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31.
Semaphorins act as attractive and repulsive guidance signals during the development of cortical projections 总被引:1,自引:0,他引:1
D Bagnard M Lohrum D Uziel AW Püschel J Bolz 《Canadian Metallurgical Quarterly》1998,125(24):5043-5053
Members of the semaphorin family have been implicated in mediating axonal guidance in the nervous system by their ability to collapse growth cones and to function as chemorepellents. The present findings show that recombinant Semaphorin D has similar effects on cortical axons and, in addition, inhibits axonal branching. In contrast, semaphorin E acts as an attractive guidance signal for cortical axons. Attractive effects were only observed when growth cones encountered increasing concentrations or a patterned distribution of Semaphorin E, but not when they are exposed to uniform concentrations of this molecule. Specific binding sites for Semaphorin D and Semaphorin E were present on cortical fibers both in vitro and in vivo at the time when corticofugal projections are established. In situ hybridization analysis revealed that the population of cortical neurons used in our experiments express neuropilin-1 and neuropilin-2, which are essential components of receptors for the class III semaphorins. Moreover, semD mRNA was detected in the ventricular zone of the neocortex whereas semE mRNA was restricted to the subventricular zone. Taken together, these results indicate that semaphorins are bifunctional molecules whose effects depend on their spatial distribution. The coordinated expression of different semaphorins, together with their specific activities on cortical axons, suggests that multiple guidance signals contribute to the formation of precise corticofugal pathways. 相似文献
32.
AW Minto R Kalluri M Togawa EC Bergijk PD Killen DJ Salant 《Canadian Metallurgical Quarterly》1998,110(3):207-217
The swelling, erosion and solvent front penetration properties of mini-matrices containing xanthan (X), locust bean (LB) and karaya (K) gums were examined, analysed and related to the overall in vitro release kinetics of diclofenac sodium, used as a model drug. Mini-matrices were produced with drug:gum ratios of 1:1 as well as formulations of drug and X in combinations of 2:1, 2:3 and 1:2. The rank order of decreasing swelling index (SI) in both axial and radial dimensions was X?K?LB and each gum showed almost Fickian swelling behaviour. The solvent front penetration rates were consistent with the rates of swelling. However, the order of decreasing drug release and erosion rates was LB>X>K and all formulations demonstrated anomalous (non-Fickian) drug release kinetics. Therefore Fickian drug diffusion and polymer erosion were both occurring simultaneously. The dominant mechanism depended on the nature and content of the gum, as well as the stage in the dissolution time period. There was a loss of matrix integrity in formulations containing a high drug:gum ratio. 相似文献
33.
RJ O''Hara J Greenman PJ Drew AW McDonald GS Duthie PW Lee JR Monson 《Canadian Metallurgical Quarterly》1998,41(4):460-463
OBJECTIVE: Spontaneous spinal epidural hematoma (SSEH) is an idiopathic accumulation of blood in the vertebral epidural space without identifiable predisposing factors. First reported in 1869, the clinical outcome in children younger than 18 years old has not been clearly delineated. DESIGN: A comprehensive review of the English language literature revealed 26 patients younger than 18 years old with reported clinical outcomes. The 27th case is presented. RESULTS: Complete neurologic recovery occurred in 14 of 27 (52%) patients, partial recovery in 12 of 27 (44%) patients, and death in 1 of 27 (4%) patients. CONCLUSION: There is an overall good prognosis for neurologic recovery in children who experience SSEH. 相似文献
34.
L Lu W Li F Fu FG Chambers S Qian JJ Fung AW Thomson 《Canadian Metallurgical Quarterly》1997,64(12):1808-1815
BACKGROUND: Failure of costimulatory molecule-deficient donor dendritic cells (DCs) to induce indefinite allograft acceptance may be a result of the 'late" up-regulation of these molecules on the DCs after interaction with host T cells. Ligation of CD40 on antigen-presenting cells by its cognate ligand CD40L is thought to induce expression of CD80 (B7-1) and CD86 (B7-2). We examined the influence of anti-CD40L monoclonal antibody (mAb) on the capacity of donor-derived DC progenitors to induce long-term allograft survival. METHODS: High purity DC progenitors were grown from B10 (H2b) mouse bone marrow in granulocyte-macrophage colony-stimulating factor and transforming growth factor beta1 (TGFbeta1). Mature DC were propagated in granulocyte-macrophage colony-stimulating factor and interleukin-4. Their phenotype was characterized by flow cytometric analysis and their function by mixed leukocyte reactivity. Anti-donor cytotoxic T lymphocyte activity in grafts and spleens of vascularized heart allograft recipients was also assessed. RESULTS: The TGFbeta3-cultured cells were (1) DEC 205-positive, MHC class II-positive, CD80dim, CD86dim, and CD40dim, (2) poor stimulators of naive allogeneic T-cell proliferation, and (3) able to prolong significantly B10 cardiac allograft survival in C3H (H2k) recipients when given (2 x 10[6] i.v.) 7 days before organ transplantation (median survival time [MST] 26 days vs. 12 days in controls, and 5 days in interleukin-4 DC-treated animals). Their allostimulatory activity was further diminished by addition of anti-CD40L mAb at the start of the mixed leukocyte cultures. Anti-CD40L mAb alone (250 microg/mouse, i.p.; day -7) did not prolong cardiac graft survival (MST 12 days). In contrast, TGFbeta-cultured DCs + anti-CD40L mAb extended graft survival to a MST of 77 days, and inhibited substantially the anti-donor cytotoxic T lymphocyte activity of graft-infiltrating cells and host spleen cells assessed 8 days after transplant. CONCLUSIONS: The CD40-CD40L pathway appears important in regulation of allogeneic DC-T-cell functional interaction in vivo; its blockade increases markedly the potential of costimulatory molecule-deficient DCs of donor origin to induce long-lasting allograft survival. 相似文献
35.
Adenoid basal carcinoma of the uterine cervix is rare and its cell origin is still obscure. We report a case of adenoid basal carcinoma of the uterine cervix discovered incidentally in a 69-year-old woman who had been hysterectomized due to endometrial adenocarcinoma of the uterine corpus. Histologically, small round-to-oval cancer cell nests with peripheral cell palisading were seen budding from the basal cell layer of the uterine cervix showing carcinoma in situ. Immunohistochemically, the basaloid cells of the adenoid basal carcinoma were positive for keratins 14, 17 and 19 and resembled reserve cells of the cervical epithelium. The results of this study clearly demonstrated that adenoid basal carcinoma shows a phenotype similar to reserve cells of the uterine cervix. A review of the literature indicated that this tumor has a favorable prognosis and should be clearly separated from adenoid cystic carcinoma, which has a much poorer outcome. 相似文献
36.
AW AD R. MANSOUR 《Chemical Engineering Communications》2013,200(1):133-135
Mixing in co-rotating sinusoidal cavity flows is studied with period, T, and phase shift, a, as parameters. Notice that the main obstacle to uniform mixing is the existence of stable :ower periodic orbits, mixing windows, where uniform mixing takes place, are found in the T— a space u:iing bifurcation analysis. The main advantage of this method is a great saving of the computation time. 相似文献
37.
The localization of cathepsin K protein in mouse osteoclasts was examined by immunolight and immunoelectron microscopy using the avidin-biotin-peroxidase complex method with anti-cathepsin K (mouse) antibody. With light microscopy, a strong immunoreaction for cathepsin K was found extracellularly along the bone and cartilage resorption lacunae and detected intracellularly in vesicles, granules, and vacuoles throughout the cytoplasm of multinuclear osteoclasts and chondroclasts attached to the surface of the bone or cartilage. Mononuclear cells, probably preosteoclasts, some distance from the bone also contained a few cathepsin K-positive vesicles and granules. Cathepsin K was sometimes found in the cisternal spaces of the rough endoplasmic reticulum and vesicles of the Golgi apparatus with electron microscopy of the basolateral region of the osteoclasts. Cathepsin K-positive vesicles and granules as lysosomal compartments were present in various stages of fusion with vacuoles as endosomal compartments that contained fragmented cathepsin K-negative fibril-like structures. Some of the vacuoles (endolysosomes), which seemed to be formed by this process of fusion, contained cathepsin K-positive vesicles and fibril-like structures that did not show the regular cross striation of type I collagen fibrils. In the apical region of the osteoclasts, cathepsin K-positive vesicles and pits had already fused with or were in the process of fusing with the ampullar extracellular spaces. There were large deposits of cathepsin K on fragmented fibril-like structures without regular cross striation in the extracellular spaces, as well as on and between the cytoplasmic processes of the ruffled border. There were also extensive deposits of cathepsin K on the type I collagen fibrils with cross striation in the bone resorption lacunae. Osteoblasts and osteocytes were negative for cathepsin K. In the immunocytochemical controls, no immunoreaction was found in the osteoclasts or preosteoclasts, or on the collagen fibrils in the resorption lacunae. The results indicate that cathepsin K is produced in mature osteoclasts attached to the bone and secreted into the bone resorption lacunae. The findings suggest that cathepsin K participates in the extracellular degradation of collagen fibrils in the resorption lacunae and in the subsequent degradation of the fragmented fibrils in the endolysosomes. It is also suggested that cathepsin K degrades the organic cartilage matrix. 相似文献
38.
AW Bach L Unger R Sprengel G Mengod J Palacios PH Seeburg MM Voigt 《Canadian Metallurgical Quarterly》1993,13(1-4):479-502
Using polymerase chain reaction (PCR) a complementary DNA (cDNA) encoding a 5-hydroxytryptamine (5-HT) receptor was isolated from rat forebrain. The amplified cDNA specifies an open reading frame of 374 amino acids comprising seven putative transmembrane regions. Expression of the cloned cDNA in human embryonic kidney cells (HEK 293) was used to establish the pharmacological profile of the encoded receptor polypeptide. Membranes containing the cloned receptor showed high affinity binding of [3H]-5-HT. Competition binding experiments with a variety of serotonin receptor ligands displayed a rank order of affinities corresponding to a 5-HT1D subtype: 5-CT > 5-HT = metergoline > CGS 12066 > methysergide > sumatriptan > mianserin = (-)alpha-Me-5-HT = yohimbine > 8-OH-DPAT > or = rauwolscine > spiperone > DOI > propranolol > or = 2-Me-5-HT > or = ICS 205930. Ketanserin and ritanserin displaced [3H]-5-HT-binding in a biphasic manner. In situ hybridization revealed highest expression of the corresponding mRNA in the pyramidal layer of the olfactory tubercle and the nucleus caudatus and accumbens. 相似文献
39.
DE Epner AW Partin JA Schalken JT Isaacs DS Coffey 《Canadian Metallurgical Quarterly》1993,53(9):1995-1997
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression is increased in Dunning R-3327 rat prostatic adenocarcinoma cell lines relative to normal rat ventral prostate tissue. GAPDH expression closely correlates with cell motility of Dunning prostate cancer cell lines and accurately distinguishes cell lines with high metastatic potential from those with low metastatic potential. Increased GAPDH expression in the cancer cell lines is not simply related to increased growth rate, since rapidly proliferating normal prostate tissue did not exhibit elevated GAPDH expression. 相似文献
40.
Colostrinin: a proline-rich polypeptide (PRP) from ovine colostrum and its nonapeptide active fragment (NP) induce maturation and differentiation of murine thymocytes, formation of helper cells from PNAhigh thymocytes and cytotoxic T cells from PNAlow thymocytes. These processes are accompanied by changes in expression of receptors for peanut agglutinin (PNA), PNAhigh thymocytes were transformed into PNAlow cells, and vice versa. It was shown, in various laboratories, that sialyltransferases are involved in the transformation of PNAhigh thymocytes into PNAlow cells. To find out whether the expression of receptors for PNA on murine thymocytes might also be influenced by other enzymes, we decided to study the effect of PRP and NP on sialidase and beta-galactosidase activities in these cells. The results obtained showed that the most of sialidase activity of murine thymocytes is present in the plasma membrane compartments. Both thymocyte subpopulations PNAhigh and PNAlow, showed similar sialidase activity, which was not affected either by PRP or NP. In contrast to sialidases, most of beta-galactosidase activity was present in the cytosol. PNAhigh, thymocytes showed a higher beta-galactosidase activity than PNAlow cells. Incubation of immature, PNAhigh, thymocytes with PRP or NP enhanced the beta-galactosidase activity in these cells. The presented results suggest that sialidases seem not to be involved in modulation of surface sialic acid content during murine thymocyte maturation. On the other hand, stimulation of activity of beta-galactosidase in PNAhigh, immature thymocytes by PRP and NP suggests that beta-galactosidase in murine thymocytes might be involved in transformation of PNAhigh into PNAlow cells. 相似文献