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121.
122.
Vanillic, syringic, gallic, and protocatechuic acids, methyl-p-hydroxybenzoate, and propyl-p-hydroxybenzoate generally inhibited respiration in vitro of Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, and Aerobacter aerogenes in human urine. In the absence of any other available carbon source, certain of the phenolic compounds were utilized. Reproduction was generally suppressed in urine buffered to pH 7, 5.6, 4.5, and 4.0. The phenolic compounds were used in the range of 0.11 to 0.99 μmole/ml. 相似文献
123.
Cultures of gram-negative bacteria with oxidative glucose metabolism were isolated from surface waters by a highly selective technique, and were classified into 11 types. The predominant type, making up about 50% of the isolated cultures, was cytochrome oxidase-positive, produced fluorescent pigment, and failed to grow at 37 C. A similar type, which differed in being cytochrome oxidase-negative, constituted about 10% of the isolates. Both types of bacteria probably were composed of more than one species. A third type, composed of purple-pigmented pseudomonads, made up approximately 30% of the isolated cultures, and probably represented the predominant species. Other bacterial types isolated constituted less than 10% of the cultures examined. 相似文献
124.
125.
The linkage between the polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei 总被引:14,自引:8,他引:6 下载免费PDF全文
1. The linkage between the polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei is rapidly hydrolysed under mild acid-hydrolysis conditions. 2. The release of the polysaccharide is accompanied by the hydrolysis of an N-acetylhexosaminide linkage. The N-acetylhexosamine residue readily forms chromogen and it is concluded that it is substituted on C(3) by the adjacent sugar. 3. Continued heating of the polysaccharide in acid results in a slower release of reactive N-acetylhexosamine due to the hydrolysis of glycosidic linkages within the polysaccharide. 4. After the linkage between the polysaccharide and mucopeptide has been hydrolysed, acid phosphatase will release approx. 40% of the total phosphorus as inorganic phosphate. 5. It is concluded that the polysaccharide component of the cell wall is joined through its reducing end group to a phosphate grouping in the mucopeptide. 相似文献
126.
Elizabeth B. Gargus Douglas H. Robinson James K. Bubien Lawrence B. Bugaisky Dale J. Benos 《In vitro cellular & developmental biology. Plant》1989,25(5):435-441
Summary Six- and seven-day post-coitus (p.c.) rabbit embryos have been cultured in an attempt to establish a trophectodermal cell
line. Results indicate that cells with epithelial characteristics (i.e. positive staining for cytokeratin) will survive in
culture until Passage 3. At that time a fibroblastlike cell becomes predominant. In addition, we have found that the presence
of the inner cell mass is required for embryo explants often results in the development of cells that spontaneously contract.
These cells stain positively for myosin, which indicates that they may be precardiac cells. Maximum diastolic potential was
−59±1.2 mV and the threshold potential was −53±2.3 mV. Spontaneously contracting cells did not respond to atropine, acetylcholine,
epinephrine, isoproterenol, or propranolol. Action potential seems to be a result of an inward calcium current, because the
beating rate is decreased in a dose-related manner with the calcium channel blocker verapamil, whereas the voltage-sensitive
sodium channel blocker tetrodotoxin was without effect.
This work was supported by grants HD21302, HD07069, DK31091, and HL37320 from the National Institutes of Health, Bethesda,
MD, with additional support from a University of Alabama at Birmingham Cardviovascular Research and Training Center Award. 相似文献
127.
The production and characteristics of a compound in Proteus vulgaris G cultures which was capable of inhibiting Vibrio parahaemolyticus and other food-borne pathogens was investigated. Production was influenced by medium composition, pH and temperature but not by the extent of aeration. The compound was most inhibitory at the optimum temperature for growth of V. parahaemolyticus. The inhibitor was most stable at pH 7·0 and inhibition occurred even after heating at 70°C for 30 min and after autoclaving. Ultrafiltration showed that the inhibitor had a molecular weight less than 1000. Thin layer chromatography of filtrates and subsequent peptidase digestion indicated that it was at least in part a peptide. The inhibitor purified by Sephadex G-15 gel filtration had a calculated molecular weight of 731 and contained only six amino acids. 相似文献
128.
129.
Eugene L. Passer Rudean H. Leinaeng Lennel W. Birmingham Hector Cruz Chantale Dupervil Elizabeth J. Persaud Emil P. Dolensek 《Zoo biology》1989,8(4):357-365
This research determined the relationships between blood lead level and zinc protoporphyrin (ZnPROTO), protoporphyrin IX (PROTO), and free erythrocyte protoporphyrin (FEP) levels in a group of 18 ring teal ducks. Blood samples were drawn from two groups of ring teal ducks as part of the routine health maintenance program of the New York Zoological Park. One group of six teals had been exposed to what is believed to be lead-contaminated dust, while the second group of twelve teals was unexposed. Blood samples were analyzed for lead by flameless atomic absorption and for protoporphyrins by fluorescence. Blood lead level and log blood lead level had positive correlations with each of the protoporphyrins: the logarithmic correlations were better than the nonlogarithmic correlations, and PROTO correlated better than ZnPROTO. With one exception, PROTO levels were higher than ZnPROTO levels. The results suggest that PROTO, FEP, or ZnPROTO could serve as a biological indicator of lead poisoning in ring teal ducks. 相似文献
130.
Charles F. Aylsworth James E. Trosko Chia C. Chang K. Benjamin Elizabeth Lockwood 《Cell biology and toxicology》1989,5(1):27-37
The effects of TPA and/or DDT and oleic acid and/or DDT on gap junction-mediated intercellular communication (i.e. metabolic cooperation) between Chinese hamster V79 cells was examined. Addition of TPA, DDT or oleic acid alone to cocultures of 6t-hioguanine-resistant (6-TG
R
) and 6-thioguanine-sensitive (6-TG
S
) V79 cells significantly increased the recovery of 6-TG
R
cells indicating inhibition of metabolic cooperation. In the presence of TPA and DDT or oleic acid and DDT the observed recovery of 6-TG
R
cells was significantly greater than the expected (calculated) additive 6-TG
R
cell recovery. No synergistic increases in 6-TG
R
cell recovery were observed when co-cultures of V79 cells were exposed to dieldrin and DDT. These results indicate that TPA and DDT or oleic acid and DDT can act synergistically to inhibit metabolic cooperation. These data suggest a role for protein kinase C in the regulation of gap junction-mediated intercellular communication.Abbreviations DDT
dichlorodiphenyltrichlorethane
- MC
metabolic cooperation defective
- 6-TG
6thioguanine
- TPA
12-0-tetradecanoylphorbol-13-acetate 相似文献