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  • Blackwell Publishing Ltd  (5)
  • Wiley-Blackwell  (2)
  • Munksgaard International Publishers  (1)
  • International Union of Crystallography (IUCr)
  • 2005-2009  (1)
  • 2000-2004  (3)
  • 1985-1989  (4)
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  • 1
    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.
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  • 2
    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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  • 3
    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.
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  • 4
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 1 (1987), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The expression of the Neisseria gonorrhoeae opacity protein (Op, protein II), a major antigenic determinant of the outer membrane, is subject to frequent phase transitions. At least nine expression loci (opaE) are involved in the production of a large number of serologically distinct Op types. Using opa-specific oligonucleotides as probes in genomic blots, we detect Op-related gene sequences (opr) in N. meninglitidis as well as in N. lactamica. DNA sequence analysis of such opr genes derived from N. meninglitidis reveals distinct regions of homology with gonococcal opa E genes. As shown in the immunoblot, the proteins encoded by ops and opr are serologically related. Like the opa E genes, the 5′-coding sequences of the opr genes include a repetitive sequence composed of pentameric CTCTT units. The number of these coding repeat (CR) units is variable. This finding, together with the observation that all opr genes are constitutively transcribed, regardless of the status of protein production, suggests a translational control mechanism identical to that of the opa genes in gonococci. The related structures and control mechanisms of opa and opr genes imply a general significance of their gene products for the pathogenic character of the investigated Neisseria species.
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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.
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  • 7
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structure of TetraphenyldisiloxaneTetraphenyldisiloxane 1 crystallizes at 298 K monoclinically (P21/n; a = 1407.6; b = 610.7; c = 1262.7 pm; β = 95.87° Z = 2) and undergoes a second order phase transition at 200 K, in an almost unchanged structure of triclinic symmetry. At 298 K the molecules are already bent (Si—O—Si = 160°) with static or dynamical disorder of the bridging atom. Both Si—O distances are different (156 or 169 pm), because the shift of the bridging O atom is not perpendicular to the Si—to—Si vector. The reason for this remarkable behavior is not yet clear. According to the vibrational spectra, the Si—O—Si bridge is bent in the crystal but, in CCl4 solution a dynamical oscillation through the linear configuration may occur.
    Notes: Tetraphenyldisiloxan 1 kristallisiert bei 298 K monoklin (P21/n; a = 1407,6 pm; b = 610,7 pm; c = 1262,7 pm; β = 95,87° Z = 2) und durchläuft bei 200 K einen Phasenübergang 2. Ordnung in eine kaum veränderte Struktur trikliner Symmetrie. Bereits bei 298 K liegen in der Struktur gewinkelte Moleküle (Si—O—Si = 160°) mit statischer oder dynamischer Fehlordnung des Brückenatoms vor. Die beiden Abstände Si—O sind verschieden (156 bzw. 169 pm), weil die Auslenkung des Brückenatoms aus der zentralen Lage nicht senkrecht zum Vektor Si—Si erfolgt. Der Grund für dieses merkwürdige Verhalten ist unklar. Die Schwingungsspektren beweisen für den kristallinen Zustand ebenfalls die gewinkelte Struktur, während in CCl4-Lösungen ein dynamisches Durchschwingen durch die gestreckte Konfiguration wahrscheinlich ist.
    Additional Material: 6 Ill.
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Structural Chemistry of Phosphides and Polyphosphides. 46. Tetrarubidiumhexaphosphide and Tetracesiumhexaphosphide. Preparation, Structure, and Properties of Rb4P6 and Cs4P6Tetrarubidium and tetracesiumhexaphosphide have been prepared quantitatively by reaction of the elements in sealed Nb ampoules at 870 K and 920 K, respectively. Both compounds are black semiconductors (EG ≍ 1.3 - 1.6 eV) and show metallic lustre. Their crystal structures are orthorhombic defect variants M4P6□2 of the hexagonal AlB2 type structure. Characteristic building units are planar isometric P6 rings with bond lengths d(P—P) = 215 and 214 pm, respectively, representing an aromatic 10° system with one double bond, delocalized about six bonds. Thermal decomposition in Ta crucibles yields quantitatively M3P7. The compounds M4P6 disproportionate in ethylendiamine into M3P7, and M3P, as revealed by 31P n.m.r. spectra. In the down field region a singulett (Δ(α-K4P6) = 331; Δ(Rb4P6) = 337; Δ(Cs4P6) = 348) is observed, which can be ascribed to the valence tautomeric hexaphosphene (4). The internal vibrations of the P6 ring have been observed by i.r. and raman-spectra. For Cs4P6 the fundamental vibrations are v(A1g)=356 cm-1 and v(E2g)=507 and 202 cm-1, respectively, and show the same sequence as for benzen. Semiempirical LCAO-MO calculations show, that in the series P6n- with n=2,4, 6 the anion P62- is the most stable one but the unit M2P6-1 becomes more stable as the other isomers by forming the M2[μ-(η6-P6)] complex. Among the isomers of P64- the hexagonal planar 10π system is about 7 eV more stable than the isomeric bicyclo-tetraanion.
    Notes: Tetrarubidium-und Tetracäsiumhexaphosphid werden beim quantitativen Umsatz der Elemente bei 870 K bzw. 920 K in Nb-Ampullen erhalten. Beide Verbindungen sind schwarze Halbleiter (EG ≈ 1,3 - 1,6 eV), die Kristalle zeigen metallischen Glanz. Die Strukturen sind orthorhombische Defektvarianten M4P6□2 der hexagonalen AlB2-Struktur mit planaren isometrischen P6-Ringen als charakteristische Baueinheiten. Die Bindungslänge d(P—P) = 215 bzw. 214 pm entspricht einem aromatischen 10° System mit einer über die sechs Bindungen delokalisierten Doppelbindung. Beim thermischen Abbau entsteht quantitativ M3P7. In Lösungen von Ethylendiamin disproportionieren die Verbindungen M4P6 in M3P7 und M3P. Intermediär treten im Tieffeldbereich von 31P-NMR-Spektren jeweils Singulett-Signale auf (Δ(α-K4P6) = 331; Δ(Rb4P6) = 337; Δ(Cs4P6) = 348), die dem valenztautomeren Hexaphosphen(4) zugeschrieben werden. Die inneren Schwingungen der P6-Ringe wurden aus IR-und Raman-Spektren ermittelt. Für Cs4P6 liegen die Fundamentalschwingungen bei n̈(A1g) = 356 cm-1, n̈(E2g) = 507 bzw. 202 cm-1. Diese Abfolge entspricht derjenigen von Benzol. Mit semiempirischen LCAO-MO Rechnungen wird gezeigt, daß in der Reihe P6n- mit n = 2, 4, 6 zwar das Anion P62- das stabilste ist, daß jedoch mit der Bildung eines M2[m̈-(η6-P6)]-Komplexes die Einheit M2P62- wesentlich stärker stabilisiert wird als die übrigen Isomeren. Unter den Isomeren P64- ist das hexagonal-planare 10°System um 7 eV stabiler als der isomere Bicyclus.
    Additional Material: 9 Ill.
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