Behaviour of methylmethacrylate-acrylonitrile random copolymers in dilute solution

Studies on the dilute solution properties of methylmethacrylate-acrylonitrile random copolymers of three different compositions, 0.236, 0.5 and 0.74 mole fraction (m.f.) of acrylonitrile (AN) designated as MAa, MAb and MAc, respectively, have been made in good solvents and theta solvents. MAa has been studied in benzene (Bz) and ethylacetate (EAc). MAb in acetonitrile (MeCN), dimethyl sulphoxide (DMSO) and a binary solvent mixture of Bz and dimentyl formamide (DMF) in the volume ratio 6.5:1 designated as BM1 and MAc in MeCN, DMSO and Bz + DMF in the volume ratio 1.667:1 designated as BM2. The Mark-Houwink exponent ‘a’ reveals that Bz is a theta solvent for MAa at 20°C. For MAb and MAc, BM1 and BM2, respectively have ‘a’ values of 0.5 at all three temperatures studied (30°, 40° and 50°C). It is not clear whether they represent theta states or preferential adsorption plays a role complicating the behaviour in solution. The values of A2 are very low in MeCN considering that it is a very good solvent for the copolymer, ‘a’ values for MAb and MAc being 0.75 and 0.7, respectively.

黑麂和费氏麂四种卫星DNA的克隆特征和染色体定位

近年来,分子细胞遗传学研究已基本证实了染色体的串联融合(端粒一着丝粒融合)是麂属动物核型演化的主要重排方式.尽管染色体串联融合的分子机制还不清楚,但通过染色体的非同源重组,着丝粒区域的卫星DNA被认为可能介导了染色体的融合.以前的研究发现在赤麂和小麂染色体的大部分假定的串联融合位点处存在着非随机分布的卫星DNA.然而在麂属的其他物种中,这些卫星DNA的组成以及在基因组中的分布情况尚未被研究.本研究从黑麂和费氏麂基因组中成功地克隆了4种卫星DNA (BMC5、BM700、BM1.1k和FM700),并分析了这些卫星克隆的特征以及在小麂、黑麂、贡山麂和费氏麂染色体上的定位情况.结果表明,卫星Ⅰ和Ⅱ DNA (BMC5,BM700和FM700)的信号除了分布在这些麂属动物染色体的着丝粒区域外,也间隔地分布在这些物种的染色体臂上.其研究结果为黑麂、费氏麂和贡山麂的染色体核型也是从一个2n=70的共同祖先核型通过一系列的串联融合进化而来的假说提供了直接的证据.

麂属动物以及六带犰狳DNA重复序列家族的克隆、序列分析和染色体定位

1．黑麂和费氏麂卫星DNA的克隆、序列分析和染色体定位 麂属动物在很短的时间内经历了快速的物种辐射，并且种间染色体数目存在巨大差异，是研究动物核型进化和物种起源的理想模型。近二十年来的分子细胞遗传学研究已基本上证实染色体串联融合(端粒－着丝粒融合)是麂属动物核型演化的主要染色体重排方式。尽管染色体串联融合的分子机制仍不清楚，但研究提示着丝粒区域的卫星DNA可能介导染色体的非同源重组。因此，着丝粒卫星DNA的克隆、分析序列以及染色体定位研究不仅有助于阐明麂属染色体核型演化规律，还可能揭示染色体串联融合的分子机制。迄今为止，上述研究工作已经在赤麂、小麂和小麂台湾亚种开展过。但是，尚无有关黑麂、费氏麂和贡山麂卫星 DNA 克隆、序列分析以及染色体定位研究的报道。 在本研究中，我成功地克隆了黑麂的卫星DNA I、II和IV，分别命名为BMC5、BM700和BM1.1k，并且从费氏麂中克隆了卫星DNA II，命名为FM700。对这些卫星DNA克隆进行序列分析，并将这些克隆探针分别与黑麂、费氏麂、贡山麂和小麂的染色体杂交。研究结果表明： 1)黑麂的卫星DNA I(BMC5)与小麂卫星DNA I(C5)序列高度相似，并且在小麂、黑麂、费氏麂和贡山麂染色体上的大部分串联融合位点处均有分布，因此卫星DNA I可能代表着染色体发生串联融合后保存下来，来源于麂属动物祖先染色体着丝粒的一种卫星DNA。卫星DNA I在这四种麂属动物染色体上的分布也表明黑麂、费氏麂和贡山麂与赤麂的核型演化过程相似，很可能从一个2n ＝ 70的共同祖先通过一系列的串联易位进化而来。 2) 将卫星DNA II（BM700和FM700）克隆探针分别杂交到黑麂和费氏麂的染色体上，只检测到几对间隔分布的信号。这提示在核型进化过程中不同卫星DNA间可能发生了广泛的重组，从而导致卫星DNA II大量丢失。大部分重组断裂位点可能位于卫星DNA I 与卫星DNA II之间，或者在卫星DNA II 区域内。 2．六带犰狳重复序列家族的克隆、序列分析和染色体定位 六带犰狳属于犰狳科、贫齿目，是六带犰狳属中唯一的一个代表物种。系统发育研究认为贫齿目与非洲兽总目是有胎盘哺乳动物中最原始的两个类群。C显带结果揭示六带犰狳30%的基因组是由组成性异染色质构成的，并且C带分布的位置也较复杂，提示在六带犰狳基因组中存在多种重复序列元件。 为了研究六带犰狳异染色质的组成，我从六带犰狳的基因组中克隆了七种位点特异性的重复序列。根据测序结果以及它们在染色体上的分布，将这些重复序列分为五个重复序列家族。其中AMD-EcoRI 837与AMD-BglII 811的序列相似，都是由大小约116 bp的单位组成，分布在大多数染色体的着丝粒区域，同时在一些染色体臂也有分布。AMD-EcoRI 832，AMD-EcoRI 836和AMD-EcoRI 934是特定染色体的重复序列，并且都分布于着丝粒区域。另外，AMD-BglII 634，AMD-EcoRI 731两个克隆都属于长散在分布重复序列(L1)，倾向于分布在G带阳性、富含AT碱基的区域，并且这两种重复序列在染色体上的定位与C带阳性的非着丝粒的异染色质区域很相似。本研究提供了六带犰狳异染色质区域的部分基因组信息，并且这些重复序列家族也可以用于研究六带犰狳及其近缘物种的系统发育关系。

The emigration of the czechoslovak inhabitants in the languaje of the communist propaganda

The contribution is explaining the methods and the forms of the undemocratic regime on the example of the communist propaganda in the field of the emigration. The task of the article is to find out how the communist political elite was looking at the people who illegally left the territory of Czechoslovakia, which means of expression it was taking advantage of the characterizing of the political refugees, which types of the emigrants were standing in the centre of attention of the negative propaganda and in which intensity, the emigrants were presented in the communist press. We assume from the hypothesis that the propaganda language of the communists directed against the emigrants did not change in dependence of the rigidity of the communist regime. So, the emigrants were considered to be the mortal enemies of the regime both in the totalitarian condition in the fifties and in the authoritarian period of the eighties. The text is processed in the form of the contents analysis of the period newspaper articles. The article is divided into four parts. In the first theoretical part, the role of the propaganda in the undemocratic regimes is presented. Subsequently, the reasons of the emigration are explained in the investigated period, the object of the communist propaganda is subsequently presented and ultimately, in the last theoretical part, the language level of the propaganda of the Communist Party is analysed.

Locomotor Virtual Patient Scene

BM1 Locomotor Virtual Patient screenshot

Characterization of B cells in healthy pregnant women from late pregnancy to post-partum: a prospective observational study

BACKGROUND: B cells play a role in pregnancy due to their humoral and regulatory activities. To our knowledge, different maturational stages (from transitional to memory) of circulating B cell subsets have not yet been characterized (cell quantification and phenotype identification) in healthy pregnant women. Thus, the objective of our study was to characterize these subsets (as well as regulatory B cells) from late pregnancy to post-partum and to compare them with the circulating B cells of non-pregnant women. METHODS: In all of the enrolled women, flow cytometry was used to characterize the circulating B cell subsets according to the expression of IgD and CD38 (Bm1-Bm5 classification system). Regulatory B cells were characterized based on the expression of surface antigens (CD24, CD27, and CD38) and the production of IL-10 after lipopolysaccharide stimulation. RESULTS: Compared to the absolute counts of B cells in the non-pregnant women (n = 35), those in the pregnant women (n = 43) were significantly lower (p < 0.05) during the 3rd trimester of pregnancy and on delivery day (immediately after delivery). The percentages of these cells on delivery day and at post-partum were significantly lower than those in the non-pregnant women. In general, the absolute counts and percentages of the majority of the B cell subsets were significantly lower in the 3rd trimester of pregnancy and on delivery day than in the non-pregnant women. However, these counts and percentages did not differ significantly between the post-partum and the non-pregnant women. The most notable exceptions to the above were the percentages of naïve B cells (which were significantly higher in the 3rd trimester and on delivery day than in the non-pregnant women) and of CD24(hi)CD38(hi) regulatory B cells (which were significantly higher in the post-partum than in the non-pregnant women). CONCLUSION: According to our study, the peripheral B cell compartment undergoes quantitative changes during normal late pregnancy and post-partum. Such findings may allow us to better understand immunomodulation during human pregnancy and provide evidence that could aid in the development of new strategies to diagnose and treat pregnancy-associated disturbances. Our findings could also be useful for studies of the mechanisms of maternal responses to vaccination and infection.

Characterization of B cells in healthy pregnant women from late pregnancy to post-partum: a prospective observational study

Abstract BACKGROUND: B cells play a role in pregnancy due to their humoral and regulatory activities. To our knowledge, different maturational stages (from transitional to memory) of circulating B cell subsets have not yet been characterized (cell quantification and phenotype identification) in healthy pregnant women. Thus, the objective of our study was to characterize these subsets (as well as regulatory B cells) from late pregnancy to post-partum and to compare them with the circulating B cells of non-pregnant women. METHODS: In all of the enrolled women, flow cytometry was used to characterize the circulating B cell subsets according to the expression of IgD and CD38 (Bm1-Bm5 classification system). Regulatory B cells were characterized based on the expression of surface antigens (CD24, CD27, and CD38) and the production of IL-10 after lipopolysaccharide stimulation. RESULTS: Compared to the absolute counts of B cells in the non-pregnant women (n = 35), those in the pregnant women (n = 43) were significantly lower (p < 0.05) during the 3rd trimester of pregnancy and on delivery day (immediately after delivery). The percentages of these cells on delivery day and at post-partum were significantly lower than those in the non-pregnant women. In general, the absolute counts and percentages of the majority of the B cell subsets were significantly lower in the 3rd trimester of pregnancy and on delivery day than in the non-pregnant women. However, these counts and percentages did not differ significantly between the post-partum and the non-pregnant women. The most notable exceptions to the above were the percentages of naïve B cells (which were significantly higher in the 3rd trimester and on delivery day than in the non-pregnant women) and of CD24(hi)CD38(hi) regulatory B cells (which were significantly higher in the post-partum than in the non-pregnant women). CONCLUSION: According to our study, the peripheral B cell compartment undergoes quantitative changes during normal late pregnancy and post-partum. Such findings may allow us to better understand immunomodulation during human pregnancy and provide evidence that could aid in the development of new strategies to diagnose and treat pregnancy-associated disturbances. Our findings could also be useful for studies of the mechanisms of maternal responses to vaccination and infection.