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101.
102.
Villalba MM Litchfield VJ Smith RB Franklin AM Livingstone C Davis J 《Journal of biochemical and biophysical methods》2007,70(5):797-802
Quinones are well established as key players in the production of reactive oxygen species within cellular environments. Many factors govern their cytotoxicity but most studies have been restricted to a few, core, derivatives. A new strategy for the in situ production of quinone derivatives has been developed such that libraries of diverse functionality can be rapidly created without recourse to extensive synthetic procedures. The approach relies upon nucleophilic addition by reduced thiol derivatives to the quinone core within a pre-culture assay mixture and provides a generic strategy that exploits the large reservoir of commercial thiols currently available. A readily accessible chromatographic method has been developed that allows the derivatisation process to be easily monitored and the purity of the resulting one pot preparation to be assessed. The viability of the combinatorial approach has been fully validated through comparison with a range of quinone-S-conjugates prepared using conventional bench synthesis. The latter have been fully characterised. 相似文献
103.
Synthesis of reference standards is needed to determine the presence and function of steroid glucuronides in the brain or other tissues, because commercial sources of steroid glucuronide standards are limited or unavailable. In the present study porcine, rat, and bovine liver microsomes were tested to evaluate their ability to glucuronidate eight neurosteroids and neuroactive steroids of various types: dehydroepiandrosterone, pregnenolone, isopregnanolone, 5alpha-tetrahydrodeoxycorticosterone, corticosterone, cortisol, beta-estradiol, and testosterone. In general, the glucuronidation efficiency of rat liver was rather poor compared with that of bovine and porcine liver microsomes. Since porcine liver apparently has a relatively large amount of dehydrogenase, its microsomes also produced dehydrogenated steroids and their glucuronides, as well as various regioisomers in which the site of glucuronidation varied. In contrast, bovine liver microsomes produced mainly a single major glucuronidation product and few dehydrogenation products and gave the best overall yield for two-third of the steroids tested. The enzymatic synthesis of five glucuronides of four steroids was carried out and the conditions, purification, and analytical methods for the glucuronidation products were optimized. The steroid glucuronides synthesized were characterized by nuclear magnetic resonance spectroscopy (NMR) and liquid chromatography-mass spectrometry (LC-MS). The stereochemically pure steroid glucuronide conjugates were recovered in milligram amounts (yield 10-78%) and good purity (>85-90%), which is sufficient for LC-MS/MS method development and analyses of steroid glucuronides in biological matrices such as brain, urine, or plasma. 相似文献
104.
The present study was conducted to characterize the binding of neurotransmitter receptors (dopamine D(2), serotonin 5-HT(2), histamine H(1), adrenaline alpha(1) and muscarine M(l) receptors) in the rat's brain after the oral administration of haloperidol, risperidone, and olanzapine. Haloperidol at 1 and 3 mg/kg displayed significant activity to bind the D(2) receptor (increase in the Kd value for [(3)H]raclopride binding) in the corpus striatum with little change in the activity toward the 5-HT(2) receptor (binding parameters for [(3)H]ketanserin). In contrast, risperidone (0.1-3 mg/kg) showed roughly 30 times more affinity for the 5-HT(2) receptor than D(2) receptor. Also, olanzapine (1-10 mg/kg) was most active toward the H(1) receptor in the cerebral cortex, corpus striatum, and hippocampus, was less active in binding 5-HT(2) and D(2) receptors, and showed the least affinity for alpha(1) and M(1) receptors. In conclusion, haloperidol and risperidone administered orally selectively bind D(2) and 5-HT(2) receptors, respectively, in the rat brain, while olanzapine binds H(1), 5-HT(2), and D(2) receptors more than alpha(1) and M(1) receptors. 相似文献
105.
Sayaka Hori Hideaki Takeuchi Takeo Kubo 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(8):825-833
We previously studied a conditioning paradigm to associate the proboscis extension reflex (PER) with monochromatic light (conditioned
stimulus; CS) in harnessed honeybees. Here, we established a novel conditioning paradigm to associate the PER with a motion
cue generated using graphics interchange format (GIF) animations with a speed of 12 mm/s speed and a frame rate of 25 Hz as
the CS, which were projected onto a screen consisting of a translucent circular cone that largely covered the visual field
of the harnessed bee using two liquid crystal projectors. The acquisition rate reached a plateau at approximately 40% after
seven trials, indicating that the bees were successfully conditioned with the motion cue. We demonstrated four properties
of the conditioning paradigm. First, the acquisition rate was enhanced by antennae deprivation, suggesting that sensory input
from the antennae interferes with the visual associative learning. Second, bees conditioned with a backward-direction motion
cue did not respond to the forward-direction, suggesting that bees can discriminate the two directions in this paradigm. Third,
the bees can retain memory for motion cue direction for 48 h. Finally, the acquisition rate did not differ significantly between
foragers and nurse bees.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
106.
在液体培养基条件下对中国产乌毛蕨(Blechnum orientaleL.)配子体发育进行了观察。结果表明:乌毛蕨的孢子为两面体型,两侧对称,极面观为椭圆形,赤道面观为半圆形或豆形,周壁具脊状褶皱;孢子萌发为书带蕨型;原叶体发育为三叉蕨型,成熟原叶体为对称的心脏形。经比较分析,蕨类植物孢子繁殖时采用混合土培养较适宜;液体培养基和混合土在研究蕨类植物配子体发育时同样具有可行性。孢子形态和配子体发育的观察结果表明,乌毛蕨是蕨类植物中较进化的种类;乌毛蕨科与鳞毛蕨科亲缘关系较近。 相似文献
107.
Makoto Ogura Abraham D. Abernethy Ryan D. Blissett Karriann Ruggiero Sovanda Som J. Max Goodson Ralph Kent Apostolos G. Doukas Nikolaos S. Soukos 《World journal of microbiology & biotechnology》2007,23(11):1637-1646
Photomechanical waves (PW), the product of an intense light beam interaction with a target material, enhance molecular delivery
across biological membranes and skin. The ability to deliver methylene blue (MB), a fluorescent probe and photosensitizer,
into bacterial biofilms was demonstrated by applying PW on saliva-derived multi-species biofilms that were developed on agar
surfaces in 24-well plates. PW were generated with a Q-switched Nd:YAG laser and were directed into the biofilms in the presence
of 25 μg/ml MB. The biofilms were then irradiated with red light at 665 nm. After illumination, adherent bacteria were scraped
and spread over the surface of blood agar plates. Survival fractions were calculated by counting bacterial colonies. Microbial
analysis was performed via a colony lift method and a DNA checkerboard assay using whole genomic probes to 40 oral microorganisms.
Visual analysis by confocal scanning laser microscopy demonstrated that the application of PW enhanced the penetration depth
of MB in biofilms. Exposure to MB, PW and light led to a significant reduction of the mean levels of log10 CFU counts compared with the group that received MB and light (P = 0.006). The DNA checkerboard assay showed some benefit from PW-assisted phototargeting in 25 biofilm microorganisms relative
to phototreatment alone. Our data provide a basis for further exploration and optimization of PW parameters for complete eradication
of microorganisms in oral microcosm biofilms. 相似文献
108.
Somatic embryogenesis (SE) is expected to play an important role in increasing productivity, sustainability, and uniformity
of future US forests. For commercial use, SE technology must work with a variety of genetically diverse trees. Initiation
in loblolly pine (Pinus taeda L.), the main commercial US forest species, is often recalcitrant for desirable genotypes. Liquid initiation medium with
no or low gelling agent or placement of the explant on gelled medium followed later by a liquid medium overlay during the
initiation process increased initiation for loblolly pine and Norway spruce (Picea abies). Loblolly pine liquid medium required reduction of NAA from 2 mg/l in gelled medium to 0.3 mg/l in liquid medium. Once the
NAA concentration was adjusted, loblolly pine initiation occurred in liquid medium with fully immersed megagametophytes, explants
supported at the liquid medium surface, or on gelled medium overlaid with liquid medium. Liquid overlays (0.25 ml) consisting
of medium with NAA reduced to 0.3 mg/l, 9 mg/l ABA and no gelling agent applied to explants on 2 ml of gelled medium provided
excellent initiation results. Greatest initiation percentages occurred when the liquid overlay was applied 14 days after placement
of the megagametophyte on gelled medium. Initiation increases ranged from +8.5% with high-value cross-pollinated seed sources
to +6.5 to +9.9% with open-pollinated and often recalcitrant seed sources. Liquid medium addition allows rapid replenishment
of nutrients and adjustment or change of pH, hormones, or other parameters without disturbing the tissue. 相似文献
109.
This study investigated the pharmacokinetic properties of crocin following oral administration in rats. After a single oral dose, crocin was undetected while crocetin, a metabolite of crocin, was found in plasma at low concentrations. Simultaneously, crocin was largely present in feces and intestinal contents within 24h. After repeated oral doses for 6 days, crocin remained undetected in plasma and plasma crocetin concentrations were comparable to the corresponding data obtained after the single oral dose. Furthermore, the absorption characteristics of crocin were evaluated in situ using an intestinal recirculation perfusion method. During recirculation, crocin was undetected and low concentrations of crocetin were detected in plasma. The concentrations of crocin in the perfusate were reduced through different intestinal segments, and the quantities of drug lost were greater throughout the colon. These results indicate that (1) orally administered crocin is not absorbed either after a single dose or repeated doses, (2) crocin is excreted largely through the intestinal tract following oral administration, (3) plasma crocetin concentrations do not tend to accumulate with repeated oral doses of crocin, and (4) the intestinal tract serves as an important site for crocin hydrolysis. 相似文献
110.
Alma Hortensia Serafín Muoz Kazimierz Wrobel J. Felix Gutierrez Corona Katarzyna Wrobel 《Mycological Research》2007,111(5):626-632
The effect of two inorganic selenium forms has been investigated in the mycelia of Pleurotus ostreatus exposed to cadmium and silver salts in the shaken cultures. The degree of toxicity was assessed by the determination of malondialdehyde (MDA; a common biomarker of lipid peroxidation). The mycelia were exposed to one element form (up to 5 mg l−1) and also to the following combinations: cadmium(II) + selenium(IV); cadmium(II) + selenium(VI); silver(I) + selenium(IV); silver(I) + selenium(VI). The concentrations of cadmium, silver, selenium, and MDA were assessed in the mixed cytosol and cell membrane fractions (CCM). A positive correlation between MDA and cadmium was found in the CCM (β = 0.7775, P = 0.0001), whereas the effect of silver was less significant (β = 0.4642, P = 0.039). These results indicate that silver(I) and cadmium(II) have different capacities to induce lipid peroxidation in P. ostreatus. The protective role of selenium against metal-induced oxidative damage was found to be dependent on the oxidation state of the element form in the growth medium. The strongest beneficial effect was observed in mycelia exposed to cadmium(II) + selenium(IV) (inverse correlation between MDA and selenium in the CCM: β = −0.7129, P = 0.009) and it has been ascribed to a lower incorporation of the toxic metal and/or to possible intracellular interaction between selenium and cadmium. Under exposure to silver(I), the protective effect of selenium(IV) was less noticeable (correlation between MDA and selenium in the CCM; β = −0.6068, P = 0.036); in the presence of selenium(VI), no beneficial effect was observed. 相似文献