皮肤组织模型中吸收和散射系数对单线态氧发光特性的影响

构建由脂肪乳剂和墨水组成的皮肤组织模型,定量研究皮肤组织模型的吸收系数μa和散射系数μs对光敏化单线态氧(singlet oxygen,~1O_2)发光特性的影响。利用~1O_2发光检测系统测量含光敏剂四硫磺基酞菁氯化铝的皮肤组织模型分别在中心波长为1 230,1 270和1 310 nm处的时间分辨发光光谱,对扣除背景信号后的时间分辨~1O_2发光光谱进行积分和拟合,获得~1O_2发光积分强度以及激发三重态寿命τ_T和~1O_2寿命τ_D。结果表明在皮肤组织模型中,~1O_2发光积分强度随着μ_a和μ_s的增大而减小,μ_a对τ_T和τ_D没有影响。τ_T随着μs的增加而增加,τ_D随μ_s的增加先骤降而后缓慢上升。当μ_a1.5 mm~(-1)和μ_s32 cm~(-1)时,~1O_2发光积分强度和τ_T、τ_D均趋于稳定,其中τ_T和τ_D分别为3.4±0.6μs和3.3±0.7μs。     

The effect of different solvents on the ATP/ADP content and growth properties of HeLa cells

Testing of the effects of xenobiotics in cultured cells often requires the use of organic solvents to effect suspension of the test agents in cell culture media. However, the toxic effects of the solvents themselves may introduce artifacts, which obscure interpretation of the experimental results. In this article, the toxicity of different solvents commonly used for solvation of a variety of xenobiotic agents was studied. We show that ethanol, acetone, isooctane, methanol, and hexane were considerably less toxic than the more commonly used solvent, DMSO, when ATP content and growth rates of HeLa cells exposed to these solvents was measured. © 1998 John Wiley & Sons, Inc. J Biochem Toxicol 13: 11–15, 1999     

Effects of isoflurane on measurements of delayed lumininescence in Acetabularia acetabulum.

The volatile halogenated methyl ethyl ether, isoflurane, used as an anaesthetic, inhibits actin-based dynamics directly or indirectly in animal cells. In plant cells, most intracellular movements are related to actin pathways. We have used isoflurane in a unicellular alga, Acetabularia acetabulum, to test the dynamics of choloroplast organization. By measuring the delayed luminescence, we found that isoflurane worked efficiently in the unicellular organism and showed dose- and time-course-dependent actin-inhibition patterns. When A. acetabulum was treated with saturated solutions of isoflurane in artificial seawater (defined as 100% isoflurane) for 3 or 6 min, the delayed luminescence (DL) was decreased and was never recovered. In contrast, if treated with 75% diluted isoflurane, the DL was firstly inhibited and then recovered several hours later, and if treated with 50% diluted isoflurane, the change of DL was small. Our work proved that isoflurane can affect actin-related pathways in both animals and plants.     

The role of the nicotinamide and adenine subsites in the negative co-operativity of coenzyme binding to glyceraldehyde-3-phosphate dehydrogenase.

The interaction of 3-aminopyridine-adenine dinucleotide, an NAD ⁺ 2 analogue which is fluorescent at the pyridine end of the molecule, with rabbit muscle glyceraldehyde-3-phosphate dehydrogenase was investigated. The fluorescence properties of the AAD⁺ molecule were used to monitor the nicotinamide subsites ou the GPDHase tetramer, the fluorescent aminopyridine moiety of the molecule serving as an intrinsic probe. Although the binding of AAD⁺ wag found to be negatively co-operative, no conformational changes induced at the nicotinamide subsite upon coenzyme binding were found to be transmitted to neighboring subunits. These findings, in conjunction with our earlier findings and with the observation that different NAD⁺ analogues which differ in the chemistry of the pyridine moiety bind with different extents of co-operativity, enable us to offer specific roles for the nicotinamide and the adenine subsites in generating the negative co-operativity.It is suggested that the structure of the pyridine moiety of the coenzyme controls the mode of binding of the pyridine moiety to the nicotinamide subsite. This, in turn, controls the orientation of the adenine moiety with respect to its subsite, thereby determining the mode of the interactions between the adenine and its binding domain. As the propagation of conformational changes caused by these interactions to neighboring subunits is believed to be the cause of the negative co-operativity exhibited by this enzyme towards coenzyme binding, the structure of the pyridine moiety controls this phenomenon.     

盐胁迫下豌豆幼苗的超弱发光

通过钠盐对豌豆 (pisumsativum)萌发时超弱发光影响的比较研究表明 ,在等渗条件下豌豆幼苗受激发光强度顺序为Na2 CO3 >NaCl>Na2 SO4 ;Na2 CO3 盐胁迫对植物的伤害程度高于其他盐类 ;多盐比单盐存在时的毒害小 ,受激发光作用降低。利用超弱发光方法 ,可以分析盐害对植物的作用 ,进一步搞清胁迫条件下植物生理反应的变化规律。     

Characterization of hydrogen peroxide production by Duox in bronchial epithelial cells exposed to Pseudomonas aeruginosa

Hydrogen peroxide production by the NADPH oxidase Duox1 occurs during activation of respiratory epithelial cells stimulated by purified bacterial ligands, such as lipopolysaccharide. Here, we characterize Duox activation using intact bacterial cells of several airway pathogens. We found that only Pseudomonas aeruginosa, not Burkholderia cepacia or Staphylococcus aureus, triggers H₂O₂ production in bronchial epithelial cells in a calcium-dependent but predominantly ATP-independent manner. Moreover, by comparing mutant Pseudomonas strains, we identify several virulence factors that participate in Duox activation, including the type-three secretion system. These data provide insight on Duox activation by mechanisms unique to P. aeruginosa.     

Rare earth complexation with 1,3,5-trideoxy-1,3,5-tris(2-hydroxybenzyl)amino-cis-inositol

The protonation constants of 1,3,5-trideoxy-1,3,5-tris(2-hydroxyl-benzyl)amino-cis-inositol (thci) in I = 1 M (NaClO₄) were determined to be: pK_a1 5.96 ± 0.03, pK_a2 7.21 ± 0.01, pK_a3 8.32 ± 0.07, pK_a4 8.95 ± 0.06. The solvent extraction studies were consistent with the formation of the Ln(thci)³⁺ and complexes. The log of the stability constants (log β₁ and log β₂) at 25 °C in 1 M (NaClO₄) at pH 4 for formation of these complexes are reported. Laser luminescence measurements of the ⁷F₀-⁵D₀ transition of Eu(III) complexed by thci indicated two species. The shifts in the peaks relative to that of Eu(aq)³⁺ were comparable to the values reported for other complexes of Eu(III) with organic ligands, but the intensities were greater. Luminescence lifetime measurements of the fluorescence spectra indicated that the complex has 5 inner sphere water molecules bound to the Eu(III) cation at pH 6.71-8.52. This was consistent with bidentate chelation of Eu(III) with each thci molecule. gaussian view energy calculations indicated bonding for M(III) to the amino and hydroxyl groups of the cyclohexanetriol and (2-hydroxybenzyl)amino moieties in the Ln(thci)³⁺ complex.     

Sensitivity and stability of optically stimulated luminescence dosimeters with filled deep electron/hole traps under pre-irradiation and bleaching conditions

PurposeWe aimed to evaluate the characteristics of optically stimulated luminescence dosimeters (OSLDs) with fully filled deep electron/hole traps, and determine the optimal bleaching conditions for these OSLDs to minimize the changes in dose sensitivity or linearity according to the accumulated dose.MethodsInLight nanoDots were used as OSLDs. The OSLDs were first pre-irradiated at a dose greater than 5 kGy to fill the deep electron and hole traps, and then bleached (OSLD_full). OSLD_full characteristics were investigated in terms of the full bleaching, fading, regeneration of luminescence, dose linearity, and dose sensitivity with various bleaching conditions. For comparison, OSLDs with un-filled deep electron/hole traps (OSLD_empty) were investigated in the same manner.ResultsThe fading for OSLD_full exhibited stable signals after 10 min, for 1 and 10 Gy. The mean supra-linear index values for OSLD_full were 1.001 ± 0.001 for doses from 2 to 10 Gy. Small variations in dose sensitivity were obtained for OSLD_full within standard deviations of 0.85% and 0.71%, whereas those of OSLD_empty decreased by 2.3% and 4.2% per 10 Gy for unfiltered and filtered bleaching devices, respectively.ConclusionsUnder the bleaching conditions determined in this study, clinical dosimetry with OSLD_full is highly stable, minimizing the changes in dose sensitivity or linearity for the clinical dose.     

Superoxide anion, the main species of ROS in the development of ARDS induced by oleic acid

It is believed that reactive oxygen species (ROS) play a very important role in the pathogenesis of acute respiratory distress syndrome (ARDS), but the mechanism has not been so clear, owing to the absence of direct measurable (experimental) data. In majority of the medical studies on free radicals, the analysis of ROS has generally been done by the way of measuring their secondary and breakdown products. In our study, we used electron spin resonance (ESR), a sensitive and accurate technique to detect ROS directly and also used some other sensitive techniques including ultra-weak luminescence and chemical luminescence to identify the species and relative amount of ROS. Furthermore, superoxide dismutase (SOD) was pre-administrated in ARDS rats to verify the results from the above studies and explore the possibility of the clinical application of SOD in ARDS. The spectra of ESR showed that the concentration of ROS increased at 10 min and reached a summit at 30 min after injection of oleic acid (OA), then dropped gradually. The scavenging effects of different scavenging agents on ROS by the analysis of ultra-weak luminescence proved that superoxide anion was the main species of ROS in the development of OA-induced ARDS. Moreover, the results of quantified measure of superoxide anion by chemical luminescence also showed the accordant tendency exhibited in ESR measurement. The pre-treatment of SOD might distinctly inhibit the production of superoxide anion, obviously improve the blood gas status, lung wet/dry ratio and lung/body ratio in ARDS rats. It is suggested that ROS may play a key role in the initiation phase of ARDS, while superoxide anion may be a leading actor in this process and SOD could effectively protect rats from ARDS. These results may provide helpful information for the treatment and prevention of ARDS.     

Measurement of photosynthetic oxygen evolution with a new type of oxygen sensor

We measured the light response curve of photosynthetic oxygen evolution by illuminating a leaf disc in an air-tight windowed chamber. Oxygen production was measured by monitoring the quenching of luminescence of an organometallic ruthenium compound. A photodiode based chlorophyll a fluorometer was used to measure the luminescence intensity. Oxygen evolution measurements with a traditional oxygen electrode gave the same numerical values at different light intensities when the same leaf disk was tested. The quality of the measurement signal of the new method was found to be similar to that obtained with the oxygen electrode method. The new luminescence based system is more stable against electrical disturbances than an oxygen electrode, its response to oxygen pressure changes is very rapid, and the new method allows the same basic equipment to be used for chlorophyll fluorescence and oxygen measurements.