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81.
J Chapman L Cervenáková RB Petersen HS Lee J Estupinan S Richardson CL Vnencak-Jones DC Gajdusek AD Korczyn P Brown LG Goldfarb 《Canadian Metallurgical Quarterly》1998,51(2):548-553
We have identified a member of the VEGF family by computer-based homology searching and have designated it VEGF-D. VEGF-D is most closely related to VEGF-C by virtue of the presence of N- and C-terminal extensions that are not found in other VEGF family members. In adult human tissues, VEGF-D mRNA is most abundant in heart, lung, skeletal muscle, colon, and small intestine. Analyses of VEGF-D receptor specificity revealed that VEGF-D is a ligand for both VEGF receptors (VEGFRs) VEGFR-2 (Flk1) and VEGFR-3 (Flt4) and can activate these receptors. However. VEGF-D does not bind to VEGFR-1. Expression of a truncated derivative of VEGF-D demonstrated that the receptor-binding capacities reside in the portion of the molecule that is most closely related in primary structure to other VEGF family members and that corresponds to the mature form of VEGF-C. In addition, VEGF-D is a mitogen for endothelial cells. The structural and functional similarities between VEGF-D and VEGF-C define a subfamily of the VEGFs. 相似文献
82.
IuN Lysov AA Cherny? AA Balaev FN Gnuchev KL Beattie AD Mirzabekov 《Canadian Metallurgical Quarterly》1995,29(1):104-113
The opportunity of DNA sequencing by hybridization with oligonucleotide matrix (SHOM) with simultaneously use continuous stacking hybridization and gapped-matrices is considered. The analysis of reconstruction efficiency for various combinations matrices and l-oligonucleotides libraries were made. In most cases combine use of continuous stacking hybridization and gapped matrices permits to decrease the number of additional stacking hybridization twice without lost of efficiency. 相似文献
83.
Prevention of T cell anergy by signaling through the gamma c chain of the IL-2 receptor 总被引:1,自引:0,他引:1
VA Boussiotis DL Barber T Nakarai GJ Freeman JG Gribben GM Bernstein AD D'Andrea J Ritz LM Nadler 《Canadian Metallurgical Quarterly》1994,266(5187):1039-1042
When stimulated through their antigen receptor without requisite costimulation, T cells enter a state of antigen-specific unresponsiveness termed anergy. In this study, signaling through the common gamma chain of the interleukin-2 (IL-2), IL-4, and IL-7 receptors in the presence of antigen was found to be sufficient to prevent the induction of anergy. After culture with IL-2, IL-4, or IL-7, Jak3 kinase was tyrosine-phosphorylated, which correlated with the prevention of anergy. Therefore, a signal through the common gamma chain may regulate the decision of T cells to either clonally expand or enter a state of anergy. 相似文献
84.
There has been increasing interest in the development of a hepatocyte bioreactor for the treatment of acute hepatic failure; however, little is known about the effect of hepatocyte byproducts on the viability of the cells in the bioreactor environment. We investigated the effects of increasing concentrations of bile on the growth and viability of the human hepatoma cell line Hep G2 and on the cytochrome P-450 content and dependent mixed function oxidase (MFO) activities, reduced glutathione (GSH) content, and glutathione S-transferase (GST) activity of primary cultures of rat hepatocytes. Our purpose was to determine whether or not it would be necessary to pretreat the plasma from patients with acute liver failure to remove elevated bile concentrations which might be toxic to the hepatocytes in an artificial liver device. Bile was found to inhibit Hep G2 cell growth at concentrations as low as 0.1% and to decrease viability at concentrations above 0.5%. The cytochrome P-450 and GSH contents and the activities of the MFO system and of GST were decreased in the primary cultures of hepatocytes following 24 h treatment with concentrations of bile at and above 0.5%. The MFO activities associated with different cytochrome P-450 isoenzymes decreased to different extents in the presence of bile with the O-dealkylation of pentoxyresorufin being more labile than that of ethoxyresorufin. Our data indicate that elevated bile concentrations are cytotoxic to liver cells, and it may be necessary to pretreat patient plasma to decrease its bile content to protect the cells during the clinical operation of a hepatocyte bioreactor device. 相似文献
85.
By repeatedly presenting an alien scent to territory-owning beavers, Castor canadensis, we tested two competing hypotheses about the function of scent marking: scent fence and scent matching. The scent-fence hypothesis predicts that territory owners should respond increasingly strongly over time towards a recurrent alien scent because of the ineffectiveness of previous responses. The scent-matching hypothesis predicts that the intensity of response should be the same or decrease because, without the presence of the intruding signaller coupled with the chemical signal, the presence of the scent itself does not advertise the ownership of a territory. The response level of resident beaver families was stable to strangers' anal gland secretions (AGSs) and decreased to strangers' castoreum during a period of 6 days. These results support the scent-matching hypothesis but not the scent-fence hypothesis. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour. 相似文献
86.
87.
MP1: a MEK binding partner that enhances enzymatic activation of the MAP kinase cascade 总被引:1,自引:0,他引:1
HJ Schaeffer AD Catling ST Eblen LS Collier A Krauss MJ Weber 《Canadian Metallurgical Quarterly》1998,281(5383):1668-1671
88.
AD Levi WG Choi PJ Keller JE Heiserman VK Sonntag CA Dickman 《Canadian Metallurgical Quarterly》1998,23(11):1245-50; discussion 1251
STUDY DESIGN: Seven cadaveric cervical spines were implanted with a porous tantalum spacer and a titanium alloy spacer, and their radiographic and imaging characteristics were evaluated. OBJECTIVE: To determine the radiographic characteristics of porous tantalum and titanium implants used as spacers in the cervical spine. SUMMARY OF BACKGROUND DATA: Anterior decompressive surgery of the disc space or the vertebral body creates a defect that frequently is repaired with autologous bone grafts to promote spinal fusion. Donor site morbidity, insufficient donor material, and additional surgical time have spurred the development of biomaterials to replace or supplement existing spinal reconstruction techniques. Although the promotion of a solid bony fusion is critical, the implanted biomaterial should be compatible with modern imaging techniques, should allow visualization of the spinal canal and neural foramina, and should permit radiographic assessment of bony ingrowth. METHODS: Cadaveric spines containing the implants were imaged with plain radiography, computerized tomography, and magnetic resonance imaging. The image distortion produced by the implants was determined qualitatively and quantitatively. RESULTS: The tantalum and titanium spacers were opaque on plain radiographic films. On computed tomographic scans, more streak artifact was associated with the tantalum implants than with the titanium. On magnetic resonance imaging, the porous tantalum implant demonstrated less artifact than did the titanium spacer on T1- and T2-weighted spin echo and on T2*-weighted gradient-echo magnetic resonance images. Overall, the tantalum implant produced less artifact on magnetic resonance imaging than did the titanium spacer and therefore allowed for better visualization of the surrounding bony and neural structures. CONCLUSION: The material properties of titanium and porous tantalum cervical interbody implants contribute to their differential appearance in different imaging methods. The titanium implant appears to image best with computed tomography, whereas the porous tantalum implant produces less artifact than does the titanium implant on several magnetic resonance imaging sequences. 相似文献
89.
90.
PURPOSE: To examine the ability of protein kinase C (PKC) inhibitors and activators to influence the rate of corneal re-epithelialization in the rat. METHOD: Rat corneas with 3 mm diameter central epithelial abrasions were organ-cultured in control medium or in medium with inhibitors or activators of PKC. RESULTS: In control corneas, the defect was completely re-epithelialized by 25 hr. In the presence of the PKC inhibitors staurosporine (100 nM), sphinganine (50 mumol/l), or H-7 (100 mumol/l) there were significantly larger epithelial defects than in controls after 5-25 hr of incubation. Re-epithelialization rates were similar to control corneas when the incubation medium contained HA1004 (100 mumol/l), an analogue of H-7 that is a potent inhibitor of cyclic adenosine monophosphate- and cyclic guanosine monophosphate-dependent protein kinases and a weak inhibitor of PKC. Two PKC activators, 1-oleoyl-2-acetyl-sn-glycerol (OAG) and phorbol 12-myristate 13-acetate (PMA), were unable to enhance the rate of epithelial wound healing. CONCLUSIONS: Our results suggest that PKC activity is an important factor in regulating corneal epithelial wound healing, presumably by influencing cell migration. Moreover, the results with OAG and PMA suggest that PKC is maximally activated during re-epithelialization in this organ-culture assay. 相似文献