bluuebunny/crossref_metadata_2025 huggingface dataset:
Intranasal administration of a synthetic lipopeptide without adjuvant induces systemic immune responses
Authors: BenMohamed Lbachir , Krishnan Radhika , Auge Catherine , Primus James F. , Diamond Don J.
Published: March 2003

Parenteral injection of a lipopeptide containing a human leucocyte antigen (HLA)‐A*0201‐restricted cytotoxic T‐lymphocyte (CTL) epitope from the human cytomegalovirus (HCMV) immunodominant matrix protein pp65 efficiently induces systemic CTL responses in HLA‐A*0201 transgenic mice. In this study, we demonstrate that intranasal (i.n.) administration of this lipopeptide, covalently linked to a universal T helper (Th) epitope (PADRE), also induces potent systemic CTL responses. Immune responses were substantially reduced when the unlipidated peptide analogue was used (P<0·01). The induced CTL were CD8+, major histocompatibility complex (MHC) class I‐restricted and CMV specific. Moreover, i.n. administration of this lipidated peptide elicited both systemic and local mucosal CD4+ T‐cell proliferative responses, as well as antigen‐specific delayed type hypersensitivity (DTH) immune responses. In contrast, mice receiving the unlipidated peptide analogue developed substantially reduced Th or DTH responses (P<0·05). These results highlight the usefulness and potential of lipopeptides delivered via mucosal routes as painless, safe, and non‐invasive vaccines.
Role of antiretroviral regimes in HIV‐1 patients in reducing immune activation
Authors: Jiménez Antonio , Molero Laura , Jiménez Ana , Castañón Susana , Subirá Dolores , De Górgolas Miguel , Fedz‐Guerrero Manuel , García Rosa
Published: March 2003

We assessed whether antiretroviral regimes are able to diminish apoptosis and markers of lymphocyte activation and restore lymphocyte proliferation. T‐cell subset, spontaneous and induced apoptosis, CD95 and soluble Fas antigen and cell proliferation were analysed in 41 human immunodeficiency virus type 1‐positive patients. Twenty‐five were in asymptomatic stage A and 16 were in stage B/C. Thirty‐five received antiretroviral treatment: 18 received two inhibitors of reverse transcriptase and one protease inhibitor and 17 received three inhibitors of reverse transcriptase. Six patients did not receive treatment, for different reasons, but continued to participate in the study. Studies were performed at baseline, 3, 6 and 12 months. Levels of CD4 increased slightly until 6 months of antiretroviral treatment, as a whole, in all the patients treated. Naïve CD4 lymphocytes, as well as memory CD4 lymphocytes, remained constant. Spontaneous apoptosis of lymphocytes, after 72 hr of culture, decreased in all patients treated, but to a much smaller extent than phytohaemagglutinin‐induced apoptosis. In both groups treated, levels of soluble Fas decreased until 6 months of treatment and then increased again. Lymphocyte proliferation reached normal levels after 1 year of treatment. In patients without treatment CD4 cells decreased slowly and no modification in activation markers was found. Antiretroviral regimes decrease immune activation as well as viral load and this deactivation restores lymphocyte proliferation.
Antibody to Cryptococcus neoformans capsular glucuronoxylomannan promotes expression of interleukin‐12Rβ2 subunit on human T cells in vitro through effects mediated by antigen‐presenting cells
Authors: Vecchiarelli Anna , Pietrella Donatella , Bistoni Francesco , Kozel Thomas R. , Casadevall Arturo
Published: March 2003

The results reported herein show that T cells responding to encapsulated Cryptococcus neoformans cells had reduced expression of interleukin‐12 receptor β2 (IL‐12Rβ2) in comparison to those responding to non‐encapsulated cells. This suggested that encapsulation with glucuronoxylomannan (GXM), the principal constituent of the C. neoformans polysaccharide antiphagocytic capsule, inhibited expression of the IL‐12Rβ2 subunit on T cells responding to cryptococcal antigens. Addition of GXM‐binding monoclonal antibody (mAb) overcame this effect by promoting IL‐12Rβ2 expression and by decreasing IL‐1R expression on T cells. This effect may be a consequence of mAb‐induced changes on antigen‐presenting cells (APC) that are closely related to increased phagocytosis. Blocking of phagocytosis with monoiodacetic acid (MIA) precluded up‐regulation of B7 expression on APC and was associated with diminished IL‐12Rβ2 expression on T cells. The observed effects on T cells were interpreted as a consequence of increased APC function due to enhanced phagocytosis. These findings suggest a mechanism by which specific antibody can promote the polarization of the cellular immune response towards a Th1‐like response and thus contribute to an enhanced cellular immune response against C. neoformans.
The strict regulation of lymphocyte migration to splenic white pulp does not involve common homing receptors
Authors: Nolte Martijn A. , Hamann Alf , Kraal Georg , Mebius Reina E.
Published: March 2003

Although the spleen is the largest secondary lymphoid organ, little is known about the regulation of lymphocyte migration towards its different compartments of red and white pulp, in contrast to the well‐studied mechanisms of lymphocyte homing to lymph nodes. Here we show that short‐term trypsin treatment of lymphocytes cleaved off molecules involved in entry into lymph nodes, while homing to the splenic white pulp was unaltered. Prolonged trypsin treatment also abolished the ability of lymphocytes to enter the white pulp. Analysis of affected cell surface molecules and adoptive transfer studies in combination with blocking antibodies revealed that l‐selectin, CD44, PSGL‐1 and the α4 integrins are not required for migration to the white pulp. Although lymphocyte function‐associated antigen‐1 (LFA‐1) is critical for entry into lymph nodes, we show here that in the absence of functional LFA‐1 molecules, lymphocytes can still enter the white pulp, in spite of the high expression of intercellular adhesion molecule‐1 on sinus lining cells in the marginal zone. The data indicate that adhesion molecules involved in lymphocyte homing to lymph nodes are not essential for migration towards the splenic white pulp, but that additional, trypsin‐sensitive, and so far unidentified, molecules are required.
The modulatory effects of prostaglandin‐E on cytokine production by human peripheral blood mononuclear cells are independent of the prostaglandin subtype
Authors: Dooper Maaike M. B. W. , Wassink Lianne , M'Rabet Laura , Graus Yvo M. F.
Published: March 2003

The production of inflammatory mediators, relevant to (auto)immune diseases and chronic inflammatory conditions, can be modulated by dietary intake of n‐3 and n‐6 long chain polyunsaturated fatty acids (PUFAs). It was suggested that these effects are related to the formation of different series of eicosanoids, in particular prostaglandin‐E (PGE). In this study we investigated whether prostaglandin subtypes metabolized from arachidonic acid (PGE2), dihomo‐γ‐linolenic acid (PGE1) or eicosapentaenoic acid (PGE3) have different effects on T‐cell proliferation and cytokine production in vitro. Freshly isolated human peripheral blood mononuclear cells (PBMC) were stimulated with concanavalin A (ConA) or lipopolysaccharide (LPS) in the presence or absence of exogenous PGE1, PGE2 or PGE3. We found that tumour necrosis factor‐α (TNF‐α), interferon‐γ (IFN‐γ) and to a lesser extent interleukin (IL)‐10 production was inhibited by all PGE‐subtypes in ConA‐stimulated PBMC concomitant with unaffected IL‐2 levels. The modulated cytokine production of ConA stimulated cells was independent of T‐cell proliferation. PGE2 and PGE1 moderately stimulated proliferation, while PGE3 inhibited the proliferative response to some extent. In LPS‐stimulated PBMC, TNF‐α production was inhibited by all PGE‐subtypes, whereas IL‐6 remained unaffected and IL‐10 production was increased. Time course experiments on the effects of PGE‐subtypes on cytokine production after ConA or LPS stimulation showed these effects to be time dependent, but indifferent of the prostaglandin subtype added. Overall, the modulatory effects of PGE on cytokine production were irrespective of the subtype. This may implicate that the immunomodulatory effects of PUFAs, with respect to cytokine production, are not caused by a shift in the subtype of PGE.
C‐reactive protein‐mediated phagocytosis and phospholipase D signalling through the high‐affinity receptor for immunoglobulin G (FcγRI)
Authors: Bodman‐Smith Katherine B. , Melendez Alirio J. , Campbell Ian , Harrison Patrick T. , Allen Janet M. , Raynes John G.
Published: March 2003

C‐reactive protein (CRP) is the prototypic acute‐phase protein in man which performs innate immune functions. CRP‐mediated phagocytosis may be indirect, through activation of complement and complement receptors, or direct, through receptors for the Fc portion of immunoglobulin G (IgG; FcγRs) or even a putative CRP‐specific receptor. No strong evidence has been shown to indicate which receptors may be responsible for phagocytosis or signalling responses. Using BIAcore technology, we confirm that CRP binds directly to the extracellular portion of FcγRI with a threefold higher affinity than IgG (KD = 0·81 × 10−9 m). Binding is Ca2+ dependent and is inhibited by IgG1 but not by phosphorylcholine (PC). CRP opsonization (using CRP concentrations within the normal human serum range) of PC‐conjugated sheep erythrocytes increased phagocytosis of these particles by COS‐7 cells transfected with FcγRI‐II chimaera or FcγRI/γ‐chain. Interferon‐γ‐treated U937 cells, which signal through FcγRI to activate phospholipase D (PLD) in response to cross‐linked IgG, were also activated by CRP without any requirement for further cross‐linking. These studies indicate that CRP is capable of binding to and cross‐linking FcγRI thereby resulting in PLD activation and increased phagocytosis. Uptake by FcγRI has been reported to promote various acquired immune responses suggesting that CRP could act in a similar way.
CD20‐mediated apoptosis: signalling through lipid rafts
Authors: Deans Julie P. , Li Haidong , Polyak Maria J.
Published: March 2003

CD20 is an effective target for therapeutic B‐cell depletion with monoclonal antibodies. One proposed mechanism of action is direct cytotoxicity mediated via tyrosine kinase‐dependent signalling pathways activated upon CD20 cross‐linking. The association of CD20 with membrane microdomains known as lipid rafts, enriched in src‐family tyrosine kinases and other signalling effectors, suggests an indirect mechanism of anti‐CD20‐induced apoptosis in which activation of src‐family kinases occurs as a consequence of lipid raft clustering.
Complete analysis of the B‐cell response to a protein antigen, from in vivo germinal centre formation to 3‐D modelling of affinity maturation
Authors: Adams Claire L. , Macleod Megan K. L. , James Milner‐White E. , Aitken Robert , Garside Paul , Stott David I.
Published: March 2003

Somatic hypermutation of immunoglobulin variable region genes occurs within germinal centres (GCs) and is the process responsible for affinity maturation of antibodies during an immune response. Previous studies have focused almost exclusively on the immune response to haptens, which may be unrepresentative of epitopes on protein antigens. In this study, we have exploited a model system that uses transgenic B and CD4+ T cells specific for hen egg lysozyme (HEL) and a chicken ovalbumin peptide, respectively, to investigate a tightly synchronized immune response to protein antigens of widely differing affinities, thus allowing us to track many facets of the development of an antibody response at the antigen‐specific B cell level in an integrated system in vivo. Somatic hypermutation of immunoglobulin variable genes was analysed in clones of transgenic B cells proliferating in individual GCs in response to HEL or the cross‐reactive low‐affinity antigen, duck egg lysozyme (DEL). Molecular modelling of the antibody–antigen interface demonstrates that recurring mutations in the antigen‐binding site, selected in GCs, enhance interactions of the antibody with DEL. The effects of these mutations on affinity maturation are demonstrated by a shift of transgenic serum antibodies towards higher affinity for DEL in DEL‐cOVA immunized mice. The results show that B cells with high affinity antigen receptors can revise their specificity by somatic hypermutation and antigen selection in response to a low‐affinity, cross‐reactive antigen. These observations shed further light on the nature of the immune response to pathogens and autoimmunity and demonstrate the utility of this novel model for studies of the mechanisms of somatic hypermutation.
Training to improve virtual team communication
Authors: Warkentin Merrill , Beranek Peggy M.
Published: March 2003

Abstract. Organizations are utilizing virtual teams, comprising workgroup members who communicate and collaborate with technology, to accomplish tasks. These teams are geographically distributed and communicate via computer‐mediated communication systems (CMCS), and may never or rarely meet face‐to‐face. Relational links among team members have been found to be a significant contributor to the effectiveness of information exchange in the use of CMCS. In most cases, team members receive little or no training to improve the effectiveness of this form of communication. When training is used, it often focuses on software utilization skills, not on interpersonal communication dynamics. This paper discusses the effect of virtual team communication training on group interactions, especially for enhancing these relational links and thereby improving communication and information exchange in virtual teams. It was found that teams that were given appropriate training exhibited improved perceptions of the interaction process over time, specifically with regard to trust, commitment and frank expression between members. Discussion of the role of training on virtual team processes and outcomes is discussed and future research implications are presented.
Striking a balance between trust and control in a virtual organization: a content analysis of open source software case studies
Authors: Gallivan Michael J.
Published: March 2003

Abstract. Many organization theorists have predicted the emergence of the networked or virtual firm as a model for the design of future organizations. Researchers have also emphasized the importance of trust as a necessary condition for ensuring the success of virtual organizations. This paper examines the open source software (OSS) ‘movement’ as an example of a virtual organization and proposes a model that runs contrary to the belief that trust is critical for virtual organizations. Instead, I argue that various control mechanisms can ensure the effective performance of autonomous agents who participate in virtual organizations. Borrowing from the theory of the ‘McDonaldization’ of society, I argue that, given a set of practices to ensure the control, efficiency, predictability and calculability of processes and outcomes in virtual organizations, effective performance may occur in the absence of trust. As support for my argument, I employ content analysis to examine a set of published case studies of OSS projects. My results show that, although that trust is rarely mentioned, ensuring control is an important criterion for effective performance within OSS projects. The case studies feature few references to other dimensions of McDonaldization (efficiency, predictability and calculability), however, and I conclude that the OSS movement relies on many other forms of social control and self‐control, which are often unacknowledged in OSS projects. Through these implicit forms of control, OSS projects are able to secure the cooperation of the autonomous agents that participate in project teams. I conclude by extrapolating from these case studies to other virtual organizations.
An empirical examination of the role of social integration in system development projects
Authors: Aladwani Adel M
Published: March 2003

In spite of the apparent importance of social integration for work collectives within organizations, information systems researchers have so far paid little, if any, attention to evaluating its role in system development projects. The present study tries to contribute to the literature by proposing and testing a model that examines some of the antecedents and consequences of social integration in system development projects. Data collected from system development project leaders working in 84 US organizations were used to test the model. The findings suggest that higher social integration and, consequently, higher system development project performance is best attained when management provides basic support for the work of the project. The results also reveal that the nature of the relationship between social integration and project performance may be contingent upon some other factors. The implications of the findings of this research are discussed.
DNA organization and length polymorphism at the 2L telomeric region of Anopheles gambiae
Authors: Biessmann H. , Kobeski F. , Walter M. F. , Kasravi A. , Roth C. W.
Published: March 2003

The molecular structure of the telomeric region at the left arm of the second chromosome of the mosquito Anopheles gambiae has been determined in the transformed strain G418 that contains a pUChsneo transgene attached at the 2L chromosome end, and in the Pink eye laboratory strain (PE). Both strains contain the same complex satellite positioned distal to a unique region. FIGE mapping of the telomeric region of the PE strain revealed distinct DNA fragment lengths that segregated with individual chromosomes. Genomic DNA fragments were cloned from the 2L telomeric region, which accounted for about half of 2L chromosomes in the PE population. In all three cases studied, long fragments of different middle repetitive sequences were found attached to the distal ends of the 2L satellite. We propose that random fragments of DNA may be occasionally added during recombination between complex satellite repeats at the chromosome ends.
The Bactrocera tryoni homologue of the Drosophila melanogaster sex‐determination gene doublesex
Authors: Shearman D. C. A. , Frommer M.
Published: March 2003

A homologue of the bifunctional sex‐determining gene, doublesex (dsx), has been identified in the tephritid fruit fly, Bactrocera tryoni, and has been found to be expressed in a sex‐specific manner in adult flies. The male‐ and female‐specific cDNAs are identical at their 5′ ends but differ at their 3′ ends and appear to be the products of alternate splicing. The level of identity of the sex‐specific DSX proteins of B. tryoni with the D. melanogaster DSX proteins, across the region corresponding to the DNA binding domain and the oligomerization domains, is greater than 85%. Four sequence motifs which are ten to thirteen bases identical to the TRA/TRA‐2 binding sites (thirteen‐nucleotide repeat sequences) are present in the female‐specific exon of the B. tryoni dsx gene.
Mitochondrial DNA sequence variation among populations and host races of Lambdina fiscellaria (Gn.) (Lepidoptera: Geometridae)
Authors: Sperling F.A.H. , Raske A. G. , Otvos I. S.
Published: March 2003

The hemlock looper, Lambdina fiscellaria (Gn.), is a recurring major forest pest that is widely distributed in North America. Three subspecies (L. f. fiscellaria, L. f. lugubrosa (Hulst) and L. f. somniaria (Hulst)) have been recognized based on larval host or adult pheromone differences, but no consistent morphological differences have been reported. To clarify their taxonomic status, we surveyed mitochondrial DNA (mtDNA) sequence and restriction site variation in two protein coding genes, cytochrome oxidase I and II (COI and COII), in populations across the range of L. fiscellaria. In addition to variation in COI and COII, we found an intergenic spacer region of 20–23 bp located between the tRNA tyrosine gene and the start of COI. Of the 141 speciments of L. fiscellaria assayed, 137 were grouped into two distinct mtDNA lineages, one of which was disproportionately associated with eastern populations and one with western populations. However, single specimens and two populations in eastern Canada had mtDNA resembling that of western populations. Three divergent and rare haplotypes had basal affinities to the two common lineages. The two major lineages of L. fiscellaria were diverged by approximately 2% from each other, as well as from the mtDNA of two outgroup species, L. athasaria (Walker) and L. pellucidaria (G. & R.). The two outgroup species had essentially the same mtDNA and may be conspecific. We interpret the pattern of mtDNA variation within L. fiscellaria as indicating genetic polymorphism within a single species without clear subspecific divisions, rather than evidence of multiple cryptic species.
cDNA sequence, mRNA expression and genomic DNA of trypsinogen from the Indianmeal moth, Plodia interpunctella
Authors: Zhu Y. C. , Oppert B. , Kramer K. J. , McGaughey W. H. , Dowdy A. K.
Published: March 2003

Trypsin‐like enzymes are major insect gut enzymes that digest dietary proteins and proteolytically activate insecticidal proteins produced by the bacterium Bacillus thuringiensis (Bt). Resistance to Bt in a strain of the Indianmeal moth, Plodia interpunctella, was linked to the absence of a major trypsin‐like proteinase (Oppert et al., 1997). In this study, trypsin‐like proteinases, cDNA sequences, mRNA expression levels and genomic DNAs from Bt‐susceptible and ‐resistant strains of the Indianmeal moth were compared. Proteinase activity blots of gut extracts indicated that the susceptible strain had two major trypsin‐like proteinases, whereas the resistant strain had only one. Several trypsinogen‐like cDNA clones were isolated and sequenced from cDNA libraries of both strains using a probe deduced from a conserved sequence for a serine proteinase active site. cDNAs of 852 nucleotides from the susceptible strain and 848 nucleotides from the resistant strain contained an open reading frame of 783 nucleotides which encoded a 261‐amino acid trypsinogen‐like protein. There was a single silent nucleotide difference between the two cDNAs in the open reading frame and the predicted amino acid sequence from the cDNA clones was most similar to sequences of trypsin‐like proteinases from the spruce budworm, Choristoneura fumiferana, and the tobacco hornworm, Manduca sexta. The encoded protein included amino acid sequence motifs of serine proteinase active sites, conserved cysteine residues, and both zymogen activation and signal peptides. Northern blotting analysis showed no major difference between the two strains in mRNA expression in fourth‐instar larvae, indicating that transcription was similar in the strains. Southern blotting analysis revealed that the restriction sites for the trypsinogen genes from the susceptible and resistant strains were different. Based on an enzyme size comparison, the cDNA isolated in this study corresponded to the gene for the smaller of two trypsin‐like proteinases, which is found in both the Bt‐susceptible and ‐resistant strains of the Indianmeal moth. The sequences reported in this paper have been deposited in the GenBank database (accession numbers AF064525 for the RC688 strain and AF064526 for HD198).
Aldehyde oxidase is coamplified with the World's most common Culex mosquito insecticide resistance‐associated esterases
Authors: Hemingway J. , Coleman M. , Paton M. , McCarroll L. , Vaughan A. , DeSilva D.
Published: March 2003

The evolution and spread of insecticide resistance is an important factor in human disease prevention and crop protection. The mosquito Culex quinquefasciatus is the main vector of the disease filariasis and a member of a species complex which is a common biting nuisance worldwide. The common insecticide resistance mechanism in this species involves germline amplification of the esterases estα21 and estβ21. This amplification has arisen once and rapidly spread worldwide. Less common and more variable resistance phenotypes involve coamplification of estα3 and estβ1, or individual amplification of a single estβ1, different alleles of the same estα and estβ gene loci. Estα21 and estβ21 are on the same large fragment of amplified DNA (amplicon) 2.7 kb apart. We have now shown that this amplicon contains another full‐length gene immediately 5′ of estα21 which codes for a molybdenum‐containing hydroxylase, with highest homology to aldehyde oxidase (AO) from other organisms. The full‐length putative AO gene is not present on the estα3/estβ1 or estβ1 amplicons, but multiple truncated 5′ ends of this gene are present around the presumed estα3/estβ1 amplicon breakpoint. Polymerase chain reaction (PCR) analysis of insecticide‐susceptible genomic DNA demonstrated that a different allele of the putative AO gene in its non‐amplified form is immediately 5′ of estα. The ‘AO’ gene on the estα21/estβ21 amplicon is expressed and resistant insects have greater AO activity. This AO activity is sensitive to inhibition by an aldehyde‐containing herbicide and pesticide. This enzyme may confer a selective advantage to these insects in the presence of insecticide, as AO in mammals is believed to be important in the detoxification process of several environmental pollutants.
Development of a Sindbis virus expression system that efficiently expresses green fluorescent protein in midguts of Aedes aegypti following per os infection
Authors: Olson K. E. , Myles K. M. , Seabaugh R. C. , Higgs S. , Carlson J. O. , Beaty B. J.
Published: March 2003

A double subgenomic Sindbis (dsSIN) virus, MRE/3′2 J/GFP, was constructed to efficiently express green fluorescent protein (GFP) in the midgut of Aedes aegypti following per os infection. The MRE/3′2 J/GFP RNA genome contained the nonstructural genes and cis‐acting sequences of the dsSIN virus, TE/3′2 J/GFP, but had the structural genes of MRE16 SIN virus. MRE/3′2 J/GFP virus, unlike TE/3′2 J/GFP virus, efficiently infected mosquitoes orally. At 1–2 days postinfection, GFP was observed as multiple foci of expression on the lumenal side of the midgut. At 10–12 days postinfection, thirteen of fifteen mosquitoes infected with MRE/3′2 J/GFP virus had high levels of GFP expression in the mosquito midgut. The MRE3′2 J dsSIN expression system should be an important tool for efficient gene expression in Ae. aegypti midguts.
Molecular characterization of a prophenoloxidase cDNA from the malaria mosquitoAnopheles stephensi
Authors: Cui L. , Luckhart S. , Rosenberg R.
Published: March 2003

Some refractory anopheline mosquitoes are capable of killingPlasmodium, the causative agent of malaria, by melanotic encapsulation of invading ookinetes. Phenoloxidase (PO) appears to be involved in the formation of melanin and toxic metabolites in the surrounding capsule. A cDNA encodingAnopheles stephensiprophenoloxidase (Ans‐proPO) was isolated from a cDNA library screened with an amplimer produced by reverse transcriptase polymerase chain reaction (RT‐PCR) with degenerate primers designed against conserved proPO sequences. The 2.4‐kb‐long cDNA has a 2058 bp open reading frame encoding Ans‐proPO of 686 amino acids. The deduced amino acid sequence shows significant homology to other insect proPO sequences especially at the two putative copper‐binding domains. InA. stephensi, Ans‐proPO expression was detected in larval, pupal and adult stages. The Ans‐proPO mRNA was detected by RT‐PCR andin situhybridization in haemocytes, fat body and epidermis of adult female mosquitoes. A low level of expression was detected in the ovaries, whereas no expression was detected in the midguts. Semi‐quantitative RT‐PCR analysis of Ans‐proPO mRNA showed that its expression was similar in adult female heads, thoraxes and abdomens. No change in the level of Ans‐proPO expression was found in adult females after blood feeding, bacterial challenge orPlasmodium bergheiinfection. However, elevated PO activity was detected inP. berghei‐infected mosquitoes, suggesting that in non‐selected permissive mosquitoes PO may be involved in limiting parasite infection. Genomic Southern blot and immunoblots suggest the presence of more than one proPO gene in theA. stephensigenome, which is consistent with the findings in other Diptera and Lepidoptera species. The greatest similarity in sequence and expression profile between Ans‐proPO andA. gambiaeproPO6 suggests that they might be homologues. Our results demonstrate that Ans‐proPO is constitutively expressed through different developmental stages and under different physiological conditions, implying that other factors in the proPO activation cascade regulate melanotic encapsulation.
Developing SCAR markers to study predation on Trialeurodes vaporariorum
Authors: Agustí N. , De Vicente M. C. , Gabarra R.
Published: March 2003

DNA markers of Trialeurodes vaporariorum were developed to detect remains of these whitefly in the gut of the predator Dicyphus tamaninii. A 2400‐bp DNA fragment of T. vaporariorum, absent in other closely related prey species and in the predator banding pattern, was identified by random amplified polymorphic DNA (RAPD) analysis. After cloning and sequencing this fragment, two pairs of sequence‐characterized amplified region (SCAR) primers were developed, amplifying single bands of 2100 bp and 310 bp, respectively. Detection of T. vaporariorum DNA in the predator gut was only possible using the primers that amplified the shortest fragment. Specificity tests performed with this pair of primers showed the presence of the 310‐bp band for T. vaporariorum in all stages.
The highly compact structure of the mitochondrial DNA polymerase genomic region ofDrosophila melanogaster: functional and evolutionary implications
Authors: Lefai E. , Fernández‐Moreno M. A. , Kaguni L. S. , Garesse R.
Published: March 2003

The structure of aDrosophila melanogastergenomic region containing five tightly clustered genes has been determined and evaluated with regard to its functional and evolutionary relationships. In addition to the genes encoding the two subunits (α and β) of the DNA polymerase γ holoenzyme, the key enzyme for mitochondrial DNA replication, other genes contained in the cluster may be also involved in the cellular distribution of mitochondria and in the coordination of mitochondrial and nuclear DNA replication. The gene cluster is extremely compact, with very little intergenic space. It contains two bidirectional promoter regions, and particularly notable is the 5′ end overlap detected in two of its genes, an exceptional situation in both prokaryotic and eukaryotic genome organization.
Comparative linkage map development and identification of an autosomal locus for insensitive acetylcholinesterase‐mediated insecticide resistance in Culex tritaeniorhynchus
Authors: Mori A. , Tomita T. , Hidoh O. , Kono Y. , Severson D. W.
Published: March 2003

A comparative linkage map for Culex tritaeniorhynchus was constructed based on restriction fragment length polymorphism markers using cDNAs from Aedes aegypti. Linear orders of marker loci in Cx. tritaeniorhynchus were identical to Culex pipiens wherein chromosomes 2 and 3 reflect whole‐arm rearrangements compared to A. aegypti. However, the sex determination locus in Cx. tritaeniorhynchus maps to chromosome 3, in contrast to Cx. pipiens and Ae. aegypti where it is located on chromosome 1. Our results indicate that insensitive acetylcholinesterase (AChE)‐mediated organophosphate resistance is controlled by a single major gene (AChER) on chromosome 2, while the AChE structural gene (Ace) is located on chromosome 1. No evidence for a second Ace gene was observed, even under very low stringency hybridization conditions.
Analysis of expressed sequence tags from subtracted and unsubtracted Ctenocephalides felis hindgut and Malpighian tubule cDNA libraries
Authors: Gaines P. J. , Brandt K. S. , Eisele A. M. , Wagner W. P. , Bozic C. M. , Wisnewski N.
Published: March 2003

Insect hindgut and Malpighian tubule (HMT) tissues regulate the contents of the haemolymph through the excretion of waste products and the specific reabsorption of nutrients. As such, they perform a role that is essential for survival and may contain molecular targets for insect control strategies. In order to discover genes expressed in the HMT tissues of the cat flea, Ctenocephalides felis, expressed sequence tags (ESTs) were generated from an unsubtracted HMT cDNA library and from a subtracted HMT cDNA library that had been enriched for HMT‐specific cDNAs. A total of 4844 ESTs were analysed from both libraries: 3657 from the subtracted library and 1187 from the unsubtracted library. Of the 1418 distinct ESTs identified from both libraries, 953 had significant similarity to other sequences reported in the GenBank™ database. A comparison of the results from the two libraries confirmed that the percentages of genes likely to be involved with metabolism, cell structure, and digestion were reduced by the subtraction procedure, whereas genes likely to be involved with ion transport were enriched. Analysis of the prevalence of three individual cDNAs in each library revealed that the actin cDNA was reduced in the subtracted library whereas the cDNAs encoding allantoinase and a peritrophin‐like protein were greatly enriched in the subtracted library. Northern blot analysis demonstrated that the actin cDNA was expressed in both the HMT and carcass tissues, whereas the allantoinase and peritrophin‐like cDNAs were detected exclusively in the HMT tissues. In total, 97 distinct ESTs that appear to encode proteins involved with ion transport were analysed. Some of these proteins may be directly involved with diuresis or the specific reabsorption of salts and nutrients, and thus may be potential molecular targets for flea control strategies.
Hidden from the host: Spiroplasma bacteria infecting Drosophila do not cause an immune response, but are suppressed by ectopic immune activation
Authors: Hurst Gregory D. D. , Anbutsu Hisashi , Kutsukake Mayako , Fukatsu Takema
Published: March 2003

Insects and other arthropods have an effective innate immune system that can clear infections with bacteria and other microorganisms. Despite this ability, one group of bacteria, the spiroplasmas, survive unharmed within the haemolymph of a wide range of arthropod hosts. We investigated the interaction between one member of this clade, a relative of Spiroplasma poulsonii, and the immune system of its Drosophila host. Expression of antimicrobial genes in spiroplasma‐infected flies did not differ from wild‐type controls either in the naturally infected state, nor after septic shock. We therefore concluded that spiroplasma infection did not induce an immune response in its host, but that this absence of response was unlikely to be because the bacterium inhibited response. Further experiments revealed immune reactions induced ectopically did reduce parasite titre. We therefore conclude that this bacterium has a novel form of interaction with its host, being hidden from the host immune system, but potentially suppressible by it.
Isolation and characterization of a termite transferrin gene up‐regulated on infection
Authors: Thompson Graham J. , Crozier Y. Ching , Crozier Ross H.
Published: March 2003

PCR‐based subtractive hybridization was used to isolate genes preferentially expressed in a termite (Mastotermes darwiniensis) following exposure to an entomopathogenic fungus. The subtraction procedure yielded a cDNA clone encoding a putative transferrin that, when sequenced to its ends, is the largest (728 amino acids) for any insect transferrin characterized to date. Cysteines and residues comprising putative iron‐binding sites are conserved in both N‐ and C‐terminal lobes, suggesting structural and functional similarity to diferric vertebrate transferrins. A quantitative PCR assay confirmed a significant increase in transferrin expression following infection, suggesting its up‐regulation is part of the innate immune response. However, codon‐based tests for selection among known insect transferrins revealed only a small proportion of codon‐sites positively selected. Thus, unlike certain vertebrate transferrin lineages, no widespread evidence for pathogen‐mediated positive selection was detected at this locus.
Apical limit of root canal instrumentation and obturation, part 2. A histological study
Authors: Ricucci  , Langeland
Published: March 2003

The results of an in vivo histological study involving apical and periapical tissues following root canal therapy after different observation periods demonstrated the most favourable histological conditions when the instrumentation and obturation remained at or short of the apical constriction. This was the case in the presence of vital or necrotic pulps, also when bacteria had penetrated the foramen and were present in the periapical tissues. When the sealer and/or the gutta‐percha was extruded into the periapical tissue, the lateral canals and the apical ramifications, there was always a severe inflammatory reaction including a foreign body reaction despite a clinical absence of pain.
The control of haemorrhage at the operative site during periradicular surgery
Authors: Sauveur G. , Roth F. , Sobel M. , Boucher Y.
Published: March 2003

Clinical technique Effective apical sealing in endodontic surgery requires a dry root‐end cavity toinsert the filling material. A number of procedures for controlling haemorrhage have been described in the literature. An improvement of these techniques is proposed in this paper: by using a mixture of surgical wax and fibres of calcium alginate. This device, easy to place, sterile and non‐toxic, permits placement of a root‐end filling under more favourable conditions.1
Clinical problems associated with unusual cases of talon cusp
Authors: Al‐Omari M. A. O. , Hat F. N. , Darwazeh A. M. G. , Dummer P. M. H.
Published: March 2003

Case report Talon cusp is an uncommon dental anomaly manifested as an accessory cusp‐like structure on the crown of anterior teeth. This report describes two unusual cases of talon cusp. Case 1 showed bilateralanomalous cusps on the palatal aspects of maxillary supernumerary teeth, causing premature contact and tooth impaction. In case 2, a double‐fused talon cusp was projected from the palatal surface of a large geminated central incisor. A talon cusp is not an innocuous defect, as it may provide a substantial diagnostic, treatment planning and procedural challenge. Early diagnosis and management are important to avoid complications.
Unusual case of bilateral talon cusp associated with dens invaginatus
Authors: De Sousa S. M. G. , Tavano S. M. R. , Bramante C. M.
Published: March 2003

de Sousa SMG, Tavano SMR, Bramante CM. Unusual case of bilateral talon cusp associated with dens invaginatus (Clinical article). International Endodontic Journal, 32, 494–498 1999.

Case report This paper presents a rare case of bilateral talon cusp in permanent maxillary central incisors, one on the labial and another on the lingual surface of each tooth. The condition was associated with dens invaginatus in a maxillary permanent lateral

incisor, but no developmental syndrome was identified. The left central incisor required no treatment because the aesthetic appearance was satisfactory and neither occlusal interferences nor caries were present. After careful investigation of the right lateral incisor, a sealant was applied. Root canal treatment was indicated for the right central incisor that had a wide open apex with thin, weak, divergent walls, and an apical radiolucency.
Mechanisms of antimicrobial activity of calcium hydroxide: a critical review
Authors: Siqueira J. F. , Lopes H. P.
Published: March 2003

Literature review The primary function of calcium hydroxide as a routine intracanal medicament is to provide antimicrobial activity. However, the mechanisms of antimicrobial activity of calcium hydroxide are not well known. Physicochemical

properties of this substance may limit its effectiveness in disinfecting the entire root canal system. In addition, calcium hydroxide is not effective against all bacterial species found in root canal infections. Association with other medicaments may enhance the efficacy of the intracanal medication in eliminating residual bacteria in the root canal system.
Cyclic fatigue of ProFile rotary instruments after clinical use
Authors: Yared G. M. , Dagher F. E. Bou , Machtou P.
Published: March 2003

Aim  The purpose of this study was to evaluate cyclic fatigue of .06 ProFile Ni‐Ti rotary instruments after clinical use in molar teeth.

Methodology  In group 1, instruments size 40–15 were used in a crown‐down technique using 2.5% NaOCl as an irrigant. Fifty‐two molars were included and 13 sets of Profile Ni‐Ti rotary instruments were used. Each set of instruments was used in four molars, and was steam autoclaved before each use. Group 2 (10 sets of new ProFile Ni‐Ti rotary instruments) was the control group. Cyclic fatigue was tested by rotating the instruments in a 908 metallic tube until they broke.

Results  One‐way analysis of variance did not show any statistically significant differences amongst the files from both groups regarding cyclic fatigue.

Conclusions  It was concluded that sterilization and clinical use in the presence of NaOCl did not lead to a decrease in the number of rotations to breakage of the files.
The use of 3D computerized reconstruction for the study of coronal microleakage
Authors: Lyroudia K. , Pantelidou O. , Mikrogeorgis G. , Chatzikallinikidis C. , Nikopoulos N. , Pitas I.
Published: March 2003

Aim

The purpose of this study was to evaluate a new method for studying coronal microleakage associated with root‐filled teeth.

Methodology

Twenty human mandibular posterior teeth were prepared chemomechanically with the stepback technique and then divided into two groups of 10 teeth each. The canals were filled using lateral condensation of gutta‐percha points; Roth’s 801 was used as a sealer for the first group, and Ketac‐Endo for the second. After 48 h, the temporary fillings in the access cavities were removed, the roots coated with three layers of nail polish and then the teeth were exposed to artificial saliva for 40 days. Subsequently, the crowns of the teeth were placed into Indian ink for 4 days before the coating was removed and the teeth embedded in a two‐phase polyester resin. Serial cross sections were taken from each specimen using a microtome, and each cross section photographed under a stereoscopic microscope. The photographs of the cross sections were digitized using an image scanner and the contours of the external surface of the teeth, the obturated root canals and the boundaries of dye penetration were followed. Finally, a three‐dimensional surface representation was achieved using the triangulation method.

Results

Although the sample size and the experimental methods were not designed to form valid groups, the results showed that all roots obturated with Ketac‐Endo sealer had dye microleakage, whilst only three teeth of the Roth’s 801 group had dye microleakage.

Conclusions

The 3D reconstruction of dye microleakage proved to be an interesting method and a useful tool for the evaluation of coronal microleakage when using different types of root canal sealers.
Shaping ability of Hero 642 rotary nickel–titanium instruments in simulated root canals: Part 1
Authors: Thompson S. A. , Dummer P. M. H.
Published: March 2003

Aim

To determine the general efficacy and shaping ability of Hero 642 nickel–titanium rotary instruments during the preparation of simulated canals. Part 1 of this two‐part report describes the efficacy of the instruments in terms of three‐dimensional canal form.

Methodology

A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by Hero 642 instruments using a crown‐down preparation sequence. The efficacy of the instruments was assessed in terms of preparation time, instrument failure, canal blockages and loss of canal length. Intra‐canal impressions were taken of the prepared canals in order to assess three‐dimensional canal form.

Results

The mean time for canal preparation was 8.6 min and was influenced significantly (P < 0.05) by canal shape. Two instruments fractured and eight instruments deformed; significant differences were observed between canal shapes (P < 0.05). All of the canals remained patent. Fifteen canals (39.5%) maintained the correct working distance, 15 lost distance and eight canals gained length. Examination of intracanal impressions demonstrated that the majority of canals (79%) had apical stops; canal shape had a significant influence (P < 0.001) on the quality of apical stops. With one exception all canals had smooth canal walls and all of the canals showed good flow characteristics. Taper was poor in 30 canals (79%) and good in eight canals (21%).

Conclusions

Hero 642 rotary nickel–titanium instruments prepared simulated canals rapidly but with a three‐dimensional form that lacked adequate taper.
A ‘one‐bottle’ adhesive system for bonding a fibre post into a root canal: an SEM evaluation of the post–resin interface
Authors: Ferrari M. , Mannocci F.
Published: March 2003

Ferrari M, Mannocci F. A ‘one‐bottle’ adhesive system for bonding a fibre post into a root canal: an SEM evaluation of the post‐resin interface. International Endodontic Journal, 33, 397–400, 2000.

Aim

This report presents a case in which a ‘one‐bottle’ adhesive system was used in combination with proprietary resin cement for bonding a fibre post.

Methodology

The fibre post was placed into the root canal of a fractured root under clinical conditions and then extracted 1 week later. Using scanning electron microscopy, half of the root was evaluated for hybrid layer formation and the other half for assessing resin tags.

Results

The investigation demonstrated that a ‘one‐bottle’ system can infiltrate etched dentine.

Conclusions

The ‘one‐bottle’ system tested in this study can create a mechanical interlocking with root etched dentine under clinical conditions.
Effects of four Ni–Ti preparation techniques on root canal geometry assessed by micro computed tomography
Authors: Peters O. A. , Schönenberger K. , Laib A.
Published: March 2003

Aim The aim of this study was to compare the effects of four preparation techniques on canal volume and surface area using three‐dimensionally reconstructed root canals in extracted human maxillary molars. In addition, µCT data was used to describe morphometric parameters related to the four preparation techniques.

Methodology  A micro computed tomography scanner was used to analyse root canals in extracted maxillary molars. Specimens were scanned before and after canals were prepared using Ni–Ti – K‐Files, Lightspeed instruments, ProFile .04 and GT rotary instruments. Differences in dentine volume removed, canal straightening, the proportion of unchanged area and canal transportation were calculated using specially developed software.

Results Instrumentation of canals increased volume and surface area. Prepared canals were significantly more rounded, had greater diameters and were straighter than unprepared canals. However, all instrumentation techniques left 35% or more of the canals’ surface area unchanged. Whilst there were significant differences between the three canal types investigated, very few differences were found with respect to instrument types.

Conclusions Within the limitations of the µCT system, there were few differences between the four canal instrumentation techniques used. By contrast, a strong impact of variations of canal anatomy was demonstrated. Further studies with 3D‐techniques are required to fully understand the biomechanical aspects of root canal preparation.