obturated without visible voids. The recesses in the other eight canals were either obturated with visible voids or completely unfilled. The percentage of filled area was significantly higher in group 1 than in group 2 (P < 0.05).

Conclusions

Uninstrumented recesses may be left in many oval canals after preparation using the balanced force technique and these recesses may often not be completely obturated with cold laterally condensed gutta‐percha.
Periapical healing of mandibular molars after root‐end sealing with dentine‐bonded composite
Authors: Rud J. , Rud V. , Munksgaard E. C.
Published: March 2003

Aim

The purpose was to present the frequency of periapical healing in first and second/third mandibular molars, after root‐end resections sealed with a dentine‐bonded resin composite.

Methodology

Root‐end sealing of resected mandibular molar roots was made with dentine‐bonded composite (Gluma‐Retroplast) as a cover on the entire slightly hollowed root‐end, in an attempt to prevent leakage.

Results

Out of the 834 roots recalled between 6 months and 12.5 years postoperatively, 92% showed complete apical healing, 1% uncertain healing and 7% exhibited failure. The healing result of 681 first molar roots was not significantly different (P = 0.21) from that of 153 second/third molar roots, and there was no significant difference in healing between mesial and distal roots (P = 0.32 for first molars, P = 0.86 for second/third molars) or amongst six age groups (P = 0.94). In the patient group: 71–89 years, 36 roots showed an average of 97% with complete healing. Out of 25 failures who were retreated surgically, 80% showed complete healing when examined subsequently.

Conclusion

Root‐end sealing of mandibular molars with dentine‐bonded resin composite is a promising technique giving 92% complete healing in cases examined between 6 months and 12 years postoperatively.
Failure of ProFile instruments used with high and low torque motors
Authors: Yared G. M. , Bou Dagher F. E. , Machtou P.
Published: March 2003

Aim

The purpose of this study was to evaluate the failure incidence of ProFile nickel–titanium rotary instruments when used in conjunction with different motors and a specific instrumentation technique.

Methodology

ProFile Ni–Ti rotary instruments (PRI) with 0.06 taper were used in a crown‐down technique. In groups 1, 2 and 3, an air, a high torque and a low torque motor were used, respectively. Each group included 30 canals in extracted human molars. One set of PRI sizes 40–15 was used for each canal; they were sterilized before each case. A 2.5% NaOCl solution was used as an irrigant. The number of deformed and separated instruments was recorded for the various experimental groups.

Results

Instrument separation did not occur in any of the three groups. One and two instruments were deformed when using the air and high torque motors, respectively.

Conclusions

The results indicated no difference between the three motors with respect to the incidence of instrument failure. The results suggest that the use of PRI in a crown‐down manner with air control motors was safe.
The long‐term sealing ability of an epoxy resin root canal sealer used with five gutta percha obturation techniques
Authors: De Moor R. J. G. , Hommez G. M. G.
Published: March 2003

Aim The aim of the present study was to evaluate the long‐term sealing ability (both apical and coronal) of an epoxy resin root canal sealer (AH26) when used with different gutta‐percha obturation techniques.

Methodology Straight single‐rooted teeth with mature apices were divided into 10 groups of 75 teeth and one group of 40 control teeth. Root canals were prepared according to the crown‐down/step‐back technique and using both 2.5% sodium hypochlorite and an EDTA paste. Root canals were obturated using cold lateral condensation, warm vertical condensation and hybrid condensation of gutta‐percha; and with Thermafil and Soft‐Core obturators. AH26 was used as the sealer in all cases. After root canal filling, each group was divided into five individual groups of 15 teeth. The first group of 15 teeth was kept for 1 day, the second for 1 week, the third for 4 months, the fourth for 6 months and the fifth for 12 months at 37°C in vacutainers in 80% relative humidity. The teeth were immersed in India ink for 90 h, each root was split and sectioned longitudinally, and the maximum extent of leakage was measured using a stereomicroscope at ×6 magnification.

Results Leakage occurred whatever filling technique was combined with AH26. The number of teeth with gross leakage increased with time up to 4 months, but did not appear to increase between 6 and 12 months storage. The degree of apical leakage and the number of leaking teeth in the Soft‐Core obturator groups was significantly higher than all four other gutta‐percha obturation techniques. Up to 4 months the degree of coronal leakage and the number of leaking teeth in the Thermafil groups was significantly higher than the other gutta‐percha obturation techniques, except for Soft‐Core. In the Soft‐Core obturator groups the degree of coronal leakage and the number of leaking teeth was significantly higher than the other gutta‐percha obturation techniques, except for Thermafil at all evaluation times.

Conclusion The hybrid gutta‐percha condensation technique was superior to the other four obturation techniques in respect of apical leakage. Coronal leakage was significantly greater during the first 4 months for the Thermafil system as compared to the three condensation techniques; coronal leakage was significantly greater at all time periods for the Soft‐Core system. There were no significant differences between the Thermafil and the Soft‐core system.
Evaluation of smear layer removal by EDTAC and sodium hypochlorite with ultrasonic agitation
Authors: Guerisoli D. M. Z. , Marchesan M. A. , Walmsley A. D. , Lumley P. J. , Pecora J. D.
Published: March 2003

Aim To evaluate smear layer removal by different irrigating solutions under ultrasonic agitation.

Methodology Twenty recently extracted mandibular incisors with a single root canal were divided into four equal groups. Three groups were instrumented using the modified double‐flared technique, the fourth remained unprepared. Each group was irrigated with either distilled water, 1.0% sodium hypochlorite alone or associated with 15% EDTAC between each file size. The final group was not instrumented but irrigated with 1.0% sodium hypochlorite and 15% EDTAC. A size 15 file energised by ultrasound was used with small amplitude filing movements against the canal walls in all groups. The teeth were split longitudinally and the roots measured to provide three sections of the same size (cervical, middle and apical). Samples were examined under the scanning electron microscope and assessed for the amount of smear layer by three independent and calibrated examiners. The scoring system ranged from 1 (no smear layer) to 4 (all areas covered by smear layer). Due to the non‐parametric nature of the data, Friedman’s test was used for statistical analysis.

Results Canal walls were covered with smear layer in the group irrigated with 1% sodium hypochlorite alone and the group irrigated with distilled water. Canals irrigated with 1.0% sodium hypochlorite associated with 15% EDTAC had less smear layer throughout the canal (P < 0.001). There were no statistical differences for the amount of smear layer found on the cervical, middle and apical thirds when each group was analysed separately.

Conclusions Under ultrasonic agitation, sodium hypochlorite associated with EDTAC removed the smear layer from root canal walls, whereas irrigation with distilled water or 1.0% sodium hypochlorite alone did not remove smear layer.