Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-2145
    Keywords: Cymbidium goeringii ; Cytoplasmic diminution ; Generative cell ; Male germ unit ; Vegetative nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pollinia of Cymbidium goeringii (Orchidaceae) were examined at a young stage (approx. 2 weeks before anthesis) and at anthesis using transmission electron microscopy, computer-assisted serial reconstruction and quantitative cytology. At the young stage, the generative cell (GC) has a spherically shaped main body with a large nucleus and 1 to 4 cytoplasmic extensions (up to 10 μm long) physically associated with a groove on one side of the vegetative nucleus (VN). By anthesis, some GCs lose their cytoplasmic extensions, becoming spherical. The GC surface becomes highly wrinkled, the distance between the GC and the VN increases and the two may separate completely. Enucleated cytoplasmic bodies (ECBs) are apparently generated by the GC, as evidenced by their similar ultrastructural appearance and distribution near the GC. ECBs are likely produced from two sites: the GC surface and the tips of cytoplasmic extensions of the GC. Vesicle-containing bodies (VCBs) may be generated from the lateral surface of the GC and may also represent a degeneration stage of ECBs, finally fusing with lipid bodies. Heritable organelles are rare and usually absent in the GC of Cymbidium: 0.176 mitochondria and 0.0042 plastids per GC were observed at the young stage and no mitochondria and 0.019 plastids at anthesis. Of 16 cellular parameters examined during GC development, all decreased with the exception of the surface area and volume of ECBs/ VCBs (which remained stable) and GC vacuoles (which increased). Significant decreases in 11 parameters presumably relate to dehydration of the pollen and male cytoplasmic diminution.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-2242
    Keywords: Cytoplasmic inheritance ; Environmental conditions ; Nicotiana tabacum ; Sperm cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In flowers grown at warm temperatures in environmental chambers and at cooler temperatures in the greenhouse, eight parameters of the sperm-cell organization of Nicotiana tabacum were examined during sperm cell maturation using serial ultrathin sectioning, transmission electron microscopy and quantitative cytology. Despite employing the same seed source, and similar soil and nutrient conditions, the surface area and volume of the cell, the nucleus and the chondriome were larger in flowers grown in growth chambers under warmer controlled conditions, whereas the number of plastids appeared to be the same, or slightly higher, in flowers grown under cooler greenhouse conditions. These results suggest that environmental conditions may influence the quantity of cytoplasmic organelles, including mitochondria and plastids, thus potentially influencing the likelihood of male cytoplasmic inheritance.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1420-908X
    Keywords: Key words: Interleukin 13 — Polymorphonuclear neutrophil — Prostaglandin E2— Cyclooxygenase 2 — Neutral esterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Objective: To investigate whether interleukin-13 (IL-13) can affect arachidonic acid metabolism and phagocytic activity of normal human polymorphonuclear neutrophils (PMN).¶Methods: Normal human PMN (1 × 106 cells/ml) were incubated with different concentrations of IL-13 (0.1–10 ng/ml) for a variety of times (30–120 min). Phagocytosis and intracellular cyclooxygenase-2 (COX-2) were detected by flow cytometry. The expression of COX-1 and COX-2 mRNA was detected by RT-PCR. The concentration of PGE2 in the PMN cultured supernatants was determined by EIA.¶Results: We found that IL-13 at an optimal concentration of 1 ng/ml significantly enhanced COX-2 gene expression and PGE2 production (121.57 ± 22.17 pg/ml in IL-13 stimulation vs. 73.16 ± 11.72 pg/ml in controls) by PMN. In addition, IL-13 stimulated PMN phagocytosis via increased complement receptor type 1 (CR1) and type 3 (CR3), but not IgG Fcγ receptor type 3 (FcγRIII). The cytoplasmic neutral esterase activity of PMN was also enhanced by IL-13 stimulation for 24 h.¶Conclusions: These results suggest that IL-13 can stimulate PMN and modulates the inflammatory reactions via the cyclooxygenase pathway.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-069X
    Keywords: Key words UVB ; Keratinocytes ; Beta 2-adrenergic ; receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Vitiligo is an acquired pigmentary disorder characterized by depigmentation of skin and hair. As the pathogenesis of this disease is still obscure, the treatment of vitiligo has generally been unsatisfactory and often disappointing. Topical tacrolimus (FK506) ointment has recently been added to the armamentarium against this pigmentary disorder. Despite its clinical efficacy, the underlying mechanisms of how topical tacrolimus induces repigmentation in vitiligo have rarely been investigated. As tacrolimus ointment is applied directly to the skin, its impact on keratinocytes (KCs) requires thorough investigation.Objectives  To investigate the effects of FK506 on melanocyte (MC) and melanoblast (MB) growth via KCs.Methods  Cultured MCs and MBs were treated with supernatant of KC cultures conditioned with various concentrations of FK506. The impact of supernatant on MCs and MBs was assessed in terms of its effect on MC/MB proliferation, melanin formation and cell migration. The activities of matrix metalloproteinase (MMP)-2 and MMP-9, known for their influence on cell migration, were evaluated. The concentrations of MC/MB growth factors in the KC supernatant were also determined.Results  Results demonstrated that proliferation of both MCs and MBs was significantly enhanced by FK506-treated KC supernatant. In addition, the concentration of stem cell factor in KC supernatant increased dose-dependently with FK506 treatment. The supernatant from FK506-treated KC culture showed a significant increase in MMP-9 activity.Conclusions  Our study provides in vitro evidence demonstrating that direct interaction between FK506 and KCs creates a favourable milieu for MC growth and migration. Furthermore, our findings provide a possible mechanism explaining how tacrolimus ointment induces repigmentation in patients with vitiligo.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Tacrolimus ointment (FK506) has been used in recent years for the treatment of atopic dermatitis (AD), with favourable results. Most of the therapeutic efficacy of FK506 in AD has been attributed to its immunomodulatory effects on different immune cell types, but its effects on keratinocytes (KCs) have rarely been discussed. Studies have shown that low expression of transforming growth factor (TGF)-β and high expression of nitric oxide synthase (NOS) are implicated in the pathogenesis of AD.Objectives  To investigate the direct effects of FK506 on KCs in terms of TGF-β and inducible NOS (iNOS), and to explore the interactions between TGF-β and iNOS in the KC system.Methods  Cultured human KCs treated with different concentrations of FK506 were used for investigation. The changes in the KC system induced by FK506 were documented in terms of TGF-β and iNOS using enzyme-linked immunosorbent assay and Western blotting techniques, respectively. The gene expression of both TGF-β and iNOS was also determined. A certain amount of tumour necrosis factor (TNF)-α was introduced to mimic atopic skin in vivo.Results  Our results showed that the release of TGF-β was upregulated in FK506-treated KCs, particularly in the presence of TNF-α, while the expression of iNOS was downregulated. The gene expression of iNOS was also downregulated, as shown by reverse transcriptase–polymerase chain reaction analysis. However, the addition of TNF-α did not further downregulate the expression of iNOS protein, suggesting that FK506 may regulate TGF-β and iNOS through different pathways.Conclusions  Our findings indicate that the direct effects of FK506 on KCs probably contribute to its therapeutic efficacy in the treatment of AD.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Epidermolysis bullosa (EB) pruriginosa is a subtype of dominant dystrophic EB (DDEB), characterized by severe pruritus and blistering localized to the extensor surface of the extremities. EB pruriginosa exhibits extensive clinical heterogeneity with variable expression and delayed age of onset. Mutations in the COL7A1 gene, especially in glycine residues within Gly-X-Y repeats, have been shown to cause this form of DDEB. Here, we report a novel COL7A1 mutation in a Taiwanese pedigree with EB pruriginosa. Using PCR and direct sequence analysis we have identified a G→T transversion at nucleotide 7097 in exon 92 of COL7A1, converting a glycine residue to valine (G2366V). The mutation resides within a consecutive, uninterrupted stretch of 17 Gly-X-Y residues in the triple-helical domain of type VII collagen. Interestingly, an affected member of this family also displayed elevated IgE levels, previously reported in some patients with this disorder. Our finding further implicates COL7A1 mutation in the pathogenesis of EB pruriginosa and underscores the heterogeneous clinical symptoms of glycine mutations in DDEB.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-069X
    Keywords: Key words T lymphocytes ; Tumor immunity ; IL-2 ; receptor ; Bowen’s disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The immune function of peripheral mononuclear cells (MNC) in patients with endemic arsenic-induced Bowen’s disease (BD) was investigated. Many cytokines and immune-related factors were determined in the present study. Interleukin-1β and TNF-α production was used as an indicator of monocyte/macrophage function. Il-2 and sIL-2R production was used as an indicator of lymphocyte activation. The release of sCD4 and sCD8 was used as an indicator of activation of respective T-cell subpopulations. Production of IFN-γ and IL-2 reflected the cellular effector function of helper T-cells type 1. In vivo cell-mediated immunity was also assessed by estimation of the percentage of T-cells in peripheral blood MNC and the nonspecific delayed-type hypersensitivity (DTH) response to 2,4-dinitrochlorobenzene (DNCB). Both assays revealed depressed cell-mediated immunity in BD. Compared with healthy controls, spontaneous and PHA-induced IFN-γ and TNF-α production was significantly decreased in BD whereas spontaneous release of IL-2, sCD4 and sCD8 was significantly increased. Although PHA stimulation increased IL-2 release, the expression of IL-2R α and β chains and the release of sIL-2R were not proportionately increased in BD. In addition, IL-2-mediated [3H]-thymidine incorporation by MNC in patients with BD was significantly decreased. These findings suggest that the defective cell-mediated immune function in BD is due to impairment of membrane IL-2R expression in lymphocytes after stimulation.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...