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Studies of proteins that inhibit tissue factor activity have generally been conducted using either an extracted tissue homogenate ("thromboplastin") or tissue factor protein reconstituted into phospholipid vesicles rather than with tissue factor expressed in cell membranes (its physiological environment). In the present study, a human fibroblast cell strain was used to evaluate the effects of lipoprotein associated coagulation inhibitor (LACI), placental anticoagulant protein (PAP), and apolipoprotein A-II (apo A-II) on human tissue factor in cell membranes. LACI was tested from 7.8 to 500 pmol/L on fibroblasts cultured at cell densities ranging from 3,500 to 9,925 cells/well, and caused a progressive inhibition of tissue factor activity. PAP was tested from 3.9 nmol/L to 1 mumol/L at cell densities ranging from 4,500 to 15,400 cells/well and caused up to 83% inhibition of tissue factor activity. Inhibition by these proteins appeared to be influenced by cell density as well as whether the cells were intact or disrupted. Apo A-II, up to 1 mumol/L, did not inhibit the tissue factor activity of intact or disrupted fibroblasts at any cell density examined even though it did inhibit the activity of tissue factor in phospholipid vesicles. Of these inhibitors of tissue factor-dependent activation of factor X, LACI was the most effective in suppressing the generation of factor Xa activity. The effects obtained with apo A-II are clearly dependent on the nature of the tissue factor preparation with which it is tested. The disparity between the inhibitory effect of apo A-II on the activity of tissue factor reconstituted into lipid vesicles and the absence of effect on the activity of tissue factor remaining in cell membranes serves to reemphasize the necessity of reexamining results obtained with model systems using as nearly physiological reagents as possible. 相似文献
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Myosin VIIA gene: heterogeneity of the mutations responsible for Usher syndrome type IB 总被引:8,自引:1,他引:8
Levy G; Levi-Acobas F; Blanchard S; Gerber S; Larget-Piet D; Chenal V; Liu XZ; Newton V; Steel KP; Brown SD; Munnich A; Kaplan J; Petit C; Weil D 《Human molecular genetics》1997,6(1):111-116
Usher syndrome is recognized as the most frequent cause of hereditary
deaf-blindness. Usher syndrome type I (USH1), the most severe form of the
disease, is characterized by profound congenital sensorineural deafness,
constant vestibular dysfunction, and retinitis pigmentosa of prepubertal
onset. This form is genetically heterogeneous and five loci (USH1A-E) have
been mapped thusfar. However, only the gene responsible for USH1 B (which
accounts for approximately 75% of USH1 cases) has been characterized. It
encodes a long-tailed unconventional myosin, myosin VIIA, with a predicted
2215 amino acid sequence. Primers covering the complete myosin VIIA coding
sequence as well as the 3' non coding sequence were designed, allowing
direct sequence analysis of each of the 48 coding exons and flanking splice
sites in seven patients affected by USH1. Four novel mutations were thereby
identified. The possibility should now be considered of a sequence-based
prenatal diagnosis in some of the families affected by this very severe
form of Usher syndrome.
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Evolutionary silencing of the human elastase I gene (ELA1) 总被引:6,自引:0,他引:6
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Schlussman SD Zhou Y Johansson P Kiuru A Ho A Nyberg F Kreek MJ 《Neuroscience letters》2000,284(3):190-194
There is increasing abuse of androgenic anabolic steroids (AAS) by non-athletes. AAS abuse has been associated with psychiatric symptoms such as mania, major depression and aggression and the development of dependence. Little is known about the effects of AAS on hypothalamic-pituitary-adrenal axis function or corticotropin releasing factor, which may be involved in mediating some of the psychiatric symptoms associated with AAS abuse. Male Sprague-Dawley rats received one daily intra-muscular injection of the AAS nandrolone decanoate (ND, 15 mg/kg) or vehicle for 3 days. Animals were sacrificed either 1 h or 24 h after the last injection, brain regions dissected and trunk blood collected. Corticotropin releasing factor (CRF), CRF receptor1 (CRF-R1) and proopiomelanocortin (POMC) mRNAs were measured with solution hybridization/RNase protection. Circulating levels of corticosterone and adrenocorticotropin hormone (ACTH) were determined using radioimmunoassays. One hour following the last injection, ND significantly increased circulating levels of both corticosterone and ACTH levels. In the amygdala, CRF mRNA levels were unchanged 1 h after the last injection of ND but were significantly reduced at 24 h. The same was found for hypothalamic POMC. No significant AAS effects were observed on: hypothalamic CRF mRNA; POMC mRNA in the amygdala or CRF R1 mRNA in the anterior pituitary. 相似文献