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1.
Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample. 相似文献
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Danielle B Rodrigues Roger Chammas Natália V Malavasi Patrícia LN da Costa Rosa M Chura-Chambi Keli N Balduino Ligia Morganti 《BMC biotechnology》2010,10(1):19
Background
Theracyte is a polytetrafluoroethylene membrane macroencapsulation system designed to induce neovascularization at the tissue interface, protecting the cells from host's immune rejection, thereby circumventing the problem of limited half-life and variation in circulating levels. Endostatin is a potent inhibitor of angiogenesis and tumor growth. Continuous delivery of endostatin improves the efficacy and potency of the antitumoral therapy. The purpose of this study was to determine whether recombinant fibroblasts expressing endostatin encapsulated in Theracyte immunoisolation devices can be used for delivery of this therapeutic protein for treatment of mice bearing B16F10 melanoma and Ehrlich tumors. 相似文献3.
L N Berti-Mattera S Harwalkar B Hughes P L Wilkins K Almhanna 《Journal of neurochemistry》2001,79(6):1136-1148
The regulation of Schwann cell (SC) proliferation and morphology is critical to nerve homeostasis. We have previously reported that endothelins (ETs) regulate the activity of different effectors in SC including adenylyl cyclase, phospholipases C and A2 and mitogen-activated protein kinases (MAPKs). These effects imply a possible participation of ETs in the regulation of SC phenotype. We have now investigated the effects of endothelins on the proliferation and morphology of SC, and compared them with the responses to platelet-derived growth factor (PDGF), a known mitogen in these cells. Both endothelin-1 (ET-1) and PDGF increased the incorporation of [3H]thymidine and the proportion of SC in S and G2/M, with a concomitant decrease in the G0/G1 stage cells. Treatment with ET-1 produced rapid changes in the morphology of the SC, characterized by the appearance of cell spreading with shorter processes. The response to ET-1 was considered to represent a proliferative phenotype, in contrast to the effects of forskolin, which decreased [3H]thymidine incorporation in immortalized SC (iSC) and lead to a differentiated morphology with longer extensions. While both ET-1 and PDGF displayed a proliferative effect on SC, treatment with PDGF did not affect the morphology of these cells to a significant extent. A role for p38 MAPK and Ca(2+)-independent phospholipase A2 in the changes in morphology and proliferation of iSC driven by ET-1 was suggested by the effects of selective inhibitors of these pathways [SB202190 and HELSS, respectively]. The unique pattern of signaling pathways recruited by ET-1 and its combined effects on regulation of phenotype and proliferation of SC suggest an important role for this peptide during nerve degeneration/regeneration. 相似文献
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Thibonnier M Plesnicher CL Berrada K Berti-Mattera L 《American journal of physiology. Endocrinology and metabolism》2001,281(1):E81-E92
We studied the role played by the intracellular COOH-terminal region of the human arginine vasopressin (AVP) V1-vascular receptor (V1R) in ligand binding, trafficking, and mitogenic signal transduction in Chinese hamster ovary cells stably transfected with the human AVP receptor cDNA clones that we had isolated previously. Truncations, mutations, or chimeric alterations of the V1R COOH terminus did not alter ligand binding, but agonist-induced V1R internalization and recycling were reduced in the absence of the proximal region of the V(1)R COOH terminus. Coupling to phospholipase C was altered as a function of the COOH-terminal length. Deletion of the proximal portion of the V1R COOH terminus or its replacement by the V2-renal receptor COOH terminus prevented AVP stimulation of DNA synthesis and progression through the cell cycle. Mutation of a kinase consensus motif in the proximal region of the V1R COOH terminus also abolished the mitogenic response. Thus the V1R cytoplasmic COOH terminus is not involved in ligand specificity but is instrumental in receptor trafficking and facilitates the interaction between the intracellular loops of the receptor, G protein, and phospholipase C. It is absolutely required for transmission of the mitogenic action of AVP, probably via a specific kinase phosphorylation site. 相似文献
6.
The present studies were performed in order to analize the "in vitro" effects of bovine growth hormone upon the RNA labelling slices from cerebrum and liver of neonatal hypothyroid rats. The [3H]-uridine incorporation was significantly enhanced by bovine growth hormone in both tissues. The stimulation was higher in liver than in cerebrum. The present results confirm the direct action of growth hormone on the RNA synthesis in liver and cerebrum during the postnatal development of the rat. 相似文献
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Berti-Mattera LN Wilkins PL Harwalkar S Madhun Z Almhanna K Mattera R 《Journal of neurochemistry》2000,75(6):2316-2326
Immortalized rat Schwann cells (iSC) express endothelin (ET) receptors coupled to inhibition of adenylyl cyclase and stimulation of phospholipase C (PLC). These effects precede phenotypic changes and increased DNA synthesis. We have investigated the role of ETs in the regulation of arachidonic acid (AA) release and mitogen-activated protein kinases (MAPKs). Both ET-1 and ET-3 increased AA release in iSC. This effect was sensitive to the phospholipase A(2) (PLA(2)) inhibitors E:-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H:-pyran-2-one and arachidonyl-trifluoromethyl ketone but was insensitive to inhibitors of PLC or phospholipase D-dependent diacylglycerol generation. ET-1-dependent AA release was also unaffected by removal of extracellular Ca(2+) and blocking the concomitant elevation in [Ca(2+)](i), consistent with participation of a Ca(2+)-independent PLA(2). Treatment of iSC with ETs also resulted in activation of extracellular signal-regulated kinase, c-Jun-NH(2)-terminal kinase (JNK), and p38 MAPK. A cause-effect relationship between agonist-dependent AA release and stimulation of MAPKs, but not the opposite, was suggested by activation of JNK by exogenous AA and by the observation that inhibition of MAPK kinase or p38 MAPK was inconsequential to ET-1-induced AA release. Similar effects of ETs on AA release and MAPK activity were observed in cultures expanded from primary SC and in iSC. Regulation of these effectors may mediate the control of proliferation and differentiation of SC by ETs during peripheral nerve development and regeneration. 相似文献
8.
Reed G Cefaratti C Berti-Mattera LN Romani A 《Journal of cellular biochemistry》2008,104(3):1034-1053
Serum and tissue Mg(2+) content are markedly decreased in diabetic patients and animals. At the tissue level, Mg(2+) loss progresses over time and affects predominantly heart, liver and skeletal muscles. In the present study, alterations in Mg(2+) homeostasis and transport in diabetic cardiac ventricular myocytes were evaluated. Cardiac tissue and isolated cardiac ventricular myocytes from diabetic animals displayed a decrease in total Mg(2+) content that affected all cellular compartments. This decrease was associated with a marked reduction in cellular protein and ATP content. Diabetic ventricular myocytes were unable to mobilize Mg(2+) following beta-adrenergic receptor stimulation or addition of cell permeant cyclic-AMP. Sarcolemma vesicles purified from diabetic animals, however, transported Mg(2+) normally as compared to vesicles from non-diabetic animals. Treatment of diabetic animals with exogenous insulin for 2 weeks restored ATP and protein levels as well as Mg(2+) homeostasis and transport to levels comparable to those observed in non-diabetic animals. These results suggest that in diabetic cardiac cells Mg(2+) homeostasis and extrusion via beta-adrenergic/cAMP signaling are markedly affected by the concomitant decrease in protein and ATP content. As Mg(2+) regulates numerous cellular enzymes and functions, including protein synthesis, these results provide a new rationale to interpret some aspects of the cardiac dysfunctions observed under diabetic conditions. 相似文献
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Pamela Orjuela-Sánchez Nadira D Karunaweera Mônica da Silva-Nunes Natal S da Silva Kézia KG Scopel Raquel M Gonçalves Chanaki Amaratunga Juliana M Sá Duong Socheat Rick M Fairhust Sharmini Gunawardena Thuraisamy Thavakodirasah Gawrie LN Galapaththy Rabindra Abeysinghe Fumihiko Kawamoto Dyann F Wirth Marcelo U Ferreira 《BMC genetics》2010,11(1):65