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  • 1
    ISSN: 1432-1246
    Schlagwort(e): Key words Mercury vapour ; CD4+ T lymphocyte ; CD4+CD45RA+ T lymphocyte ; CD57+CD16+ NK cell ; Occupational exposure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objectives: To examine the effects of metallic mercury vapour on the cellular and humoral immune system. Methods: We measured T lymphocyte and natural killer (NK) cell subpopulations, B lymphocytes, and serum immunoglobulins (i.e. IgG, IgA and IgM) together with total T (CD3+) lymphocytes and total lymphocytes in blood samples from 20 male, fluorescent-lamp makers (mercury workers) and the same number of gender-, age- and smoking-matched controls. Urinary concentrations of inorganic mercury (UHg) in the 20 workers ranged from 1.8 to 163.5 (mean 44.8) μg/l. They had been exposed to mercury vapour for 4 to 62 (mean 31) months. Results: Numbers of CD4+CD45RA+ (suppressor-inducer) T lymphocytes and total CD4+ T lymphocytes in the mercury workers were significantly smaller than those in the controls (paired-sample t-test, P 〈 0.01). The number of CD57+CD16+ NK cells was inversely correlated with UHg. Conclusion: It is suggested that numbers of CD4+CD45RA+ T lymphocytes and CD57+CD16+ NK cells are inversely affected by exposure to metallic mercury vapour in workers, with an average urinary inorganic mercury concentration of 45 μg/l being found.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Annals of biomedical engineering 21 (1993), S. 311-320 
    ISSN: 1573-9686
    Schlagwort(e): Anastomotic neointimal fibrous hyperplasia ; Vascular grafts ; End-to-end anastomoses ; Compliance ; Wall shear stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract In this article, a numerical simulation of steady flow across an end-to-end vascular bypass graft anastomosis is presented.In vitro experiments were performed to determine the variations in the conduit cross section at the anastomosis. Penrose surgical drainage tubing was used to simulate an artery and was anastomosed with Polytetrafluoroethylene (PTFE) vascular grafts using a continuous suturing technique. Artery to artery anastomosis was simulated by suturing two Penrose tubing segments. The anastomotic specimens were subject to static transmural pressure in the physiologic range to determine the instantaneous diameter and compliance as a function of the distance from the anastomotic site. The experimentally determined geometries were used to simulate steady flow through an end-to-end anastomosis using the finite analytic (FA) numerical solution technique. The results demonstrated a region of flow separation 2 mm distal to the Penrose tubing-Penrose tubing anastomosis (simulating an artery-artery anastomosis) at higher transmural pressures. Moreover, wall shear stresses increased proximal to the anastomosis in flow from the Penrose tubing to the graft. In flow from the graft to the Penrose tubing, low wall shear stresses were observed distal to the anastomosis. Flow separation was observed distal to the anastomosis at higher transmural pressures with uniform inlet velocity condition. The region of low shear stress in flow from PTFE graft to the Penrose tubing was located nearer to the anastomosis with thin wall grafts than that with standard wall thickness grafts. Our steady flow model studies suggest a correlation between regions of low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia in end-to-end anastomoses.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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