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  • Blackwell Publishing Ltd  (9)
  • Wiley-Blackwell  (2)
  • Munksgaard International Publishers  (1)
  • International Union of Crystallography (IUCr)
  • 2005-2009  (1)
  • 2000-2004  (3)
  • 1990-1994  (8)
  • 1
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Variants of Neisseria gonorrhoeae MS11 show distinct colony morphologies because of the expression of a class of surface components called opacity (Opa, PII) proteins. Southern analyses combined with molecular cloning of genomic DNA from a single variant of MS11 has identified 11 opa genes contained in separate loci. These opa genes code for distinct opacity proteins which are distinguishable at their variable domains. The opa gene analyses were also extended to divergent variants of MS11. These studies have shown that, during in vitro and in vivo culture, 10 of the 11 opa genes did not undergo significant change in their primary sequence. However, in these variants, one gene (opaE) underwent non-reciprocat inter-opa recombinations to generate newer Opa variants. Phylogenic analysis of the opa gene sequences suggests that the opa gene family have evolved by a combination of gene duplication, gene replacement and partial inter-opa recombination events.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Toll-like receptor (TLR)-7 agonists represent a new group of immune response modifiers, which include imiquimod and resiquimod (R-848). Topically applied imiquimod is used for the treatment of both external and perianal genital warts, and benign and malignant epithelial lesions. Based on the induction of interferons and other cytokines in vitro and in vivo, regression of epithelial lesions probably depends on induction of both innate and cellular immune responses. As clinical remission is not always associated with inflammation, other mechanisms may also be involved. Using two different assays for detection of apoptosis (TUNEL test and gel analysis of DNA fragmentation), we observed induction of apoptosis by imiquimod in human epithelial cell lines (HeLa S3) and keratinocytes (HaCaT, A431 cells), as well as in mouse fibroblasts (McCoy cells). These findings suggest that the mode of action of imiquimod to eliminate virus-infected, dysplastic or neoplastic epithelial cells may also include the induction of apoptotic processes.
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  • 4
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The long-term success of organ transplantation depends on the prevention of allograft rejection and improvement in quality of life for the patients. This has been achieved through better immunosuppressive regimens with lower dosages and a new generation of immunosuppressive drugs. However, these immunosuppressive agents not only impair the patient's reactivity to the graft, but also to infectious organisms, thereby making them more susceptible to opportunistic pathogens. Because of this, organ transplant recipients are predisposed to epithelial malignancies and infections. The majority of transplant recipients will develop warts induced by human papillomavirus (HPV). Some of these viral warts may present with atypical histological features and may progress into squamous cell carcinomas. The risk for cutaneous cancers after transplantation is much higher than in the immunocompetent population. Current therapies for HPV-associated skin tumours mainly depend on the destruction of affected skin areas. These treatment modalities are of limited efficacy and are usually painful for the patients. A promising novel therapeutic agent is imiquimod, an immune response modifier. Clinical efficacy of imiquimod has been observed for different skin lesions, including viral warts in both immunocompetent and immunosuppressed patients.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Premaligant and malignant epithelial lesions are acknowledged as being the most frequent neoplasia in long-term immunosuppressed patients such as organ-transplant recipients. Paralleling the constant improvement in modern transplant techniques, their incidence increases together with the growing survival time post-transplantation, reaching 40% to 60% after 20 years. Against the background of lifelong immunosuppression, the impact of accepted cancer inducers and promoters such as ultraviolet radiation, oncogenic viruses and individual susceptibility has to be closely scrutinized. Precancerous lesions such as actinic keratoses in transplant patients progress more rapidly into squamous cell carcinomas, showing an increased tendency to metastasize. As it remains impossible to identify and consequently treat those lesions that may progress into invasive carcinoma, the best prophylaxis for nonmelanoma skin cancer in organ-transplant recipients may be the treatment of all existing precancerous lesions. As reduction of the immunosuppressive therapy is rarely practicable, other terms of prophylaxis and treatment, such as immune response modifiers, have to be considered.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Worm infestations may play a role in preventing allergies. There is a lack of epidemiological information from Western countries on the association between worm infestation and eczema.Objective:  To investigate the association between worm infestation and eczema in a proper temporal sequence and under consideration of allergic sensitization.Methods:  Two surveys were performed in East German school children. Questionnaire data included the history of eczema and worm infestation and their time of onset. Specific IgE antibodies to five common aeroallergens were measured and used to define nonatopic and atopic eczema. Logistic regression analyses were performed to control for relevant confounders (age, sex, parental school education and history of allergies). In order to confirm the findings a corresponding conditional regression analysis was applied on cases and controls matched by age and sex.Results:  A total of 4169 children participated (response 75 and 76%) who were, on average, 9.2 years old (47% girls). Overall 17.0% reported a prior worm infestation (Ascaris 44%, Oxyuris 33%) and 18.1% had a history of eczema. Eczema occurred significantly less frequent in children who had a worm infestation (prior to the onset of eczema) compared with children without such a history (8.1%vs 16.5%, ORadj: 0.45, 95% CI: 0.33–0.60). The finding was confirmed by the corresponding matched case–control analysis (ORadj: 0.57, 95% CI: 0.41–0.79). Atopic eczema was affected more by a prior worm infestation (ORadj: 0.31, 95% CI: 0.18–0.56) than the nonatopic eczema (ORadj: 0.58, 95% CI: 0.40–0.84). A total of 29.1% exhibited specific IgE antibodies to at least one aeroallergen. Sensitized children gave significantly less frequent a history of worm infestation (14.2%vs 18.3%, ORadj: 0.74, 95% CI: 0.60–0.92). Stratified analysis revealed that this effect most pronounced for a sensitization to house dust mite.Conclusions:  A worm infestation is associated with a reduced frequency of subsequent eczema, especially the atopic type. Furthermore allergic sensitization, especially to house dust mite, and worm infestation are negatively associated. The data support the concept that a lack of immune-stimulation by parasitic infections contributes to the development of allergies.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Murine T cells and T-cell lines express receptors for the Fc of IgA (FcαR); however, their molecular properties remain to be elucidated. In the present study, we examined three candidate molecules for IgA-binding receptors including FcαR, β-galactosyltransferase (β-GT) and anti-secretory component (SC) reactive proteins (ASCP) expressed on T cells which might participate in the binding of different molecular forms of IgA. T-cell lines derived from CD4+ T cells of mouse Peyer's patches (PP) (designated PPT 4–6and PPT 4–16) and from cloned PP T helper (Th) cell lines (ThHA1#9and #10) bound both monomeric and dimeric IgA (mIgA and dIgA), while the fusion partners (BW 5147 and R 1.1) did not. In contrast, both FcαR+ and FcαR- cell lines bound to high molecular weight polymeric or aggregated IgA (pIgA). All cell lines reacted with a monoclonal anti-β-GT(MoAb) and β-GT enzyme activity was associated with the cell lysates and membrane fractions of all cells tested. The anti-β-GT MoAb stained a 47-kDa band on immunoblots which was identical to that seen with native enzyme. mRNA analysis with β-GT cDNA showed that all cell lines constitutively produced enzyme-specific mRNA. Both FcαR+ T cells and FcαR- control cell lines showed cell surface specific β-GT activity. This is the first study which shows that mouse T cells produce β-GT. However, FcαR and β-GT appear to be separate receptors, because FcαR+ T cells bound mIgA and dIgA, and this treatment did not affect staining with biotinylated anti-β-GT MoAb. Further, preincubation of the FcαR+ cells with anti-β-GT MoAb did not block mIgA binding. However, the anti-β-GT MoAb partially blocked binding of pIgA to both FcαR+ and FcαR- T cells, suggesting that β-GT may be a receptor for pIgA. Others have shown that T cells may bind IgA through a receptor serologically related to SC. We found that antibodies both to human SC and to rat SC specifically bound to both FcαR+ and FcαR- T cells. Further, a 72-kDa band was detected when cell membrane fractions were analysed with these antisera (ASCP) by solid phase immunoisolation technique and immunoblot analysis. The ASCP is not an IgA-binding receptor, since anti-SC did not block either mIgA or pIgA binding. Further, the effects of proteolytic enzymes were different on these three IgA-binding molecule candidates. FcαR and ASCP were shown to be sensitive to pronase proteolytic degradation, but were resistant to trypsin and trypsin/EDTA treatments. In contrast, β-GT was sensitive to both pronase and trypsin treatments. We conclude that multiple IgA receptors are present on mouse T cells, and include those which bind to mIgA or dIgA (FcαR) as well as those which bind to pIgA (β-GT). Further, ASCP is also present on mouse T-cell lines, but its role in IgA binding to T cells remains to be further determined.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A macro-restriction map of the Neisseria gonorrhoeae chromosome was constructed using the enzymes Nhel and Spel. Combinations of one-and two-dimensional electrophoresis of completely or partially digested chromosomal DNA were performed to align the restriction fragments. The chromosome is circular, with an estimated size of 2.33Mb±35kb. A genetic map was derived from the physical map; positions of over 60 defined loci were determined by Southern hybridization.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Phase- and antigenic variation of pilin expression in Neisseria gonorrhoeae is based on the genetic exchange between silent pilin genes (pilS)and the pilin expression locus (pilE). Similarly, the non-piliated L-variants of strain MS11, which show an increased resistance to certain antibiotics, are the result of recombination with the pilElocus. However, this recombination is atypical in that pilE(L) carries a tandem arrangement of a complete pilin gene and additional partial pilin genes under the control of the same pilE promoter. Since the two pilin gene copies are tandemly arranged and are often in the same translational frame, oversized pilin molecules are produced, which do not assemble into pili. The tandem gene copies introduced in a piiE(L)locus originate from silent loci where they are already joint. Upon reversion to the P+ phenotype the L-variants lose one pilin gene copy from the pilE(L) in a process reminiscent of the deletion events that otherwise lead to the formation of the non-revertible and non-piliated Pn mutants of MS11 gonococci. Thus deletion of pilin genes from pHE can be regarded as a third mechanism of pilin variation in gonococci.
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  • 10
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Capsule-deficient mutants of Neisseria meningitidis serogroup B strain B 1940 were constructed by allelic replacement using the plasmids pMF120 and pMF121, which contain the flanking regions of the gene locus for the biosynthesis pathway of the group B meningococcal capsular polysaccharide. Southern blot analysis of chromosomal DNA of the capsule-deficient meningococcal strains confirmed the generation of large deletions in the chromosomal cps gene complex. The same strategy proved useful in constructing meningococcal strains with capsular types A, C., W 135, Y and Z.
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