Activity levels of 7-ethoxycoumarin O-deethylase (ED), aminopyrine N-demethylase (APD), p-nitroanisoleO-demethylase (p-NAD) and glucose-6-phosphate dehydrogenase (G-6-PDH) were determined in incubation mixtures for the liver-microsomal assay (LMA) at time 0 and after 1 and 2 h incubation under conditions for mutagenic assay. The experiments were performed with S9 liver fractions from mice (induced with Na-phenobarbital and β-naphthoflavone) and rats (induced with Aroclor 1254) with and without G-6-PDH in the incubation mixtures.
In the absence of G-6-PDH the activities were significantly lower at time 0 in the mouse. The pattern of stability, however, was similar for the activities, with an increase of stability after 1 and 2 h of pre-incubation (an exception for p-NAD).
Only ED activity showed a similar behaviour in the rat. No differences were present for APD and p-NAD activities at time 0 in the rat, but the enzyme stabilities were significantly decreased after 2 h of incubation (about 15% and 10% for APD and p-NAD respectively) in the absence of G-6-PDH.
At time 0, the amounts of G-6-PDH differed between mouse and rat fractions; however, during the incubations for LMA they decreased by about 57% and 53% for the two species, respectively. In addition to the above biochemical results, the presence of exogenous G-6-PDH in the incubations for the mutagenic assay, significantly increased the mitotic gene conversion and mitotic crossing-over of dimethylnitrosamine (DMN) and AR2MNFN (a nitroimidazo[2,1-b]thiazole) in the D7 strain of Saccharomyces cerevisiae. 相似文献
Immunoaffinity purified Sm/RNP antigens from buffalo and goat liver were studied to determine the role of RNA and proteins
towards the antigenicity of Sm and RNP antigens. A more direct approach using enzyme-linked immunosorbent assay on nylon beads
has been utilized to look into the problem. The effect of enzyme treatment and the role of RNA and protein fractions in influencing
antigenicity have been described. RNA seems to be involved in the maintenance of RNP specific polypeptides in suitable conformation
so as to keep them in solution. Removal of RNA leads to insolubilization of RNP specific polypeptides. Antibodies to Sm and
RNP antigens have been shown to cross react with poly A containing heterogeneous nuclear ribonucleoprotein with no cross reactivity
with thymus RNA or DNA. 相似文献
The observations that liveMycobacterium leprae after entry into cultured peritoneal macrophages from mice, reduced the EA rosetting macrophages, have been exploited to
determine the minimum inhibitory concentration of diamino diphenyl sulphone and rifampicin. Diamino diphenyl sulphone showed
a minimum inhibitory concentration of 0.028 μg/ml and rifampicin 0.11μg/ml when given externally. However, there was accumulation of diamino diphenyl sulphone inside the macrophages. At an external
concentration of 0.028 μg/ml the concentration inside the macrophage was 0.5μg/ml. The minimum inhibitory concentration for diamino diphenyl sulphone in this assay system is higher by several folds and
that for rifampicin is slightly lower, than what is reported earlier with mice foot pad experiments. The minimum inhibitory
concentration reported in this assay system is quite close to what is observed forin vitro inhibition ofMycobacterium lufu with both the drugs 相似文献
Using a specific radioimmunoassay for gonadotropin releasing hormone, the presence of gonadotropin releasing hormone like
material in the first trimester human placenta has been demonstrated. The material has been partially characterized using
carboxy methyl cellulose chromatography, high pressure gel permeation chromatography and reverse phase C18 high pressure liquid
chromatographic analysis. Analysis for bioactivity revealed that placental gonadotropin releasing hormone is much more active
than synthetic gonadotropin releasing hormone inin vitro rat pituitary lutinising hormone release assay.In vitro biosynthetic studies using labelled precursors and immunoaffinity chromatography indicated that first trimester human placenta
synthesizes gonadotropin releasing hormone like material. 相似文献
Monoclonal antibodies were prepared against two species of Methanomicrobiaceae. Antibody 1A is specific for Methanospirillum hungatei strain JF1 and the determinant it recognizes is expressed on the surface of JF1 cells, where it is exposed and accessible to antibody. The determinant is found in a polypeptide (MW<12,000) in the sheath that covers the bacterial cell; it is not present in Methanospirillum hungatei strain GP1; and it is not expressed on the surface of whole cells of the other 24 methanogenic bacteria tested. It is therefore a marker of strain JF1, consequently, antibody 1A is potentially useful for tracking JF1 and fragments thereof in a variety of samples. Antibody 7A is specific for Methanogenium cariaci JR1c. It did not react with any other methanogen tested, not even with Mg. marisnigri or Ms. hungatei JF1, although these cross-react with Mg. cariaci if tested with polyclonal antisera. Therefore antibody 7A recognizes specifically a marker of Mg. cariaci JR1c.Abbreviations SIA
slide immunoenzymatic assay
- SDS-PAGE
sodium dodecylsulfate polyacrylamide gel electrophoresis 相似文献
Seven antischistosomal drugs, two antimalarial drugs, and one antiamoebic drug were tested in all five Ames strains for induction of mutation, as well as for induction of cytotoxicity, inhibition of cellular progression, and the induction of sister chromatid exchanges in two cultured mammalian cell lines. We found that two agents shown to be negative in the Ames test were positive for sister chromatid exchange induction. Based on qualitative and quantitative evaluation, we find that all but three of the pharmaceuticals should be considered to be potential human carcinogens.Abbreviations AA
2-aminoanthracene
- 9AACC
9-aminoacridine
- AM
amoscanate
- BrdUU
bromodeoxyuridine
- CA
chloroquine diphosphate
- CHO
Chinese hamster ovary
- CQ
chloroquine
- DAPI
46-diamidino-2-phenylindole
- DHY
dehydroemetine
- DMSO
dimethyl sulfoxide
- EB
ethidium bromide
- FCS
fetal calf serum
- FN
4-fluoro-3-nitrophenyl azide
- HY
hycanthone
- ICP
inhibiting cell progression
- LU
lucanthone
- MEM
minimal essential medium
- 2NF
2-nitrofurantoin
- 4NPD
4-nitro-O-phenylenediamine
- NZ
niridazole
- OL
oltipraz
- OX
oxaminiquine
- PBS
phosphate buffered saline
- PQ
primaquine
- PZ
praziquantel
- SA
sodium azide
- SCE
sister chromatid exchange 相似文献
The reduction of ferric iron from microbial iron-binding compounds (siderophores) releases the iron from the siderophore so that it may be utilized by the microorganism. A method to detect aerobic ferrisiderophore reductase activity using ferrozine as a ferrous iron trap is shown to be applicable to cytoplasmic fractions from Rhodopseudomonas sphaeroides and four other different species of bacteria. The ferrisiderophore reductase uses reduced nicotinamide cofactors as reducing agents, and activity is stimulated by flavins. This assay has been adapted as a staining method to locate ferrisiderophore reductase activity in native polyacrylamide gels. 相似文献
Pores formed in the membranes of animal cells by complexes of sterols and the polyene antibiotic amphotericin B can efficiently kill the cells. Thus, in the absence of exogenous sources of cholesterol, inhibitors of enzymes in the cholesterol biosynthetic pathway render cells resistant to amphotericin B. Preincubation of Chinese hamster ovary cells with compactin or 25-hydroxycholesterol, inhibitors of the synthesis of the key intermediate mevalonate, protected cells from amphotericin B killing and this protection was reversed by the addition of exogenous mevalonate. The ability of compactin to confer amphotericin B resistance on normal cells was abolished when cells were provided exogenous cholesterol by the receptor-mediated endocytosis of low density lipoprotein. Low density lipoprotein receptor-defective Chinese hamster ovary cells were not subject to this low density lipoprotein-dependent amphotericin B killing. Exogenous mevalonate did not prevent 4,4,10 beta-trimethyl-trans-decal-3 beta-ol, an inhibitor of mevalonate conversion to sterols, from protecting cells from amphotericin B. A simple two-step protocol in which cells are preincubated (15-24 h) with potential inhibitors and then treated (3-6 h) with amphotericin B was devised to provide a sensitive method for detecting direct (e.g., competitive) and regulatory inhibitors of cholesterol biosynthesis. This protocol may prove useful in detecting potential antihypercholesterolemia drugs and is currently being used to isolate mutants in receptor-mediated endocytosis. 相似文献