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41.
1. The trans-epoxide of diethylstilboestrol and its pinacolone were synthesized chemically and the pinacolone shown to be formed from the epoxide by a non-enzymic process. 2. [14C]Diethylstiboestrol epoxide was converted by rat liver microsomal fraction into 4'-hydroxypropiophenone by a new type of cleavage reaction involving mono-oxygenase. Conditions for the formation of this metabolite and also water-soluble products were investigated together with the effect of inhibitors. A sex-difference in the conversion of diethylstilboestrol epoxide into 4'-hydroxypropiophenone and to polar and water-soluble products was observed. 3. Diethylstilboestrol epoxide was found to be a relatively stable compound that did not form a glutathione conjugate readily without further microsomal activation. A purified preparation of epoxide hydratase did not enhance its rate of conversion into the pinacolone. 4. Diethylstilboestrol epoxide was found to have about one-tenth the oestrogenic activity of diethylstilboestrol as measured by the increase in uterine weight or the induction of peroxidase in immature rat uteri. It was inactive as a mutagen when tested for its ability to inhibit bacteriophage phi X174 DNA viral replication. 5. The possible role of diethylstilboestrol epoxide as an intermediate in the metabolism of diethylstilboestrol and in mediating the harmful effects of this synthetic estrogen is discussed. 相似文献
42.
B C Bowen 《Nucleic acids research》1981,9(19):5093-5108
Following extensive digestion of HeLa metaphase chromosomes with either Hae III endonuclease or micrococcal nuclease, nonhistone protein scaffolds may be isolated. Scaffolds isolated after Hae III digestion have about 1.5% of the chromosomal DNA attached to them. This DNA is heterogeneous in size, ranging from about 0.2 to 20 kbp. It can be cleaved with either Eco RI or Hae III - Eco RI, producing a series of repeated fragments, of which the most abundant is 1.7 kbp in length. The 1.7-kdp fragment is tandemly repeated and is enriched (about 50-fold) in the scaffold-associated DNA. It is located primarily on human chromosome 1 and is probably a component of human satellites II and III. Scaffolds isolated after micrococcal nuclease digestion have about 0.1% of chromosomal DNA attached. This DNA is present in two size classes - fragments larger than 10 kbp and fragments approximately 0.2 kbp long. Restriction enzyme digestion of this DNA gives no prominent repeated fragments. Its reassociation kinetics are similar to those of total DNA, indicating that it is not enriched in either highly repetitive or middle repetitive sequences. 相似文献
43.
Stanley A. Robrish Claes-Göran Emilson Christopher W. Kemp Doreen Eberlein William H. Bowen 《Current microbiology》1981,5(6):343-347
The effects of three antimicrobial agents on smooth surface dental plaque in monkeys were assessed using a plaque index, bacterial viable count, and adenine nucleotide analysis. The effects of the agents were revealed equally well when, viability was assayed by extractable adenosine triphosphate (ATP) or conventional viable cell counts. A persistent effect of one of the agents was revealed by both viable count and extractable ATP. These interpretations were supported by calculations of adenylate energy charge from the adenine nucleotide content of the smooth surface dental plaque samples. 相似文献
44.
45.
A. W. Procter† G. C. Stratmann P. T. Francis S. L. Lowe P. H. F. Bertolucci D. M. Bowen 《Journal of neurochemistry》1991,56(1):299-310
[3H]Glycine binding and glycine modulation of [3H]MK-801 binding have been used to study the glycine allosteric site associated with the N-methyl-D-aspartate receptor complex in postmortem human brain. The effect of glycine on [3H]MK-801 binding appeared sensitive to duration of terminal coma, and possibly postmortem delay. Thirty percent of the binding occurred in a subfraction of brain tissue and did not show enhancement by glycine and glutamic acid. [3H]Glycine binding to a subfraction free from this component was studied and showed high specific binding. KD and Bmax values showed considerable intersubject variability which did not appear to be due to demographic features or to tissue content of amino acids with an affinity for this site. The pharmacological characteristics of binding in this subfraction and a correlation between Bmax values and the maximal enhancement of [3H]MK-801 binding by glycine are consistent with [3H]glycine binding occurring to an N-methyl-D-aspartate receptor complex associated site. Further support for this is provided by a significantly lower Bmax value for [3H]glycine binding in subjects with Alzheimer's disease and reduced glycine enhancement of [3H]MK-801 binding. However, the effect of perimortem factors makes it difficult to confidently attribute this solely to a disease-related change in the receptor. The possible role of the glycine allosteric site in the treatment of neuropsychiatric disorders is discussed. 相似文献
46.
The effect of praziquantel on phosphoinositide turnover was examined in Schistosoma mansoni to determine if this anthelminthic modulates signal transduction pathways in parasites. Adult worms were radiolabeled with [3H]myoinositol for 24 hr and total inositol phosphate levels determined in the presence of praziquantel. Praziquantel inhibited inositol phosphate turnover when activated with NaF plus AlCl3 or with the nonhydrolyzable guanine nucleotide-binding protein analogue GTP gamma S. Furthermore, praziquantel decreased basal turnover of inositol phosphates. Inhibition was seen in both male and female worms as well as in schistosomula. These data indicate that inhibition of phosphoinositide turnover may contribute to the effect of praziquantel on parasite survival within the definitive host. 相似文献
47.
Visualization and solubilization of rat brain opiate receptors with a “κ” ligand selectivity pattern 总被引:2,自引:0,他引:2
Remi Quirion Wayne D. Bowen Miles Herkenham Candace B. Pert 《Cellular and molecular neurobiology》1982,2(4):333-346
1. Specific binding of [3H]ethylketocyclazocine (EkappaC), a prototype kappa-opiate agonist, to slide-mounted rat striatal sections is increased in the presence of 100 mM NaCl at 4 degrees C. 2. Under similar incubation conditions, binding of mu and delta prototype opiates is reduced to almost undetectable levels. 3. Correlation (P less than 0.01) of the ligand selectivity pattern of [3H]EKC displacement with the potencies of various opiate drugs in inhibiting the contractions of the rabbit vas deferens, a kappa-opiate receptor bioassay, suggests that the binding site under study represents the pharmacologically relevant kappa-opiate receptor. 4. Visualization of these kappa-opiate receptors with tritium-sensitive film reveals a striking, highly discrete brain distribution pattern (e.g., striatal patches, habenular stripe) which is similar to that of [3H]dihydromorphine and [3H]naloxone. 5. Soluble [3H]EKC binding sites obtained from rat membranes also possess a kappa-like ligand selectivity pattern, with bremazocine being a potent displacer while mu and delta ligands are almost inactive. 6. A possible explanation of these data is that the "kappa"-opiate binding site in rat brain is one transitional state of an opiate receptor capable of assuming distinct conformations with characteristic ligand selectivity patterns. Other possibilities such as pre and post-synaptic locations should also be considered. 相似文献
48.
Structure of Sendai viral proteins in plasma membranes of virus-infected cells. 总被引:6,自引:4,他引:2 下载免费PDF全文
Purified plasma membranes attached to polycationic polyacrylamide beads by their external surface were isolated from BHK cells infected with Sendai virus. Each of the viral proteins could be identified in the membranes of infected cells. Proteolysis with trypsin, which digests only the cytoplasmic surface of these membranes (because the external surface is protected by its attachment to beads), revealed that the internal proteins, L, P, NP, and M, were present on the cytoplasmic surface of the membrane and that small segments of the viral envelope glycoproteins, HN and F0, were partially exposed on the cytoplasmic surface. Since the major portions of HN and F0 are known to be present on the external membrane surface, these glycoproteins are transmembrane proteins before Sendai virus budding in infected cells. 相似文献
49.
Summary The fine structure of the pore cells in pre- and post-hatched Deroceras reticulatum is described. The cells have been divided into three main types on morphological grounds, one type being particularly rich in glycogen. Certain pore cells contain haemocyanin granules in grooves below cytoplasmic tongues, and in characteristic double-membrane-bounded vesicles within dilated cisternae of rough endoplasmic reticulum, as well as in other identified areas. All types of pore cells show fine fibres reminiscent of collagen associated with the basal lamina and pore complexes.In addition to acid phosphatase activity in lysosomes and Golgi elements, intra- and extracisternal activity has been demonstrated in association with the rough endoplasmic reticulum. The intracisternal activity is in close proximity to the Golgi apparatus and may represent enzyme that is about to enter the GERL system. Extracisternal activity may be associated with cellular lysis and death, or may represent local areas of degradation leading to cytodifferentiation. Remnants of lysed pore cells appear to be taken up by connective tissue amoebocytes.The authors wish to acknowledge the financial support of the Agricultural Research Council (G.B.) Grant No. AG 72/21, the photographic assistance of Mr. Nigel Green, and some technical assistance from Miss Jane Morgans 相似文献
50.
This study describes and quantifies the social organization and agonistic behaviour of adult male collared lemmings (Dicrostonyx groenlandicus) in an indoor enclosure. Five groups of four lemmings were observed during separate 8-day tests. Experimental design permitted an increase in group size while density remained constant. When in groups of two, males established stable dominant-subordinate relationships and, when in groups of four, they formed stable non-linear dominance hierarchies. For either group size, frequency of agonistic behaviour declined over time. Habituation, formation of dominance relationships and spatio-temporal partitioning of space are suggested as possible explanations of this decline. Percentage of initial body weight lost during the experiments varied inversely with social rank. Possible causes of this weight loss are discussed. Social relationships in this study are discussed in light of field observations of male lemming home range distribution. 相似文献