Acidic retinoids synergize with vitamin A to enhance retinol uptake and STRA6, LRAT, and CYP26B1 expression in neonatal lung

Vitamin A (VA) is essential for fetal lung development and postnatal lung maturation. VA is stored mainly as retinyl esters (REs), which may be mobilized for production of retinoic acid (RA). This study was designed 1) to evaluate several acidic retinoids for their potential to increase RE in the lungs of VA-supplemented neonatal rats, and 2) to determine the expression of retinoid homeostatic genes related to retinol uptake, esterification, and catabolism as possible mechanisms. When neonatal rats were treated with VA combined with any one of several acidic retinoids (RA, 9-cis-RA, or Am580, a stable analog of RA), lung RE increased ∼5–7 times more than after an equal amount of VA alone. Retinol uptake and esterification during the period of absorption correlated with increased expression of both STRA6 (retinol-binding protein receptor) and LRAT (retinol esterification), while a reduction in RE after 12 h in Am580-treated, VA-supplemented rats correlated with a strong and persistent increase in CYP26B1 (RA hydroxylase). We conclude that neonatal lung RE can be increased synergistically by VA combined with both natural and synthetic acidic retinoids, concomitant with induction of the dyad of STRA6 and LRAT. However, the pronounced and prolonged induction of CYP26B1 by Am580 may counteract lung RE accumulation after the absorption process is completed.     

Polymerization study of o-Si(OH)4 and complexation with Am(III), Eu(III) and Cm(III)

The stability constants of Am⁺³, Cm³⁺ and Eu³⁺ with ortho silicate, were measured at pH 3.50 and in ionic strengths of 0.20-1.00 M (NaClO₄) by the solvent extraction method. The Am⁺³, Cm³⁺ and Eu³⁺ forms 1:1 complex with ortho silicate ion at pH 3.60 with the stability constant (log β₁) value of 8.02 ± 0.10, 7.78 ± 0.08 and 7.81 ± 0.11, respectively. The stability of these metal ions decrease with increased ionic strength from 0.20 to 1.00 M (NaClO₄) for silicic acid concentrations of 0.002-0.020 M. Increasing silicic acid concentration above 0.02 M increased the amount of M³⁺ extracted into the organic phase, contrary to the trend usually observed for increased ligand concentration in solvent extraction. This reversed trend is likely due to the extraction of cationic species of silicic acid by HDEHP. Aging time (60-300 min) had no effect on the stability constant of these metal ions for 0.002-0.020 M silicic acid at pH 3.50 and I = 0.20 M (NaClO₄).The fraction of polymeric silicic acid present in solutions of 0.20-4.50 M NaClO₄ solutions at pH 3.0-10.0, T = 0-60 °C and aging time = 5-300 min was measured for determination of the silicomolybdate reaction to ascertain the proper conditions to study metal-silicate complexation.     

国产牡竹属野龙竹和版纳甜龙竹的订正

通过对模式标本和原始文献的研究,确认<中国植物志>、、<云南植物志>、<中国竹类植物图志>、<云南树木图志>、<中国竹类图志>等重要专著中广泛使用的版纳甜龙竹学名Dendrocdanus hamittonii Nees et Arn.为错误鉴定,其正确学名为D.parishii Munro;野龙竹(D.semiscandens Hsueh et D.Z.Li)为D.ham iltonii Nees et Arn.的异名.     

气候生态因子与皖南花母猪繁殖力关系的研究

通过最小二乘模型分析了 113头不同Am基因型的皖南花母猪在不同气候条件下 6 70胎次的繁殖力指标 ,以探索气候生态因子及血清蛋白 (酶 )多态性对母猪繁殖力的影响 .结果表明 ,母猪的繁殖性能随着气候条件的变化呈现出有规律的变化趋势 ,7～ 9月高温剌激对母猪繁殖力有较大的危害 ,并出现了显著差异 (P <0 .0 5 ) .不同淀粉酶类型的皖南花母猪繁殖性能存在一定差异 ,其中AmAB型母猪繁殖性能较好 (窝产仔数、产活仔数和断奶头数分别达到 12 .2 8、11.6 1和 11.2 3头 ) ,AmBB和AmBC型母猪相应指标较差 ,但不同Am型母猪的繁殖性能差异均不显著 (P >0 .0 5 ) ,Am型与分娩季节之间的互作效应对母猪繁殖性能的影响显著 (P <0 .0 5 ) .同时 ,窝产仔数、产活仔数、断奶头数等产仔性能与月平均气温和日照率均存在着较强的负相关 ,相关系数都在 0 .6 4 97以上 ,均达到显著或极显著水平 .     

The influence of phospholipid polar groups on gramicidin channels

The influence of well-defined changes in the polar part of phospholipid molecules on the properties of black lipid membranes was studied using a series of phospholipids with identical hydrocarbon chains, but systematically changed polar groups. The hydrocarbon tails of the lipids under study were composed of 1,2-dipentadecylmethylidene glycerol. The polar parts differed in the degree of $\text{N-}\text{methylation}$ and comprised phosphocholine, $\text{-N,N-}\text{dimethylethanolamine}$, $\text{-N-}\text{methylethanolamine}$ and ethanolamine. Stable black lipid membranes could be formed with the solvents octane, decane, dodecane, tetradecane and hexadecane. The properties of gramicidin-induced single ionic channels changed systematically in membranes from the phosphatidylcholine to the phosphatidylethanolamine analogue, as indicated by an increase in the amplitude A of the unit conductance step and a decrease in the average channel life-time or duration τ. The series of τ-values was opposite to that expected from hydrocarbon thickness (specific capacitance). It is suggested that the surface tension γ is a relevant parameter for the prediction of τ-values.     

Plutonium,241Am,90sr,and137cs concentrations in some antarctic matrices

A radioecological survey in Antarctica shows that the^239+240Pu,²³⁸Pu,²⁴¹Am,⁹⁰Sr, and¹³⁷Cs activities were detectable in nearly all the samples. The activity level of^239+240Pu,²⁴¹Am, and¹³⁷Cs in antarctic sediments was about 5–20 times lower than in the northern Adriatic Sea sediments, but the²³⁸Pu activities were relatively high. It was interesting to note that the⁹⁰Sr concentrations in all the sediments tended to be low, which could be the result of the easier exchangeable behavior of⁹⁰Sr in water. High concentrations were detected in mosses and lichens and their activity levels were comparable to those in central Italy. The radionuclide ratio analyses show that the major part of^239+240Pu,²⁴¹Am,⁹⁰Sr, and¹³⁷Cs was a result of nuclear weapon tests. The higher²⁴¹Am/^239+240Pu ratio was observed and it could perhaps be the result of fallout of nuclear weapon tests prior to 1962. The²³⁸Pu/^239+240Pu ratio in the antarctic matrices was about seven times higher than in the Northern hemisphere and it could be inferred that the major part of²³⁸Pu was originating from the SNAP-9A satellite accident.