共查询到20条相似文献,搜索用时 15 毫秒
1.
Takahashi S Chi XJ Yamaguchi Y Suzuki H Sugaya S Kita K Hiroshima K Yamamori H Ichinose M Suzuki N 《Mutation research》2001,490(2):199-207
Bisphenol A is used as a monomer in the production of polycarbonate plastic products. The widespread use of bisphenol A has raised concerns about its effects in humans. Since there is little information on the mutagenic potential of the chemical, the mutagenicity of bisphenol A was tested using human RSa cells, which has been utilized for identification of novel mutagens. In genomic DNA from cells treated with bisphenol A at concentrations ranging from 1x10(-7) to 1x10(-5)M, base substitution mutations at K-ras codon 12 were detected using PCR and differential dot-blot hybridization with mutant probes. Mutations were also detected using the method of peptide nucleic acid (PNA)-mediated PCR clamping. The latter method enabled us to detect the mutation in bisphenol A-treated cells at a dose (1x10(-8)M) equivalent to that typically found in the environment. Induction of ouabain-resistant (Oua(R)) phenotypic mutation was also found in cells treated with 1x10(-7) and 1x10(-5)M of bisphenol A. The induction of K-ras codon 12 mutations and Oua(R) mutations was suppressed by pretreating RSa cells with human interferon (HuIFN)-alpha prior to bisphenol A treatment. The cells treated with bisphenol A at the concentration of 1x10(-6)M elicited unscheduled DNA synthesis (UDS). These findings suggested that bisphenol A has mutagenicity in RSa cells as well as mutagens that have been tested in these cells, and furthermore, that a combination of the PNA-mediated PCR clamping method with the human RSa cell line may be used as an assay system for screening the mutagenic chemicals at very low doses. 相似文献
2.
The role of arachidonic acid metabolites in norepinephrine (NE)-induced N-acetyltransferase (NAT) activity and melatonin release was examined from 6 h-incubations of rat pineal glands. A cyclooxygenase inhibitor, indomethacin (5×10−8 − 5×10−6 M) was ineffective on melatonin release, in the presence of absence of NE (5×10−6 M) while a lipoxygenase inhibitor, nordihydroguaiaretic acid (5×10−7 −5×10−5 M) had an inhibitory effect. Among the lipoxygenase metabolites, 12-hydroperoxyeicosatetraenoic acid (12-HPETE) and 15-HPETE stimulated both NAT activity and melatonin release in a dose-dependent manner, with a maximal effect occuring at 10−6 M, while 5-HPETE or hydroxy derivatives of these compounds (12-HETE, 15-HETE and 5-HETE) were ineffective. These results indicate that 12-HPETE and 15-HPETE can be involved in NE-induced melatonin release. 相似文献
3.
Effect of prostaglandin F2α on propulsive activity of the isolated segmental colon of the guinea-pig
The effects of prostaglandin F2α (PGF2α) on propulsive activity in segments of isolated colon and on isolated strips of guinea-pig colon were investigated.Using experimental conditions under which spontaneous propulsive activity was negligible, PGF2α (5×10−8×1×10−6M), added to the bathing medium, increased propulsive activity in a concentration dependent manner. This increase of propulsive activity was abolished in the presence of atropine or tetrodotoxin (1×10−7g/ml).The contractions produced by PGF2α(5×10−7 − 1×10−5M) in isolated longitudinal and circular smooth muscle strips of guinea-pig colon were unaffected in the presence of atropine or tetrodotoxin (1×10−7 g/ml).From these results it is concluded that under the conditions employed in this study propulsive activity stimulated by PGF2α may depend on the contractions of both muscle layers and stimulation of the peristalic reflex. 相似文献
4.
Ana Lucía De Paul Andrs Maximiliano Attademo Ruben Walter Carn Marta Soaje Alicia Ins Torres Graciela Alma Jahn María Ester Celis 《Peptides》2009,30(11):2081
The neuropeptide EI (NEI) is derived from proMCH. It activates GnRH neurons, and has been shown to stimulate the LH release following intracerebroventricular administration in several experimental models. The aim of the present paper was to evaluate NEI actions on pituitary hormone secretion and cell morphology in vitro. Pituitary cells from female rats were treated with NEI for a wide range of concentrations (1–400 × 10−8 M) and time periods (1–5 h). The media were collected and LH, FSH, PRL, and GH measured by RIA. The interaction between NEI (1, 10 and 100 × 10−8 M) and GnRH (0.1 and 1 × 10−9 M) was also tested. Pituitary cells were harvested for electron microscopy, and the immunogold immunocytochemistry of LH was assayed after 2 and 4 h of NEI incubation. NEI (100 × 10−8 M) induced a significant LH secretion after 2 h of stimulus, reaching a maximum response 4 h later. A rapid and remarkable LH release was induced by NEI (400 × 10−8 M) 1 h after stimulus, attaining its highest level at 2 h. However, PRL, GH and FSH were not affected. NEI provoked ultrastructural changes in the gonadotrophs, which showed accumulations of LH-immunoreactive granules near the plasma membrane and exocytotic images, while the other populations exhibited no changes. Although NEI (10 × 10−8 M), caused no action when used alone, its co-incubation with GnRH (1 × 10−9 M), promoted a slight but significant increase in LH. These results demonstrate that NEI acts at the pituitary level through a direct action on gonadotrophs, as well as through interaction with GnRH. 相似文献
5.
C. Delarue F. Leboulenger F. Homo-Delarche M. Benyamina I. Lihrmann I. Perroteu H. Vaudry 《Prostaglandins & other lipid mediators》1986,32(1)
The role of prostaglandins (PGs) in the mechanism of action of acetylcholine (ACh) on frog adrenocortical cells has been examined. Administration of a single dose of ACh (5 × 10−5 M) to perifused frog interrenal fragments, for 20 min, stimulated the production of corticosterone, aldosterone, PGE2 and 6-keto-PGF1α. In contrast ACh did not significantly alter TXB2 production. The effect of ACh could be mimicked by muscarine (10−5 M). Conversely, nicotine (10−6 to 10−4 M) was totally inactive. The increase in PG biosynthesis preceded the peak of corticosteroid release. Repeated 20-min pulses of ACh (5 × 10−5 M) or muscarine (10−5 M) given at 130-min intervales induced a desensitization phenomenon. In presence of indomethacin (5 × 10−6 M), the effect of ACh on PG and steroid secretion was totally abolished. In calcium-free medium, the effect of ACh on PG and corticosteroid production was completely blocked. These results indicated that, in the frog, ACh stimulates corticosteroid secretion through a PG-dependent mechanism. 相似文献
6.
The concentrations of PGE, PGF, and 6-keto-PGF1α were increased in rat seminal vesicle tissue following mating activity. Likewise, synthesis of PGE and PGF was stimulated by epinephrine (3 × 10−7to 3 × 10−6 M) in tissues and media from
incubations of intact rat seminal vesicles. The
stimulation was inhibited by phentolamine, an α-adrenoreceptor blocking agent. Carbamylcholine (2 × 10−6 M) and bradykinin (1 × 10−6 M) had no effect on PGE or PGF synthesis, even though both compounds stimulated contractility of the rat seminal vesicle at these concentrations. These data suggest that mating and adrenergic stimulation increase prostaglandin synthesis in] the rat seminal vesicle, probably through an α-adrenergically mediated mechanism. 相似文献
7.
In this study, the hydraulic conductivity (Lp), Me2SO permeability (
Me2SO), and the reflection coefficients (ς) and their activation energies were determined for Metaphase II (MII) mouse oocytes by exposing them to 1.5 M Me2SO at temperatures of 30, 20, 10, 3, 0, and −3°C. These data were then used to calculate the intracellular concentration of Me2SO at given temperatures. Individual oocytes were immobilized using a holding pipette in 5 μl of an isosmotic PBS solution and perfused with precooled or prewarmed 1.5 M Me2SO solutions. Oocyte images were video recorded. The cell volume changes were calculated from the measurement of the diameter of the oocytes, assuming a spherical shape. The initial volume of the oocytes in the isoosmotic solution was considered 100%, and relative changes in the volume of the oocytes after exposure to the Me2SO were plotted against time. Mean (means ± SEM) Lpvalues in the presence of Me2SO (
Me2SOp) at 30, 20, 10, 3, 0, and −3°C were determined to be 1.07 ± 0.03, 0.40 ± 0.02, 0.18 ± 0.01, 7.60 × 10−2± 0.60 × 10−2, 5.29 × 10−2± 0.40 × 10−2, and 3.69 × 10−2± 0.30 × 10−2μm/min/atm, respectively. The
Me2SOvalues were 3.69 × 10−3± 0.3 × 10−3, 1.07 × 10−3± 0.1 × 10−3, 2.75 × 10−4± 0.15 × 10−4, 7.83 × 10−5± 0.50 × 10−5, 5.24 × 10−5± 0.50 × 10−5, and 3.69 × 10−5± 0.40 × 10−5cm/min, respectively. The ς values were 0.70 ± 0.03, 0.77 ± 0.04, 0.81 ± 0.06, 0.91 ± 0.05, 0.97 ± 0.03, and 1 ± 0.04, respectively. The estimated activation energies (Ea) for
Me2SOp,
Me2SO, and ς were 16.39, 23.24, and −1.75 Kcal/mol, respectively. These data may provide the fundamental basis for the development of more optimal cryopreservation protocols for MII mouse oocytes. 相似文献
8.
Prostaglandins (PGs) E1 or F1α (1.4−8.4 × 10−8 M) contracted strips of rabbit aorta and increased the contractions produced by 1−6 × 10−7 M phenylephrine (PE). The addition of the PGs simultaneously with PE or after a low concentration of PE (2 × 10−7 M) significantly increased the PE-induced contractions. However, when the PGs were added after a higher concentration of PE (6 × 10−7 M) an additional increase in the PE-induced contraction was produced with PGF1α but not with PGE1. Isobolic plots of the data obtained from the simultaneous addition of PE and the PGs indicate that both PGs interact with PE in a synergistic or potentiative manner, suggesting that their effects are mediated through different receptor mechanisms. Addition of the PGs after a high dose of PE indicates that there may also be either qualitative or quantitative differences between PGE1 and PGF1α. 相似文献
9.
W. Lippmann 《Prostaglandins & other lipid mediators》1975,10(4):479-491
The effects of various II-deoxyprostaglandin E analogs on the basal and prostaglandin E2 (PGE2)-induced cyclic AMP accumulation in the rat anterior pituitary were studied in vitro. 13-Hydroxy-9-oxoprost-14-ynoic acid at 5 × 10−4M, but not 5 × 10−5M, decreased (45%) the induced accumulation and did not alter the basal accumulation; 15-hydroxy-9-oxoprost-13-ynoic acid at 5 × 10−4M caused less of a decrease (29%) in the induced and also did not alter the basal accumulation. (14Z)-13-Hydroxy-9-oxoprost-14-enoic acid at 5 × 10−4M did not alter the induced and caused a slight increase (5 fold) in the basal accumulation. 7-Oxa-13-prostynoic acid increased slightly the basal accumulation at 5 × 10−5M (2 fold) and 2.33 × 10−4M (6 fold) and did not antagonize the induced accumulation. Thus, the 9-ketoprostynoic acids are effective PGE2 antagonists in this system. 相似文献
10.
W. Lippmann 《Prostaglandins & other lipid mediators》1975,10(3):479-491
The effects of various 11-deoxyprostaglandin E analogs on the basal and prostaglandin E2 (PGE2)-induced cyclic AMP accumulation in the rat anterior pitutiary were studied
. 13-Hydroxy-9-oxoprost-14-ynoic acid at 5 × 10−4M, but not 5 × 10−5M, decreased (45%) the induced accumulation and did not alter the basal accumulation; 15-hydroxy-9-oxoprost-13-ynoic acid at 5 × 10−4M caused less of a decrease (29%) in the induced and also did not alter the basal accumulation. (14Z)-13-Hydroxy-9-oxoprost-14-enoic acid at 5 × 10−4M did not alter the induced and caused a slight increase (5 fold) in the basal accumulation. 7-Oxa-13-prostynoic acid increased slightly the basal accumulation at 5 × 10−5M (2 fold) and 2.33 × 10−4M (6 fold) and did not antagonize the induced accumulation. Thus, the 9-ketoprostynoic acids are effective PGE2 antagonists in this system. 相似文献
11.
A. Swift M. Karmazyn D.F. Horrobin M.S. Manku R.A. Karmali R.O. Morgan A.I. Ally 《Prostaglandins & other lipid mediators》1978,15(4):651-657
IN perfused male rat hearts concentrations of prostaglandins (PGs) E2 and F2α in the range 1 pg/ml to 10 ng/ml (2.8 × 10−12 to 2.8 × 10−8M) consistently caused rhythm irregularities. Higher concentrations had no effect themselves and stabilized rhythm in hearts made unstable by lower concentrations. Copper ions (as the sulphate) at 2 × 10−6M stabilized hearts made unstable by PGs and when present prior to the PGs prevented PG induced disturbances. Chloroquine also reversed PG-induced rhythm changes. 相似文献
12.
Single-cell and DNA fiber autoradiography, cytophotometry and velocity sedimentation in alkaline sucrose gradients were used to analyse DNA replication and nascent replicon maturation in 5-fluorodeoxyuridine (FUdR)-synchronized cells of Pisum sativum. The replicon size was not significantly changed by the protracted FUdR treatment. When the synchronized cells were released from the inhibitor, labeled with [3H]TdR for 30 min, and chased in medium containing 1 × 10−6 M or lower concentrations of cold thymidine, DNA replication stopped after approx. 25% of the genome had replicated, and the nascent strands failed to grow above 9–12 × 106 D single-stranded (ss) DNA. When the cells were chased in medium with 1 × 10−5 M cold thymidine, the DNA content of the labeled cells steadily increased with time and the size of the nascent molecules grew continuously until replicon size was achieved; then they were accumulated at replicon size until the cells arrived in late S or G2. When the FUdR-synchronized cells were chased in medium containing 1 × 10−4 M cold thymidine, the size of the nascent strands increased continuously with time, indicating that some neighbouring nascent replicons were joined as soon as they completed their replication. These observations led us to postulate that in FUdR-synchronized cells the rates of chain elongation, cell progression through the S phase and nascent replicon maturation are controlled by thymidine availability. 相似文献
13.
Fluorescence redistribution after photobleaching (FRAP) was utilized to select a “fast” lateral mobility clone from Kirsten murine sarcoma virus-transformed 3T3 (KMSV-3T3) fibroblasts. The clone, E7G1, demonstrated a lateral mobility for membrane wheat germ agglutinin (WGA) and succinylated concanavalin A (sCon A) receptors of (2.1 ± 1.6) × 10−9 cm2/s and (2.7 ± 2.3) × 10−9 cm2/s, respectively. These mobilities were approximately equivalent to phospholipid mobility (2.8 ± 1.9 × 10−9 cm2/s). The fast mobility phenotype is observed when the cells are unattached and spherical. Upon attachment, the mobility decreases to (0.19 ± 0.19) × 10−10 cm2/s. In addition, the ability of Con A to initiate global modulation was completely lost in spread as well as spherical cells in the E7G1 fast mobility clone. A comparison of F-actin patterns between untransformed Balb/c fibroblasts and the E7G1-transformed line suggests a correlation between well-developed stress fiber assemblies and the ability to induce global modulation. The fast mobility clone was stable for at least 23 passages. 相似文献
14.
Infusions of prostacyclin (PGI2) (3 × 10−10 − 3 × 10−7M) into the coronary circulation of isolated hearts from guinea pigs or rabbits resulted in a concentration-dependent decrease in the coronary perfusion pressure (CPP). There was a slight decrease in left ventricular systolic pressure in the heart of the rabbit, whereas the heart rate remained unchanged. PGE2 was without effect on the heart of the rabbit but was as potent as PGI2 in decreasing the CPP in the guinea pig heart. 6-oxo-PGF1α (up to 3 × 10−6 M) did not affect any of the parameters measured. 相似文献
15.
Experiments have been undertaken to correlate physiological changes, observed in two YC8 cells variants (P and L) and some of their immunological and enzymatic properties. These cell lines show different responses towards antilymphocyte and anti-Moloney sera. Subcellular fractionations have been made. The A fractions (d: 1.14/1.16) have the highest ouabain-inhibited Mg2+-stimulated (Na+-K+)-dependent ATPase and galactosyltransferase activities. Some properties of the latter enzyme have been studied: whereas optima pH and requirements for Mn2+ ions have been found to be the same for both cell line enzymes, on the contrary, different kinetic parameters have been shown with respect to sugar donor (UDP-galactose) on endogeneous or exogeneous (ovomucoid) acceptors. Apparent Km for UDP-galactose is 1.7 × 10−6 M (P-cells) and 3.3 × 10−6 M (L-cells), on endogeneous acceptors, and P-cell V max < L-cell V max; on ovomucoid it is 0.61 × 10−6 M, for both cell lines. These results suggest the presence on L-cells of more endogeneous acceptor sites, the higher affinity of P-cells for UDP-galactose being balanced by less endogeneous acceptor sites for galactose. When ovomucoid is added, galactose transfer on endogeneous acceptor sites of both cells is negligible. Apparent Km for ovomucoid is 8.6 × 10−5 M (P-cells) and 4.3 × 10−5 M (L-cells). These data support the above-mentioned hypothesis: L-cell enzymes would be more rapidly saturated than P-cell enzymes because of the higher number of endogeneous sites on L-cells.This supposed acquired character of L-cells as well as their immunological behaviour could explain the modified properties of L-cells as compared to P-cells. 相似文献
16.
P. E. Lindahl 《Experimental cell research》1973,81(2):413-431
Mg2+, Ca2+ and Mn2+ were found to act as activators of the ATP-dependent surface reaction, leading to head-to-head association in bull spermatozoa. Ca2+ was more efficient than Mg2+, while Zn2+, like Na+ + K+ in combination with Mg2+, seemed to have no such effect. High ionic strength induced head-to-head association, as did higher concentrations of Mg2+ and Ca2+ than those necessary for the activation of ATP, Ca2+ acting in a lower conc. than Mg2+. To this effect was added that of the ATP-dependent reaction when ATP was also present. As activators, Mg2+ and Ca2+ did not potentiate each other; their effects were cumulative when the ions acted together.When the ATP concentration within the range 1 × 10−5 to 8 × 10−5 M was increased stepwise in the presence of 2 × 10−5 M Mg2+ or Ca2+, the association resulting from each single concentration step progressively increased. At low cation concentrations, the increase was about the same for the two cations: at higher concentrations it was much steeper in the presence of Ca2+ than in that of Mg2+. In the latter case, it was not statistically significant above 4 × 10−5 M ATP.Increasing the cation concentration in the range 1 × 10−5 to 4 × 10−5 M in the presence of 2 × 10−5 M ATP produced an immediate high increase in association, which was followed by a lower increase. The optimum concentration ratio for Mg2+:ATP was at least 1:1 and for Ca2+: ATP at least 1.5:1.Oubain, containing enone structure, abolishes association. 相似文献
17.
Although certain prostaglandins have been found to be inhibitory to nerve-evoked salivary flow, little is known of the effects the leukotrienes on salivary secretion. It was the purpose of this investigation to examine the effects of leukotrienes C4 (LTC4) and D4 (LtD4) on salivary secretion in the rat, using methacholine or substance P to induce basal secretion, and to test whether or not the observed effects of these eicosanoids were receptor-mediated by using the leukotriene receptor blocker FPL-55712.Methacholine (3 × 10−4 M), or substance P (1 × 10−6 M) was infused intra-arterially to stimulate secretion and saliva was collected separately from the parotid gland and the submandibular gland of anesthetized rats. LTC4 and LTD4 (each at 1 × 10−9 to 1 × 10−6 M) were found to reduce methacholine- and substance P-induced salivary flow in a dose-related manner. Salivary protein concentration and amylase activity were not significantly altered by the leukotrienes; however, arginine-esterase activity, stimulated by substance P, was increased by both leukotrienes. FPL-55712 (1 × 10−8 M) was shown to reduced the inhibitory effects of LTC4 and LTD4, suggesting the involvement of leukotriene receptors for these agents in their action. 相似文献
18.
Yu-Chi Hsieh Jiun-Ly Chir Hsiu-Han Wu Po-Sheng Chang An-Tai Wu 《Carbohydrate research》2009,344(16):2236-2239
A fluorescent sensor, 5, based upon the sugar-aza-crown ether structure with two anthracenetriazolymethyl groups was prepared and its fluoroionophoric properties toward transition metal ions were investigated. In methanol, the sensor exhibits highly selective recognition of Cu2+ and Hg2+ ions among a series of tested metal ions. The association constant for 5·Cu2+ and 5·Hg2+ in methanol was calculated to be 4.0 × 105 M−1 and 1.1 × 105 M−1, respectively. The detection limits for the sensing of Cu2+ and Hg2+ ions were 1.39 × 10−6 M and 1.39 × 10−5 M, respectively. 相似文献
19.
When a Euglena, in a medium containing ATP, is microinjected with 7 × 10−14 l of 0.02 M EDTA, which binds Ca2+ and Mg2+, flagellar motility stops. Flagellar arrest in Chlamydomonas occurs with the injection of 2 × 10−14 l of 0.02 M EDTA. The injection of similar amounts (7 × 10−14 l in Euglena and 3 × 10−14 l in Chlamydomonas) of 0.02 M EGTA, which preferentially binds Ca2+, did not significantly alter flagellar motility. This suggests that a decrease in the internal Ca2+ concentration in Euglena or Chlamydomonas did not stimulate flagellar beating. Further, flagellar motility decreased when internal Mg2+ was chelated. The microinjection of Zn2+ into these cells caused a decrease in flagellar frequency analogous to the decrease in frequency caused by the injection of Ca2+ and EDTA. The microinjection of 7 × 10−14 l of 0.2 M Mn2+ caused an approx. 1.5-fold increase in Euglena flagellar motility. Chlamydomonas flagella, which cease to beat upon impalement in an Mg2+-free medium, resume a flagellar frequency of 18 Hz when injected with 3 × 10−14 l of 0.2 M Mn2+. In the experiments reported here, Mn2+ acts as an analog of Mg2+. 相似文献
20.
Phrommanich S Suanjit S Upatham S Grams SV Kruatrachue M Pokethitiyook P Korge G Hofmann A 《Microbiological research》2009,164(4):486-492
Quantitative detection of the oil-degrading bacterium Acinetobacter sp. strain MUB1 was performed using the SoilMaster™ DNA Extraction Kit (Epicentre, Madison, Wisconsin) and hybridization probe based real-time PCR. The detection target was the alkane hydroxylase gene (alkM). Standard curve construction showed a linear relation between log values of cell concentrations and real-time PCR threshold cycles over five orders of magnitude between 5.4±3.0×106 and 5.4±3.0×102 CFU ml−1 cell suspension. The detection limit was about 540 CFU ml−1, which was ten times more sensitive than conventional PCR. The quantification of Acinetobacter sp. strain MUB1 cells in soil samples resulted in 46.67%, 82.41%, and 87.59% DNA recovery with a detection limit of 5.4±3.0×104 CFU g−1 dry soil. In this study, a method was developed for the specific, sensitive, and rapid quantification of the Acinetobacter sp. strain MUB1 in soil samples. 相似文献