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331.
Stephanie Gordon Phillips Shiu-Lan Lui David M. Phillips 《In vitro cellular & developmental biology. Plant》1982,18(8):727-738
Summary Epithelial cells may relate to their basement membrane substrates via lectin-like interactions. In a model system for study
of this type of interaction, lectin-coated bacteriological plastic petri dishes were presented as substrates for epithelial
cell adhesion. Of 21 lectins tested by mixed agglutination against two epithelial cell types, Madin-Darby canine kidney (MDCK),
and human embryonic kidney cells (HEK), nine gave less than 5% rosettes and 12 gave 5 to 50% rosettes. Wheat germ agglutinin
(WGA) andGeodia cydonium lectin gave the highest percentage of rosettes. Wheat germ agglutinin was readily adsorbed to plastic surfaces and maintained
specificity in binding interactions. Both MDCK and HEK cells attached as well to WGA coated petri dishes as to conventional
tissue culture dishes. Furthermore, both spread over the lectin-coated surfaces. The MDCK cells grew to confluence and could
be subcultured and maintained indefinitely on such surfaces, although WGA in solution was toxic to the cells in concentrations
as low as 0.1 to 1.0 μg/ml. Cell attachment to WGA coated dishes was blocked by cycloheximide only if the cells had been preincubated
with the inhibitor for several hours. Cell attachment was not inhibited by pretreatment of cells with neuraminidase. Precoating
cells with WGA blocked binding to both WGA-coated surfaces and untreated tissue culture dishes. Cells attached to WGA-coated
dishes could not be readily dislodged by trypsin-EDTA for the first 2 h after subculture. By 4 h, attachment was again trypsin
sensitive, suggesting that the cells synthesized a trypsin-sensitive material that was laid down between the cell surface
and the WGA-coated dish. Regeneration of trypsin sensitivity was not blocked by cycloheximide.
This work was supported by Research Grant AG01986 from the National Institutes of Health, Bethesda, Maryland. 相似文献
332.
David End Nathaniel Tolson Mei-Ying Yu Gordon Guroff 《Journal of cellular physiology》1982,111(2):140-148
The phorbol ester tumor promoter 12-0-tetradecanoylphorbol-13-acetate (TPA) specifically inhibited the binding of radioiodinated epidermal growth factor (125I-EGF) to rat pheochromocytoma (PC12) cells in a noncompetitive fashion with an apparent Ki of 11–26 nM. Both TPA and EGF elicited similar biological responses in PC12 cells including enhanced incorporation of 3H-choline and 32P-orthophosphate into macromolecules, induction of ornithine decarboxylase, and stimulation of the phosphorylation of a 30,000 MW nonhistone, chromosome-associated protein. These effects were also elicited by nerve growth factor (NGF) which, in contrast to the former agents, is a differentiating stimulus for the PC12 cells. The effects of TPA were additive or more than additive to the effects of NGF and EGF. When PC12 cells were induced to differentiate by treatment with NGF for 72 hours, the binding of 125I-EGF and responses to EGF were reduced by approximately 70%. The response of PC12 cells to the tumor promoter TPA was unaffected by treatment with NGF. Thus, the qualitatively similar effects of TPA and EGF seemed to be mediated through separate receptor systems with only the EGF receptor system reduced by NGF treatment. 相似文献
333.
Effects of isolation and culture on prostaglandin synthesis by porcine aortic endothelial and smooth muscle cells 总被引:10,自引:0,他引:10
A Ager J L Gordon S Moncada J D Pearson J A Salmon M A Trevethick 《Journal of cellular physiology》1982,110(1):9-16
Freshly isolated neonatal porcine aortic tissue (smooth muscle with or without endothelium present) produced approximately 30 ng/mg wet tissue of 6-oxo-prostaglandin F1 alpha (the stable hydrolysis product from prostacyclin) and approximately 15 ng/mg of prostaglandin E2, as measured by radioimmunoassay after 24 h incubation in culture medium. Primary cultures of porcine endothelial and smooth muscle cells (isolated by enzymic digestion of aortic tissue) exhibited the same pattern of prostaglandin production, but absolute values were greater than for fresh tissue, particularly in the case of endothelium. Subcultures of endothelium produced smaller amounts of prostaglandins, although the pattern remained similar. In contrast, subcultures of smooth muscle cells produced a greater total amount of prostaglandins than did primary cultures, and the main product was prostaglandin E2. Experiments with [14C] prostaglandin H2 or [14C]arachidonic acid confirmed that aortic tissue, cultured endothelium, and primary cultures or aortic smooth muscle cells synthesized prostacyclin, and demonstrated that subcultured smooth muscle cells enzymically isomerised prostaglandin H2 to prostaglandin E2. Kinetic studies showed that prostaglandin production by cultured vascular cells was transiently increased by subculture or changing the growth medium, and that production per cell declined with increasing cell density. The change in pattern of prostaglandin production during culture was shown to be due to a rapid decline in the rate of prostacyclin production (which apparently began immediately after tissue isolation), together with a more gradual rise in prostaglandin E2 production. These results indicate that the amounts and ratios of prostaglandins produced by vascular endothelial and smooth muscle cells are greatly affected by the conditions used to isolate and culture the cells; vascular cells in vivo may similarly alter their pattern of prostaglandin production in response to local changes in their environment. 相似文献
334.
Mg2+ - or Ca2+ -Activated ATPase in Squid Giant Fiber Axoplasm 总被引:1,自引:0,他引:1
A divalent cation-activated ATPase in axoplasm from the squid giant axon is described. The enzyme requires Mg2+ or Ca2+, has a K+ optimum of 60 mM, and has a pH optimum of 7.5. Several nucleotide triphosphates other than ATP can serve as substrates. The enzyme is inhibited by excess ATP or Mg2+. The enzyme is enriched in a rapidly sedimenting fraction of the axoplasm, and is eluted in the exclusion volume of a Sepharose 4B column, suggesting that it is associated with a highly aggregated structure. Comparison of the properties of enzyme with those of myosin and Na+-K+-ATPase suggests that differs from both of these enzymes. The enzyme has many similarities to vertebrate nerve ATPases previously described. The demonstration of the presence of this ATPase in squid axoplasm proves the neuronal localization of the enzyme. 相似文献
335.
A mathematical model of body fluid volume and osmolality regulation was developed which incorporated the major nonlinearities of fluid assimilation, exchange, distribution and excretion. The non-linear differential equations define compartmental material balances for water, urea, sodium, protein and antidiuretic hormone (ADH). The parameters of these equations were calculated using analytical solutions and available steady-state experimental data. The model was used to simulate the renal response to five input forcings: (1) intraesophageal water infusion; (2) water ingestion; (3) intravenous ADH injection; (4) intravenous water infusion; and (5) intermittent water loading. The model yielded continuous simulation curves which agreed reasonably well with the available transient and steady-state experimental data. The model predicted that stimulating volume receptors via changes in left atrial pressure accounts for only 15–20% of changes in ADH secretion rate, whereas stimulation of the osmotic receptors via changes in plasma osmolality accounts for the remaining 80–85% of changes. Thus, it appears that regulation of ADH secretion is largely dependent upon plasma osmolality during forcings which do not appreciably alter the cardiovascular blood volume. 相似文献
336.
Lectin histochemistry of human skeletal muscle 总被引:3,自引:0,他引:3
S D Pena B B Gordon G Karpati S Carpenter 《The journal of histochemistry and cytochemistry》1981,29(4):542-546
Biotinyl derivatives of seven plant lectins-concanavalin A (Con A), peanut agglutinin (PNA), Ricinus communis agglutinin I (RCA I), Ulex europeus agglutinin I (UEA I), soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA), and wheat germ agglutinin (WGA)-were bound to cryostat sections of biopsied normal human muscle and visualized with avidin-horseradish peroxidase conjugates. A distinct staining pattern was observed with each lectin. The most general staining was observed with Con A, RCA I, and WGA, which permitted strong visualization of the plasmalemma-basement membrane unit, tubular profiles in the interior of muscle fibers, blood vessels, and connective tissue. PNA gave virtually no intracellular staining, while SBA and UEA I selectively stained blood vessels. DBA was unique in providing good visualization of myonuclei. In each case, lectin staining could be blocked by appropriate sugar inhibitors. Neuraminidase pretreatment of the cryostat sections altered the pattern of staining by all lectins except UEA I and Con A; staining with RCA I became stronger and that with WGA became less intense, while staining with PNA, SBA and DBA became stronger and more generalized, resembling that of RCA I. These effects of neuraminidase pretreatment are in conformity with the known structure of the oligosaccharide chains of membrane glycoproteins and specificities of the lectins involved. 相似文献
337.
The Receptor-Mediated Activation of Tyrosine Hydroxylation in the Superior Cervical Ganglion of the Rat 总被引:10,自引:5,他引:5
Takeyuki Ikeno Geneva Dickens Tom Lloyd Gordon Guroff 《Journal of neurochemistry》1981,36(5):1632-1640
The addition of carbachol to superior cervical ganglia causes a rapid increase in tyrosine hydroxylation in situ. The increase occurs in ganglia from both newborn and adult animals, and in ganglia from animals pretreated with reserpine. The increase is not due to increased transport of the substrate. The increase is dependent upon the presence of calcium, and is additive to the stimulation produced by dibutyryl cyclic AMP. The stimulation seems specific for tyrosine hydroxylation; dopamine beta-hydroxylation is not increased. Preincubation experiments suggest that the carbachol-induced stimulation is due to a change in the availability of, or the affinity of the enzyme for, reduced pterin cofactor. The stimulation is inhibited by atropine and also by low concentrations of phenoxybenzamine or haloperidol, which suggests that it is caused by an action of carbachol on the interneurons in the ganglia. 相似文献
338.
incubation studies using fluoride and iodoacetate as glycolytic inhibitors have been carried out on red cells of the two subjects with adenosine deaminase deficiency. For comparison, similar studies have also been carried out on red cells from a normal subject and from a child with severe combined immunodeficiency with normal adenosine deaminase activity. The adenosine formed in the adenosine deaminase deficient red cells is a measure of adenosine 5′-phosphate breakdown initiated by 5′-nucleotidase, whereas inosine 5′-phosphate, inosine and hypoxanthine formation is a measure of adenosine 5′-phosphate breakdown initiated by adenylate deaminase. With fluoride as inhibitor, nearly all of the adenosine 5′-phosphate breakdown proceeded by way of adenylate deaminase, while with iodoacetate as inhibitor, 20–30% of the adenosine 5′-phosphate breakdown was initiated by 5′-nucleotidase acting on adenosine 5′-phosphate. In addition, significant amounts of adenine were produced in adenosine deaminase deficient red cells in the presence of the glycolytic inhibitors. Possible explanations for the findings noted in this study are discussed and related to recent studies on the properties of the pertinent purine nucleotide catabolic enzymes. 相似文献
339.
J E Morley T Yamada J H Walsh C B Lamers H Wong A Shulkes D A Damassa J Gordon H E Carlson J M Hershman 《Life sciences》1980,26(26):2239-2244
This study demonstrates that, during morphine addiction and withdrawal in rats profound alterations in the concentrations of a variety of brain peptides occur. Somatostatin, cholecystokinin, neurotensin and substance P concentrations increased during morphine addiction. Naloxone-induced withdrawal decreased brain concentrations of TRH, somatostatin, neurotensin and substance P. Naloxone alone decreased thalamic substance P and neurotensin concentrations. Vasoactive intestinal peptide concentrations were unaltered by any of the treatments. The fall in the tissue concentration of somatostatin during naloxone-induced withdrawal correlated well with the fall in the circulating growth hormone, suggesting that this could be secondary to somatostatin release. Our data support the hypothesis that brain peptides, acting locally in the brain as neuromodulators, play an important role in the genesis of the syndromes of morphine addiction and withdrawal. 相似文献
340.