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251.
We have determined the NMR structure of a ligand-binding domain of the granulocyte colony-stimulating factor (G-CSF) receptor, containing the highly conserved WSxWS motif. The domain consists of seven beta-strands with the fibronectin type III-like topology seen in several cytokine receptors. Comparisons between the spectra of the 15N-labelled domain with and without G-CSF indicate that the major ligand-recognition site is on the FG loop just upstream of the WSxWS sequence, and not on the BC loop which is mainly used in the growth hormone system. The WSxWS residues are suggested to contribute to ligand-recognition and to the protein architecture of the G-CSF receptor.  相似文献   
252.
Apart from main classic neuron types there is a small group of neurons known in literature as intermediate Lugaro cells. Two Lugaro cells types are distinguished: fusiform and those with triangular cell body. Fusiform cells vary not only in vertical, horizontal or diagonal position of cell body, but also have certain morphological peculiarities. Axons of some fusiform cells project either to molecular layer or reach Purkinje cells layer or remain at the level of granular layer. Along with it, there are true intermediate cells, described by Lugaro. These cell processes project from layer to layer. Neurons with triangular cell body located at different granular layer levels relate to the second group of Lugaro cells. Due to great extension of their processes Lugaro cells possess projection area ranging from molecular layer to white substance. Lugaro cells are independent neurons, always present in cerebellar cortex.  相似文献   
253.
The introduction of high molecular weight DNA into mammalian cells is useful for gene expression studies. However, current transfection strategies are inefficient, necessitating propagation of stable DNA transformants prior to analysis of gene expression. Here we demonstrate that transient lipid-mediated DNA transfection can be used to assess gene expression from yeast artificial chromosomes (YACs) containing the 230 kb cystic fibrosis transmembrane conductance regulator gene ( CFTR ) and Escherichia coli lacZ . We also show that psoralen-UV inactivated adenovirus significantly enhances transfection efficiency. The ability to deliver high molecular weight DNA using lipid-mediated transfection should expedite the analysis of large human genes contained within artificial chromosome vectors.  相似文献   
254.
We describe the cases of two premature infants carrying a central venous line who developed on the fourth day of life a catheter related intracardiac thrombus. Although they were clinically asymptomatic we opted for thrombolytic treatment considering the potential risks of this situation. Treatment with recombinant tissue plasminogen activator (rt-PA) was performed for one day in the first case and for three days in the second one, in association with fresh frozen plasma. Thrombus dissolution occurred in both patients and no adverse effects were noted. In our experience tissue plasminogen activator was a therapy acceptably safe and effective inducing clot lysis in very low birthweight neonates into critical situations.  相似文献   
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An immune response to heparin, which is clinically manifested by the development of thrombocytopenia with or without thrombosis, is stimulated by a complex of heparin with platelet factor 4 (PF4). The primary thrombotic events in patients with heparin-induced thrombocytopenia (HIT) are more frequently venous than arterial. The development of antibodies, however, does not always result in thrombocytopenia or in catastrophic events. The antibodies, which are of the IgG, IgM, and IgA isotypes, can be easily measured by an ELISA that contains a complex of heparin-platelet factor 4 (PF4). Initial antibody formation can be greatly reduced by limiting the exposure to unfractionated heparin or by the use of low-molecular-weight heparin. For those patients who require anticoagulation and who have antibodies to heparin-PF4, danaparoid (Orgaran), a low-molecular weight heparinoid that does not react with the antibodies, is now commercially available; argatroban, a thrombin-specific inhibitor, can also be obtained for compassionate use. The use of these agents during anticoagulation with warfarin is preferable to the simple discontinuation of heparin and intitiation of warfarin, because the latter treatment can result in ongoing thrombosis.  相似文献   
258.
Fuzzy-trace theory's concepts of identity judgment, nonidentity judgment, and similarity judgment provide a unified account of the false-memory phenomena that have been most commonly studied in children: false-recognition effects and misinformation effects. False-recognition effects (elevated false-alarm rates for unpresented distractors that preserve the meanings of presented targets) are due to increased rates of similarity or false identity judgment about distractors or to decreased rates of nonidentity judgment. Misinformation effects (erroneous acceptance of misleading postevent information and erroneous rejection of actual events) are also due to variability in rates of similarity, identity, and nonidentity judgment. Two experimental paradigms are presented, one for false recognition (conjoint recognition) and one for misinformation (conjoint misinformation), that allow investigators to tease apart the contributions of these processes to children's false-memory reports. Each paradigm is implemented in a mathematical model that provides numerical estimates of the processes.  相似文献   
259.
To the complex action of human embryonal neocortex transplanted into the eye anterior chamber and cyclosporin A injected daily to prevent graft rejection rat thymus reacts by accidental involution, layer inversion and vascular disturbances (without hematoma formation). After 3 wks reparative period sets in and by the end of 5th wk thymus approximates to the control in all parameters.  相似文献   
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