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101.
IgA antibodies impair resistance against Helicobacter pylori infection: studies on immune evasion in IL-10-deficient mice 总被引:2,自引:0,他引:2
Akhiani AA Stensson A Schön K Lycke NY 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(12):8144-8153
We recently reported that Helicobacter pylori-specific Abs impair the development of gastritis and down-regulate resistance against H. pylori infection. In this study, we asked whether IgA Abs specifically can have an impact on H. pylori colonization and gastric inflammation. To obtain a sensitive model for the study of inflammation we crossed IgA- and IL-10-deficient mice. We found that IL-10(-/-)/IgA(-/-) mice were significantly less colonized than IL-10(-/-)/IgA(+/+) mice, which in turn were less colonized than wild-type (WT) mice. The IL-10(-/-)/IgA(-/-) mice exhibited a 1.2-log reduction in bacterial counts compared with that in IL-10(-/-)/IgA(+/+) mice, suggesting that IgA Abs rather promoted than prevented infection. The reduced colonization in IL-10(-/-)/IgA(-/-) mice was associated with the most severe gastritis observed, albeit all IL-10(-/-) mice demonstrated more severe gastric inflammation than wild-type mice. The gastritis score and the infiltration of CD4(+) T cells into the gastric mucosa were significantly higher in IL-10(-/-)/IgA(-/-) mice than in IL-10(-/-)/IgA(+/+) mice, arguing that IgA Abs counteracted inflammation. Moreover, following oral immunization, IL-10(-/-)/IgA(-/-) mice were significantly better protected against colonization than IL-10(-/-)/IgA(+/+) mice. However, the stronger protection was associated with more severe postimmunization gastritis and gastric infiltration of CD4(+) T cells. There was also a clear increase in complement receptor-expressing cells in IL-10(-/-)/IgA(-/-) mice, though C3b-fragment deposition in the gastric mucosa was comparable between the two. Finally, specific T cell responses to recall Ag demonstrated higher levels of IFN-gamma production in IL-10(-/-)/IgA(-/-) as compared with IL-10(-/-)/IgA(+/+) mice. Thus, it appears that IgA and IL-10 help H. pylori bacteria evade host resistance against infection. 相似文献
102.
Comparative, experimental studies on sediment cores from freshwater andbrackish-marine conditions reveal major differences in the benthic exchangeof phosphate across the sediment-water interface when shifting from anoxicto oxic conditions. The flux of phosphate to the sediment during this shiftwas found to be mediated mainly by scavenging from newly formed colloidalferric oxohydroxide. The capacity of the iron-rich particles to scavengephosphorus depended on the stoichiometric ratio between dissolved iron andphosphorus built up in the supernatant water during reducing conditions. Thefreshwater system was characterized by high iron to phosphorus ratios in thedissolved phase and thus most of the phosphate was incorporated into thecolloidal iron oxohydroxide during the oxygenation. In contrast, the marinesystems reached lower iron to phosphorus ratios during the anoxic period whichresulted in less efficient phosphate scavenging. Consequently, significantamounts of phosphate remained dissolved in the marine systems after the changeto oxic conditions, possibly increasing the proportion of phosphate recycledto the euphotic zone. Manganese showed a consistent redox-dependent behaviourin all the investigated systems, but interacted neither with phosphate norwith iron. 相似文献
103.
104.
The morphology and location of crystals encountered in the mature seeds of Norway spruce, Picea abies (L.) Karst., were examined using light and field emission scanning electron microscopy (FESEM). Crystals of various forms
and sizes were discovered in different regions and tissues of seeds, particularly in the testa and the nucellus. Both solitary
crystals and druses were occasionally enveloped by protrusions of the megaspore membranes or the cuticle of the megagametophyte.
Histological studies and acid solubility tests coupled with analysis using energy dispersive X-ray microanalysis and X-ray
diffraction evinced the crystals as calcium oxalate, but were unable to identify different hydration forms. Calcium oxalate
crystals were most abundant in the damaged and infected tissues, and in the structures that desiccate during the development
of the seed. Based on these observations we concluded that the accumulation of calcium oxalate is a regular process belonging
to maturation and defense mechanism in spruce seeds.
Received: 1 July 1998 / Accepted: 20 September 1998 相似文献
105.
Dominique Mazzi Jenni Kes?niemi Anneli Hoikkala Kirsten Klappert 《BMC evolutionary biology》2009,9(1):132
Background
Conflicts of interest between the sexes are increasingly recognized as an engine driving the (co-)evolution of reproductive traits. The reproductive behaviour of Drosophila montana suggests the occurrence of sexual conflict over the duration of copulation. During the last stages of copulation, females vigorously attempt to dislodge the mounting male, while males struggle to maintain genital contact and often successfully extend copulations far beyond the females' preferred duration. 相似文献106.
Eimre M Puhke R Alev K Seppet E Sikkut A Peet N Kadaja L Lenzner A Haviko T Seene T Saks VA Seppet EK 《American journal of physiology. Regulatory, integrative and comparative physiology》2006,290(5):R1271-R1275
The cellular energy metabolism in human musculus gluteus medius (MGM) under normal conditions and hip osteoarthritis (OA) was explored. The functions of oxidative phosphorylation and energy transport systems were analyzed in permeabilized (skinned) muscle fibers by oxygraphy, in relation to myosin heavy chain (MHC) isoform distribution profile analyzed by SDS-PAGE, and to creatine kinase (CK) and adenylate kinase (AK) activities measured spectrophotometrically in the intact muscle. The results revealed high apparent Km for ADP in regulation of respiration that decreased after addition of creatine in MGM of traumatic patients (controls). OA was associated with increased sensitivity of mitochondrial respiration to ADP, decreased total activities of AK and CK with major reduction in mi-CK fraction, and attenuated effect of creatine on apparent Km for ADP compared with control group. It also included a complete loss of type II fibers in a subgroup of patients with the severest disease grade. It is concluded that energy metabolism in MGM cells is organized into functional complexes of mitochondria and ATPases. It is suggested that because of degenerative remodeling occurring during development of OA, these complexes become structurally and functionally impaired, which results in increased access of exogenous ADP to mitochondria and dysfunction of CK-phosphotransfer system. 相似文献
107.
Peltonen LM Sankari S Kivimäki A Autio P 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2006,144(4):432-441
To study the role of the skin in differential calcium metabolism in White Leghorn chickens, we compared the composition of suction blister fluid (SBF) collected from cutaneous blisters with blood and serum in female and male animals in various physiological states. As an estimate for interstitial fluid (IF), SBF was used as a determinant of local cutaneous metabolism. Sample collection was carried out under ketamine–xylazine anesthesia. Eight chickens of both sexes were raised freely in similar environmental conditions and fed with similar food during their growth from juvenile to sexually mature and fully adult state. SBF, blood and serum were examined for concentrations of ionized Ca2+, Na+ and K+ with ion-selective electrodes (ISEs), and osmolalities by freezing point osmometry. pH and total protein content were also assessed. Our results showed that SBF of chickens is calcium-poor at the juvenile state and that it draws more Ca2+ in adult males than laying females of the same age. Interestingly, Ca2+ accumulation was observed also in females after laying had ceased. There was a positive correlation between blood and SBF Ca2+ in females but a negative one in males. In general, it was found that SBF of chickens was rich in Na+ and K+, was hypertonic compared to serum at the juvenile state and had a protein content of 36–47% of that in serum. Different from mammals, SBF in adult chickens was alkaline with the mean values of 8.7 ± 0.14 in females and 8.8 ± 0.06 in males. Age- and sex-related variability in cutaneous Ca2+ concentrations in chickens, and the differences of SBF composition between that of mammals point to a novel role of skin functions in avians. Possible functions of the skin as a dynamic calcium source balancing the free circulating Ca2+ levels and, also, as an excretory organ for Ca2+ are discussed. 相似文献
108.
109.
Pernilla Örtqvist Johan Gising Angelica E. Ehrenberg Aparna Vema Anneli Borg Anders Karlén Mats Larhed U. Helena Danielson Anja Sandström 《Bioorganic & medicinal chemistry》2010,18(17):6512-6525
Herein, the design, synthesis and inhibitory potency of a series of novel hepatitis C virus (HCV) NS3 protease inhibitors are presented. These inhibitors are based on a 2(1H)-pyrazinone P3 scaffold in combination with either a P2 phenylglycine or a glycine, and they were evaluated on the wild type as well as on two resistant variants of the enzyme, A156T and D168V. Molecular modelling suggested that the aromatic side-chain of the P2 phenylglycine occupies the same space as the substituent in position 6 on the pyrazinone core. The versatile synthetic route applied for the pyrazinone synthesis made a switch between the two positions easily feasible, resulting in phenyl- or benzyl substituted pyrazinones and leaving glycine as the P2 residue. Of several P1–P1′ residues evaluated, an aromatic P1–P1′ scaffold was found superior in combination with the new P3–P2 building block. As a result, an entirely new type of achiral and rigidified inhibitors was discovered, with the best of the novel inhibitors having fourfold improved potency compared to the corresponding tripeptide lead. We consider these achiral inhibitors highly suitable as starting points for further optimization. 相似文献
110.
Eddudóttir Sigrún Dögg Svensson Eva Nilsson Stefan Ekblom Anneli Lindholm Karl-Johan Johansson Annie 《Vegetation History and Archaeobotany》2021,30(6):759-771
Vegetation History and Archaeobotany - Shielings are the historically known form of transhumance in Scandinavia, where livestock were moved from the farmstead to sites in the outlands for summer... 相似文献