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1.
Batch ethanol fermentation by cells of Zymomomas mobilis ATCC 29191, ionically adsorbed on a DEAE-cellulose ion exchanger, was investigated in a stirred fermentor. Adsorption isotherms in different media were determined and used to interpret the effects of the environment on cell immobilization. Other factors affecting cell immobilization during an actual fermentation were studied. Mechanical agitation was found to cause detachment of cells from the ion exchange particles. The results suggest that the amount of cells adsorbed during a fermentation process is different from that found from adsorption isotherm data. Consequently, application of equilibrium adsorption data to actual fermentations should be done with caution. 相似文献
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Endothelial cells in culture synthesize the growth factors transforming growth factor beta (TGF-beta), basic fibroblast growth factor (bFGF), platelet derived growth factor (PDGF) and, perhaps, insulin like growth factor I (IGF-I). We have previously demonstrated that IGF-I and PDGF have both high affinity receptors and stimulate glucose and AIB uptake in the microvessel cells under study and that IGF-I, but not PDGF, has similar high affinity receptors in cultured large vessel endothelial cells. In the present study, cultured bovine endothelial cells were exposed to these four growth factors to determine a) their effects on the acute metabolic processes of neutral amino acid (AIB) and glucose uptake and b) their interactions at the endothelial cell surface. In microvessel endothelial cells, each growth factor stimulated AIB and glucose uptake 2-4 fold whereas in large vessel endothelial cells only bFGF stimulated glucose uptake. Each growth factor had specific high affinity binding to the microvessel cells that was not influenced by the presence of the other growth factors. In large vessel endothelial cells, similar high affinity binding was present only for IGF-I and to a lesser degree TGF-beta. When cells were exposed to a given growth factor for 18 hours, homologous receptor downregulation was observed, with a maximal 60-95% decrease in surface binding. These findings suggest several potential levels of interaction of the growth factors TGF-beta, bFGF, PDGF and IGF-I in cultured vascular endothelial cells. 相似文献
5.
P Gauduchon E Bar D Barbé J F Héron J Y Le Tala?r 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1985,300(12):453-456
Chromatofocusing is used to separate the multiple isoenzyme forms of human serum galactosyltransferase. At least 11 major peaks of activity are observed in normal sera, which are eluted between pH 4.3 and 6.9; a fraction of activity is eluted above pH 7.0. The normal patterns are compared with those obtained with sera from cancer patients and with an ascitic fluid. Chromatofocusing appears as resolutive as agarose isoelectric focusing. 相似文献
6.
Pteroptrix smithi (Compere) is a gregarious internal parasite of the diaspine scaleChrysomphalus aonidum. During the last few years, both host and parasite were mass reared in the laboratory on squash fruits. Releases were made in scaleinfested citrus orchards that were not reached by the parasite’s natural spread. Parasites were recovered from many of the release sites. 相似文献
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Raphael Bar 《Applied microbiology and biotechnology》1990,32(4):470-472
Summary Inclusion of cyclodextrins into an agar gel enabled a homogenous incorporation of water-immiscible lipophilic organic liquids and solids as substrates for surface microbial growth or conversion. Surface cultivation ofCandida lipolytica andC. tropicalis was demonstrated in and-cyclodextrin/hexadecane-agar media. 相似文献
8.
E. Yefenof I. Gafanovitch E. Oron M. Bar E. Klein 《Cancer immunology, immunotherapy : CII》1996,41(6):389-396
Polysaccharide K (PSK) is a biological response modifier used for adjuvant immunotherapy of malignant diseases. We studied the potential applicability of PSK for preventing tumor progression using an experimental model of murine lymphoma. Mice inoculated with the radiation leukemia virus (RadLV) develop thymic lymphomas after a latency of 3–6 months. However, 2 weeks after virus inoculation, prelymphoma cells can already be detected in the thymus. We found that PSK treatment induced hyperresponsiveness to concanavalin A and heightened production of interleukin-2 (IL-2) and IL-4 in spleen cells of both control and prelymphoma mice. The response was transient and was accompanied with a dominant usage of T cells expressing V8, but other T cell subsets were also stimulated by PSK. T lymphoma cells expressing V8.2 underwent apoptosis when incubated with PSK. Treatment of RadLV-inoculated mice with PSK delayed the onset of overt lymphoma (and mortality) but could not protect the mice from the disease. Combined treatment with PSK and a RadLV-specific immunotoxin prevented synergistically the progression of the prelymphoma cells to frank lymphoma. The results suggest that PSK contains a superantigen-like component that selectively activates V8+ T cells. Its administration prelymphoma mice interfered with the process of lymphoma progression. 相似文献
9.
The enzyme adenosine deaminase (adenosine aminohydrolase EC 3.5.4.4) from calf intestinal mucosa is commercially available at high purity grade yet, at the sensitivity at which fluorescence studies may be undertaken, a nonpeptidic fluorescence is detectable at lambda exmax = 350 nm and lambda emmax = 420 nm. A sevenfold decrease of this nonpeptidic fluorescence was obtained upon irradiation by the third harmonic (355 nm) of a Nd:YAG laser for 16 min, at 5 mJ/pulse, with a pulse width of 6 ns at a repetition rate of 10 Hz. The decline of fluorescence was accompanied by a negligible loss of enzymatic activity. Moreover, the integrity of the protein was ascertained by (i) its fluorescence (lambda exmax = 305 nm, lambda emmax = 335 nm) and lifetime distribution and (ii) its kinetics in the presence of the substrate adenosine and two inhibitors, all of which remained essentially unaltered. Laser photobleaching is a simple way to achieve a fluorescence grade adenosine deaminase. 相似文献
10.
P Baráth I Strausz E Kékes A Szántó 《Acta physiologica Academiae Scientiarum Hungaricae》1979,53(3):311-322
The regional decrease of the speed and extent of the contraction and the relaxation of the canine myocardium induced by coronary ligation was enhanced by intravenously administered nitroglycerin (GTN), simultaneously with the decrease of the left ventricular pressure, while the increase of myocardial fiber length caused by that procedure was partly abolished. The above changes could be reproduced by GTN applied directly onto the ischaemic myocardial surface even before the decrease of the left ventricular pressure. These changes induced by GTN might play a role in the decrease or abolishment of regional asynergic wall motion. 相似文献